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Post Info TOPIC: Counting rivets - Mark IV, 1/16 scale
MRG


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Counting rivets - Mark IV, 1/16 scale
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Hello landship enthusiasts,

over the last 2 years I have been visiting this forum every so often and had been asking weird questions about details - the reasons will follow in this documentation: Scratchbuilding a Mark IV in 1/16 scale as precisely as possible, RC-enabled if the tracks allow it.

I had promised to do this report, so I better get started as it is going to be rather detailed and extensive. And there is still much to do. Tell me if I am boring you! yawn

I have been making models since I was a kid, concentrating on 1/32 scale aircraft in my teens. Over the last few years I discovered the 1/16 scale tanks of Heng Long, providing very reasonably priced RC toys which make a good base for more detailing. I started with modifying a Panther G tank, then a T-34 /85. As I am also very interested in history I did a lot of research on the originals - here also to get the details right - and this lead me inevitably to the first tanks of the Great War.

Diving into their history, I am fascinated and have the greatest respect for the early tank crews. And, there being no model kits in "my" scale around, I would have to make one myself.

I bought the Emhar 1/35 scale kit, hoping it would provide something to start on, but I quickly realized that it is merely "similar" to the original, so that just would not do.Collecting as much pictures and data as I could, I started drawing plans, calculating sizes, de-perspectifying photographs with Photoshop...

Making the plans takes up as much time as the actual building does, and I have still more to do - so this report will evolve over time. Hopefully not too long.

So I had to decide on which bit to start on - and chose the "face" of the tank.

To save weight and costs, I decided on hardpaper circuit board as basic material for the "big bits". It is light, rigid and you can glue and solder it - perfect for my means.

So here goes, I started with drilling the basic holes tor the visor lids and the ball bearing for the Lewis gun.

DocMarkIV-001-1.jpg

It is my aim to have as much "working" detail as possible, and as no ready-made hinges are available, here goes the DIY.Hardsoldering various tubes to their bases...

DocMarkIV-002-1.jpg

DocMarkIV-003-1.jpg

..and constructing little helpers to bend the surrounding girders for the "windows"..

DocMarkIV-004-1.jpg

In the front you can see the two already bent girders.

Lids and hinges evolving:

DocMarkIV-005-1.jpg

Where possible, actually riveted or bolted instead of glued.

In the beginning, I thought "it's all flat plates and stuff, easy..." but then you stumble upon bits which are not so, like the protectors for the outer end of the lid hinge axis. More tools had to be devised, thats the "shaper" in the background...

DocMarkIV-006-1.jpg

... and the lids are laid out to see if all fits as planned.

DocMarkIV-007.jpg

Here in the making are the "ratchets" for the lid levers which are inside the cabin, and more detailing going on the lids.

DocMarkIV-008-1.jpg

Both parts of the lid work individually. This was the test setup.

CabMarkIV.jpg

Of course, mistakes happen. I had to take the drivers tower apart again, as the side panels were too long - an error deriving from taking the Emhar kit too much into account. So I had to remake the sides, "shoulders", roof and back plate - with rivets and all. evileye

Next section, the vehicle roof....



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MRG


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The not-quite finished drivers tower after the remake..

DocMarkIV-009.jpg

Next step was the roof construction. In the aftermath, I have no idea why - but I cut out the single panels of which the roof is made, riveted them to the main L-girders, held tothether by the T-shaped ones on top. Just like the original - I just could have used a single board. confuse Here is the exhaust panel with the odd covers - I still have not found out which function they had.

ExhaustPanel-1.jpg

The pyramid-like tower was difficult as the shape was hard discern right - I might have to correct that yet, I noticed that the upper back end is too wide. I had no 0,8 mm brass at that time, so, I took aluminium. Not so nice. Well, it's going to be painted over in the end anyway..

DocMarkIV-011.jpg

The hinges for the tower lid were the first reason to ask questions here at Landships - I just could not find satisfying material on these. But I received great help! Thank you very much again.

DocMarkIV-010.jpg

Opens and closes... This will later be the access to the on/off switch and reset button for the Arduino microcontroller - but more on that at a later point.

DocMarkIV-013.jpg

The grey stuff is were the copper plating had lifted off the board - that's what you get for soldering stuff with too much heat. I had to use some filler to repair that area.

Next was the silencer and exhaust.

Here is the silencer, the ends are waiting to be soldered in. Plan is to have a smoke generator (as I also have in my other tanks) to make nice amounts of smoke coming out of the end, if I ever get so far....

DocMarkIV-020.jpg

test fitting... it is not pushed down far enough in this picture.

DocMarkIV-023.jpg

from the underside.. rubber hoses from the smoke generator will be attached to the three nozzles.

DocMarkIV-025.jpg

The luggage holder came next. The fasteners were a challenge. Again, another tool had to be made to get them all correct and equal, a stamp and die.

In the background there is the piece of sheet metal I cut those bits out of. I have an old pantograph rotary engraver from the 60ies, but it still works perfectly. If adjusted right, it is just able to cut through 0,3 mm material.

DocMarkIV-014.jpg

Here are the odd attachments in the back of the luggage box. They must have held some standard equipment, as all Mark IV are fitted with them. No idea what they held, though.

DocMarkIV-016.jpg

A mounted fastener in detail...

DocMarkIV-015.jpg

and the complete view, mounted on the roof.

DocMarkIV-019.jpg

The supports for the unditching beam rails had to be made, to get them all the same size, I made them all at once, by bolting the single plates together, drilling and shaping all in one go.

DocMarkIV-035beamrailholder1.jpg

More progress on the supports:

DocMarkIV-037beamrailholder2.jpg

DocMarkIV-038beamrailholder3.jpg

Yes, they are bolted together. Nut and bolt thread size is M1.

Here is the view with the exhaust cover fitted in the luggage rack and the pipe itself.

DocMarkIV-033roofrear-1.jpg

The rubber band held the inner body sides together at that point. Here's about the body itself:

As I do not have much machinery at hand, I needed to make sure that all the axle holes for the rollers align exactly, as also with other details. I was not able to get circuit board material in the right total length of the model, so I had to think of some way to join two boards for each for the four body sides to achieve the length - and get the holes right. This is what I did, the ends overlap in different lengths, so I was able to bolt all four layers together:

DocMarkIV-024.jpg

Now I could drill and cut all sides at once, to achieve the needed precision. Here are the two inner sides, cut out and drilled out accordingly - and the belly plates.

DocMarkIV-027.jpg

It all fits together like this, the interlocking bits making the structure quite rigid already:

DocMarkIV-026.jpg

At this point, at least I could see that I was approaching something.

DocMarkIV-028.jpg

Next section: The rear end.



-- Edited by MRG on Friday 8th of March 2013 09:13:05 PM

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Legend

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Gobsmacking! Martin, your photos make it all look so easy - but in truth there is so much skill and effort on show, it is a delight to behold. Thanks for posting these photos.

Regarding your plans for radio control, may I ask if you plan to make it move as realistically as you are building it? By this I mean, do you have any thoughts of the steering action being somewhat perfunctory - from both tracks ahead to inside-track slowed to a given rate (fixed turn radius) to track stopped - without the smooth transition that would result from the normal choice of two motors, two ESCs and channel mixing?

Also, you referred early in your post to using Photoshop to correct perspective in photos: may I ask how to do this?

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MRG


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Let's start with some boring pictures of the petrol tank plates.

DocMarkIV-043petroltank3.jpg

DocMarkIV-041petroltank1.jpg

Girders, rivets and bolts. The petrol tank is made up the same way as the original one, I guess. The adhesive tape stops the rivets from falling out when I turn the thing over to hammer them.

DocMarkIV-042petroltank2.jpg

DocMarkIV-044petroltank4.jpg

The top plate with the cut-out for the filler flap.

DocMarkIV-045petroltank5.jpg

Anyway, the flap houses the electrical jack for charging the battery later on. I can refill it almost the same way as they did back then biggrin

Here's the jack from below, with all that brass around I needed to come up with a well-insulated mounting.

DocMarkIV-047petrolwires.jpg

Jack from abowe:

DocMarkIV-046petroltank6.jpg

Serial production of the petrol flap hinges - glueing the hinge strip I soldered (which was made as described in the first section) to a piece of wood before drilling and cutting helps a lot:

DocMarkIV-048hinges.jpg

I needed some attempts before I got that handle right in shape and size.Here are the hinges and handle bits.

DocMarkIV-049hinges.jpg

Looking like this

DocMarkIV-050hinges.jpg

to reveal the jack when in need of recharging.

DocMarkIV-051hinges.jpg

I believe these things were intended to hold wooden posts, supporting camouflage nets, but I could be wrong. Please correct me if so.

DocMarkIV-047petroltank7.jpg

The lower protective plate and the holders for it. The thing in the background is yet another tool I had to make to bend them in the correct angle - it also was for making the post holders above:

DocMarkIV-052rearplate-1.jpg

And attached to the petrol tank.

DocMarkIV-054rearplate.jpg

DocMarkIV-053rearplate-1.jpg

The rear compartment panel was needed now. Here it is, not all cut out yet. I do this with a jigsaw, as I do not have a mill or such.

DocMarkIV-055rearpanell.jpg

After my visit to Brusseles, taking a very good look at Lodestar III, I noticed that tjhe cover I made here in the middle is wrong. At that point it was guesswork, based on various pictures of the survivng examples. It is corrected now.

DocMarkIV-058rear.jpg

Now came one of the most complicated bits yet, the radiator cover. I made myself a tool to be able to bend all segments equally - and then bolted them together with M0,8 nuts and bolts. I must be slightly (if not completely?) mad. aww

DocMarkIV-056ventillation.jpg

I had a hell of a time trying to get those nuts in between the segments - don't ask how many times I was crawling on all fours in the workshop, trying to find the tiny nuts I dropped.

DocMarkIV-057ventillation.jpg

The upper protective rear plate, here already with the holders. The notches in the lower edge are to make room for the petrol lid hinges:

DocMarkIV-059upperplate.jpg

The plate fitted, at that point I had also fitted the hinge blocks for the "door" to the rear compartment plate..

DocMarkIV-029rear.jpg

The radiator grille is also fitted already, complete with the rain roof and the mud visor.

DocMarkIV-061rear.jpg

Test-fitting into the body...

DocMarkIV-031rearfitted.jpg

Next section: The rear "door". (I was shocked to see how tiny it actually is, back there in Belgium. I might just fit through there, crawling through on my side.).



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MRG


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TinCanTadpole wrote:

Gobsmacking! Martin, your photos make it all look so easy - but in truth there is so much skill and effort on show, it is a delight to behold. Thanks for posting these photos.

Regarding your plans for radio control, may I ask if you plan to make it move as realistically as you are building it? By this I mean, do you have any thoughts of the steering action being somewhat perfunctory - from both tracks ahead to inside-track slowed to a given rate (fixed turn radius) to track stopped - without the smooth transition that would result from the normal choice of two motors, two ESCs and channel mixing?

Also, you referred early in your post to using Photoshop to correct perspective in photos: may I ask how to do this?


Hi TCT,

thank you very much!

About the radio control - I will use the cheap RX-18 Heng Long controller - it does not have a fine variation of speeds, which is ideal for my purpose. It also has a rather appropriate sound generator... The rest, I guess, is driving it in a manner which comes close to the original way they moved. I have looked at some documentary film clips to see how.

De-perspectifying, I hope I can explain this in an understandable way.... You can do this in Photoshop, as long as you have some original size - scaled, if necessary - to aim for. Lets say, you have a picture of the side of the tank, and you know how long the tank is. You open a new document with the correct length. Make the document as high as you might need it. You copy the picture of the tank into a new layer and warp it, until it aligns with the length of the document. Now continue to warp it to achieve the correct height, using some known geometric form to go by (lets say the circular covers for the gearing axles). Warp the layer until these are to be seen really round - not oval, as they were in the original picture. Done!

Some parts of the picture will be out of focus, but you can use further overlays of other sources to counter this. I had multiple overlays of Grit and Liberty side views and sections until all the details aligned and matched - it became a very large PSD file. The result was more precise than I ever expected, I was able to verify my size calculations on Lodestar back when I visited her.

With best regards,

Martin



-- Edited by MRG on Friday 8th of March 2013 10:34:31 PM

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Legend

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Holy moly, that is INCREDIBLE work! I am utterly gobsmacked.

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MRG wrote:

The rear compartment panel was needed now. Here it is, not all cut out yet. I do this with a jigsaw, as I do not have a mill or such.

Whow! This is a really big deal! Ok, there are some really talented engineers around equipped with professional CAD tools ... but YOU do this with your jigsaw !!!!!!!
Awesome!
Peter


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Absolutely amazing!!!



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MRG


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Hello all,

thank you very much!

After all, I have to admit that I did have some training in metalwork, until 10 years ago I used to be a goldsmith - had to quit it though because it's a poor mans job (at least in Germany) and when my daughter came up I needed to do something completely different, just for the money's sake. It was frustrating back then anyway (stupid hearts and stuff furious), so I am still not very keen on jewelry - but I still have most tools and I kept my skills upright by modelmaking - but just as a hobby.

But now for more, here comes the door. Cut out and drilled..

MarkIVdoor01.jpg

Some test-fitting - the gunport-lid was made in the meantime.

DocMarkIV-032door.jpg

I drilled the holes for the hinge arms with the door in place, to be sure everything works out..

MarkIVdoor02.jpg

As you can see, the "keyhole" and the bolts for the lock mechanism are inserted already. The inside looks like this, here with the hinge arms riveted in place already (the pink discoloration comes from the solder flux - it takes the zinc out of the brass, so you get pure copper "stains"):

MarkIVdoor03.jpg

The thing with the handle is the lock bolt for the gunport-lid - I made this work like the original one does. Pull the thing out, slip the lid up and push the bolt back again, so that the lid cannot damage the cooling sleeve of the Lewis gun.

MarkIVdoor04.jpg

MarkIVdoor05.jpg

The door in place with the nuts on the hinge axis and the little triangular stopper on the lower one. Now I could file the notches into the side edge of the upper armour plate. These allow the "door" to open that little bit more.

Working on these bits, you forget the actual size of the original. In reality, the hinge arms are only 20 cm long. blankstare

MarkIVdoor06.jpg

The order in which I post this is not necessarily chronological. Two very recent discussions I started on the tanks section here in the forum led learning that the bracket I added here is actually for a tail light...

MarkIVrearbracket.jpg

... and looking at the surviving tanks I noticed I had to decide what covers the view port - a drilled plate or a priscope block. As I have a certain tank - made by Metropolitan - in mind, I decided for a periscope block. "Flirt" and "Deborah" were also made by Metropolitan - there is certainly a periscope block fixed to the rear door of "Flirt" and with "Deborah" one cannot be sure until further evidence turns up - but I believe she has one too. Thanks to Gwyn Evans on this one!

So another tool needed to be made, after all, there is also five more periscope blocks in the commander and drivers compartment. If they are all to be the same, a certain serial production needs to be set up.

MarkIVperiscope03-1.jpg

Here is the die and core, next to the raw stamped copper sheet. To make copper really soft and malleable, heat it until it glows cherry red, then throw it in water. It behaves the opposite way to steel, this way it gets soft as chewing gum - and easily shapeable.

MarkIVperiscope02.jpg

The copper basin was cut out accordingly, the thing in the background is the stencil for the fixing ends of the block. I could not resist, after cutting the viewing hole into the block , I just had to put some mirrors in.

MarkIVperiscope05-1.jpg

These are made of mirror-plated styrene, easy to cut and shape. So, the periscope blocks will actually "work":

MarkIVperiscope06-1.jpg

Here it is fitted to the door. The inside grip for the gunport lid and the "lock-blocker" (or whatever you could call it) are not mounted yet.

.MarkIVperiscope07-1.jpg

Next section will be details on the roof, especially the pistol port lids.



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Hero

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This is just sooooo good. It will be a crime to put paint over all your workmanship
Paul

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!!! , , .



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MRG


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81.gif Thank you all!

Well, I try to do my best but it still is easy to find better.. there are modelling gods out there which I just cannot match.. So you are worthy all right! smile

So I will continue with some details to the roof, here the pistol port lids. These were a bit I had feared over, because I did not really want to make countless identical lids by hand. Lasercutting was the solution. But first I had to get into basic CAD to make the necessary vector file for this online lasering service I had found. The price was better than I ever dreamed, so I had a sufficient lot made. A few days after placing the order, I found them in the letterbox, much more precise than I could ever have done by hand.:

MarkIVpistolports00.jpg

I could hardly wait to get started. So I needed to make the handles, here before soldering the blocking rings on. I solder minute stuff by placing a tiny crumb of solder together with the fliux on the bits and then carefully go over it with a small gas burner. Much easier than trying to do that with a soldering iron. After soldering, I cut the M1 thread onto the lid end, that's why I tapered them.

MarkIVpistolports02.jpg

Here is the set: Lid and handle, already soldered and bent and with a M1 thread cut to the end.

MarkIVpistolports01.jpg

Here is the setup with the blocking bolt and the locking hook. The hook was cut out of 0,3 mm material, with help of the pantograph engraver, like I did with the rope fastener bits of the luggage rack.

MarkIVpistolports03.jpg

MarkIVpistolports04.jpg

And it "works", as I had desired.

MarkIVpistolports05.jpg

MarkIVpistolports06.jpg

To be continued....



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Legend

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You cut the fine threads yourself?? I can say little except that I am much impressed.



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Commander in Chief

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Bud, this is so good, it must wind up on public display somewhere!

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Hero

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It's looking amazing! It really would be a shame to cover the model in paint. n

Maybe a second one?? b



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MRG


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Thank you all again!

Well, yes - I am going to splodge paint all over it.w Alone the burnt bit on the roof and the aluminium turret demand the paintwork. Hopefully the job will then look as good as on that stunning FT-17 turret in the other thread here in the modelling section - but I will have to practise hard to reach that excellence. I want to drive "Cynic" around, after all.

Metal is the stuff I like working with most, so that's just what I use. It is also the reason why I am documenting this in detail, because I need to remind myself then what it looked like without the paint - when I started it, I never thought about publishing a "making-of".

Sometimes, with stuff I made in my life, years later I wonder "How did I actually do this?", so all this was rather intended as a reminder for myself.

But I let you in on a secret which I kept so far - I am making parts for three tanks. Well, I need a male sooner or later... Maybe I will not paint the third one, because it will be better made than number one, and also probably made entirely of brass and copper, maybe even with the machinery in the interior, as a static model. But that is far in the future.

It is not much more trouble marking out three pieces - than only one - once you have the compass or caliper adjusted.

RearTrio.jpg

So, here are in fact three rear ends. I have not made the big pieces for the other two yet - I regard no.1 here in the report as the research piece.

After all, I still have not completely solved the track problem, but I have a good idea how to.

And TCT- cutting the small threads is really not such a big deal as it may seem, the threadcutter is just a somewhat smaller than the regular ones, but the technique is the same.

With best regards,

Martin



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Hero

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THREE OF THEM!!!!!

I'm trying to work out if that's inspired... or a sign of insanity. :)

I didn't think it was possible to make this project any more spectacular... then you go and reveal there's three on the build.... impressed!

Helen x



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MRG


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Hi Helen,

insanity, without a doubt... biggrin. Well, I somewhat believe that without my hobbies, I might really go insane...? It's my way of Zen-ing out, tanks in wintertime, scooters when it gets warmer..

So, here comes more about the madness: Doing the inner side details. I hope this does not get boring now... The girders around the horns were pretty difficult to bend into right shape, no chance without some selfmade tools. Making the brass red hot (literally) and shocking it in cold water softenes it up, as opposed to steel. I had to soften it several times to get it "round the bend".

MarkIVside01.jpg

One fine thing about using circuit board, you can solder stuff to it. That's what I did with the horn girders before inserting rivets. After riveting these, I made the track-maintenance-gap-lids. Or whatever you can call them. Here again, the trick is bolting several sheets together, so that they come out identical.

MarkIVside03.jpg

MarkIVside04.jpg

Here is the other type lid bolted in position. It will do exactly what the original was for - I can unbolt it to get at the track pins later.

MarkIVside08.jpg

Aligning the long girder at the bottom, I had to make that one a bit longer by hard-soldering an extra few centimetres to it.

MarkIVside05.jpg

Slowly but surely inserting rivets along the length...

MarkIVside06.jpg

..and sinking the other end of the rivets on the inside girder. These have been smoothend then, so that the running track does not catch on any protuding bits later. The bolt was only temporarily, to hold the girders in position while riveting.

MarkIVside07.jpg

The same had to be done on the insides of the horns, where there is no inner girder to guide and hold the track. here you can also see the big girder already fixed to the inside sides, the maintenance gap and the smaller girder below the mud chute opening. This will hold the brass sheet which will serve as the floor of the mud chute cavity.

MarkIVside09.jpg

Several rivets later, some more bits added. Here are the connectors for the single plates of which the original is constructed. Each side is made up of two circuit boards, as I could not find any long enough to cover the entire length of the model..

The area where the separate boards meet has been fillered and sanded. Originally, I had intended that that part gets covered by the connectors, but I had to make corrections to my plans after I had cut the sides out. You see, this is the research "prototype".

Mistakes included...

MarkIVside10.jpg

Many more rivets later, it looks like this. The triangular bit is the big strengthener which sits at the sides above the upper front glacis plate. I believe only "Flirt II" does not have these, maybe they were not replaced when it was restored.

MarkIVside11.jpg

More work on the rear insides, the upper beam holders above the petrol tank. I wish there were some photographs showing what they were used for, and how.

First, I had to make yet another tool, to bend the raw material as needed, here are the raws in the front and the tools in the background. They look a bit strange, but they became remade to cover for several tasks, sort-of "homebrew-multitools"

MarkIVside12.jpg

The lower clamp in place, bolted to the girder. As you can see, I needed to relocate the bolt positions for the mud chute floor and the petrol tank support (That was one of the results of visiting "Lodestar" in Brusseles last year) so I had to close and filler them over.

MarkIVside13.jpg

The beam holder in place.

MarkIVside14.jpg

MarkIVside15.jpg

So, it's getting late again, more to come! Next chapter - the track tensioners.

Best regards,

Martin



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Legend

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Stunning, stunning, stunning. Please don't paint the final model!

Martin, you mentioned earlier that you plan to use an Arduino motor controller: I'm wondering why this is necessary if Heng Long radio is being fitted?

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MRG


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Hi TCT,

final number 3, (if ever it gets done) I will not paint over, but this one, I just will have to. Too many flaws which are too obvious. Areas were I burnt the circuit board, some displaced bolt holes, gaps I had to filler over... And giving a model a good paint job is a challenge in itself.

Anyway, about the Arduino, it's only for the guns. No point in having an expensive 12channel remote just to twiddle the gun turrets manually. So I have written myself a program which keeps 10 small servos busy (2 for each gun, left/right, up/down) at random speeds and (restricted) angles, at random times.

As I am completely new to the subject of microcontrollers, I had to study quite a bit beforehand. A slow process, as I am not familliar with all the commands and stuff at all. Paste-and-copying codes from the net, a lot of trial and error here too...It took quite a few hours.

I made a small test setup with which I was able to monitor the changes to the programm, the servo behaviour looks fine now, just as I had wanted. They move and react like people sitting behind the guns, checking out the landscape, taking aim, moving off etc. Not too much movement, some pauses, some short simultaneous movements which look like the gunners being jerked inside the tank when passing over bumps - I am quite happy with the result.

The HengLongs also have machine gun sound (which is sort of acceptable for the Lewis) and flash, the Arduino re-routs it via transistors and LEDs over optic fibres into the 5 Lewis guns, also at random intervalls. First of all I wanted to programm a "machine gun routine" with flash and sound myself, but I quickly gave up on that. Sometimes it's the seemingly simple things that prove almost impossible - at least for my rudimentary "programming skills".

But I admit - fiddling about with the Arduino is fun, even total n00bs like me can get stuff done with it. To start with, I was somewhat afraid of it - but there are great tutorials out there in the net. The possibilities are amazing. Someone with true programming skills could have the tank driving around by itself, also avoiding or climbing obstacles, without any remote at all.

With best regards,

Martin



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Legend

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Ah! That should be something to look forward to then.
For myself, I had been wondering if motor controllers might be of use in small RC tanks instead of using normal ESCs, which can be bulky and pricey, but most of the blurb accompanying them on sales websites is aimed at using motor controllers with a PC interface or something like that. There are some which say they can be used with RC input signals, but these are usually bulky and pricey themselves! It would certainly be useful to know if those motor controllers that can work from a PWM input just need some cables soldered on with a suitable connector for the receiver, to be able to act as low-cost speed controllers.

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Hi TCT,

from what I know about the Arduinos, it should be possible to program them to function as an ESC. But - I am not the expert here. All sorts of input can be processed by the Arduino, analogue, digital, PWM. There's people building entire robots with them.

It would certainly need an additional "motor shield" (these are available ready to use, more or less) or a self-made circuit board with an array of transistors, as the Arduino itself cannot handle high currents. Size should not be the problem, I have the "Duemillanove" which is the size of a cheque card - but there are much smaller ones around. I am quite sure that there would already be some codes on the net for such an application, which could then be modified to your needs. I am afraid I cannot help much on the subject - yet. wink

Best regards

Martin



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On to the track tensioners, some of the more complicated bits on the model. Starting with some brass sheet, I noticed I did not have any 1,5 mm material, so I had to solder 0,5 onto 1mm sheet to get there.

I guess you know how it is, the weekend's on, the DIY store would never have it in stock - and waiting for ordered stuff to arrive is a no-no as you have it in your mind that you want to get things done... furious

MarkIVtensioners01-1.jpg

The discoloration comes from the soldering, here the tensioner plates are cut to basic shape and the axle hole is measured out. So next were the strengthening bridges, I noticed that the shape varies on the surviving Mark IVs. I went for the one I encountered most.

MarkIVtensioners02.jpg

Soldering to the plates, cleaning...

MarkIVtensioners01.jpg

The thread of the tensioner bolt needs something in which it can run, so I needed to add these blocks to the underneath.

MarkIVtensioners04-1.jpg

Now I needed to think how I could make those cover pans behind the bolt. And yet another tool is added to the set: A simple die and core.

MarkIVtensioners06.jpg

The length is sufficient for two pans, again, some copper sheet was softened...

MarkIVtensioners07.jpg

... and given new and exiting shapes. This is what you get:

MarkIVtensioners09.jpg

Cut in half, and the end towards the tensioner is soldered on. Here you can see how I solder small stuff, I lay small cuttings of solder next to the gap I want joined, then I carefully heat it with a small bunsen-burner thingy, taking care to heat all bits equally. The solder melts and shoots into the gap. No messing about with a soldering iron, where you inevitably throw your setup over or move the bits out of line.

MarkIVtensioners10.jpg

Checking if all fits as planned. Almost every Mark IV has straight edged pans, "Lodestar III" has flared ones. No idea why. Apart from having them looking more elegant (which is not really an issue on a tank) I cannot see any reason for making them this way.

I stuck to straight edges.

MarkIVtensioners04.jpg

and the final result with the correct bolt sizes and rounded corners.. All of this four times, uurgh.

MarkIVtensioners11.jpg

The headlamp bracket is also in place now, the headlights were another topic I had started a discussion on here, as I was not sure if the tanks had the headlights fitted by default or not - they were certainly removed when going for action - but the brackets are always there.

It might take a while now before I have more to show. I am moving onto the motors and "gearbox" now, lets see when I get that done. At least I have all the necessary bits ready, I need to make the housing yet, though.

With best regards, and thank you all again for your motivating appreciation!

Martin



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More metal madness, I have done some work on the "gear box" recently. The gears themselves are actually combined with the motrs themselves, so the "gear box" only flips the movement by 90 degrees. So the usual busines, first the drawing, then marking and cutting and drilling some nice solid 2mm brass sheet.

MarkIVGearbox03.jpg

Which can be put together like this:

MarkIVGearbox06.jpg

The trick is that I can later take off the body with the motors and the sides can stay in the model. So, if this should ever need service, I only need to take the side axles out and then I can take the engines out of the model without having to totally dismantle it.

Here with the floor and the central bearing holder...

MarkIVGearbox08.jpg

... and with the motors, drive cogs and bearings fitted.

MarkIVGearbox11.jpg

Here is the assembly test-fitted to the belly plate group.

MarkIVGearbox14.jpg

The sides are fitted with just a few screws here, so there are still some gaps which will close up when all of them are fitted.

MarkIVGearbox16.jpg

The battery fits exactly under the gear box...

MarkIVGearbox21.jpg

... and I have enough clearance...

MarkIVGearbox22.jpg

... to adjust the battery's position to find that perfect point of gravity, which the original Mark IV has:

MarkIVGearbox23.jpg

That strip of wood is all the model is resting on. The point of gravity is essential if the model is supposed to move in that special manner later on.

Next: Some details on the electrical equipment.



-- Edited by MRG on Thursday 16th of May 2013 08:53:41 PM

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All and all, the poor model has to carry quite a lot of electronic stuff. As mentioned before, there's the Heng-Long RX-18 remote receiver, the Arduino microcontroller, the voltage adjuster for the gun servos and the muzzle flash router.

The Arduino's job is to put random movement on the Lewis gun servos. This means random speeds, random pauses and random extent of movement. Now I never had anything to do with microcontrollers before - not even to mention actually programming them.

So, amongst the other things I learnt when making this model, being somewhat able to write programs in C is now amongst them - as well as fiddling about with transistors, resistors and capacitors and making crude circuit boards for my needs.

The Heng-Long RX-18 simulates machine-gun fire with a flashing LED and sound. But only for one gun - so I also needed to randomly route the flash to five different LEDs. The Arduino also does this, by randomly activating 5 transistors which in turn switch the LED flash from the RX-18 to 5 different LEDs. So, when I do short gun bursts, it will be a different Lewis gun firing each time. After designing the layout for the muzzle flash router, I engraved a circuit board accordingly on pantograph engraver. I always use hardpaper board so this is no lung-killing glass dust which can be seen here...

MarkIVElectrics01.jpg

Then, there is the "master circuit board" to which all components are fitted. This saves me a lot of cables - the 7,5 Volts from the battery come through it as well as the 5 Volts I neend for the servos and LEDs. Here the Arduino is fitted, the marker-pen sketch got washed off later.

MarkIVElectrics26.jpg

Here is the master board with all the things on it, in place:

MarkIVElectrics29.jpg

The pins in the front is where the servos get their current from. The signal line comes from the Arduino. The actual RC-receiver sits nicely on the gear box, which is good as the antenna cable is right underneath the place I intended for the detachable antenna wire which will be in that tube poking through the roof in front of the luggage box.

MarkIVElectrics30.jpg

Here is the electronic assembly from the side, the black thing underneath is the loudspeaker.

MarkIVElectrics31.jpg

More will follow - but its getting late again

Best regards,

Martin



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Legend

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Great work again, Martin. I'm looking forward to seeing more.

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Hero

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You built your own gearboxes!!!! I do love your metal working skills. My Brother Rae would also be impressed by the use of an Arduino board, he loves those things. At some point I will have to teach myself how to use those as well.confuse

Helen x



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Prod! Prod! Prod!! Anything new? :)

H x



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Hello again,

it has been a while since the last update but I usually mess around with my scooters during the warmer months, one of the reasons being this custom job on a East-German "Schwalbe". The apology looks like this:

blackbess1

and it bears the name - and will also have the Art Nouveau-style signature on the side - of this:

blackbess2 So, it is slightly landships-related. biggrin  It is unfortunate that the little painting underneath the name can hardly be made out....

But enough of that - next things I did to the model was constructing a smoking unit, it is controlled proportional to the revs of the motors, so the "faster" it goes, the more smoke there will be. It works pretty well but I have no photo of it in action - yet.

smokin

In the mean time, a good friend of mine made me all the track rollers I need on his CNC-lathe - a whole bag full, sufficient for all three tanks. The material is POM plastic, which will turn very well on the axles even without any bearings -  and will not harm the track links.

rollers



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Next in line were the Lewis guns.

As the inside of the model is all tech-filled anyway, I did not bother detailing beyond the visible part of the cooling sleeves. They were enough work as it is. Here are the sleeves, made up from two soldered thin tubes of brass, then worked upon on the lathe.

By the way, if anybody needs thin-walled but sturdy brass tubes in odd diameters, consider taking a car radio antenna apart.

lewis1

Here are the inserts with the internal muzzle and the cooling fins. As they are only visible from the front, when looking into the gun, I only jigsawed the fins into the front ends.

The muzzles are 1mm tubes, which will have an optic fibre inserted, for the muzzle flash when firing.

lewis2

I spent a lot of time thinking about how to make the front gun moveable, as the space in the drivers cabin is now very limited due to the other tech inside the model. But I solved the problem. First I had to prepare the brass gunbearing ball.

frontgun1

The Lewis gun sleeve fits through now. I also had to file the "vision duct" (for lack of a better word) into the brass ball.

lewis3

Next I had to figure out how to hold it in place without loosing its mobility. I came up with this:

lewis4

In real life, this would not be wise to do, looking down the barrel of a gun wink

lewis5

The gunsight is already soldered to the sleeve, the cross-shaped thing is the servo coupler. The groove in the coupler allows room for the optic fibre going into the muzzle. The coupler fits into the gun sleeve from the back, the fins on the coupler and on the holder are fixing points for the springs which will keep the gun upright, even if the servo is moving the setup around. A ball bearing has no limit in which way is moves and I needed a way to avoid movement around the Y-axis. It took some time to get the idea for the solution.

lewis6

Here is the assembly complete with the tiny servo - it does not need to be powerful anyway.

lewis7

And - its "alive". I mounted it for testing onto one of the fronts I have prepared for the sister models.

lewis7

So, now it seems as if there could be someone behind the gun, looking for someone unfortunate enough to be in its line. For all the fascination I have for this piece of human ingenuity and the respect for the crews inside, the intention behind it is horrible. I am a pacifist, no doubting that. Researching the Great War for the model I came upon so many dreadful images..

Anyway, the red-glowing thing behind it is the servotester. The servo itself will later be steered by the Arduino, which will feed it with signals for random speeds, angles and pauses. The speeds and angles are within a set limit, making the gun's movements much more life-like.

lewis8

So, thats it for now, more to come!

 



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Hi Martin,

So good to see this project of yours making progress again. Sometimes a break is just what's needed to get the ideas flowing again.

Black Bess is worth the break from your tank build, it's a lovely vintage scooter. 

Helen x

 



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Metal GOD!

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So, I am back again with some news!

Thanks to Schnuck's great entry on this thread I was able to solve my greatest issue with the project yet - the dreaded track plates. Thank you again, Volker!

I had asked some friends for help with the construction of a stamp and die - but my original plans were much more complicated than Schnuck's solution. And I could not wait any longer - so I tried it out it myself.

I had been constructing madly these last few days, to come up with this: The "Trackplater 2000" biggrin

trackplater01.jpg

With this crude device, I am now able to torture metal sheet into the shape I need so badly... but it took some failed attemps to get the shape and depth of the stamp right. There's the stamping lever and the clamp at the back, to hold the actual stamp and die in place.

Here is the heart of the device:

trackplater06.jpg

During my experiments I had to somewhat fill in the guiding side again, with liquid metal epoxy. Thats the grey polygonal stuff on the stamp plate (top). The stamp is in the middle, next to a stamped plate. At the bottom, the die plate.

The thickness of the material was also an issue. For 1/16 scale, 0,7 mm sheet would be fine but with steel sheet in 0,75 mm (the closest I was able to get) I was only able to slightly dint the material although I applied as much force as I could. That's the plate at the back, right side:

trackplater02.jpg

0,5 mm sheet works fine but it is just that little bit too thin for the model. The other plates are the results of different width and depth of the stamp.

Top left - the second attempt -  not wide enough and having fixed the plate through the rivet holes while stamping resulted in bending the stamp due to the material having to slide into the die from only one side.

Middle - stamp too wide (although in the exact profile shape) resulting in a too sharply bent "nose". Another reason for this effect was having filed too much off the guiding side from the stamp plate - thats why I needed to fill it in again  with epoxy. All the try-outs were then with freely sliding sheet.

Bottom left - Eureka!

So I then tried 0,8mm aluminium which shapes almost by itself - looks good regarding material thickness and this would be very ok for a static model - but for ma evil RC plans much too soft. At best, it would resist the forces when driving over a carpet. You can scrath the stuff with your fingernail...

This is the aluminium track plate - cut, drilled and sanded after stamping:

trackplater13.jpg

Anyway, I continued with the 0,5 material and even the overlap comes out to my satisfaction.

trackplater11.jpg

So I will try brass sheet next, with 0,7 mm which I will pre-soften if necessary. As for the brass colour, I would coat the brass with tin later on, which should give it a nice iron-darkish patina. Tinning brass also results in a hardened surface - so the tin does not scratch off as easily as one might expect.  I will keep you updated!

So, this is the proof, it is possible to make the track plates yourself, at any scale needed.  Although it is going to be very tedious, making 178 plates per tank... uuurgh. (If I counted correctly, its 89 plates per side - please correct me if I am wrong.) blankstare

 

 



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Sweet! Some of the best metal work as always & I look forward to seeing more.

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Hello Hermill, thank you! And so it shall be..  smile

I recently received my roller axles from a good friend, who happens to have access to some CNC tools. All ready-to-use, with the small cut-in in which the L-shaped holder girder later grips in to. Yeehaa!

Here they are! Lots...

rollers.jpg

There will be brass sheet washer plates between the hull plates and the rollers, so the rollers are that bit shorter than the thicker inner part of the axle, which is the actual inner distance between the side hull plates.

I am now waiting for some brass sheet which I ordered, so that I can continue my trials with the track plates. As for my question above, never mind - I found the thread discussing exactly that issue. So, 90 on each side. hmm

To be continued..

 



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Hi Martin,

what do I see, after I have been one week on hollidays ? ...a great job... keep on going

Volker



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... regards, Volker



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It´s HARDCORE!
My RESPECT!

Best regards,

Ernst

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Testing..to see if I can undo Photobucket's assasination attempt...



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It's a masterpiece.

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