1/16 Long Tom Project

[wibblywobbly]

This one is going to take a different tack to most builds, or anything that I have ever done before. It will be a project simply to see whether I can design a 1/16 scale Long Tom using a free 3D software program called Openscad, but do it in a way that will allow me to print each component on a 3D printer.

I will say from the outset that I have never:

1. Used Openscad before to do anything like this.
2. 3D printed anything other than small test parts.

I have had nothing more than 'learn as I go' experience over a few hours with Openscad. I am using this to force myself how to do what I need to do, in order to get what I want, if that makes sense. It is just something to do while I am watching tv, I can do this on my laptop.

There are several things to consider doing it this way, but mainly:

1. Designing components that can actually be transferred to a 3D printer.
2. Making each compenent strong enough to withstand towing behind a cargo tractor.

It will be printed in PLA, which is very close to polypropylene in texture and strength, quite difficult to snap, but flexes a bit under pressure. The parts will need to be self supporting, the barrel may be an issue, as anything over 20cm's will have to be printed in two or more parts.

3D printing presents problems with horizontal overhangs. This can sometimes be resolved by printing parts upside down, on their side etc, or by splitting parts down. Split parts then need to be redesigned with dowels/slots etc so that they all fit back together again.

So after that brief waffle this is where I am so far. The different parts are in different colours, though this may change as the design progresses. Some of the detail is not on there, as at the moment creating a shape, rotating it through different planes and then sticking it exactly where I want it is hard work. Not all detail is symmetrical.

Just to get this far has meant writing stacks of code, but it is teaching me a great deal. This isn't a five minute job that's for sure, and before anyone says it, I could probably have made the whole thing in styrene in a fraction of the time???

[AlwynTurner]

Great looking project Rob. Will be following this with great interest. Alwyn

[wibblywobbly]

I thought that I had better do something in the way of printing a part for this project, so I did the main barrel support. It was quite a chunk, took five hours to print. It's not totally scale accurate, the reason being that this part is the main support for most of the gun, so I went for strength whilst making it look the part.

I will do the barrel next, as that is all ready to print, though I have had to split it down into several sections that I will have to assemble.

[AlwynTurner]

Sure could use that technology with the 105mm for the priest, it's a bitch, but I guess by the time all the bits were coded I could have built it in styrene. I suppose it's therapeutic - that's what I keep telling myself! Following this with great interest. Alwyn

[wibblywobbly]

You are spot on. There is no time saving with a 3D printer, it takes a lot longer to design a part, and potentially hours to print, that's assuming that it doesn't take several attempts, and even then the printed one may need modifying...so its start all over again.

Some parts simply cannot be printed as a whole so they have to be designed as parts that will fit together...and that is another ballgame altogether.

[Woz]

It's like building your own kit model.

Best part is that once you have all the parts coded you can print out as many kits as you like.

[wibblywobbly]

That is very true, the one area where a 3D printer is good is creating multiple identical parts, or solid items made up of complex parts that would be difficult to do in styrene.

[jackalope]

Sorry I haven't been able to get you the measurements for your gun but my mom has been in the hospital for almost 2 weeks now and today she will have her 4th surgery. Between her and work I hardly have time to sleep and my 1 day I get off a week I try to just relax.

Real sorry man hope you understand but I still feel bad.

[wibblywobbly]

Don't worry about that at all, family comes way before anything to do with the hobby. Hope your mum gets the treatment that she needs.

In case anyone else is thinking of buying the Barbarossa book on the Long Tom, well mine arrived today. Ok, so it was only £2, but it is simply a ring bound set of A4 printed paper containing blurry photo's from what I am guessing is the parts manual. There are no line drawings, and no measurements at all. It is good for getting detail as the pics are all close ups, but there isn't a single one of the barrel?

Not one of my best buys but it may come in useful one day....

[AlwynTurner]

Hi Rob, found these but don't know if they'll help
http://ww2photo.se/gun/us/ha/155mm%20m1 ... %20tom.htm
http://ww2photo.se/gun/us/ha/155mm%20m1 ... %20tom.htm
http://planetarmor.com/forums/showthread.php?t=7874
This one looks like it could be what you're looking for
http://www.primeportal.net/artillery/di ... _long_tom/

oh and this one
http://www.toadmanstankpictures.com/8inch.htm
Hope they help
Alwyn