RC Tank Warfare community hobby forum

Hi Alwyn ,Nice Job love your builds always something different , I too have had problems when scratch building something with compound angles very hard to get right from drawings , I like a small scale model to work from when doing angles makes it much easier.

regards pete

Love the drivers position hatches mate. Great work on the upper to match the lower effort
But lets be honest, its the gun work we are all hangin for

Thanks Philipat, Pete and Herman, yes the gun is the bit that is probably going to drive me bonkers!

The problem is with the 88mm that the pivot point is right at the loader end, and I'm anticipating problems with getting the elevation servo to work, but I'll deal with that when I get there. It may need a bit of extra gearing to solve the problem. I first need to get hold of a plastic 88mm barrel from a king tiger or elephant that someone has upgraded to metal, then build the extra pieces of barrel, and I'm probably going to have to use brass tube as aluminium is too heavy and there isn't any styrene tube that diameter.

I think on my travels around Spain I'll keep a look out for broken fishing rod as there are usually a few strewn around the beaches/harbours and that should be near to the diameter I need and light enough. The 1/72 model is giving me a fairly detailed picture of how the gun needs to be put together but I think I'll have to do some prototyping before I get it right.

Thanks for watching
Alwyn

Having decided that building the gun with styrene is too flipping hard, I have started the design work using openscad to produce it on a 3d printer when I get back from Spain. Here it is so far....


Obviously lots more work required but a reasonable start.

I'm going to need a printer that handles at least 150x100x60 and it's going to take a while to print!

Alwyn

Done the design for the barrel, I had to split it into 4 to make it printable. I suspect there will be a few failed prints before I get it right and accurate

I can't wait to get the printer and give it a try!

Alwyn

Designed the cradle and barrel mounts

I had to make sure the barrel mounts were free running so I can get the recoil working

Now I'm very frustrated because I have to wait until December when I get back to get the 3d printer Dagnab It!!!
Alwyn

Well enough sangria and tapas, so now back to work!
With the 3D printer in full swing the components are coming off the production line so the build can restart.
The learning curve for the printing has been very steep with a lot of wastage in the early stages. The most annoying thing is when you print a part and find that the design was subtly wrong and the parts don't fir. Then it's back to the CAD program and reprint.
I also had a couple of quality problems with some parts delaminating and splitting but I've solved that by increasing the print head temperature by 5 degrees. That probably also accounts for the relative weakness of some of the early prints, plus I hadn't set the shell thickness correctly.

Just had a problem with delamination on the latest print and because it is only occurring on one side of the print I think I am getting drafts affecting the print so I've put up a shield, I'll see what happens




The new prints are coming off the printer much cleaner, sharper, and stronger.

The gun barrel is now printed and just needs some brass tube which is on order


Now starting to look like a Nashorn but needs the gun carriage and barrel mounts


Well tomorrows another day but progressing quickly
Alwyn

Looks like you have mastered Openscad, it's what I use as it suited my way of thinking.

Layers delaminating is a pain, especially when it happens halfway through a print. I sometimes drip superglue into the crack and apply pressure rather than reprint. Several things cause it, print temp too low, trying to print a vertical wall that is too thin to print, nozzle height, print speed, outer wall thickness, infill not 100%...there are probably others. Cura has to make a wild guess when small/narrow parts are sliced, and it doesn't always get it right.

Top modelling going on there, I like the way that you build models that are out of the ordinary.

Rob

More progress on the build and more parts printed for the gun carriage

The slewing turret is fitted



I printed off the cradle and the front gun support but the design was wrong , so back to the drawing board, then reprints, and presto I have a carriage and the front and back supports which I'm delighted run freely so recoil is going to happen!



The gun is pretty big and I'm waiting for brass tube to reinforce the middle.

Just have to print the cradle supporting bracket and then the whole cradle assembly is complete.

Rob thanks for the advice and good words, I have built a shelter to keep off drafts and it seems to be doing the trick with the delamination.

Alwyn

It's coming along quite nicely and I keep checking back for more! You are an artist and have mastered that printer in my opinion.[THUMBS UP SIGN]