Bruder 320 conversion with 3d printed parts

[Cre8rc]

Very nice work on the 3D printed parts and custom cylinders.

[5inchman]

Wow those cylinders look absolutely superb.
Please could you publish drawings/details of them?
Have you used lost wax castings for some of the parts?
I would like to be machining these out of barstock

5

[NebraskaTrevor]

Thanks for the compliments. The cylinders are simple in theory but I am finding that having the gland end seal without leaks is easier said than done. I made 4 cylinders. 2 are great while the other 2 leak so my design of using o rings as a seal may not prove to be workable in the end. No casting is involved, all lathe work. the barrels are just 1/2" copper pipe which happens to already pretty much have a mirror finish inside (I assume from the drawing process) and the end caps are machined from brass stock. the internals of the cylinders consist of aluminum pistons with steel shafts. No drawings, but if you look on the MagomHRC website you will see that they have very good exploded drawings. Honestly for about 50 bucks a cylinder it is probably best to just buy the cylinders from them, but where is the fun in that!

[5inchman]

Originally Posted by NebraskaTrevor

Thanks for the compliments. The cylinders are simple in theory but I am finding that having the gland end seal without leaks is easier said than done. I made 4 cylinders. 2 are great while the other 2 leak so my design of using o rings as a seal may not prove to be workable in the end. No casting is involved, all lathe work. the barrels are just 1/2" copper pipe which happens to already pretty much have a mirror finish inside (I assume from the drawing process) and the end caps are machined from brass stock. the internals of the cylinders consist of aluminum pistons with steel shafts. No drawings, but if you look on the MagomHRC website you will see that they have very good exploded drawings. Honestly for about 50 bucks a cylinder it is probably best to just buy the cylinders from them, but where is the fun in that!

Thanks for those details, MagomHRC do have some nice detail drawings. My experience with "O" rings is limited to fire service breathing apparatus pressure reducing valves. These had a hollow piston about 1/4" diameter sealed in a cylinder with static "O" ring the pressure on one side was 3000psi the pressure on the other side 125psi. It was sometimes found that the pressure on the low pressure side increased. On close inspection it was often down to scratches on the piston or poor "O" rings. The remedy was to polish the piston to remove longitudinal scratches and check the "O" rings discarding any that showed damage or moulding flash etc. Crikey I do seem to go on

[NebraskaTrevor]

It has proven to be a bit more difficult than I thought it would be to eliminate the leaks around the shaft of the cylinder. I haven't done anything with them for a couple weeks but I will get back to them soon, in the meantime I will follow the links posted above to see what I can learn. Thanks!