me and a couple of friends want to build a Mark IV RC model in 1/16 scale. Therefore we are currently designing a CAD model and are testing the first parts from our new 3D printer.
some 3D CAD shots:
the first quick-and-dirty printouts:
Right now we need some detailed information about the idler wheel as well as the track adjuster mechanism. So far I know that the idler wheel is round in the Mark IV as opposed to the version with sprockets in the Mark I. What is the exact diameter of this idler wheel and which other parts are there to fill in the holes in the frames? I know that there was already another thread about the idler wheel but this was very confusing and I could not find the value for the diameter there
Helen Lawson showed already some beautiful images for the track adjuster parts of the Mark I here on the forum. But she mentioned that the hole in the frame where these parts go into looks different in the Mark I compared to the Mark IV. Can someone tell me what the differences are between the track adjusters of these two tanks? A CAD model or the exact measurements of the parts would be awesome! Otherwise I would be very grateful if you could point out some sources where to find such info. I already have the Mark IV plans from Bovington but could not find the desired information there.
And finally: could someone tell me how the whole mechanism of adjusting the tension of the tracks with the mentioned parts worked?
Great results from a 3d printer, maybe the future of modeling to come. As for information it may pay you to visit a museum and take measurements from an original tank and scale the part down.
-- Edited by BC312 on Monday 20th of January 2014 01:03:25 PM
I'm drawing the CAD model for the project that was mentioned by Volker.
As he said, any information about the geometry of the idler wheel would be very welcome.
I guess that the idler wheel bearings are directly shifted by turning the massive screws in the
recessed bays on each side, is this correct? Are there any drawings available that give more
details of the parts in that area, perhaps with some measurements?
Hi, The track tensioners are basically the same as used on the MK1, it seems all they did was square the ends of the slots so they could get a few more inches of adjustment.
I guess that the idler wheel bearings are directly shifted by turning the massive screws in the recessed bays on each side, is this correct? Are there any drawings available that give more details of the parts in that area, perhaps with some measurements?
I can't help with drawings or measurements, but if you look at the following photos of the track adjusters (all on the landships.info website), you should hopefully get a good idea how they worked. The axle seems to be carried at each end in a small block that can slide back and forth in the adjuster casting; this block is carried on the front end of the adjustment turnbuckle. Turning the turnbuckle moves it backwards or forwards, carrying the block and axle with it.
You'll notice in the first photo that there is a nut on the threads of the turnbuckle, between the bolt-head of the turnbuckle itself, and the adjuster casting; in most pics this nut is tight against the casting, but in the first photo (of Lodestar III in Brussels) it is a little way along the threads, so it might be intended as a marker to limit the movement of the adjuster - so that the track is not over-tightened after any maintenance is carried out, but the idler is returned to it's previous position. Only a suggestion, but hopefully it may help.
Exact details differ between these pictures: Lodestar shows most clearly the mechanism, because the cover plate is missing from the slot in the casting, and it also lacks the backing plate behind the turnbuckle.
I want to thank all of you for your input - that's exactly the information we were looking for! Now we should be able to build something that looks and works like the original!