Scratchbuilding C&Cs Mammoth Tank

[blimp]

- Hi M , the yellow triangle is just the track , i'll leave the bogies up to you for now

[Von kraftwerk]

tracks look good thought you were going to have a nightmare,but you're doing well,I had a little idea about stength,ribs maybe an alloy strip on the inner faces epoxyed,

[Munty]

Ohhhh right I'm with you blimp, like a snowmobile? Would save making a whole lot of track too lol Only difficulty is I'd still want to follow the shape of the armour so would still need to tension it at the front and rear. How about running a metal rod straight through both sides of the armour and fitting sime free-spinning rollers to it that could act as mini-bogeys? They could be fixed in position with a tensioner elsewhere and that should allow the track to move freely while still following the shape I want it to...

Thanks VK, it seems to be all about time and patience, much more patience than time I'm pleased with how the first track has turned out though so this is definitely a system I'll use. I'd really like to replace all the pins with single piece full width ones but I think it'll be very expensive and another very boring time-consuming job so not sure... If I can't do that then reinforcing strips laid widthwise could help mimic them but would also make 'steps' for all the bogeys to pass over. Likewise I've already had a reinforcing strip running lengthways, with the track, but I'm not sure how that could be implementing without seriously hampering the flexibility of the construction...

Whatever I do, I'm not planning to modify the current setup any further until I've been able to test it properly with drive and bogeys all in place. I'm currently watching some ebay auctions of 2 tanks worth of Tiger bogeys and a bunch of turret hardware. They finish tonight so will see about them but I'd need both sets of bogeys to be able to use them how I want to so fingers crossed!

[blimp]

- Me again , I have some tiger wheels looking for some where to go . . . 1 full set + some extras .

[Munty]

Ooh nice one Blimpy Is that a full set of 16? I think I'll need 32 to realise the dream so if you can let me have one set I could try to get hold of the other ones off ebay? I'm going to see if I can find someone to make me an extra 4 drive wheels as I think there's a lot to be said for your snowmobile track system I just rigged it up with a few piles of coppers to mimic the front and rear rollers and it looks good (and means the track is long enough!) There wouldn't be too many teeth in contact with the track which is a little concerning though, maybe nine at a time? Is that going to be ok do we reckon?

Anyway here is what it looks like in the flesh.


Here's how the drive wheel would sit at the top.


And here's my issue with where I want the track to run.



This last one is so I can try and find someone willing and able to make me 4 more similar pieces! Of course it'll never be seen so needs to be purely functional so I'll update if I progress with that...

[sassgrunt]

Hi Munty;

I just had a thought about trying to drive this. Maybe it's possible to fit some sort of sprocket (like a fairly-flat hub that a belt would run on) right at the center of the hub of your three-piece drive sprockets. (It would have a large hole in the center to fit over the tapered hub - right inside the center toothed ring). Then on the center (motorised) sprocket, you wouldn't need the same kind of sprocket teeth for the track - just whatever hub would fit the belt that runs to the two sprockets, and outside of that, just any kind of wheel that the track contacts and runs over. In truth, maybe the center sprocket would need two hubs; each running a belt/chain to one of the two sprockets. It would kind of be a belt-within-a-belt, but would be hidden by the roadwheels. It WOULD bypass the need for more sprockets, though. -Mike

[blimp]

- I see what you mean about the sprocket tooth engagement .

. . . at the top of your sketch there are four return rollers , one or both , positions closest to the centre can be used to tension the track and hold it onto the sprocket at the same time ( one could be permantly fixed ) the other pressing onto the track from the top .

• 

p.s. Is the triple-row sprocket really needed on the gearbox mainshaft ? the normal one should be more than adequate for the drive , the overhang won't be under load at this point . it keeps it simple , is easier to set up and gives you extras to play with , you can always redo them later when you get enough .

p.p.s. - BTW Tiger 1 wheels are 50mm dia. (too big?) - Pershin / Pz 111 -1V /KV 1's might be better for the road wheels - idlers . B .

[Munty]

Cheers Sass, I think I get what you mean The difficulty of using a belt drive is that it relies solely on tension so I'd imagine a fair bit of power could be lost in this kind of setup as the end product would have to be perfect for proper running...

As for the triple sprocket at the top, I could conceivably use a double one and I actually managed to use a small piece of plastic tubing and 2 of the 8 spare sprocket faces (meaning I have enough to do this four times) to make a very adequate drive gear for use at the top. I placed the 2 pieces back to back and just placed a tube between them, cut it to the right length so that it was driving the two outer edges of the track with the centre unpowered.

As for tensioning, I'm not sure how it would work to push on the track from the outside as I've actually had this thought myself. The problem I forsee with it is the surface of the track itself. You can see from earlier images that it's peaks and troughs, like a ploughed field, so I wouldv'e thought trying to run a wheel over that would be rather difficult. I can imagine it having large fluctuations constantly and also creating some additional friction that we really don't want...

Thankfully I measured the wheels off my Tiger before I placed a bid on any and they are WAY too big! I need something that's more like 30mm but honestly I'm starting to think I could just make them myself... Don't forget I need to have these contraptions at the front and rear of the track to ensure it follows the path I want it to so they need adding to your very neat image above

Still no grill but I now know there was a holdup with postage so I'm hoping to see it when the posties go back to work on monday! As a parting thought, how about moving the drive wheel either forward or backwards so rather than forming the top of an isosceles triangle it forms the top of something closer to a right-angle triangle. This would see a lot more track in contact with it and also allow plenty of space for an internal tensioner if necessary.

[blimp]

There ya go . Cracked it !

[Munty]

Hah, well maybe! Still need to sort out these other 2 points of contact in the front and rear though hey...