1/6th Scale Scratchbuild T-72

[CHRISTOPOPPIN]

JB Weld and not sticking to aluminium...my first thought would be the aluminium oxide layer... I believe that it oxidises very quickly to form a skin tight oxide layer that protects the raw aluminium surface below from further corrosion, unlike steel...
Perhaps try removing the oxide layer and even roughening up the surface before applying the JB Weld to create a better surface for it to grab onto.

I think you are right about the oxide layer on aluminium - thats why you have to do the crazy scraping action under the molten solder when you are using the aluminium soldering rods or whatever.

I dont know how quickly the oxide forms after sanding or scraping. I suppopse one could try and put a dollop of JB on the surface and then try and scrape through it or something. Saying all that, Ive JB'ed one or two things that have actually held - mostly flat things being glued to other flat things with a decent contact area between them.

But once it gets to things like glueing sheets of aluminium at right angles to each other - it doesnt hold very well at all.

Its a pity.....aluminium is perfect for building things and if it was a bit easier to fasten, it would probably give styrene a run for its money......

p

It's not too bad on thin pieces of aluminium - as long as you don't apply huge amounts of stress on the joint.

Rubbing it over with steel wool before gluing helps a ton!

[CHRISTOPOPPIN]

[/quote]

Hey Chris, I don't mean the links wearing down, I mean snapping. I've seen a few people would build 6th scale tanks that went the resin route for tracks and had no end of trouble. This was on a scorpion which is much lighter than yours.

Not trying to poo poo your efforts just don't want you to be frustrated further down the road when you come to use it[/quote]

Thanks for the heads up - Been giving it some thought and the other alternative is perhaps rubber inserts/full belt.

I have yet to see this resin *snap* as such, but the possibility is still there.

Do you know which resin in particular other people have used? What type? (Polyurethane, Polyester, etc.)

[morganp]

Great to hear how you're getting on and see the photos. I'm getting close to the end of a scratch built 1/12 Challenger 2 and have put off the tracks until they're almost the last things to do. At the moment I'm looking at 5mm uPVC sheet cut and routed into the shape of the tracks with laser cut links and extra long pins held in 2mm brass beads connecting the tracks. The plastic won't snap, is rigid enough and I'm bonding 1mm thick rubber rectangles to act as track pads. At the moment each track has about 20 parts and at 200 tracks, I've got my work cut out.

[RobW]

What do the links look like? I'd assume the primary stress is localised to the link pins, and will be mainly along the axis of the track? Can you break the link into layers for manufacture (machine the strong bit from metal & cast pads etc) to get the best of both worlds?

[morganp]

The links are 10x4mm overall, with 2mm radiused ends, cut from 2mm aluminium. As it is quite critical that they are accurate and identical, I decided to get them laser cut. The pins fit neatly through the beads with almost no play and hopefully the stresses will be spread more evenly. It would be quite possible to mill or cast the tracks, they are a simple rectangle with a slot cut out in the centre of both edges for the middle link, but I decided, after a lot of trial and error, to cut them from PVC sheet because it's easy to shape, lightweight and doesn't absorb water. If it works, I'll post some pictures.