Sand casting Caterpillar track links in aluminium

This is as rough as I can get.

 

Here is an example of a purpose-made track about 9 feet long with pavement-friendly and durable rubber faced tracks in a proven design. It costs much less than the cost of A356 ingots to cast a track:


Denis

 

Just for the record, the rollers are also correctly called "rollers" by Caterpillar among others.

Denis

 

Hi Kelly,
The actual tread will be a 5mm thick, 80A urethane pad, so the aluminium will not be in contact with the surface. Yes I could just buy rubber tracks and save myself all that effort, but where is the fun in that. Besides with the Covid 19 lockdown, I’ve got plenty of time on my hands.
Jim

 

A bit too long and heavy for me David, 110lb a pair and 9’ long. I only need about 5’. In case I can’t overcome the casting problems, I m taking your earlier advice and looking again at the design to try to eliminate the undercut.
Jim

 

We will have to send Dennis to the naughty corner then

 

Thanks Fishbonz, that helps. I’ll try to draw it up to see if I can make it work.
Jim

 

In case I can’t overcome the undercut problem in a doable manner, as was suggested earlier I’ve had a quick look at redesigning the part. Here is rough draft of my first thoughts, instead of teeth on the sprocket, the two drive/locating teeth are on the track links which locate in sockets on the drive wheel. I haven’t thought this out properly, so other problems may come to light.

Looking at this again, with my sensible head on this time, it doesn’t solve the undercut problem at all so it’s back to the drawing board.

 

lol.... This is ours, it's probably like what you've got. It cost 10grand and it's a piece of SHIT! We have to replace the tracks once a year to the tune of almost 1000bucks.
My suggestion, pay the man. You aint making these! The real problem with ours is the tracks won't stay tensioned and then they slip.
When it works, it's a great bit of kit. Makes moving large aircraft by yourself a breeze.
I'm just glad I didn't pay for it. The owners of our FBO got stupid and it showed up one day.

 

Hi Jason,
That’s one of AC Air’s bigger tugs, looks like a small business jet nose gear on it. If you are having so much bother with it, I’m glad I didn’t buy. To get one over to the UK, shipping is extortionate then add import duty plus 20% on the landed price. Besides it’s more fun this way.

 

You'd be better off motorizing s pallet jack instead of screwing with tracks.

 

Dennis,
I’ve just had a close look at the Kira track link, and it looks to me like it has the same problem that I have, ie. undercuts at both ends. If the split line is through the centre of the pin holes, then the shallow concave curves will be undercuts. I still haven’t overcome the problem yet, but I’m still looking.

 

Hi Jeff,
Being a relative newbie to casting, I’m still getting to grips with the basics and haven’t ventured into anything exotic, like cores, yet. I can cast lumps of metal that machine up to look presentable, but I’m learning. I’ll have a look at combining the undercut shuts with the core pins, but I’m not even sure that 6mm x 110mm pins in core sand are viable.

 

Sorry I'm late for the party, but from your first pictures I would stand the pattern on edge and put draft on the top and bottom of the link, on the wear surface. In other words put one row of rollers in the drag and one in the cope. Easy casting job because you don't care too much about shrinkage on the wear surfaces.

The complex castings shown later in the thread probably have the undercuts to avoid shrinkage.

I may disagree with Kelly, for limited movement aluminum would work, but aluminum bronze, if you can cast it to machine, would be a good alternative.

 

Hi Andy, thanks for that, your idea works a treat however, I have a couple of questions -
How do I hold the pin core in the cope? The top face of the tread link has a rim to locate a rubber tread (see photo). This will be an undercut; what can I do about that?

 

You hold the pin core in the cope by running the core down to the surface of the drag, like a swing set with filled in ends. Or you add a cheek with core prints at the cheek to cope joint.

However I question using cores at all. You need to line bore the holes and both sides need to be parallel. Cast holes are difficult to drill off center. I would leave them blank and bore them where I want them.

I really can’t see why the rim is an undercut. Can you kindly sketch a cross section?