Sand casting Caterpillar track links in aluminium

Sorry it’s just a rough sketch, hope it helps

 

The image does show two concave areas where you indicated. But, why does it need to be concave there at all? The track would function fine if that surface were convex instead of concave.

Also, for what it's worth, I would definitely not fool with cores for 1/4" holes. They will ultimately require boring. Having a hole present from a core would add practically nothing and might actually make boring them on location more dificult. (If I had to bore an accurately located hole over a void made by a core, I would use an endmill for as much of the hole as possible as they will cut a hole pretty well where centered rather than follow a hole that may be eccentric to their location.) Certainly the hole could be conventionally bored much faster than the original core box and cores could be made, let alone located in the mold, prints made to support the core etc.

Denis

 

I've had some idle time and read this thread a bit more. The concaves are probably there to allow clearance for the adjacent ears to clear going around the sprockets.

Actually those should cast fine if you cut to the parting line.



Cutting to the parting line is beyond the scope of this answer. But it is easy. You could also add the cavities from the lug side which will probably be necessary to keep shrinkage under control. This would be a great match plate casting as well but it would take a thick plate and some good woodworking. With the match plate you can avoid cutting to the parting line.

 

Thanks Andy,
I can now see how it will work, the problem was in my head, when I looked at it right way up, the concave looked like undercuts, your upside down sketch cleared that misconception up.
I have seen Myford boy’s video on cutting to the parting line but a split pattern would make life easier. That will be easy to do as I will be 3D printing the pattern In the final design. I might consider a match plate, but I’ll try the split pattern first.
Thanks for your help Andy, you guys are the reason the forum works so well.
Jim

 

I suspected that the thin pin cores wouldn’t be viable, so plan “B” was always to bore them on the mill. Andy’s sketch helped me get the layup sorted in my head, but I will try a test casting with the prototype 3D prints that I have before finalising the design.
Thanks for your help Dennis and the rest who have taken the time to help, it’s appreciated.
Jim

 

Of course the split pattern is what allows you to cut to the parting line easily. When you first reverse the drag full of sand you still have to cut down to where you want the parting line. Although a full pattern could be used, you would just have to cut to the parting line everywhere and it would get tedious after several castings.

Glad you're making progress!

 

One other option would be to use a follow board. I use one on a pattern that has 7 or 8 cutout windows. Eliminates parting down.

Eventually you will want to cast ten-up. Using a match plate with runners and gates would be ideal.

Denis

 

I think that I’ll try a single first from one of the prototype patterns to find the weight, that will give me an idea of how many I’ll be able to cast from my crucible capacity. Just need a generous allowance for spruce/runner/gate/riser etc. I feel a bit more confident of it working now, thanks to everyone for the help.
I’ve just started doing a 50 hour inspection on the aircraft, so it might be a while before I can get on with it. At least it will give me some thinking time instead of rushing straight in, as is my normal approach.

 

I've got to study up on follow boards. I've read about them but really don't remember. Like everything else, until you do it, it makes little sense. Thanks Denis!

 

Thanks, Jeff.

 

Found this video on youtube showing how catepiller tracks being cast in steel, lots of cores!

 

Yes, those deep cavities would be challenging in green sand. Several interesting “advanced” techniques shown. I was just at a commercial foundry discussing with the owner the reinforcing bars hung in deep green sand molds—-he called it “hanging daggers.” Nice to see chaplets in use as well as learn the term “sprig” as applied to reinforcing nails driven into fragile protrusion of sand and “densener.” I could find reference to neither via Google search.

Denis

 

Nw that looks a bit complicated , I’ll have to watch the video several times to get my head around it. But certainly informative.

 

I think I’ve found the answer to my aircraft tug

 

4 miles, or 6.5 kilometers, to the bale of lichen.

 

Turbo boost with a bag of carrots

 

A bag of carrots gives full screech with Marmots:

" “So I need to go there,” I thought, “as Sarah will go out of her mind with those marmot-driven wood-lathes that are all running at full screech right now.”

“Full Screech is right,” said the soft voice as I made ready for bed, “though tomorrow might not be the best day for you to go. Mention the matter to Hans before you go to bed so he can fetch some for you if he has the time.”

“Is he bothered by marmot-powered lathes?”

“Yes, but not nearly as much as you would be,” said the soft voice. “Recall all of those farmers who needed buggy repairs?”

“Full screech, right?” I asked.

“They might not be as loud as that blower is at full 'howl', but they're a lot higher pitched – and every one of those animals has a bundle of carrots hung when it's running on the treadmill.”"

From https://www.google.com/url?sa=t&sou...FjABegQIBBAH&usg=AOvVaw0jih4L6FHPR6hcfXqVsz-W

 

If anyone is interested, the pretty little home build aircraft in the photo is a Bristell NG5, designed by Milan Bristella in the Czech Republic. Reindeer are an after market optional extra.

 

Jim, have you looked into the tracks that some of the Battle Bots use?
Those bots weigh in @250 lbs so they should have some beefy tracks.
Just a thought