M-35 trollys.

[Monkeypirate]

I like to try different things as such I am now moving into the area of metal sand casting and such.  As such I would like to make my own trollys for my M2. But I am in need of a trolly to make a pattern from.  Is there any one who would be willing to lend or rent one too me ? I would like to take the whole thing down, make silicone molds of the cast parts and measurements off all other parts such as bolts and bearings. Then I am going to use the silicone casts to make wax plugs and cast the parts using investment casting. Right now this is in a planing stage but I like to research things and see what others think of the idea. 

[Tranham]

Might help to know your location and previous experience / current access to casting metal fabricator.   Not a lot of people want to let a $1500 trolley be borrowed by a stranger.

[Monkeypirate]

I understand that. I am in Wittman AZ.   Like I said.  Im just getting into casting and We are still building the equipment. Right now we only have a small burner that melts aluminum. I will need to build a small Copula to melt iron or steel. I would prefer to buy a trolly, but finding one for sale and having the money at the same time are not likely.  even if there is some one around that would be willing to let me come out and take a lot of measurements off a trolly and possibly their skate rail that would work for me too.  like i said. this is just kinda a planing stage. I have a lot to do before I'm to this point.

[autocar925]

You can't make a pattern off a casting of a casting.  When making a pattern, the pattern must incorporate "shrink" into it.  For steel this is usually around 1/4" per foot.  The molten metal fills the mold void but when it cools it shrinks and is smaller than the void made by the pattern.  If you make a pattern by casting a pattern off a finished piece, your casting will come out smaller than the original part.  A trolley is about a foot long so your casting will be 1/4" too short in length and a proportionately shorter amount in all directions.

[Monkeypirate]

That is a good point. I guess I will just have to make a plug that's about 5% larger. I can see why even replicas are so expensive. Lots of effort going into them.

[johne504]

looking for a trolley for my M2A1 track, for the .50 cal ring... any leads would be great.  thanks. john 509 554 0526   engelkeelectric@hotmail.com

[Monkeypirate]

BMGparts has the 6540721 Skate on their site but it does not say weather they are in stock.

[woodwalker]

Fella in Italy on eBay had them.
If you had access to a 3d printer you could print a trolley with the shrinkage figured in but knowing the exact amount for the metal composition you are using would take a few experiment

[superjeep]

I have NOS trollies but they have no parts on them. You could make some rollers for it and be able to attach them to the ring and put a gun on it but they would be no brake or any other parts. I think BMG may have some of the parts but not all. I'm asking $225 for the bare NOS trollies

[SgtKish]

Would you happen to still have those castings ?
I would be interested, thank you.
Mark

[Monkeypirate]

No Castings. I have a 3D model i made of the parts but it is by no means "professional". Eventually i will get to it and make a 3D scan or the parts i have but i was planing to just 3d print a mold and sand cast the parts out of Aluminum.  Thats a ways down the road though.

[cfaust]

Hello, I'll add what little I know about metal (cast iron) casting and that's not much......but you can make a casting from a casting and there is shrinkage involved.  However you can control the shrinkage if you know how.  That is done by adding control points of extra material in/on the part being cast, this acts as heat sinks that control shrinkage to a minimum or none at all.  Also matters in the alloy, not all cast irons are created equally.  Not trying to cause a blow-up here just adding my two cents, probably where it is not wanted.  Anyway there you go.

Chris

[Monkeypirate]

Casting is definitly not a " just start doing it" hobby. Cast iron and steels teand to shrink about 2-5% depending on mix. Thats the reason im planing to make molds with my 3d printer as i can scale them up or down to compensate for shrinkage. I will have to start by making a mold of a rod with a known dimension, cast that with the material i plan to use then messure it and calculate the shrink rate. Its gonna be a lot of trial and error. Casting the main carige frame will require green cores and multi piece mold. The better option is to do lost wax casting. More expensive but much easier to do. I always like to hear views on what people think or experience as long as its not the usual " you cant do that because i dont think you can" reply that is famous on a lot of sites.

[cfaust]

If someone else did it, it can be done....no doubt.  I've studied on and talked to lots of people about casting and always wanted to set up a small foundry but just haven't found the time.  But when studying what others have done, I read where this one well experienced guy was casting model T or A Ford engine heads  and other parts without any shrinkage by adding the "heat sinks" on his new casting and then cutting them off during the finishing process.  I use to work for Kohler Co. and talked with a couple of our their metallurgical engineers that worked at our foundry and others foundries in the area of Kohler, Wisconsin about casting iron and other materials (stainless steel, alloy steel, brass, etc.) even got to tour the brass foundry once but not the cast iron foundry (at that time Kohler had moved a lot of their cast iron to China from Wisconsin, I felt it was a shame).