[jcposada]

Hello everyone -

I have a customer who is requesting a thin bowl-shaped part. He said someone who did parts for him in the past machined it by doing the hollow side first, then filling the cavity with a heat-release epoxy made by 3M before flipping the part over to machine the other side.

I did a quick search looking for an epoxy made by 3M that can be heat-released and came up empty-handed. Does anyone know of such a product or have any other tips on how do make this?

Thanks!

[popspipes]

https://www.google.com/webhp?sourcei...wax%20compound

I think this is the stuff you need.......

[kstrauss]

I've had some success with similar jobs using fixturing wax., See MachinableWax.com - Product Details | Rigidax Tooling & Fixturing Wax | Fixturing Waxes | Rigidax | MachinableWax.com, Inc. for the stuff that I've used. Unlike an epoxy you can melt it and reuse many times.

[MichaelHenry]

That sounds like the sort of part that might be better made by metal spinning. I have a friend who does that sort of work and once the pattern is made, I think that the spinning part goes pretty fast.

[jcposada]

I don't know much about spinning, but is my assumption right that it only works for symmetrical parts?

[GLCarlson]

Agree with the metal spinning comment.

You might also try fusible alloy (Wood's metal, Rose's, that whole set). The advantage is that it's re-usable, melts at hot-coffee temperatures, and very handy for fixturing because it expands on cooling. Self tightening, in other words. And it doesn't wet much of anything very well; cast iron is sometimes a bit tricky. The disadvantage is that it's heavy, expensive ( for volume bigger than about 4-8 ounces, very expensive!), and some of these alloys contain nasty to very nasty metals (cadmuim is the one that comes to mind). But. If you happen to have some of this stuff, it'll solve problems nothing else will and it stands up to aggressive -though not interrupted- cuts on lathe or mill. The toxicity is greatly overblown, in my opinion- wash hands, don't overheat, and don't season lunch with it, and it's fine.

Added: most epoxys are not very heat stable (several hundred degrees). Fumes are medium to bad news. Might try polycaprolactone, too. One trade name is Instamorph. Also great for fixturing, but not real resistant to machining forces. Also re-usable.

[kstrauss]

Yes, the parts are symmetrical about the axis of rotation. If the pattern completely fills the part (some items are spun without an internal pattern) then obviously the open end must be larger than the middle/bottom. The original poster didn't specify the thickness of his part but spun items are typically quite thin. Search for "metal spinning" on Youtube for some fascinating videos.

[jcposada]

Thickness of part I question is 2mm. Unfortunately it's not symmetric, the shape is similar to a clam shell.

[kstrauss]

Material?

[CadRhino]

Spinnings can have lots of cleanup.

I don't know much about spinning, but is my assumption right that it only works for symmetrical parts?

[MichaelHenry]

As you've already figured out, metal spinning is not an option for unsymmetrical parts. Explosive metal forming, however might be a possibility