Hand grinding a 3" long 1/4" diameter straight flute, single flute, endmill for cutting styrofoam

[homebrewed]

Hopefully not to take this thread too far afield, I found a very interesting thread on a totally different way to cut styro. It uses a rapidly reciprocating needle to basically punch out the shape-- see here. Some of the background threads on that web page are dead, but there should be enough info here & there to get the details.

The advantage of the needle idea is that you can use a much smaller tool. I'd guess there is a lower limit -- if the diameter is too small the "tool" would flex....but it's likely you could go to something much smaller than 1/4".

Not knowing exactly what kind of setup you have, it's hard to tell if this would be relatively easy to try. The original application is on a CNC router table type setup, so there is plenty of Z available for the reciprocating mechanism. It would not be so straightforward to fit on a milling machine.

 

[python50]

Hopefully not to take this thread too far afield, I found a very interesting thread on a totally different way to cut styro. It uses a rapidly reciprocating needle to basically punch out the shape-- see here. Some of the background threads on that web page are dead, but there should be enough info here & there to get the details.

The advantage of the needle idea is that you can use a much smaller tool. I'd guess there is a lower limit -- if the diameter is too small the "tool" would flex....but it's likely you could go to something much smaller than 1/4".

Not knowing exactly what kind of setup you have, it's hard to tell if this would be relatively easy to try. The original application is on a CNC router table type setup, so there is plenty of Z available for the reciprocating mechanism. It would not be so straightforward to fit on a milling machine.

Holy Cow! (pardon my language) That is an amazing, and clean, way to cut 2D shapes from Styrofoam. I think I need one of these.

Thank you for sharing!

 

[pontiac428]

I make aluminum castings via the lost foam method.

Please stand away and upwind while pouring! Sounds like a useful method, minus the cancer death smoke.

 

[python50]

Please stand away and upwind while pouring! Sounds like a useful method, minus the cancer death smoke.

Indeed, I always try to do quick pours and hold my breath - there are plenty of fumes in casting even without the burning investment. The vaporized foam imbues the sand and casting boxes will a very strong and particular smell that takes weeks to dissipate.

The upside of the process is that it doesn't need special sand and no draft angle is required. Complex shapes with internal cavities are easy. The downside is porosity and "flow" (or lack thereof) through thin foam sections.

 

[whitmore]

Hopefully not to take this thread too far afield, I found a very interesting thread on a totally different way to cut styro. It uses a rapidly reciprocating needle to basically punch out the shape

Cute idea, and... on looking into sewing needles, the 'for leather' types are actually slicer/cutter needles.
If you use the flat on a sewing-machine needle for alignment, that means you could divvy up the CAD curves into
E-W, N-S, NE-SW, NW-SE nearest-orientations, and make several passes, to really make cutouts of the foam (with
a lot fewer cycles of the needle per inch of travel). I was also thinking of Cricut, and swivel-knife, options, but
this one seems simplest, and ought to be effective.

What I don't know, is how the CAD software can support
the 'orientation of curve' decisions that are required.
A CNC router wouldn't have cut-direction-dependence, of course. But, it might be able to
do a down/up cycle and so not require a reciprocating mechanism.

 

[Latinrascalrg1]

Indeed, I always try to do quick pours and hold my breath - there are plenty of fumes in casting even without the burning investment. The vaporized foam imbues the sand and casting boxes will a very strong and particular smell that takes weeks to dissipate.

The upside of the process is that it doesn't need special sand and no draft angle is required. Complex shapes with internal cavities are easy. The downside is porosity and "flow" (or lack thereof) through thin foam sections.

To counter act this have you ever tried dipping your foam forms into a thinned plaster slurry a few times to build up a thin shell? This will help with surface finish as well as helping with the flow in the thin areas.