Thats not a bad idea Hul. Maybe some of those toggle type clamps would
make it easy to do. Thanks.


On 20-Mar-18 5:54 AM, Hul Tytus wrote:
Perry - do all as you describe but skip the vacuum and use two hold down
clamps on the surface you're cutting. Use the clamp on the left while you
surface the right side and the opposite. If too costly timewise, you'll at
least get a look at the finished appeareance.

Hul

Perry wrote:
I need to flycut the top face of an irregularly shaped cast epoxy part.


The part is cast using epoxy into an open top aluminium mold.
When the part is removed from the mold there is a meniscus type sharp
flashing along the edge.


What I want to do is flycut about 1mm of material off this face to
remove the sharp casting flashing and to create a smooth surface.

The only way I can think of holding it is in a vacuum chuck of some sort
as the four sides are sloped (like an inverted flat top pyramid).


Part side view is as below;


Need to flycut this top face
----------------------------------------------------
\ /
\ /
\ /
\ /
-------------------------------------------


-----------------about 7"/175mm long-------------

The part is about 2"/50mm wide and just over 1"/25mm tall.
The bottom face is say 6" x 2" = 12" squared.

If the vacuum pump sucks down to say 1/2 of atmospheric then I should
see 12 Sq Inch x 7.5 Pounds/Sq Inch = 90 lb down force.

The angled sides of the mold should prevent the part being thrust
sideways when flycut.


As all four sides are sloped I had thought of using a second aluminium
mold as a vacuum chuck. I would have to machine 5mm machined off the top
to expose the top face of the casting that needs to be machined back. chuck.

I could plumb a vacuum line into the base and use a refrigeration style
vacuum pump to hold the part down and then flycut the top.


Will it work?

Should I use a die grinder to run a few slots for the vacuum to spread
around in the bottom of the mold base used for clamping?