Re: [CAD_CAM_EDM_DRO] Re: Green florist foam is great!

Hi Roger

Would you have any idea if this material could be painted? And if so what kind of paint would work?

Thanks,
Bob

----- Original Message -----
From: vrsculptor
To: CAD_CAM_EDM_DRO@yahoogroups.com
Sent: Friday, November 21, 2008 9:04 AM
Subject: [CAD_CAM_EDM_DRO] Re: Green florist foam is great!


Steve,
The following process is dangerous and, according to some scientific
types on these boards, just an urban legend like cold fusion. I can
only say it works for me.

The problem with machining regular petroleum based "Gulf" brand wax is
that it melts as much as cuts leaving a rough surface and loaded
cutter. Commercial machinable wax is much harder, machines great but
costs about as much as aluminum. I saw a suggestion on the web to add
polyethylene shopping bags to wax to make it harder and therefore
easier to machine.

The process for making bag wax is simple, melt standard petroleum
based wax and add shredded thin grocery store plastic shopping bags.
The more bags you add the harder the wax. From watching the process I
can't say if the bags melt or are chemically dissolved by the hot wax.

Unfortunately the bags only combine with the wax at high temperature,
probably very close to the wax's flash point. Caution, wax fire are no
fun. I heated the wax very slowly with a single strip of bag. When I
saw the bag start to dissolve I slowly added more strips. It seems
that as you add strips you raise the flash point of the wax which in
turn allows you to gently raise the temperature which melts more bag.
I don't know what ratio I used. I killed a lot of bags. I made about a
10 pound batch. I think that the temperature is easier to control in
larger batches.

It remelts strangely. When it first melts it is a lumpy mixture much
like cold gray. At some magic point it transforms into a clear amber
liquid. When used as a brushing medium the usable temperature range is
narrow.

My wax is pretty hard and machines fairly well. I was cutting with a
1" 4 flute ball end mill at ~6K RPM at 80 IPM. The shape was very
organic very 3D. Roughing was done with a .5" step over and .5" step
down. 2 parallel finishing passes were done at 90 degrees to one
another with step over set to leave .010" of fluting. After first
passes on foam I brushed on wax and repeated finishing passes. Finish
was good.

Your mileage may vary.

Roger

>
> Could you elaborate on the "bag wax" procedure
>
> Thanks
> Steve Tompson
>





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