Also my first litho

[dighsx]

You could always put the plexglass behind it to stiffin it up a bit?

[CRFultz]

You could always put the Plexiglas behind it to stiffin it up a bit?

Good ideal Jay...they are fragil...the plexi would add to the strength...

[dighsx]

What would be best is if you could glue the plexglass to the corian. That would really make it stronger. The other thing that's good about plexglass is you can get it at just about any hardware store worth it's salt.

[Perry]

Here is a couple of shots of a recent litho done of my son (always a favorite test subject!!)

[Peter Stenabaugh]

Perry, can you clarify your settings that you used. You stated that the cutting board was .5" and you dressed it down to .250". Then you roughed it to .220 and you final machining pass to .245" That all adds up to only .005" of material left!

Are these numbers correct, or have you given us some mixed up ones?

I want to try some PVC on my mill but I cannot attain speeds of 2.5 ips, but then again my mill does not run at 16,000 rpm either, so I will have to do some extrapolation and slow down the speeds and feeds.


Pete

[Perry]

Hi Peter.
No, there are no mixed up numbers. On that first sample that I started this thread with, I did use a poly cutting board and at the "thinnest/brightest" areas, it was permitted to machine down to within 0.005" of cutting through. I found with the opaque white of the board that this did not give an excessive contrast.

Now having said all that, I will say that I no longer use the poly. I have discovered for myself the true benefits of cast acrylic. With it, I will allow the software to calculate a depth no deeper that 0.025" of cutting through. Or said another way, the brightest areas will be no less than 0.025" thick. I have found that in this bone coloured acrylic that any deeper than this gives the "brighter" areas too much contrast as compared to the areas with minimal machining.

[Perry]

Hey stewbidasso.
I have too apoligize. I had missed your message from Aug with your question.
The closest town to us is Belle River. This is just outside of Windsor, which is across the river from Detroit, Michigan.
Came to this part of the province while looking for work (about 13 years ago).
I am originally from Cambridge/Kitchener area of Ontario.

Where are you residing now?
Should you be in this neck of the woods, look us up!

[Peter Stenabaugh]

Thanks Perry.

I will have to check out a local source for cast acrylic. I have a bunch of free 3/8" lexan I can experiment with as well. A friend wants me to do a photocarving of his pet MG car, so that will be a good test with some lexan.

Pete

[Perry]

Hey Peter, I would approach Lexan with caution.
It is an extruded plastic, therefore it has a lower melting point.
I beggered up some tooling a while back (pre cast acrylic knowledge days). I managed
to get about 2 minutes of cutting before the material (plexiglass I think) went from hot to cold quick enough to solidify
the bit stationary.
TOTL DISASTER! Since then I stayed away from plastic. UNTIL.....
The ebay company I bought my cast acrylic from is here:

http://www.delviesplastics.com

I have no complaints about this company and my transactions with them.

[dighsx]

Hey Perry thanks for the site. I've been looking for a good deal on buffing wheels and there prices are pretty good when you buy by the dozen. Their plastics prices are good too. I bought 5 12"x12" squares off of ebay for 67+shipping. You can get a 24"x48" (which would be 8 - 12" squares) for $99.52+shipping. So they're cheaper then the deal I got on Ebay.

Thanks again I'll add these guys to my suppliers bookmarks.

[Perry]

That's why we are all here. To either help or be helped.
Glad it helps you.

PS. Look for Delvies stuff on ebay. Better prices yet

(We really should get together and "talk shop").

[Peter Stenabaugh]

Thanks Perry,

Actually Lexan will machine quite well, it is just a matter of finding the correct speeds and feeds for your cutters.
My previous tests on my wood router were no good as my machine will only feed at 20 ipm max before it starts to
skip steps (really tight machine). My min router speed is 8000, which may be ok if the feed was high enough, but now
I can do it on the mill........

Here is a link to a site that shows one good method of testing for correct feeds and speeds in various materials:

http://precisebits.com/tutorials/calibr ... speeds.htm

It give a good explanation on the subject. I have yet to do the testing, although perhaps this week, as I now have
my cnc milling machine conversion completed, painted, finished.........just have to work out the 4th axis adapter to
attach a stepper to my rotary table, then we are totally done.

Next project design and build a proper cnc wood router, something that will be rigid and give me feed rates up to about
250 ipm at least.

Later.

Pete