any better method on 1/2" acrylic?

[knight_toolworks]

if I am cutting thinner stock I use the pressure foot to hold it. But when I am cutting 1/2" like I am now most of the letters are not really large. so I have been cutting it with a standard 1/8" upcut endmill I had been cutting it at 1ips in three passes. but today I tried it at .7 in two passes without problems. Sometimes I can get away with 1ips in two passes sometimes the bit breaks. I use vacuum to hold it in place but sometimes the sheet lifts around the edges so I screw around the edges to make life less problematic.
I use a 1/8" bit as it leaves the shavings in the slot so the parts stay put they don't melt though. The bad part is it takes work to get them out of the sheet as they are wedged in well.
this method works well but it is pretty slow. but I don't loose parts and I can use cheap endmills.

[Brady Watson]

Vacuum Film (http://talkshopbot.com/forum/showthread.php?t=11481&highlight=vacuum+film) :rolleyes:

-B

[letterman7]

Yep, Brady's method, or start putting bridges on the letters to keep them stable. More work in the end, but whatever makes the job easier to manage..

[knight_toolworks]

well ya but that would cost more then the extra time it would take. but would the tape hold with a 1/4" bit? a lot of times I have to use a 1/8" bit anyway and if I do I never have lost parts as long as I add a few screws around the outside . I was thinking of trying a 5/32 upcut in the 1/2"
The method only works for letters over about 3" smaller letters will come loose then I have to use some other method.

[jerry_stanek]

on small letters I use carpet tape. Also use the pressure foot. If I cut with a 1/4 bit I leave a skin and use this router bit to clean up.

http://www.amazon.com/Amana-Tool-MR0102-Bearing-Diameter/dp/B002QB0PVU/ref=sr_1_1?ie=UTF8&qid=1326321322&sr=8-1

[Brady Watson]

When cutting acrylic, you want the largest diameter bit you can get away with in order to keep vibration and deflection to a minimum...because...you want the best edge quality you can get when you pull parts off the table. Even a 3/16" diameter is better than 1/8" because if you do the math, (solving for cylinder volume), 3/16" is 2X as stiff as an 1/8" cutter of the same length, with a minor penalty of and additional .031" radius on the inside corners (.0625" diameter increase).

Waterline/stepdown marks are unacceptable, especially because you can cure this with your toolpath strategy. Customers happily pay for quality. If they can't swing the extra cost of coroplast @ $7 for a 4x8 and some tape...then it might be time to get new customers. If you kick up your quality a few notches, you'll get customers who appreciate quality...and then you get the bigger jobs...and you make more money...I'm being practical again :rolleyes:

-B

[knight_toolworks]

yes you are. Most of this is for signs and my main customer told me not to worry about the edge quality. I mean you don't see it for the most part and I have not been able to raise his prices much since he was my first customer for signs. He just wants it fast and I seem to specialize in turn around speed.

[gundog]

on small letters I use carpet tape. Also use the pressure foot. If I cut with a 1/4 bit I leave a skin and use this router bit to clean up.

http://www.amazon.com/Amana-Tool-MR0102-Bearing-Diameter/dp/B002QB0PVU/ref=sr_1_1?ie=UTF8&qid=1326321322&sr=8-1

Jerry Amana makes a 3/16" flush trim bit I use them I like them better than the 1/4" it is much easier to maneuver the bit in the 1/4" slot.

[jerry_stanek]

the bit I posted a link to is a 3/16