[buddym]

Hi all,

Today I put a speed controller on my router and set the speed as low as it will go. Cutting softer plastic at .08" per pass was easier than ever. I am using a 1/16 solid carbide Onsrud upcut bit made for plastic. I had no problems with melting or material gumming onto the bit.

My machine is very slow (9-10 IPM) and I know that's a problem. I have new hardware on the way and will soon be up to at least 70 IPM. Using my current configuration I was still unable to make cuts on plexiglass (from HomeDepot) without almost instant melting and gumming of material onto the bit. Will the faster feed rate on the new machine really improve the cutting of plexi to the point where I wont have this issue?


I had made a more succesful cut at higher bit speeds a few days back by using a spray of water mist onto the bit while cutting. While this did help some it seemed as though it possibly had a negative effect on the bit, maybe rapid heating/cooling made it even more brittle (solid carbide). It broke while making a slow, shallow, straight cut. I can't afford to keep breaking these bits at $20+ each.

It will be about a week until I can assemble the new machine and make test cuts at the higher feed rates. I am anxious but leary of getting my hopes up that this will put an end to my problems cutting plexi. I wanted to know what you all thought..

thanks,
Buddy
Tampa,FL

[SatanKlawz]

I am still building my cnc but I have been working with acrylic for years with conventional tools, a hand held router, and using a router table. I mainly work with 1/4" and 3/8" material but have worked with thickness up to 1.5". My router speed is non adjustable (24k rpm) and I use both a 1/4" width and 3/8" bits. In my expierience it does not care how slow I am going but it does start to do some weird stuff when I pick up the speed. I always try to set it up where I can make a finish pass because pretty much any interior cut is going to leave a bad edge and a finishing pass cleans it up perfectly. Also cast and extruded acrylic machine totally different. Cast has a much higher heat tolerance and will be easier to machine perfeclty without it "gumming up" all over your mill. I would suggest making several passes to cut through the material.

[BobF]

Yep, cast acrylic is the way to go. I slow down the bit and run the feed rate as fast as I dare, depending on the part shape. The Onsrud single flute cutters are the way to go if you can. The site has a lot of good info on feeds and speeds. Just googl Onsrud cutter.

[woodworker2]

I buy and cut quite a bit of HDPE, and the supplier I buy fromn has always recomended to me to use a single flute bit and run it between 45 to 65 ipms. The single flute should keep the acrylic from melting and gumming up the bit. I can usually cut up to 3/8" at one time on some thick hdpe. Hope this info helps.