[lclore]

Hello,
I am hoping I can tap into the knowledge out there... I need to mill a small disc (80mm dia x 12mm height), ideally on a cnc router (so I don't have to buy another machine). It could be aluminum, but for cost reasons, I want to evaluate a plastic.

I am looking for a material recommendation- The router likes to run at 10k+ rpm. I have outfitted the router with high speed feed motors/drives so it can rip thru material at a pretty good feed rate. In reading the threads in the forums, it looks like melt is a problem with these router motors unless there is a high speed feed rate with a high rake 2 flute end mill. I also saw some references to light soap water based cutting fluid.

Sounds like UHMW is about the lowest cost material that will run ok. What about PVC or some other low cost materials?

Any one cutting plastics with a higher speed router motor? Can I tap into your experience?

Thanks
Lee

[BobF]

Use a super O flute bit from Onsrud. You can cut most plastics. Run the router at 12k or less. Feed rate high as you dare. Acrylic cuts reasonable well as does UHMW and HDPE. Look at the Onsrud site and find the plastic cutting info as well as lots of good info on other materials. https://www.onsrud.com/xdoc/FeedSpeeds
Don't know your application so can't recommend a material.
You can also cut aluminum with the that bit and a router. Slower feed rates and small cuts are your friend for this.

[lclore]

Thanks for the feedback BobF- I appreciate it!

The part application is for an industrial control device that has the following machined features-
* Finish OD to 80mm- should be esthetically good finish on this cut only
* Finish Height to 12mm - rough cut with finish pass
* Relieve interior of disc with rough cut and finish pass to 3mm base leaving 6mm on outside wall
* handfull of thru holes in the base, not much of a concern there.
* here is maybe the tough one- in the wall between the OD and ID is a 1mm groove at 5mm depth.

Tool change will be necessary.

The material color will ideally be flat black. other colors ok, but not clear.

[BobF]

Thanks for the feedback BobF- I appreciate it!

The part application is for an industrial control device that has the following machined features-
* Finish OD to 80mm- should be esthetically good finish on this cut only
* Finish Height to 12mm - rough cut with finish pass
* Relieve interior of disc with rough cut and finish pass to 3mm base leaving 6mm on outside wall
* handfull of thru holes in the base, not much of a concern there.
* here is maybe the tough one- in the wall between the OD and ID is a 1mm groove at 5mm depth.

Tool change will be necessary.

The material color will ideally be flat black. other colors ok, but not clear.

Sounds like it only leaves 4 mm thickness below the groove.
I would try black UHMW first. You can buy it in 1/2" thick sheets and and that should allow for 12 mm finished size. You may also find 12mm, but I haven't seen it in a quick google.

[lclore]

I am reading on Onsrud's Super O Cutting tools. They endorse milling ABS with the Super O at higher spindle speeds (~18k RPM). ABS is attractively priced... Before I go buy some bar stock, I thought I'd ask if anyone can share their experience with ABS... good/bad/ugly?