smooth finish turning acrylic

[dlh422]

Attached is a pic of the cnc lathe that I got this year. It uses a horizontal laminate trimmer as the cutting tool. I've been turning wood and acrylic and using a triple fluted upcut solid carbide router bit. It removes the material well enough I suppose but leaves a rough surface. Does anyone have any suggestions on what type of bit to use to get a smooth, or at least as smooth as possible finish. Perhaps an v-grooving bit. I'm tired of sanding and polishing. especially the acrylic.

thanks,

dh

[Pat2000]

Can you give any more details as to what kind of finish you are getting?
You might want to reduce the cutting speed if possible if you are getting burning/whitish marks, maybe drop down to two flutes? to help with swarf removal and maybe use coolant if thats not going to be too messy for you, do you have an air-line? we use them a lot at work to blow the swarf from the flutes,

I mill quite a lot of acrylic at pretty slow speeds compared to routing, hope that helps but you need to detail the problem a bit more!

[dlh422]

thanks, I actually have a couple of video clips which might help but haven't been able to attach either one, even zipped. and I'll get some close ups of the finished pieces too. I'll get more details for you but have a hungry 4 yr old yanking on my arm at the moment. thanks for the reply.

[dlh422]

Pat,
Attached are a few more pics. One of the machine, and two of the parts. One of the parts is polished and next to it is how it comes off the machine. As you can see it's rough, whitish and includes the swirl tracks. I don't use coolant and I suspect it would be pretty messy and I'm sorry nor do I have an an air-line either. I still can't attach the video clip. It must be too large.
thanks,
dh

[dlh422]

well, not all that whitish but mostly just rough with the swirl tracks.

[JoeFL]

It looks like you might be turning a bit too fast.. I'd try slowing it down a little.

I also agree with Pat on using a 2-flute tool and compressed air directed at the cut area for cooling/swarf removal. See if that doesn't help...

Nice work, by the way.

-Joe

[ger21]

If it's cutting on the end of the tool, you're going to have a very hard time getting rid of it. I'd recommend using the shortest tool possible, to minimize deflection, and make sure it is extremely sharp. Have you tried a round nose 2 flute bit?
http://www.pricecutter.com/product.a..._A_cn_E_243667

[dlh422]

yes, it is cutting on the end of the tool. I haven't tried anything but the flat end bit. I thought the v-groove might be good but I'll give the round nose a try too. The router is removable so ultimately the best solution may just be to remove it and mount a stationary cutting tool. I'll have to have that machined though.

thanks for suggestions.

DH

[chan luci]

Hi,
I have lots of experience in acrylic turning. High speed is a MUST. And after the final cut, you can use a smooth silk or synthetic cloth to wipe part when the job rotates on the turn machine. Repeated run gives an excellent glossy and transparent finish.
Let me know the outcome of the result.

[Pat2000]

Sorry dh not to get back to you, interesting parts you're making, it seems that cutter deflection may be one of your probs?, hard to see quite tho, so go with that short cutter if you can, bigger shank on the cutter maybe? have fun!! where do you get that kind of greenish shade of Acrylic, I do like Acrylic it has such a juicy transparency!!

[dlh422]

I've been meaning to get back with an update but just been covered up... I ended up ordering a round nose like ger21 recommended. In fact it should be in today so I'll give that a try and see if it helps. I'll post an update when I get some results.

there's a place called delvies plastics that I've been ordering my acrylic from. They have a pretty good selection of colors to choose from to so it's lots of fun.

thanks,

[scubanick]

looks kinda like some duck calls we are making