The problem with router speeds and plastic.

[dbtoutfit]

I tell ya, I have been at this hard for 3 straight days and off an on over half a year and I am about to pop.

I am having a haaaa-raaa-able time trying to decide what to do about my spindle issue.

Right now I am running a RotoZip R20 (with the built in SC) the slowest I can run it down to is 15,000 RPMs. Needing to run a 1/32 end mill through plastic, is causing a major issue with melting.

So I looked at some fixes/options:

1) Grab a Router speed controller.
Result: This will not work at all. Will not even turn the spindle.

2) De-soldered the built in speed controller from the rotozip and then use the router speed controller.
Result: All this does is cause glitches in the spindle turns. It feels like pulses being sent through the brushes so the spindle is very unreliable.

3) Try a variac, this should work (I'm thinking) as the spindle slows down to a nice speed when I have my portable heater plugged to the same power strip and turned on.
Result: Well seeing as I have read a bit about the risk involved with a variac and the cost it seems I would be better off thinking of going with a new router/spindle.

4) Get a new router/spindle. Other than having to make a hole new bracket to hold the new router. I run into other problems.
Result: A) At best I have found a router that runs as low as 8,000 RPMs.
Is this slow enuff? If not will my router speed controller work?
Specs do not say its a soft or slow start so does that mean it will
work? The rotozip doesn’t say that either but it doesn’t work.
B) Will only accept 1/4 or 1/2 bits ( I am using mostly 1/8th shaft bits)
so I have to spend another $70 for a collet?

I hope someone can take the time to answer these questions as I am sure I could not be the only one that is having or will have these issues.

Thanks,
Eric

[ger21]

How about some type of coolant? Even compressed air blown on the cut to keep the chips clean. Also try increasing the feedrate. With a bit that small, though, it's going to be tough to keep the plastic from melting . You need to get the chips out of the cut.

[dbtoutfit]

I agree.

I through my dremel on and brought it down to the slowest speed.
It was doing great but then on some passes it would gum up.

It looks like I am going to have to go to different material.

Due to where my machine is I cant used compressed air to remove the build up.


Anyone have an suggestions on cutting fiber glass or carbon fiber?

Would my rotozip melt the epoxy?


Eric

[lepton]

I had same problem trying to cut 1/8" ABS Plastic. My speed control is an Light dimmer and a AC volt meter controlling a 2 HP router.

I tried a 1/4" two flute straight bit, but melts, so I got an 1/8" upcut spiral bit. works a lot better. The up cut design pulls chips up. I would recommend to still blow/vacuum chips out.

[dbtoutfit]

Well after all the problems I finally got a finished product only to find it's to weak.

I need to use some kind of plate material like carbon fiber or harder plastic around .060" thick.

The bits I am using are $32 carbon upward spiral flute end mills from a machining company and are suppose to be perfect for these materials.
So I was told.

Can someone suggest an attractive plastic material that would be a good replacement for Carbon Fiber or aluminum? I like HDP but it's typically heavy and I am not sure I can even order it thin as I need it.

I would like something I can mill with my rotozip which runs only as slow as 15000 rpms.

I am willing to use aluminum as well. I have never milled aluminum with my machine, yet.

Thanks for any replies.
Eric

Weight is an issue.

[InspirationTool]

Glass filled nylon or polycarbonate? I have no idea how they cut.

Can you use a laminate trimmer instead of the dremel?

-Jeff

[dbtoutfit]

Thanks for the reply, yea I can use my rotozip. but im limited to 15000 min rpm

I hate the dremel poor accra.

Eric

P.S. I did grab some of art hobbies last batch of gold Carbon Fiber from the hobby store so I guess I'm going to learn how to cut CF now till I come up with something else. $33 bucks shew, for 12.6 x 6.5". Might be an expensive learning curve.

[Smackre]

I would go with a garolite. I believe its what alot of people call fanolic. It machines like butter but yet is vary strong. Its 10x nicer to machine than plastic. I buy it from mcmastercarr.

[Dennis_f]

Originally Posted by dbtoutfit Anyone have an suggestions on cutting fiber glass or carbon fiber? Would my rotozip melt the epoxy?

Where i work we use diamond bits to cut in fiberglass. No coolant fluids or compressed air.
Epoxy can not melt when it is has hardend, because it is not a thermo plastic.

[broncosis]

where I used to work we made prosteics and we used a rotozip to cut plastics and fiber glass by hand using the actual rotozip bit with no speed control at all


not quite sure what the application for this part is but you could try a delrin there are a few types available I know Mcmaster has some also I get mine from IPP.net not sure if there is one near you though

[mklb]

You need to look at

www.precisebits.com

They are absolutely the best when it comes to small specialty bits for different kinds of materials. Us pool cue makers swear by them and they cut all kinds of plastics, hard woods, reconstituted stone and Ivory. I also cut carbon fiber and use their special bits for that. If you look at their site and don't find what you are looking for, then just call them. They have the best customer service I have found.

By the way, I am not affiliated with them in any way other than being a satisfied customer for the last 15 years.

As far as what material to use, I am not sure what you are building, so that makes it difficult. By the sounds of it sheet phenolic would suit your needs. Sheet phenolic is available in different colors and thickness in just about any decent sized city in the US. You can also find it at McMaster Car and others like them.

Royce Bunnell
www.obcues.com

[thinkntink]

The main problem with using a RotoZip is that the runout of the collet/spindle- bore combination can wobble the bit so much that plastic is melted and "flashed" up by the non-cutting surfaces of the cutting tool. Nonetheless, you can often find a sweetspot that will accommodate the bit wobble using a pretty simple method. Go to:

http://www.precisebits.com/tutorials...s_n_speeds.htm

Set up for woodworking but works great on plastics. Also read:

http://www.precisebits.com/tutorials...moplastics.htm