Which CNC or mini-mill for plastics?

[daveb08]

Hi,
I'm new to this website (and forum) so I thank everyone in advance for putting up with my ignorance on the subject of CNC machining and terminology! I'm currently "milling" acrylic and delrin on my benchtop drill press with a x,y vise. Obviously, I'm very limited in what I can do with this setup. So, I want to purchase a benchtop CNC or mill machine - Sherline? Micromark? HF?

My projects include making discs (4"-8" diameter) out of square plastic sheets (1/4 - 3/8" thick acrylic or delrin), milling angles in discs (think of a wedge cut out of the top of the disc as you are facing the diameter), and milling down cylinders to create a half cylinder.

Thank you for any information.

cheers

[jalessi]

Dave,

What kind of budget do you have?

Welcome to the Zone,

Jeff...

[daveb08]

Hi Jeff,
my budget is < $2,000. Probably doesn't leave many options...?

cheers

[knudsen]

How fast do you need to remove the plastic? (meaning is speed a concern, or not/Chinese power vs. Sherline accuracy)

How important is accuracy? (again power vs. accuracy)

How much room do you have? (Two machines dedicated to two different tasks)

Is setup time an issue? (CNC or two mills vs one mechanically better machine)

Just guessing, if what you have is almost enough, you might benefit from a CNC'd Chinese mill, or two Chinese mills leaving your drill press to do some of the work. One mill always trammed 90 degress, the other tilted for the wedge cuts, DP setup for a single operation it's good at or for general use so you don't have to disturb a setup mill.

I don't know if you can do a reasonable CNC in your price range, but you should be able to swing two small Chinese mills + tooling that have plenty of power at the low speeds for plastics. Sherline would be nice, smooth, quiet and very accurate. The one I used was nice in every way, except it wouldn't hold a very large end mill, it wouldn't know what to do with it if it could, and you could bog it down easily in plastic. I haven't even seen a modern one, so I won't say that is true today.

BTW: Micro - HF - Grizzly - other China dealers, for the most part, if it looks the same, it is the same.

[ChrisPDX]

You may also want to consider the Taig CNC ready micro mill. I would order from Nick Carter at http://www.cartertools.com

Any machine in this class and budget will be somewhat limited in its travels (particularly the Y), but there are work arounds.

-Chris

[daveb08]

Hi Chris,
thanks for the input. I will check it out.

cheers
-Dave

[daveb08]

Hi knudsen,

1) accuracy is more important than speed
2) I have a lot of room (my entire basement)
3) setup time is not an issue as long as it doesn't "kill" the save timings of CNC milling vs. manual milling

thank you for the other information. Sorry, I don't know what "trammed 90 degrees" or "DP setup" means.

thank you
-Dave

[judleroy]

Why not get a cnc router? They can cut plastics just fine. The small taig and sherline type mills will not allow you make 8" circles without cutting half and then rotating the part 180 deg.(hard to get accurate parts that way)Maybe more like 5" if your lucky. A router or a somewhat larger mill would be needed to get that length Y axis stroke. Good luck!
Judleroy

[syil]

we just done a air spindle speed at 56000rpm.
also,we have speedmaster model.
later you can check our web for more details
www.syilnorthamerica.com

[knudsen]

Sorry,

DP = drill press

Tram = the art of getting the milling spindle exactly at 90 degrees to the table.

[Fixittt]

your going to be hard pressed to fit your needs within your budget. Even if you get a machine for $2000 your still left without adequate tooling.

For the projects your talking about it might be a better option to get a couple manual mills. One with a manual rotary table to blank your round parts and another to do most of the needed work.

Always check craigs list...... you never know what you might find. Sherline and taig sound like they will be to small for your project. But no matter what...... under any circumstance, stay the hell away from the maxnc line of machines. Trust me on this.

I bet that with a rotary table setup off center on the table of a Taig you can probably squeek the OD that your talking about. But heaven forbid you have to machine anything on the surface.

[Teyber12]

round parts 8" in diameter remove a lot of options.

I would consider a small metal router that you can mount a vice to. Maybe one day ill build a 2'x4' router out of 8020 or something. I do a lot of plastic work on my cnc x3. You definitely don't need the rigidity of a mill, but the small y axis will limit a lot of work.

good luck

edit: me and judelroy are on the same page