[Rhodan]

I'm looking for ways to cut aluminium and plastic on my wood router machine. I've managed to do some aluminium with poor results (works, but with very rough vertical surfaces and very shallow cuts). I'm thinking my two biggest problems are runout on the wood router and spindle speed.

The slowest I can get the router is 10K RPM. While you can cut aluminium and plastic in that range, you really have to be moving fast in order to not melt the workpiece. Of course, once I start moving fast the lack of stiffness in the machine results in horrible chatter.

I was thinking of buying a Sherline milling headstock & motor combo (PN# 6514) and mounting that for these materials. This way I could run at much lower spindle speeds and not be forced into using high IPM settings.

I wouldn't expect to get the same cutting speeds/depths of cut as a sherline mill since the wood router table is still nowhere near as stiff as a Sherline.

What do you think, would this be worth doing?

[tsalaf]

You can easily cut aluminum and plastic with a wood router if you use the correct feed and cutting speed range. What type of aluminum are you trying to cut?

[Oldmanandhistoy]

You can buy over here (UK) so I have no doubt over there also, cutters designed to be run in a router spindle for aluminium and plastics. Might be worth your while investigating before going to the trouble of using two different spindles in the one machine.

[Rodm1954]

Rhodan
It is not a crazy idea to run a Sherline spindle on a wood router. I looked seriously at the Sherline but decided on the heavier and more powerful X2 for a machine I am building. Spindle runout on cheap routers can be quite high and they really do not spin slow enough for the lower feed speeds of home built machines.
As has been mentioned a bit of experiementing with different cutters might be worth looking at before you spend the dollars.

[ger21]

I wouldn't expect to get the same cutting speeds/depths of cut as a sherline mill since the wood router table is still nowhere near as stiff as a Sherline.

Since you're saying that the problem is somewhat due to the machines lack of stiffness, I'd think you'll get similar results with the slower spindle. Although going very, very slow with very shallow cuts might help.

[Rhodan]

Well, with a 1/8th upcut router bit (2 flute) I can get about 20-30 IPM at 0.02 DOC without chattering but the sides are still very rough (sort of like corrugated cardboard). I'm thinking the router runout/slop is causing the rough sides. Its not a cheap router either, a PC892.

I tried a 1/4 upcut spiral at 10K rpm but I can't get the feed slow enough to both not chatter and still fast enough to not melt.

I also tried running the 1/4 fairly fast (40 IPM) @ .01 DOC to cut out a part from 3/8ths 6061 but about 2/3 of the way through the bit snapped. It looks like the machine deflected a bit at a rounded corner and the flute suddenly had to cut about 1/4" of metal along its length on one side.

I also tried a for-real endmill (from Sherline even) but that's even worse. It was a 3 flute and I didn't realize until after the purchase that 3 flutes just causes more heating (like running at 15K RPM with 2 flutes).

I think the main problem is the unsupported rods holding up the gantry. I replaced the ones on the Y with Thomson supported rods and that helped a LOT with just about everything (Vbit plunges real nice now).

I have no problems with taking shallow cuts as time isn't really a factor. I do this for a hobby and if I decide at some time to try and make (regular) money from this I'd spring for an actual mill.

I can afford to either buy Hiwin rails/carriages or get the sherline spindle. While the guides would likely improve the metal cutting performance I don't see how it would help with plastics.

Unless someone knows of some bits that would work a lot better?

[Pres]

FWIW: Whatever you do, don't machine it dry!

Use some kind of cutting fluid and lots of air to keep the chips cooler so they will quickly 'eject' from the cutter flutes.

Pres

[ZipSnipe]

I agree with Prez, at least attach an airline to blow out chips.

[tpworks]

I usea 3 flute end mill for aluminum on my router, Dewalt lamiate timmer 20,000 rpms 18 ipm .025 depth with moderate success. Giving it a shot of WD periodically.
It all depends on the ridgidity of your axis'.

[Rhodan]

Well, I did try using 20w non-detergent oil (compressor oil) which did help with the heat but made the chips very difficult to clear (I have a compressed air gun that I blow them out with).

I'll try WD40. Its much lighter and might help.

[Rodm1954]

Traditional coolant/lubricant is kero for aluminum but WD40 works well. The only problem with WD40 is it is slightly tacky and causes the chips to stick to your machine.

[Khalid]

would u post some pics of machine and the work piece u machined

[tsalaf]

I routinely cut aluminum with a Makita RF1101 attached to a homebuilt machine. For rough cutting, I use a solid carbide, two flute, upcut spiral spinning at 12,000 RPM at 10 IPM. Depth of cut is .250”. This does not work in the ShopBot that I own, due to machine flexibility.

Lube helps quite a bit, although cutting metal is hard on the router, causing frequent repairs.