Replace Spindle/Router with Metal Milling Head?

[gerryv]

Has anyone replaced their router/high speed spindle with a milling head or perhaps added some sort of speed reducer head so that standard metal milling machine tooling can be used? My standard Buddy with PC router has an extended axis so there would be room for a speed reducer of some sort.

The thought is that this would allow us to use this machine exclusively for metals and stay isolated from the PRT alpha machine and other woodworking operations so we don't get contamination from metal fragments. The application would mostly be for the machining of variously shaped brass and stainless steel feet and accessories for custom made premium furniture. The pieces would still be hand polished and finished so we don't need to worry about getting the kind of resolution or simultaneous 4 axis machining one expects from milling machines.

While I'm aware that soft metals like brass can be machined with the standard routers and spindles and if we'd be willing to forego the SS, the impressions (which could well be wrong) I've formed from reading archived posts is that one cannot "hog" as much metal in a given amount of time and that router/spindle tooling costs due to wear and breakage would like be much higher.

The other impression I've come away with is that while spindle speeds can theoretically be dialled down quite low, they don't run well at their bottom end speeds for some reason - perhaps not enough torque to power something like a 1/2" diameter tool? Is anyone using a spindle with success for this type of application? If yes, has anyone found suitable bits/procedures for doing SS, even slowly...successfully?

It would seem to be a pretty simple adaptation to pull off the router and holder and replace them with the head from a smallish bench top square column mill and tram it with shims. A lot quieter too :-)

[knight_toolworks]

it's not the head that's the issue it is the rigidity and the mass and slop that would be an issue.
Metal is very hard to mill well because it is hard (G) even my 600# mill/drill can only take light cuts to keep vibration down and accuracy up.
when you look at this
http://cdn8.grizzly.com/pics/jpeg500/s/sb1024.jpg
do you see a shopbot? even getting .01 on a shopbot on a regular basis can be a battle in metal it would be far worse.

[gerryv]

Yes, you're right on that Steve, I had metalworking equipment before we switched to woodwork. The key of course is that in our case there is no need to push speeds at all because there is no volume expected being a custom hardwood furniture shop doing mostly one-off pieces. Also, because the Buddy 32 has such as short Y axis but uses the same extrusion as the 4' and 5' ones there is actually a lot of rigidity there and there is the added benefit of the gantry being fixed. Heck, the extrusion and support members alone likely weigh 20 x what my little Sherline mill weighs :-)

I also had one of those Chinese lathe/mill/drills and I know from experience that the quills on those things are terribly sloppy and at full extension, might as well be a boat mast - yet some guys still manage to produce pretty fine hobby work on them by going slow and using extra care. Hell of a lot better than a vise, chisel and file anyway (chuckle).

Also, we'll not being needing to hit the same tolerances as a decent milling machine as these pieces will be hand finished; kind of like what a traditional toolmaker does - now those guys were/are skilled!

What I really want is CNC capability that can give us within a 32nd or, hopefully, 64th with the "final passes" being done by hand. My son is first a fine fine furniture builder who wants to maintain the fully hand built wherever possible but at least hand finished. I'm simply looking for a way to speed up the roughing aspect and make use of our existing machines and software (Aspire 3) for those pieces that are commissioned as hand-finished only.

The PRT Alpha will actually be used as a parallel business operating in the same facility with someone else doing fairly low volume hardwood and plywood products as a sideline to help keep the lights on so that my son can chase his passion :-) We're actually looking for that someone now but, finding an available 'botter is not proving to be easy.

Like I said though, I agree with you fully that it could not be expected to do the job of a HAAS or even a refurbished Bridgeport or any of the offshore knee mills like the one you posted.

Thanks much. Gerry

[michael_schwartz]

Use the right tool for the job, I don't think a shopbot would be well suited for this. Vibration, flex, wear and tear aside, I doubt the motors would even have enough torque.

I would buy an old milling machine for scrap price and convert it to CNC.

[Gary Campbell]

Gerry...
The frame on the SB is much too light to function well as a mill. High RPM routing doesnt load the machine near as much as a mill would. Like Mike says, use the right tool for the job.

[gundog]

Gerald,
I have considered doing this myself for machining aluminum I think SS would need a heavier machine unless you take light cuts. I also do machine work and there is no substitute for heavy rigid machines when machining steel & SS.

Here is a head I have thought about buying for mine and making a mount to take the place of a spindle. If I had room for another machine I would probably do it.

http://littlemachineshop.com/product...=2517&category=

They convert these mini mills to CNC and as you can see they are very light and no more rigid than a SB but you can't take heavy cuts with one. I think one of these small heads would work they weigh about the same as a spindle but turn the appropriate speeds for milling metals. They also do not cost any more than a good router.

Mike