5 Likes
I saw that the other day and was thinking about posting it 
@cbrtrk just had this conversation this weekend. He had this exact problem.
Yea, talked with Joe about it and he recommended Amazon.com techniks collets. I bought two 1/8" ones for the Tormach as I have been inconsistently been breaking mills and I think that might be why. I’ll be back next week and I’ll measure the TIR on the ones I’ve been using and then see what the Techniks produce. Could also be the collet holder too. But the collets are a good start.
Does the Tormach spindle get fast enough to run such small bits? They offer a few high-speed accessories marketed for use with 1/8" collets.
It spins up to 5k which is less than ideal for small bits but can still work. Just means you have to run at a slower feed.
They make a speed booster that can get it to 20k (30k for short durations)
Might be worth looking into. 5k is really slow in terms of cnc mills. Most of them seem to be at least 10k.
Presumably the High Speed Spindle kit would be better than the speed booster?
I thought that until I read the install instructions. The high-speed spindle takes the place of the standard spindle; swapping between them is non-trivial.
Oof. You have to drop the whole spindle? Ouch.
Normally, I just expect these to take the place of a tool holder.
It’s far too long to fit between the tool holder and table.
These spindles alone are only a few hundred $. If you can think of a way to do a removable mount that goes beside the existing spindle with reduced usable table travel, that could be interesting, but I don’t think there’s any room to do that.
They do make some smaller high-RPM ER11 spindles, but they’re junk, and still 190mm long, so probably not going to fit in a tool holder.
There’s also pneumatic spindles, but I don’t see any short ones there either.
It’d be interesting to try to design something that mounts in the tool holder with a static shaft and a support arm to keep it from turning, then go through bearings to have an inline ER collet underneath with a toothed belt driving the collet from an offset motor. Sounds quite difficult.
They also have this option, which really looks like something anyone could make themselves (especially if they happen to have a CNC handy…)
(“Not intended for use with Flood Coolant.” I guess waterproof Dremels are hard to find?)
Well, if you have enough room to mount that offset, then you’d just get an entire 65mm dia ER20 spindle and add another VFD:
Then you’ve got a brushless system with precision bearings intended to handle thrust, low runout, and mounts a proper ER collet and will probably handle flood coolant ok.
Do they have an er25 collet version?
a real spindle does seem like a better choice than an electric die grinder, but I think the limiting factor on your lateral force is going to be the fact that it’s just mounted by its nose.
I can imagine a mount that has an R8 taper and a clamp with a big-ass wingbolt on it and a high-speed spindle mounted on the side. Take out your tool, insert the high-speed spindle, tighten the drawbar, tighten the clamp. It’d look like a cross between the sidesaddle die grinder and the spindle speeder.
I think we could use our existing VFD with the quick-change spindle kit (which might just be a couple nice connectors?) they sell for the RapidTurn.