I've been looking at a CNC package from Techno and I need some recommendations on spindles. The standard spindle in the package is a 3hp HSD spindle (6000-18000RPM). What is the general opinion on the HSD spindles? Considering that I'll be working with hardwoods such as maple, ebony, ash & rosewood, is this spindle adequate? Also, should I be looking for a constant torque or a constant speed spindle?

Kevin

Our Masterwood point to point has 2 9HP HSD's. One rarely gets used, but the other one has been working fine for about 7 years now. Whether a 3HP is adequate depends on how rigid your machine is, and how fast can it go? How deep do you want to cut in a single pass?

I thought most spindles have relatively constant torque? Depending on what tooling you'll be using. most likely you'll want to use a wide range of RPM's.

I've got a 7hp HSD spindle on my router good up to 24,000 rpm, and I have been very happy with it.
I mostly cut aluminum with it, and it just gobbles it up at 85 ipm at 18,000 rpm with a 1/4" bit. I've watched the tachometer when the bit goes from air to metal and the speed doens't change at all.
The hardwood I've cut with it (mahogany) doesn't even phase it. I do some fine detail work with really small bits (1/32") at times and the 24,000 rpms comes in handy in these situations.
I've got a stack of Brazilian rosewood I'm getting ready to turn into expensive dust. I'm more worried about getting the right bit for the job than anything else. The oil in the rosewood is pretty gnarly and is hell on tooling.

The machine that I'm looking at is the Techno LC3024. The max depth of cut that I'm looking at is 2". Whether I'd do that cut in a single passs is another thing. I'm guessing that the 3hp HSD probably wouldn't be able to handle 2" in a single pass.

I have been a user of this spindle for nearly 4 years, and for 3 years involved with Techno as their distributor in New Zealand. We have 12 of these little troopers working tirelessly down here. None have ever given any trouble, and this includes machines working round the clock. You can stall them if you are really careless by burying a tool several inches deep and feeding it too fast, but even that doesn't seem to cause problems. The oldest of these spindles (formerly my own one) is a little noisy now on a cold morning, so we are looking to replace the bearings soon. The power only drops off at below 12000 rpm.

I Have read that different brand spindles develope peak torque at different RPM. The shape of the torque to RPM will be different. I think it depends on the material being cut with your machine. Wood vers metal will be quite different.
Hardwood to plywood or partical board is different. The spindle suppliers should be able to give some advise.