Spindle speed-multiplier (NMTB 40) source & opinions needed

[dogstar]

I'd like to be able to do fine engraving/machining in a number of different materials: plastics to steel, so I need speed. My existing setup is a Clausing/Kondia CNC 40-taper, w 3hp spindle motor with variable-speed adjustment via V-belt & hand-crank. Max speed is 4000 RPM (and I get a little worried when it's cranked up to this). I'd like to get 15 to 20K. spindle RPM. The sort of power I'd need is similar to a Foredom/Dremel sort of tool. Volume of work would be rel small.

I cannot spend a lot on this; it's a pretty tight budget.

I understand there are 3 different ways to go:
-1) mechanical speed-multiplier through existing spindle motor
- 2) electrically-driven motor, externally powered (similar in size & concept to a Dremel)
A variation on this is to make a custom adaptor that allows me to attach my Dremel onto the spindle (Spindle OFF obviously). This seems kinda rinky-dink though.
- 3) air-driven spindle motor, externally powered by compressed air (I do have a compressor.) Speeds here can reach 30K+ I understand.

Anyone have advice & opinions? Thanks for our help.
Dogstar

[philbur]

2) is probably the simplest and cheapest. I just bought a Proxxon IB/E. Haven't fitted it yet though. From reading my understanding is that the main issue for this solution is bearing durability over long term running.

Air spindles are expensive but nice.

Mechanical speed multipliers that I have seen didn't make the rpm requirement and was either build you own or expensive ready out of the box.

Regards
Phil

Originally Posted by dogstar I'd like to be able to do fine engraving/machining in a number of different materials: plastics to steel, so I need speed. My existing setup is a Clausing/Kondia CNC 40-taper, w 3hp spindle motor with variable-speed adjustment via V-belt & hand-crank. Max speed is 4000 RPM (and I get a little worried when it's cranked up to this). I'd like to get 15 to 20K. spindle RPM. The sort of power I'd need is similar to a Foredom/Dremel sort of tool. Volume of work would be rel small. I cannot spend a lot on this; it's a pretty tight budget. I understand there are 3 different ways to go: -1) mechanical speed-multiplier through existing spindle motor - 2) electrically-driven motor, externally powered (similar in size & concept to a Dremel) A variation on this is to make a custom adaptor that allows me to attach my Dremel onto the spindle (Spindle OFF obviously). This seems kinda rinky-dink though. - 3) air-driven spindle motor, externally powered by compressed air (I do have a compressor.) Speeds here can reach 30K+ I understand. Anyone have advice & opinions? Thanks for our help. Dogstar

[Richards]

Budget is probably the problem here, but a lot of us who have CNC routers have Colombo spindles that have top speeds up to 24,000 RPM. Mine is a 3hp spindle that I limit to 18,000 RPM. Smaller spindles are available, down to fractional hp. The spindles are 3-phase and require a VFD (variable frequency drive). The VFD, at least on 5hp and smaller units can be configured to run from 240VAC here in the USA. With an external fan instead of a shaft-mounted fan, the spindle can be set to any RPM; however, on my unit, full power is only available from 12,000 RPM to 18,000 RPM. At lower speeds, the power is proportional to the speed. An added advantage is that, compared to normal routers, spindles have almost no run-out. Using a dial indicator on my unit, there is no discernable run-out.

[dogstar]

Richards
Can you tell me more about the Colombo spindle? Will it fit in place like other tool holders? I already have 240V/ 3-phase power to the mill.

Note that my 3-hp, 3-phase spindle motor is fitted to a factory-cast metal housing & motor-mount. The motor turns a 2"-wide V-belt pulley, like a snowmobile drive.

So can I make this Colombo thing work? ...and What sort of cost?

Dogstar

[Richards]

My terminology was not clear, because, in the Shopbot CNC router world, when we talk about a spindle, we're talking about a spindle motor and tool holder. (My Colombo uses ER-25 collets to hold the tooling. In size it is roughly the size of a 2hp wood router.)

The Colombo web site in the U.S. is www.pdscolombo.com, where you'll find specs on the various models. Another web site that has another brand of spindle is www.ekstromcarlson.com. The Colombo unit that I bought cost about $3,500 ready to install - motor, Delta VFD, 30' of cable, six collets, two collet nuts and wrenches. If you're comfortable wiring up and programming a VFD yourself, you can get similar components for closer to $2,000 - $2,500 depending on model. Remember, I'm describing a 3hp unit. From what you first posted, I'm assuming that you could buy a much smaller unit which would probably cost a fraction of what my unit cost.

BTW, a 3hp spindle is adequate to cut most cabinet material (MDF, melamine, plywood) full depth at 10-inches per second. My Shopbot, as currently configured, has cut speeds up to 12-inches per second and jog speeds up to 30-inches per second. Cutting up a full sheet of 49" X 97" melamine into cabinet parts takes about 2-1/2 to 5 minutes depending on whether I'm mostly cutting side panels and backs or whether I'm mostly cutting drawer fronts. Sweeping and vacuuming the 120" X 60" table normally takes longer than cutting.

This is totally off the subject, but if you want to watch something that's absolutely incredible, visit the next industrial woodworking show in your area where they have some of the 'big iron' machines operating. Last January, I drove down to L.A. and watched a Thermwood CNC router demonstration. The Thermwood machine had a spindle that was much larger, in the 12 to 18 hp range. It also had an automatic tool changer. I watched several demos, where the Thermwood people handed out paper napkins to various on-lookers and asked them to sketch a base cabinet or bathroom vanity on the napkin, including dimensions. As soon as a napkin was received by the Thermwood people, someone went to a computer, which was running eCabinet software, and designed the cabinet, then routed a fresh full sheet of MDF, and finally dry assembled the cabinet - all in 15 minutes or less, start to finish.

[dogstar]

Thanks for the Colombo drive info. I had a quick look at their website. It doesn't look to me as though they make a speed-multiplier accessroy that fits into my NMTB-40-taper spindle.

Can anyone suggest a way to go...that won't break the bank?

Thanks