Hi Speed Spindle for BP Series II Erikson 40 (NMTB 40) toolholder

[scmw]

Hi,

I'm new to this forum and look forward to learning much from all of you.

We recently purchased some Bridgeport Series II NC Machines with 4HP heads (6000 pounders, not the 2000 pound original BP variety) that have been converted to Mach3 with steppers. While we still have to move them into the shop (another question to that later), I'm starting to collect info regarding upgrades that I intend to make to these machines.

These brutes have the Erikson 40 taper (40 quick change) toolholding system.These machines will do a fine job for our purposes. However I'm looking for a way to expand upon their capabilities. Currently the high end goes up to 3500 RPM. As an example, I mill details into model parts using 45-75 LB density tooling board and 6061 aluminum with miniature flat and ball end mills running from .040" down to .005". Usually I'll take .001-.003" off in a typical pass as I'm basically running profiles. The tooling for the most part is .125" shank on these smaller cutters. My benchtop mill (A2Z/Sherline Frankenmill) can handle 10K RPM with no problem but the work envelope is much smaller (the main reason for buying the BP's).

I'd like to find a way to do the same with our new (well, new to us) BP's. Can anyone suggest a good high speed spindle that will fit Erickson 40 taper tool holders? I'd like to hit speeds of at least 12K RPM and possibly go up to 24K RPM. My main concern is durability. I'd like to find a solution that lasts and can be rebuilt when it fails. It could be air, electric, or mechanical. What are the benefits of one type vs. the other.

Thanks,
Terry

[philbur]

Why do you need a 40 taper for small diameter cutters. I think balancing is going to be an issue for standard 40 taper tooling. A 24,000rpm 40 taper spindle will probably cost you more than the milling machines did. Big tapers means big horsepower, plus high rpm equals big bucks. You don't get money back if you don't use the horsepower capability.

Phil

Can anyone suggest a good high speed spindle that will fit Erickson 40 taper tool holders? I'd like to hit speeds of at least 12K RPM and possibly go up to 24K RPM. My main concern is durability. I'd like to find a solution that lasts and can be rebuilt when it fails. It could be air, electric, or mechanical. What are the benefits of one type vs. the other.
Thanks,
Terry

[macona]

You wont hit more than 6000RPM with the stock spindle without going to ceramic bearings and maybe oil mist lube.

You need to look at other options. One is a spindle speeder. I have one made by Nikken. Though they are only rated for a certain duty cycle.

Next is an externally powered speeder that goes in the taper. NSK and other make some air powered ones. You will need a big compressor to run these.

Last is an external spindle. Something like a Precise brand spindle. Mount it off to the side of the head.

[scmw]

You guys are right. I should have stated that I'm looking for something that will fit into the spindle. Basically I'm looking for something that will give me the higher RPM's whether it's a speeder or an air or electric unit that uses the tool holder just to hold it in place. I'm open to any ideas.

It could be something that fits into a collet too. Maybe 3/4 or 1" shank?

Thanks,
Terry

[scmw]

Macona,

When you mention big compressor, would a 60 or 80 gallon unit with 5 HP or better do the trick or are you thinking something larger? I suspect that an air spindle would require clean dry air.

Thanks again,
Terry

[macona]

I have a 5HP and have used a vulcanair jig grinding head to run tiny end mills (Which I am selling, dont need it any more) It does ~65,000 RPM max if I recall. Worked fine for 1/32" end mills. My compressor barely kept up. The compressor would kick off and then kick on shortly thereafter. Though my compressor is lower CFM than standard 5HP since it is a scroll pump, ~15cfm I think.

The NSK spindles are around $3k and so are the spindle speeders. The advantage of the air heads is they can be ran continuously where most of the speeder heads have a duty cycle based on how fast you run them. They do get pretty warm. Not sure if one were to make a water jacket that attached to it if it would increase that time.