[SPEEDRE]

What if, an E series collet extention was machined to accept the proper bearings, then coupled a short splined shaft, similar to a drill press, then to a holder and mounted to the Z axis carriage. The Z axis servo would then be mounted, where the hand crank would be on a drill press, and the spindle motor could be mounted, and used as a counter weight, on the opposite side of the X axis way, where it could also be drive from. This would counter any X axis flexing, theoreticaly of course. I recently tried to use a 1.5 hp motor as a spindle drive, and the wieght, caused the X axis way to flex in a counter clockwise direction. In practice, this concept, would essentialy mimic that of a Bridgeport style machine only on a smaller scale. The sizes commonly built here among our members. Any comments on the practicality of such a setup?

[wizard]

I have thought about going this route for a belt driven spindle. Haven't actually tried it yet but the extensions are readly available and you should be able to find inch bore bearings to fit the shaft.

The biggest problem I see is that the extensions are likely to be very hard. This might require a novel approach to fastening hardware to the shaft. The other problem is that he spindle (extension would need a solid shoulder to take thrust.

I've also flirted with the idea of directly coupling the spindle to the motor. This is a bit more work but has potential. I'd stay away from spline drives if you expect to obtain high RPMs.

Dave

[SPEEDRE]

Well how does a Bridgeport run? Does it not also have a spline drive? I'd want the extention collet ground to accept the bearing and then encased in a proper enclosure mounted to the Z axis carriage. I think, acceptable speeds could be achived with spline drive. Putting the motor in back on the Y axis could be a real benifit to DY'er all over.

[wizard]

When I first saw your post my thinking was that you had limited shop capabilities thus the interest in fabing a spindle from na ER extension. If your shop is indeed limited then extending an ER extension with a spline shaft might be an issue.

On the other hand is you have a well equiped shop then I have to wonder why you wouldn't build the entire spindle and extension one piece? I understand working with limitaitons, but if you are without limitaitons why not go whole hog and do up a nice spindle.

Even so do realize that the spline drive on a Bridgeport type mill maxes out about 5000 RPM. Ideally routers will more that double that speed, thus things that you can get away with on a drill press or a mill might not work as well. You may very well be able to accomplish what you want, but my experience with high speed spindles is that they are either direct drive or belt driven.

Thanks
dave

Well how does a Bridgeport run? Does it not also have a spline drive? I'd want the extention collet ground to accept the bearing and then encased in a proper enclosure mounted to the Z axis carriage. I think, acceptable speeds could be achived with spline drive. Putting the motor in back on the Y axis could be a real benifit to DY'er all over.

[SPEEDRE]

Just an idea. I want to find a way to have a high speed spindle with a small strong motor for direct drive if it kills me!!!

[wizard]

Don't misunderstand me the idea of using a ER extension is not that bad, like I said I've thought about it my self. It is just a matter of how you would do it and who's extension you will use.

The higher you go in speed though the more that a purpsoe designed spindle is a good idea. It should be easier to keep things balanced and manage bearing preload.

Dave

Just an idea. I want to find a way to have a high speed spindle with a small strong motor for direct drive if it kills me!!!

[SPEEDRE]

No harm done. In my fantasy I'd like the motor to be like a router, but much more quiet, and less prone to over heating. Currently I have a 1 hp. Grizzly var. speed router I will use soon as my spindle. Here's where fantasy takes over. I'd like the case of this and many other makes to be round. No fancy ergonomically designed art work, just plain old round. It must also have a collet that will take 1/2" shank with sleeves to take both 1/4 & 3/8th shanks, like the Makita 3hp's. I really wish someone would make a nice 3 hp. var. speed router motor that is 3.5" in dia., and wisper quiet. Now there's a wish I think many of us share.

[wizard]

As to wish list for routers I have a few. in fact I mentioned some of them on the warranty return cards I sent back last time. ER collets are a must, I see little reason for these custom collets that offer nohting over ER collets. A brushless DC design with a built in motor drive, this is very doable with todays electronics and shoule allow for some of the things on your wish list. Ideally the "motor" part of the router would fit into a standard spindle housing. The only other thing to consider is real spindle bearings but this would likely have a dramatic impact on the price of any such motor.

Dave

[ger21]

http://www.ekstromcarlson.com/spindle%20motors.htm

I think this is what you guys want. Unfortunately, you have to pay for it. And yes, the majority of the cost is the bearings, and the VFD to run them. But they are much more powerful than a router (for the same rated HP), and very, very quiet. I think I read a while back that the 2.6HP one was $2000-$2500, maybe a little less. And you need 220V to run them (single phase for the 3HP and less)

[NC Cams]

Here is the equation that regulates wishes from reality when it comes to making power:

HP = torque (ft-lb) times RPM divided by 5252

or

watts = (torque x rpm) /(5252 x 745) where torque again is in ft-lb.

or

watts = (torque x rpm) /(12 x 5252 x 745) if torque is in in-lbs.

If you have low torque, you MUST have hi rpm and vice versa to make the same power.

You usually find that the noise factor goes UP as you increase speed. Thus, a low torque motor turning at astronomically high revs is probably not going to be quiet.

Thus, it is simple to get a quiet motor - make gobs of torque at a low rpm. However, slow spindle speeds don't generate good surface finishes.

Sadly, ones desires often end up creating unresolveable conflicts with the perverse nature of inanimate objects.

[carlnpa]

In the commercial units you might consider the Hitachi M12VC 2.25 hp variable speed (8k to 2+K) it is much of what you have on your wish list except for the 3/8" collet. Very low runout less than 0.001", very quiet (lowest noise level router I know of), less than $130 at Amazon or Lowes. I have three and can't speak highly enough of them, one is run 50 hours a week now cutting OEM plastic parts on a cnc router and is holding up very well.

Carl

[SPEEDRE]

Yes, I do have a tendancy, to fly in my mind every now and then. A recent trip thru my catalogs has made my rethink my goals. It turns out there are at least three such routers from strong mfg.'s out there. But, these do not support lower speeds as well. I find that running a fly cutter at 10k, just a little hairy. I guess it's on to another idea.

[ger21]

Also, my PC 892 is really quiet at the slowest speed, I think 10K.

[wizard]

Yes, I do have a tendancy, to fly in my mind every now and then. A recent trip thru my catalogs has made my rethink my goals. It turns out there are at least three such routers from strong mfg.'s out there. But, these do not support lower speeds as well. I find that running a fly cutter at 10k, just a little hairy. I guess it's on to another idea.

One the other hand do you really need to run a fly cutter now that you have a router with a high speed spindle? You also have the option of going with a smaller diameter shell mill or such that is likelyt to be better balanced.

Obviously we are talking about a CNC router here so if you are thinking about something different than this doesn't apply.

Thanks
Dave