Return of the Spindle Motor Power 2 x 72 Sander

[BelnapCustomKnives]

About 9 months ago I posted about testing a tiny spindle motor to drive a 2 x 72. The motor is an 11 pound, 3 hp, 3 ph, 400 hz, 24,000 rpm, 220 volt, liquid cooled spindle motor. After several months of hard testing it has proven itself ready to move from the test machine to a production frame.
This is the first entry level production frame with the motor mounted and drive system mounted on it. This is the same motor and drive that I have been using on the test frame. I will put it in this frame and loan it to other knife makers to run it through the paces and get their feedback on it pros and cons. It powers the belt from a creep to over 7100 sfpm with excess of power. I tested it on single pass removals up to .030" with great performance results.

The frame is also unique. Not so much in its shape but in the material and construction. It is tubular aluminum welded frame with the bar inside tube clamp system that I developed. The clamp self-centers the bar when tightened and leaves no damage like a set bolt system. NO SLOP!! NO SLIP!!

It will be powered up and running on this frame in about another week and I will send it to the maker for a few months of trials in his shop.

If you have question feel free to ask. This motor can be seen in action on my youtube channel BigIronTV search for spindle motor videos on my channel.

 

[Ken H>]

Interesting design you have there. Lots of thinking and work went into the mockup you've got. I also have to complement you on the desire to send it around to difference knifemakers to use before releasing it to general production. I do have a couple of questions and comments.

1. What prompted the decision to use the spindle motor? At first glance I don't see any advantage over the standard 3ph 1800/3600 rpm motor when these can be had for $200 or less for 2hp. Of course a person could spend $300 to $400 or more for a high end name brand vs the Chinese motor, but since the spindle motor is Chinese let's keep the comparison to Chinese motors. This high rpm motor requires a very small drive wheel which will give problems with belt slippage. OR - is the drive wheel from rubber to prevent slippage? How well does the rubber wheel at 24,000 rpm? The water cooling system is another requirement that will add expensive and hassle in use.

2. Yes, that clamping system you've got for the tooling arm will hold it solid and prevent the tooling arm from getting marked up by the bolt during use. BUT - a "possible" problem I see is the amount of slop in the tooling arm from left to right, which determines the plane the platen wheels will be running. If that split where vertical so it would clamp the tooling arm in same position each time it would be slick for sure. The benefit of the tradition tooling arm holder is the bolt presses the tooling arm into the same plane so the platen wheels are clamped into the same "true" plane each time.

I'll tag this thread to watch - interesting concept. I really like "WIP on grinders" because I tend to learn from each one.

Ken H>

 

[Stacy E. Apelt - Bladesmith]

Another possible problem would be the very small drive wheel. The surface contact on a 4"-6" drive wheel is many times more than that small spindle. When doing heavy hogging the belt might slip. Spinning at 24,000RPM and slipping would burn the belt in a fraction of a second.

 

[Maineiac1]

Another possible problem would be the very small drive wheel. The surface contact on a 4"-6" drive wheel is many times more than that small spindle. When doing heavy hogging the belt might slip. Spinning at 24,000RPM and slipping would burn the belt in a fraction of a second.

I thought the same thing. May need a couple deflector wheels in order to get more surface contact..? kinda like a small wheel attachment