High Speed Spindle for SIEG X2 Mill - getting technical

[scubasteve_911]

Yes Sir, I'm all ready to go with Solidworks. I'm eager to check out what you have done

Steve

[bilinghm]

Is the limiting factor on high speed spindles the bearings? If so, cannot high speed bearings be retrofitted into a machine like the X2 or X3? Certainly the balance of the spindle would become a factor at really high speeds, but 10,000 rpm doesn't seem extreme.

[pzzamakr1980]

There are quite a few limiting factors. The bearing are a major one, with heat dissipation a part of that. There are also vibrations, which at 4000rpm or 2000rpm are not noticeable, at 10,000 they are a problem. There is also the factor of motor hp, generally too little. And consider runout on the spindle as well. When you use small cutters spinning at high rpm, runout can break those expensive little cutters.

[philbur]

Expensive bearings only work if they are setup exactly right. So the housing and spindle shaft need to be manufactured to tight tolerances with regard to diameters, squareness, surface finish, and concentricity. You can put the glass slipper on the ugly sister but she'll still the ugly sister.

Phil

Is the limiting factor on high speed spindles the bearings? If so, cannot high speed bearings be retrofitted into a machine like the X2 or X3? Certainly the balance of the spindle would become a factor at really high speeds, but 10,000 rpm doesn't seem extreme.

[bilinghm]

Well, I bought a 700 watt motor, 10,000 RPM bearings, made the pulleys and mounting plates, and I'm about ready for a test. So we shall see.

[Herbertkabi]

I have built dozen high speed spindles. The first problem - bearings. First spindles I used thin section 1/2 ID bearings - four in lower side, two in upper side ... yes, good enough, but only for couple of months when every day millings. Only super precision angular contact bearings are really good. For shaft I use ER11 straight shank extensions. When 1/2" shank, then 1/2/001 AC1 TA from
http://www.grw.de/english/spindellager.htm. Collet chuck like ebay Item number: 160201209960
http://cgi.ebay.com/ER11-1-2-SS-COLL...713.m153.l1262
Some kind of labyrinth you have to design. I added my own "flying-seal" too.
See on the drawing how.
Of course direct drive but not rigid, my selfmade flex coupling I is the best for me. How coupling - its very important.
Motors I have built myself as well, but never was able for needed balancing. Lehner 19** are good, 22** also - up to 50k RPM. Last spindle I built used Kontronik Tango 45-13 , with 24V it makes nice 33.000, no load current few ampers, when normal cutting with 1.6...2.6mm endmill then you even do not see difference, when 6mm endmill then current still 3...4...5A , even in extreme situations never jumps higher than 10...15A. Tango never hotter than 50C degrees, well balanced ... the only problem is woooooooooo-howling because number of fan blades made especially for this effect" ... but hopefully you can find out how to reduce this. Lehner need good cooling, I used milling coolant system for cooling Lehner. Lehner and Tango are slottless motors, no cogging but Plettenberg HP 220, especially HP 300 are also very(!!!) good up to 25k rpm, HP 370 ise perfect for more larger spindles.
Better when possible to select the best motor from bigger store - to try in own hand with full rpm - some motors are more balanced than anothers ... but mostly all mentioned are OK. Plettenberg allways! Used ones from ebay are good enough when bearings replaced. Motor bearings I replace even when brand new motor!
Outerrunners? Yes, but not so high rpm and you need sure protect it from metal dust ... Outerrunners never balanced as needed.
I use very good AEG AC 2000 power supply regulated for 24V, speed control - common RC stuff as well - I use Schulze ... and common servo tester for.
Attached some photos about my last spindle. Dust protection, simple thing, you do not see, also included picture where some parts machined from 4, 5 and 6mm 7075 aluminium - it takes ca 2 hours to cut this quantity of parts (some are even anodized - I do not anodize myself). Very seldom I mill with less RPM than 33k.
Regards,
Herbert

[praetor]

Herbertkabi would you happen to have any more spindles...maybe for sale?
or could you possibly share the process of making one as per your diagram?

[Herbertkabi]

Seems next week I will start with new spindle. Then, when interest indicated of course, I will show the progress step by step.
For sale? Im not sure I can find so much time right now.
OD of main housing is 43mm x 110mm, stainless steel, next housing wheres motor - aluminium (aluminum ;-)
And please do not forget - this is Kabi Spindle - high speed spindle what every at least mediocre machinist is able to build himself ;-)
There is no special color codes - wast just my odd joice. Type of shaft and bearings you know, at least I hope so.

Regards,
Herbert

[bilinghm]

Here is my modified X2 spindle. Read more about it at:
http://www.cnczone.com/forums/showth...019#post459019

Bill

[praetor]

Herbertkabi would it be ok if you shred the motor portion of your high speed spindle? I would like to replicate this spindle..i have the ER 16 extension and would like to adapt this concept to make my own spindle...if it's all right?

[Herbertkabi]

No problem with "replication". What is shank diameter of your ER16 extension, what bearings you plan? About what RPM you are thinking? When everything is ready I have "over machined" even collet nut - it caused vibration.
Yesterday I finished my new stainless housing, bottom flange, sleeve for upper bearing.
This time everything have been precise made with first try.
Unfortunately ER11 extension I ordered 22. May not received up till today.
My new spindle will make 45.000 RPM (24V). Water cooled - - milling coolant will flow first off through Spindle - no dust inside, no fan howling anymore.
Regards,
Herbert

[Herbertkabi]

You can see the cone, will be hot-pressed (!) on to the shaft (collet shank) and then at least one time more precise machined. One of my previous pictures you can see collet nut key and clamp made from C10 fiber - I hope you understand why and how, Im very pleased with this system. Cone is also part of labyrinth together with bottom flange. This side of flange will be also one time more machined to get precise shape. Inside of this flange will place teflon seal against inner ring of demolished R1212 bearing - very simple and works sure. This bottom flange is bolted with 6 x M2 screws to housing (Im not able to make precise inner/outer thread ;-), teflon seal just tightly sitting inside flange.
Herbert