If the noise is not a real problem and you have an adequate air supply, look at the Sioux pencil die grinders, # 5978A (54K rpm) and # 5979A (70K rpm). the 5978A is the one Sherline uses in their high speed head.
Fred
The Anodizer
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If the noise is not a real problem and you have an adequate air supply, look at the Sioux pencil die grinders, # 5978A (54K rpm) and # 5979A (70K rpm). the 5978A is the one Sherline uses in their high speed head.
Fred
The Anodizer
Little late of a reply, but I have considered outrunner motors.. One huge problem is that they cannot get rid of heat when they are at rest.. Airplanes give access to tremendous amounts of airflow, a CNC, however...Quote:
Originally Posted by Stepper Monkey
Another problem is their tiny 2mm-3mm shafts. Finally, the fact that the outer-rotor spins creates problems with vibrations. The only good way is to use inner rotor brushless motors, which are hard to find with a large enough shaft diameter. You could use a frameless brushless motor from Danaher Motion, but they're damn expensive.
Steve
DC servo motors are brush motors. That implies limited life at high speed.Quote:
Originally Posted by whelen
There are many either 3-phase 400 Hz aircraft typr motors or BLDC (Brushless DC) motors which should have no brush life issues and may be reasonable choices.
High frequency drive (e.g. well above 60 Hz) tends to result in a lighter, higher speed motor.
Dave
I strongly agree about heat dissipation problem, but some motors are coming with water cooling units. For most of hi quality inrunners are pretty easy to fit some homemade water cooling jaket.Quote:
Little late of a reply, but I have considered outrunner motors.. One huge problem is that they cannot get rid of heat when they are at rest.. Airplanes give access to tremendous amounts of airflow, a CNC, however...
Another problem is their tiny 2mm-3mm shafts. Finally, the fact that the outer-rotor spins creates problems with vibrations. The only good way is to use inner rotor brushless motors, which are hard to find with a large enough shaft diameter. You could use a frameless brushless motor from Danaher Motion, but they're damn expensive.
Steve
Another realy BIG problem - a very BIG current consumtion. You PSU should be ready to provide from 30A(min) till up to 200A at 12 - 36 VDC.
5 & more mm are avaible.Quote:
Another problem is their tiny 2mm-3mm shafts
Look at&HTML Code:www.kontronik.com
brushless inrunners and electronic speed controllers. I think that these are the best for diy hi speed spindles. Now I`m planing to build one withHTML Code:www.neumotors.com
such motor.
Tolik,
I don't really have a problem with cooling of inrunners, that's not very difficult. For the savings in comparison to a commercial precision spindle motor, you can afford watercool it without much effort. I didn't know these existed, it is starting to make me think :)
I would use a car battery charger for the supply. Any other option requires rewinding the motor, then finding a decent high frequency drive. I don't think most VFDs can run that high.
I would be very grateful if you kept me in the loop of your spindle progress. You've gotten me to consider doing my own, since I didn't know that they existed as inrunners. Perhaps a good spindle setup would be a set of preloaded angular contacts at one end, the rotor magnets, then a smaller rear radial bearing. This might make assembly possible. Disassembling the magnets might not be worth it..
Direct drive is the only way that I would put forth effort for a spindle. I have a 400W brushless motor taken apart that I was considering converting from an 8-pole to a 2-pole for higher speeds, but it is hard to find magnets I know will work.
I'm actually designing a fully magnetic-bearing based spindle for my degree project this year. I was gearing it for the DIY community since it will be relatively inexpensive compared to commercial units. But, you would need a lathe and milling machine to make it.. Also, the circuitboard will be quite expensive. But, it will last a long time without wearing out and will be very accurate.
Steve
Scubasteve 911,
Here is example of water stuff from NEU MOTORS - less than 20 USD (without shipping) & you are ready to go with more than 2.1 cont / 3.3 max (30 second) KILOWATT, & rich up to 60 000 Rpm with NEU 1527 series motor.Quote:
I didn't know these existed, it is starting to make me think :)
For 400 Watt motor should be enough. I tested the motor like this - 540W/5200 RPM/V, connected to my PC SMPSU 12V rail. It was working fine. With your charger that able to provide 14.4 - 16V will be even better.Quote:
I would use a car battery charger for the supply.
Strongly agree with you - this is the best possible way.Quote:
Direct drive is the only way that I would put forth effort for a spindle.
I need to talk with my boss. If he will allow me, I`ll use one of CNC lathes / mills at my work. The thing I learned : for all DIY activitys, industrial stuff is the best choice... But $$$ :(Quote:
But, you would need a lathe and milling machine to make it..
If you about motor controller - I`m not shure. 100A/ up to 40V controller will cost around $120...150 including delivery.Quote:
Also, the circuitboard will be quite expensive.
In addition, to control the controller you will need some pulse modulator. The signal used to control ESC is a square pulses 70-220 mS length, 50 pulses per second. I already have some schematics of this stuff, so just ask me if you interesting. Parts for modulator at any local store should cost less than $10 for analog, or $15-40 for PIC based project.
Now I`m trying to design more advanced controlling unit, that will able to work with spin/RPM encoder (& even may be work with PC) , to provide :
A - stable amount of RPM (to eliminate RPM drop when tool touching the part, or if PSU/mains voltage changed)
B - feedback to PC/CNC controller to allow change RPM for each cut/job, & to make possible to use G96, G97 commands.
I`ll be happy to share any information, but I need a time to complete this project. Especially electronic part.Quote:
I would be very grateful if you kept me in the loop of your spindle progress.
Now I have one question.
Look at this ER 8 3/8" STRAIGHT SHANK COLLET EXTENSION . Is it possible to fit it to 3/8 ID bearings without additional tooling ? Anybody tried to do this, and what are you experience or suggestions ?
Hi,
The circuitboard expense I was referring to was the one I am designing to control the spindle. This includes the magnetic bearings, sensor-feedback loop, position loop, current control loop, and the pwm for the motors and bearings. It's a 6-layer PCB and will have about 400$ in parts on it.
You can rig up a basic velocity loop with hall-effect feedback and output the standard pwm to interface with the driver very easily. I would prefer using a PSoC microcontroller since they're extremely easy and quite powerful.
For the ER collet system with the 3/8" shank, I can't think of an easy way to use it. Sure, you can load some 3/8" ID bearings into an open-ended housing, then loctite the ID of the bearings after a bit of roughing up, but I am not sure how reliable that is. Furthermore, how would you couple the motor? I've heard of some inline couplings that could work with a motor, but I'm not a fan of them. The motor should be in between these bearings, so, I don't see how that is easily implemented. You also need a method to preload these to minimize axial and radial play, not sure how you'd do this either.
Steve
Hi,
I`m prefer the optical sensor (for speeds below 40-60K RPM), but your idea seems to be good also.Quote:
You can rig up a basic velocity loop with hall-effect feedback and output the standard pwm to interface with the driver very easily.
Thank`s for you sharing your look to the collet system. I considered that I`ll
need to make my own shaft that should to be be precicely fitted to ID of bearings. Loctite is useless here. Some later I`ll plase here my entry design.
Can you to read Solidworks part & assembely files ?
Yes Sir, I'm all ready to go with Solidworks. I'm eager to check out what you have done :)
Steve
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.
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.
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
Quote:
Originally Posted by 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.
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
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?
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
Here is my modified X2 spindle. Read more about it at:
http://www.cnczone.com/forums/showth...019#post459019
Bill
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?
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
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