[tskguy]

Well I have been building this for the last month or so and finally thought I would show some pics to you'all and see what you think. I have most definitely stood on the shoulders of others during my design fase. Mostly Herbert(Thanks!!). My goal was for it to semi high speed, no more than 20,000 rpm and for it also to slow down and act as a spindle for milling as well. Rigidity and low vibration are also very important. Herbert's spindles have been completly direct drive (from the ones I have seen at least) and very high speed but I really liked his way of preloading the AC bearings. The housing is Stainless and so are a few other parts. Im also using aluminum, bronze and some delrin as well. Bearings are all super high precision angular contact bearings. Two in the front face to face and one in the rear in a floating cup with a wavy spring underneath. The preload is set by tightining the bolt on the end kinda sandwiching it all together. I hope that makes sense! As for the motor I have a 1200kv brushless close to 800watts that I plan on spinning at a max of 40,000 rpm witha 2 to 1 reduction. This spindle is going on my diy 12"x12" router. I have yet to fire it up, Im still machining the motor mount. And yes I plan on water cooling the motor!! Well anyway here are some pics.

[diyengineer]

This is REALLY NICE!

What kind of power supply do you use to power the 800watt motor?

[tskguy]

Well Im still trying to figure out what I will need for a power supply. But my first test will be with a 750 watt 12volt ps. That will only give me around 14400 rpm at the motor and 7200 at the spindle. But my needs arnt much greater than that so we will see. I am going to use a RC heli speed control that will allow me to hold specific RPM hopfully that will help out.


Glad you like it. I learned a bunch!!

[diyengineer]

Well Im still trying to figure out what I will need for a power supply. But my first test will be with a 750 watt 12volt ps. That will only give me around 14400 rpm at the motor and 7200 at the spindle. But my needs arnt much greater than that so we will see. I am going to use a RC heli speed control that will allow me to hold specific RPM hopfully that will help out.


Glad you like it. I learned a bunch!!

Have you checked your run out yet by chance? Pretty good?

Do you use mach 3? Would you be able to hook up the controller somehow so mach could control it?

CNC4PC

There are some controllers located @ the link above. I hope to make my own in the future when my 2.2KW Chinese spindle dies. Just needed a lathe to make all the parts?

[diyengineer]

You should make a full build log tutorial of how it was done. You would sure help out a lot of people and i'm sure many people would be interested in making one! I would rather spend more money and make something i know will last then give money back to the chinese haha!

[tskguy]

Hey,

Runout seems very good but I havent tested with a dial indicator yet. I plan on checking it after I mount it on the router. A lathe is a must for this kind a project. Every piece was machined on my crappy Harbor Frieght 7x10 lathe. Cutting stainless really SUCKS!!! I killed a bunch of carbid bits. Its also really hard keeping the run out 0 when using the lathe. A steady rest is also very important.

I do use mach3 (just the demo for now) and havent really thought about trying to controll the rpm. I do want at least controll spindle on or off though and to be honest I havent even gone down that road yet. I forsee problems with a rc brushless conroller though. In order to controll a brushless esc you need to use a servo tester. Its a device that emulates the pulses created by a rc reciever. Im sure it could be done but it would uncharted territory. For now just using a relay to controll the power supply will be good for me.

Saddly I always intend to document my builds but I always get cought up in the build. Then its to late if you havent taken pics the entire time.
Like I said before, none of this is an original idea. There are a few threads I have pointed out before that have every bit of info I used to build mine.
Look for any post from herbertkabi, that dude has really figured out the hard stuff.
Read this entire thread!!!
http://www.cnczone.com/forums/showth...p=94477&page=5

That thread is chocked full of good info. Also read as much as you can about Angular contact bearings. Before I started down this road I really had no idea how complicated mounting bearings can be.

Have fun, I will add more pics after I get this running a 100%

[mactec54]

tskguy

Your spindle should be back to back for the lower bearings, normal spindle bearings are mounted this way

Great build

[tskguy]

Shoot I meant to say DB or back to back! I just checked the spindle and I do have them facing the correct way .

Eric

[dwalsh62]

Don't take this wrong but your wasting time on a spindle design that has limited versatility, why not design the spindle to support tool-change?

You're going through a lot of work and using a spindle shank for an ER11 (or ER20) collet.

I have already drawn some roughs on the requirements and it's not really that difficult once you understand the mechanics involved.

If you or anyone else is interested in going this route perhaps we can create a reasonably priced solution that increases the usefulness/versatility of the machine.

I'm developing a heavy-duty router/mill machine based on several different designs I've seen and I'm now getting to the point of machine assembly and will make the plans for the machine available.

It will cut steel (depending on spindle) and a tool changer is a nice feature that seems to be missing from all of the DIY designs.

[tskguy]

Shoot I hope I didn't waste my time!

Honestly even though it would be extremely cool, I have no need for a tool changer. The design goal of my entire machine was to accurately drill tiny holes in brass. (microphone capsule to be exact)

I'm actually very lucky I built a machine that cuts aluminum at all. Steel is out of the question in its current form. Although maybe after my new spindle is mounted!
Right now I just have a crappy 1/4 inch router from Harbor freight. Its far from stiff enough for steel. I also only have 12 inches of XY travel so a tool changer would be restrict my cutting area. Depending on the design of coarse.

Lets see what you have planned though I'm sure its very cool!!
E

[Iron-Man]

Hey,

Runout seems very good but I havent tested with a dial indicator yet. I plan on checking it after I mount it on the router. A lathe is a must for this kind a project. Every piece was machined on my crappy Harbor Frieght 7x10 lathe. Cutting stainless really SUCKS!!! I killed a bunch of carbid bits. Its also really hard keeping the run out 0 when using the lathe. A steady rest is also very important.

I do use mach3 (just the demo for now) and havent really thought about trying to controll the rpm. I do want at least controll spindle on or off though and to be honest I havent even gone down that road yet. I forsee problems with a rc brushless conroller though. In order to controll a brushless esc you need to use a servo tester. Its a device that emulates the pulses created by a rc reciever. Im sure it could be done but it would uncharted territory. For now just using a relay to controll the power supply will be good for me.

Saddly I always intend to document my builds but I always get cought up in the build. Then its to late if you havent taken pics the entire time.
Like I said before, none of this is an original idea. There are a few threads I have pointed out before that have every bit of info I used to build mine.
Look for any post from herbertkabi, that dude has really figured out the hard stuff.
Read this entire thread!!!
http://www.cnczone.com/forums/showth...p=94477&page=5

That thread is chocked full of good info. Also read as much as you can about Angular contact bearings. Before I started down this road I really had no idea how complicated mounting bearings can be.

Have fun, I will add more pics after I get this running a 100%

There are many articles on rc servo testers using the 555.
Here is a link and simple schematic: R/C Central Article: Servo Driver

Hope this helps,

Iron-Man

[diyengineer]

I think he has done a awesome job. He had a problem and designed a spindle from scratch as the solution. Not many people can say they did it from scratch. (flame2)

Don't take this wrong but your wasting time on a spindle design that has limited versatility, why not design the spindle to support tool-change?

You're going through a lot of work and using a spindle shank for an ER11 (or ER20) collet.

I have already drawn some roughs on the requirements and it's not really that difficult once you understand the mechanics involved.

If you or anyone else is interested in going this route perhaps we can create a reasonably priced solution that increases the usefulness/versatility of the machine.

I'm developing a heavy-duty router/mill machine based on several different designs I've seen and I'm now getting to the point of machine assembly and will make the plans for the machine available.

It will cut steel (depending on spindle) and a tool changer is a nice feature that seems to be missing from all of the DIY designs.

[RotarySMP]

Thanks for posting your photos TSKGuy. I share you pain, trying to machine a precise bearing seat in steel on the 7x Lathe. You must be a real masochist to do it in stainless. I hate turning stainless on these lathes.

How did you do your bearing seats?

I used my Proxxon die grinder to ID grind my spindle bores. Once I stopped wasting my time using the 3mm thick grinding wheels, and swapped to the 1mm thick cutoff wheels I got pretty good results.

Build Thread My homebuilt spindles - CNCzone.com-The Largest Machinist Community on the net!

Did you have to polish down the ER collet chuck OD for a sliding fit on the bearings, or did you heat you bearings for installation? I have an ER16 collet chuck with 20mm shaft for my next spindle, but the shaft is an interference fit for the P2 AC bearings I bought for it.

[tskguy]

Yes I am a little crazy for cutting stainless on my 7x10. It was a huge pain in the ass!!! And to be very honest my front bearing ID was complete luck!! I did have to make my own steady rest in order to keep it all centered. I only threw it once. Landed right on the top of my left foot!! Ouch!! Pretty deep cut and bruised for a couple of weeks

And yes i sanded the OD of my ER16 collet just a touch and then just used a warm hand on the bearings, they slid right on no problem. The rear bearing is press fit in the cup and the fronts are red loctited.

E

[RotarySMP]

Ouch.

I have the Sieg steady, which worked fine. Did you turn the bearing seats or grind them? I don't have a decent internal mic, but since I bought a box of 20 bearings off e-bay, I just sacrificed one and used it as a gauge, sneaking up on it until I had a nice slip stick sliding fit.

[tskguy]

I just used a spare bearing and some calipers. And just turned it a fairly hi RPM.
It kept it really smooth. Bearings just slide in nice and easy The fit could be a little tighter but red loctite holds them in great. I would probably need to heat them to get them loose. I really think I got lucky turning the ID for the fronts. I easily could have over shot!!

Wow 20 bearings! Are they all super precision?

Eric

[RotarySMP]

No, these ones are just regular SKF 7204's.

I bought two P2 7200's for the future ER-16 spindle.

[tskguy]

Very cool,

I got pretty lucky and found a pair of matched NSK Super precision bearings for 15 bucks still sealed in the package!. The rear is regular precision, nothing special. I'm in the middle of making the motor mount and spindle holder. What a pain!! I chose 1 inch thick 6061 and man it takes my little machine awhile to dig through it! I'm almost done though I can see the light at the end of the tunnel!!


E

[RomanLini]

What kind of bearings does the RC motor use? It sounds like lots of RPM and lots of power, and to me that kind of says "infrequent use" especially if they are plain bearings. And even with ball bearings I suspect they would be tiny and may not be best for hours of use at a time at 30-40 k RPM.

Have you considered using a lower RPM motor more suitable for long hours of use, and step-up gearing to give you the desired spindle RPM? Many people with engraving spindles seem to use those little sewing machine type motors and step-up gearing, then the life of it basically comes down to the bearing life in your spindle.

Beautiful build by the way, and extra points for stainless too!

[tskguy]

The bearings in the motor are plain not AC bearings. They are precision but not anything special. These motors are designed for relatively short runs but from my experience can take amazing abuse. They are also easily replaced. And the motor should see very little side force. I also have a plan to liquid cool the motor. Also my real goal isn't to go full 30000 rpm all the time. In fact I would rarely do that. I will most likely dial it in around 6000 most of the time.
All that being said I have considered using an AC single faze motor but to find one with the power I want it would be pretty big!
Eric