[kevincnc]

Hi All,
I've seen pictures of disassembled 2.2kW spindles here but not much talk of the 3kW's, so I thought I'd post some. I bought this from a guy who got it about 2 years ago but never used it. Curiosity about the construction and build quality got the best of me, so I decided to take it apart. I also figured the bearings would need re-greasing after sitting so long, so there was no reason not to. It comes apart a little differently than the 2.2kW's and I learned some lessons along the way that I'll try to share. Hopefully this will do someone some good in the future. I have 21 pictures, so this will be a little long-winded. They are mostly shown in reverse-order of reassembly.

The first picture shows the engraving on the spindle, made by GDZ. I looked up their website a while back, but now I get a warning that it may harm my computer, so I won't post the link. I looks to be the same one sold by "smpart" on ebay. All of the others that I've seen there have a black nose end, and smaller electrical connector.

The second picture shows the spindle mostly disassembled along with two special tools at the top that I made to help take it apart. After figuring out how it came apart, I think it could be done without them, but they make it a lot easier. At least I have them now, and am confident that I can change the bearings when the time comes.

Picture 3 shows what the bearing looked like after removing the rear cap and bearing cover. The spindle was already removed, but it would be there if this were the initial disassembly step. As you can see, it looks pretty dry.

4 & 5 show the 4-pin electrical connector. It has a ground pin that is connected on the back side to the connector housing. As you can see, there is is a nice thick rubber gasket that insulates the connector from the spindle end cap, and thick paint under the screw heads. Nice try but no cigar, there was no continuity between the pin and the spindle housing. More on that later.

6 & 7 show the tool that was made to take out the rear screw, which has left hand threads. The screw is in a pretty deep countersink, but it could probably be removed with some ground down pliers or whatever else you can come up with. I was happy to have the tool to make it easy though. Those pictures are of re-assemby so the bearing as shown has already been cleaned an re-greased.

Time for bed, more to come later..

[fizzissist]

Interesting machining/grind marks on pic#3....
What's your take on the quality of mfg?

[kevincnc]

Interesting machining/grind marks on pic#3....
What's your take on the quality of mfg?

I was going to get to that, but since you asked..

I am very impressed with the build quality, except for the crappy Chinese screws that I replaced with good SST ones. I did have to clean out chips from some tapped holes which allowed me to use some longer screws. I’ll talk more about quality as it related to specific pictures.

#8 shows the rear screw wrapped with Teflon tape as it was originally, and the bearing greased for reassembly. I over-greased it, but there's plenty of room for the excess to fling out.

#9 shows the next disassembly step. There are two tapped holes in the front section for jacking screws to remove it from the body. It's a fairly tight fit, but you could also tap it out from the read with a soft punch if your bearings are already ruined.

#10 shows more clearly the bearing/wave spring arrangement. The Chinese angular contact bearing comes out first, and then there are 3 wave springs, then a washer. The bearing fit to the housing is a nice slip fit with no play to allow the springs to preload the bearing and allow for thermal expansion. The shaft fit was also a nice sliding fit with no play.

I found the design interesting, not what I expected. Although there is pair of angular contact bearings in the front, they are arranged in tandem (facing the same direction) not face-to-face or back-to-back as I expected. So, the spring washers not only preload the rear bearing, they preload the front ones as well. This means that the spindle should be able to take twice the thrust assuming the bearing pair is accurate enough that they really share the load. I guess the downside would be the chance of the spindle jerking down during heavy cutting with a spiral bit. I didn't have a good was to check the preload, but I'm guessing it's enough to prevent that.

The next step is to remove the aluminum front bearing retaining nut, as shown in picture #11. For this I used the tool with 4 pins that go into the 4 (fragile) holes on the face of the nut. I say fragile because on my first disassembly attempt, I screwed them up so bad that the outer edge cracked and it looked like a chunk could come flying off at high speed. On the first attempt, I didn't have the nose end removed from the body, so no good way to hold the rotor still. I did use heat from a torch both times, and it came off easily with the right tool. A spanner wrench with 2 holes could be pretty easily made and should work also, or possibly even a heavy-duty set of retaining ring pliers with 90 degree tips. Mine is definitely overkill.

Picture 12 shows the black bearing retaining plate with 6 screws already removed. Taking these out allows the rotor/bearing assembly to be removed from the housing. It seemed to be a light press fit, but turned out to be low strength Loctite. Once I cleaned up the bearings and bore, it was a nice tight sliding fit.

#13 & 14 show the bearings on the shaft. There are inner and outer race spacers ground to the same thickness between the bearings. The only reason I can figure for them was to allow the front housing to be longer since it has coolant passages for the bearings. That was also a nice unexpected surprise.

#15 shows the front end of the body, with counterbores where the coolant passage o-rings sit. The o-rings were in good shape and sprung back to life, so I re-used them. The windings look pretty nicely done to me.

That's enough for now, more to come...

[Al_The_Man]

4 & 5 show the 4-pin electrical connector. It has a ground pin that is connected on the back side to the connector housing. As you can see, there is is a nice thick rubber gasket that insulates the connector from the spindle end cap, and thick paint under the screw heads. Nice try but no cigar, there was no continuity between the pin and the spindle housing. More on that later.
..

Somehow I am not surprised after seeing some of the other electrical equipment out of the R.O.C.
All those that have fitted one so far are probably under the impression their spindle is grounded, and some of these have been having noise problems and been urged to make sure the spindle has a ground conductor, so much for that!
Al.

[fizzissist]

Thank you for the time spent with pics and posting.
This is VERY interesting, and enlightening.

[kevincnc]

Agreed on the connector Al, although this is one of the nicer ones I've seen. They just needed to go the extra 2% and use a jumper wire to the cap. Glad this helps fizzissist!

So here are the rest of the pictures-

#16 shows the other side of the rear bearing with it's crusty old grease. I'm glad I didn't run it like this. The next picture shows the grease that I used after cleaning the bearing with Kerosene. I'll probably re-grease it periodically.

#18 shows the ground wire that I added. It has star washers on each side of the lug.

If you look carefully at the aluminum nut in #19, you'll see a SST ring around where the holes are. Rather than risk a chunk of aluminum flying off, I decided to make and shrink-fit a ring on since there was already a step there. I have no idea why they machine a step and made the side walls where the holes are so thin. I was concerned about messing up the balance, but it didn't seem to affect it. There is also a labyrinth seal between the nut and the end ring that I forgot to mention.

#20 & 21 show the spindle all reassembled, ready to test. I ran in the bearings slowly, ramping up the speed over several hours. I'm happy to say that it runs quiet and smooth all the way up to 24k RPM. How long it will last- who knows, but like I said at least I know I should be able to replace the bearings when they get noisy.

The bearings by the way are UTE H7005C-2RZ/2RZ/P4 DT -1 and -2 for the front pair, and HRB 7003CETA for the rear. I already have a pair of 7003's, so two backups for the rear, and good 7005 pairs can be purchased on ebay for around $150. Another thing I forgot to mention is that the front bearings are a very light interference fit with the shaft- light enough that I wouldn't even call it a press fit.

That's about it for now. I don't expect my machine to done for several months, but I'll post an update once it's been running for a while.

[JerryFlyGuy]

Kevin I'm curious on the water cooling side of things, how are the channels configured? Does it just go the length of the body and return or? Are there circular channels someplace that it can get even cooling around the spindle?

I've had a hankering to build my own spindle for some time now. I'm getting closer but it's still somewhere in the future

[kevincnc]

Hey Jerry,
Since the housing is aluminum with a Stainless sleeve on the outside, I assume that there are channels machined on the OD of the aluminum. One hole goes from one fitting straight through to the bearing housing and back out of that into body again. Where it goes back into the body, it's definitely not a straight shot back through to the other fitting. I would guess the sleeve is shrink-fitted to the aluminum part.

Building one of these would be a pretty ambitious project!

[JerryFlyGuy]

Thanks Kevin.. just one more pc of the puzzle. I've designed [but never built] many many spindles... industrial design is my day to day bread earner.. one of those things where I think I can make something that fits my needs better than I can buy it but prob not for less $$ than just buying it

One of my bucket list items...

JFG

[kevincnc]

No Problem..I also design automated machinery for a living so it's hard to resist tearing things like this apart to see what's inside. I have an ISO 30 ATC designed in Solidworks, just need to build it now.

[lukewarm]

Our spindle just burnt up yesterday so I thought I'd share my experience in hopes you can prevent it. The water jacket leaked into the main housing and burnt up the windings. I think the O-rings that connect the cap to the main body were responsible. You can see the burnt windings in the bottom of the first picture along with residual water left behind.


I'm not sure the best way to prevent this issue but I hope this helps.

We've been looking at replacing it with a Colombo built spindle, I just wish the price of ATC spindles would come down to a reasonable price (under 2500$).

[JerryFlyGuy]

Great minds!

I've got a Cat40 done exactly the same. Now I've started a 're-do' because I wanted to look at doing what this 'trail blazer' did w/ his..
CNC Milling Spindle @ DIESELRC.COM

Except mine would be one step farther in having ATC via air.. now if a guy could get Neu Motors to build a motor which I could wire such that I could run it w/ a VFD... it'd be like falling off a log [not]..

[kevincnc]

Thanks for posting that lukewarm, makes me feel like I should replace those o-ring with good silicone ones. I think I'll do that.

Jerry, that is a very cool project. It looks like a 3 phase motor, why couldn't you run it with a VFD? I never thought about turning an off-the-shelf motor into a spindle. Come to think of it, my list of projects is way too long and I probably shold not have seen that..

[JerryFlyGuy]

Sorry to hear that Luke! certainly not the way a guy wants to have a spindle end up..!

Kevin, I'd not thought of a motor to be used like that either but.. it's pretty ingenious really! You can get the Neu motors up to like a 5" OD [4400 series??] and they will custom make sizes [lengths] for you.. so it'd be possible to build a spindle that would have a pretty good size motor.. The Neu motors are brushless, I just assume that ment Brushless DC? you can buy a speed control for them from castle creations which will control it [and it HAS to interface w/ a control for RC [airplane/heli/truck] use so there will be a way to interface it to a cnc control] it would be 'fairly' seemless installation, I'm just not sure if it would have the 'life' that we're used to w/ a AC spindle? I think I could even get it to run off the DC that my power supplies send for my DC servos.. mind you.. by the time I get it all build I'll prob have upgrade to AC servos but..

I hear you on the 'I prob shouldn't have seen that!' side of things. The end of my 'list' is far outta sight.. I'll be lucky if I get it all done before I kick off [I'm 34] and that doesn't count the new things that will get added as more/new tech comes out in the years ahead.. I'm sure there are some widgets out there [yet to be invented] that I will want as well!!

LOL

JFG

[kevincnc]

Ah, R/C stuff. Now I get the "Fly Guy" username. I recently designed some Dynamixel hobby servos into a serious industrial application. Funny how useful "hobby" parts can be.

If the controller speed is governed with a PWM signal like most hobby stuff, it seems like you could control it with Mach3, right?

[JerryFlyGuy]

Actually the Fly Guy thing was from my days as a student pilot [I'm a corporate pilot in addition to my day job of designing industrial stuff... flying doesn't pay well enough ]

Ya Hobby stuff can be suprisingly useful at times!

I would think thats exactly how the speed controler works, either than or a 0-10vdc [which could be made into or used w/ a PWM style speed control..]

The bigger question is would it last, the speed control is like $220 the biggest Neu 44xx motor is like $1100 so there are some serious dollars in parts for it.. if it lasts for several thousand hours of operation I'm good w/ it.. if it burns out in a hundred.. I'm not so good w/ it I'll have to keep in touch w/ the other fella who built his.. and see how it lasts.

Fun fun!

JFG

[cambosoup99]

Our spindle just burnt up yesterday so I thought I'd share my experience in hopes you can prevent it. The water jacket leaked into the main housing and burnt up the windings. I think the O-rings that connect the cap to the main body were responsible. You can see the burnt windings in the bottom of the first picture along with residual water left behind.


I'm not sure the best way to prevent this issue but I hope this helps.

We've been looking at replacing it with a Colombo built spindle, I just wish the price of ATC spindles would come down to a reasonable price (under 2500$).

best way to prevent this is... REPLACE THE O-RINGS IF YOU TAKE APART THE SPINDLE..assuming you took it apart. Which most people do to ground out pin 4 and forget to replace the o-rings with new o-rings.

[Dbl_Tap]

I know this thread is several months old but I'm hoping someone can answer this before I try anything.

I have a brand new 3kw spindle that looks almost identical but made by SK (SK121215056) and I could hardly get any water pumping through the spindle so it was heating up to almost 150 degrees F . I ruled out the pump and the hoses so I took off the nipple fittings on the spindle and looking inside the holes are barley big enough to get a pencil point in them. If I take off the top cap only are the water channels inside this small as well or are they bigger through the jacket and since it is new do I need to get new O rings first so I can replace them?

[kevincnc]

Can you take off the cap and post a picture? I would replace the o-rings if you do.

[Dbl_Tap]

Before I disassemble it where would I get the o rings from so I don't have any downtime?