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HELP PLEASE Spindle Rebuild Mill Partner 1

mb4343

Plastic
Joined
Apr 11, 2018
Greetings,

I recently tore apart my spindle on a mill I got, It had been sitting sometime. Its a Milltronics Partner 1D (The bearings had rusted inside an Im doing a Yaskawa Retrofit)I have not rebuilt a spindle before and budget does not allow for me to out source. I have got talked to Milltronics and managed to get the bearings specs I need, Ordered NSK bearings. Im aware how to grease the bearings. Dont need to touch on that. What I am looking for advice on is how to get the shaft back into the cartridge without hurting the bearings and making sure that the spindle doesn't turn into a noisy heater after. Currently Cartridge is still in the Z axis. I was able to pop everything apart. I thought if I leave the cartridge in the Z axis I have the "hydraulic press" I need if I introduce a bottle jack on the table.(I dont have a press, but need be I can get access) I have a lathe I can make anything I need to for pressing the bearings on correct shoulders and such. Its 2 flush angular contact bearings on bottom with a nut holding them down and 1 deep grove ball bearing on top (no fastener). KEEP IN MIND!!!: This is not a 40hr a week machine. This thing may run a couple hours a week and no big production line is waiting on it. If the spindle would last 2 years at that duty cycle Id be pumped. By then I would be able to justify a professional rebuild. If I knew the mechanical steps to do this Id be more confident.

What can I do to ensure the bearings go in well?
Should I be looking into the Drawbar Spring Washer condition before reassembly?
Is it dumb not to get taper reground?
Was it dumb for me to try this?
What else am I not thinking of?

Edit:
should I press A/C bearings onto shaft, press ball bearing into cartridge, put shaft and A/C assemnly into freezer then try to pressing shaft into cartridge?
do I need to support inner race of the upper ball bearing while pressing shaft through if I follow above method?
Is cooling shaft a bad idea due to condensation?


Any and all help greatly appreciated.
Thanks
 
What can I do to ensure the bearings go in well?
Should I be looking into the Drawbar Spring Washer condition before reassembly? YES
Is it dumb not to get taper reground? IT'S A GOOD IDEA AFTER REPLACEMENT OF BEARINGS
Was it dumb for me to try this? THAT'S UP TO YOU...
What else am I not thinking of? WHAT I'M HAVING FOR DINNER, HOW TO BRING ABOUT WORLD PEACE

Edit:
should I press A/C bearings onto shaft, press ball bearing into cartridge, put shaft and A/C assemnly into freezer then try to pressing shaft into cartridge?
do I need to support inner race of the upper ball bearing while pressing shaft through if I follow above method?
Is cooling shaft a bad idea due to condensation? IT CAN CAUSE ISSUES, BUT IS SOMETIMES USEFUL. TRY THIS WHEN HUMIDITY IS LOW
Rebuilding a spindle can be "easy", or a disaster depending on how the spindle was designed and whether custom tools or fixtures were part of the process. You can probably do a "good enough" job, but any press fits of bearing races can damage them if performed in haste or without good general practices.

There's a wealth of information on Youtube and from bearing manufacturers websites on spindle bearings and spindle rebuilding, you should spend an hour a day for a week (at least) reviewing the more general rules and tips for such work, then put together a process sheet for your spindle with questions such as:

1) Safe removal from machine
2) Proper disassembly, noting every part that comes off in order, with plenty of pictures and notes on condition.
3) Attention towards sensors/tachs and wiring. Anything damaged, any cracked wires or boards?
4) Note how elements are clamped together - slip fits, retaining plates with rings of screws, press fits or slip?
5) Proper cleaning of all elements. Note condition of bearings and seals, retaining clips, etc. Skid marks on races? Brinelling? Discoloration from overheating? Lube system working, or do bearings look dry?
6) Process for reassembly - all fresh parts clean, on lint-free paper or cloth. Every tool you'll need wiped down and spotless, plenty of disposable surgical gloves. Right lubes, greases, Loctite compounds at hand? All fasteners and tapped holes clean? Right screw going in right hole?
7) Helper for heavy parts? Winch if you're on your own? Orienting bearing pairs correctly? All slip fit surfaces burr/ding free? Housings the same?
8) PATIENCE during assembly - do you get frustrated and force things, or do you step back and see what's not working right?
9) Process rigor - do you make sure all screws are tight to proper values, torqued in right order? Do you measure end play, spindle rotational torque, TIR, uniformity of manual rotation?
10) Reinstallation without hurting spindle or you? All wiring reconnected properly, all terminals clean and tight? Lube lines connected?
11) Proper run-in, with temperature checks to ensure bearings aren't overheating? After correct break-in, is there excessive noise or vibration at higher speeds?

And all that's just off the cuff, lots more that could be written. As I mentioned spend a week reviewing videos and bearing sites. You may decide getting the spindle professionally rebuilt is the way to go, even if you have to wait to get the funds together.
 
CNc spindles are such a close fit a little heat and it should slide right out. If you have to press anything it better not put force through the balls. Have you done a search? When I did mine I got great advise from the guys here.
 
Hey I should explain, I do have some technical skills.. i troubleshoot and repair cnc routers and other automated machinery at a large woodworking plant, I'm not completely starting from scratch here, Milland I did spend for sure that week researching and and watching vids. But all the spindles were a bit different (more complicated assembly then mine)Regrinding taper I wont worry about for now, LOWcountryCounty-- Im concerned about heating a bearing due to the grease not liking the heat, is this over paranoid? (I already have spindle apart.Parts will all be cleaned adequately.

1.I will press the lower A/C bearings onto the spindle shaft, No issue,
2.I will torque the nut that preloads? the 2 A/C bearings. (I dont have a preload value yet, where how can I find this?)
3. I will press the top ball bearing into the cartridge, No issue,
4.I Will maybe put Spindle shaft and A/C bearings into freezer and get them small. And press them up into cartridge and top ball bearing... Do i make myself a nice machined spacer that I can hold the inner race of the ball bearing while I press the shaft through, Or...

Do I press the top ball bearing onto shaft also and then send it into the cartridge? (I like this... however when the top ball bearing is going in the cartridge I have no way of supporting the outer race of it, any friction is going through the balls... Would it help if I put together a drawing of the spindle and components?

thanks guys for input this is good
 
I have spent a bit looking for a Partner 1 D and found your other thread in April and it looks like it's a Bed Mill? I found this thread on replacing a spindle. Just the way your asking us. I am hot a big fan of doing it without removing the quill and flipping the quill over. and sliding in the assembled with new bearings in. If your spindle had a bottom bearing cap I would screw it in before hand. Also screw on the bearing retainer nut on to make sure it turns with your fingers I would also heat the bearings up before sliding them onto the spindle I have a bearing heater I made myself. I just read a thread someplace how a guy heated up a bearing in a microwave inside a wet towel. So you can look for that. How did the bearings come out? fall out or did you have to drive them out.

It amazes me how people come here and expect us to know what the machine looks like with no photo's or a link to a maintenance manual making us look for their machine. What I did was google "Bed mill spindle" and found this one. I would also like to ask you how you plan on mounting the bearings and greasing them. you said you know, but please tell us your plan. I am assuming you know about the TIR marks on the bearings? Do you have a surface plate and some V Blocks? How does the spindle taper look? Rusty? What RPM will the spindle run? What are you going to mill on the machine? What sort of spec's do you hope to get off the machine?

Mill spindle bearings project. - davesastroshop
 
Richard, Sorry If I bothered you by not attaching pictures or anything.. Thank you for attaching that link, I will look into making a bearing heater as well, I did not know that was a thing to be done. Seems like a nice controlled way. And yes at my work place we have a nice press and v blocks,that was my plan for getting the A/C bearings on. Im guessing tho if I make the heater i could probably slide them on. During disassembly everything came apart with out much fuss. grease.. im using the well recommended kluber isoflex nbu15 I believe its called. I have the spec on how much to to pack for the 7010 bearing. And yes im aware of the marks on the bearings, a bit fuzzy but ill refresh before I press and go according to a checklist ill be making beforehand while I assemble.

Ill be machining mostly aluminum and some steel, Its a hobby/beer money machine, as far as specs Im trying to achieve.. smaller the better,

If I take what i beleive you called the quill out, (Outer housing?) Would you say i do it the same way still press 2 A/C bearings on shaft, press ball bearing into quill. Press Shaft into Quill while supporting the inner race of the upper ball bearing with a machined spacer? I am attaching pictures of all the spindle parts. I hope its more clear then, my apologies I thought it would be more of a common assembly pattern amoung mills but I was wrong.

Note: Im aware the parts need to cleaner before assembly.

IMG_20180716_195250.jpg
IMG_20180716_195348.jpgIMG_20180716_195354.jpg
IMG_20180716_195417.jpg
IMG_20180716_195430.jpg
 
It appears it is a casting and not a quill that holds the bearing. It sounds as if your qualified to put the spindle in from the bottom. I would not try to freeze the bearings as they warm up the get wet. If it came out easy and your very careful and have a check list as you install it...give it a shot. In the othern thread from April somoen suggested you contact Miltronics. Did you and did they send you documentation on how to? Or you could call and chat with someone in service and they could probably tell you how over the phone.

Also it looks like the bottom outer race may have spun in the casting? I know those Asian made machines are not the best built machines and it may have been a lousy bore from the factory.

I just had another idea. Put the original bearings on and do a test run on them to make sure your install method works. :-) Rich
 
It's very unlikely that the bearings are a press fit on the outer race and the inner race. It's one or the other. Most likely, the bearings press fit on the spindle and slide fit on the OD in the cartridge. The bearing retainer plate holds the outer race of the bottom bearing set. The top bearing floats on the OD or ID to account for thermal expansion.

You need to check that the bearing retainer plate has the proper amount of squeeze on the outer races.

I can't think of a reason to drop the spindle cartridge except to fix a tram issue.
 
Okay I will try heat instead of cold. I did try contacting milltonics... they werent overly helpful on the info, maybe if try again ill have better luck with another person. Im not sure if the bearing spun or not in person it doesnt look as bad as in the pictures.. I was under the impression that milltronics was made in Minnesota. Or is that an "assembled in Minnesota?"

Hah.. Your last note is some of the simple best advice ive heard, I will definitely give that a test run... I dont know why I didnt think of that. One question i have as well, when it comes to preloading the A/C bearings... I have no spec (I will try milltronics again) but is there a rule of thumb for tightening them if i cant get a spec? Bearing manufacturer? A grey beards feel? my best guess? (Note when i took it apart I took my worn flat screwdriver and on the bench holding spindle by hand gave the screwdriver a tap with a small hammer and the nut started to turn, very little effort required.)
 
It's very unlikely that the bearings are a press fit on the outer race and the inner race. It's one or the other. Most likely, the bearings press fit on the spindle and slide fit on the OD in the cartridge. The bearing retainer plate holds the outer race of the bottom bearing set. The top bearing floats on the OD or ID to account for thermal expansion.

You need to check that the bearing retainer plate has the proper amount of squeeze on the outer races.

I can't think of a reason to drop the spindle cartridge except to fix a tram issue.


ewlsey, thanks i was wondering about this as well. Is there an easy way for me to find this out for sure that the bearing press fit on inner race? I dont have all the micrometers and gadgets yet.. I have a caliper and dial indicator (I know :(... (try assembly it with old bearings to find out?)

say I press on all bearings and everythings peachy when I slide it into cartridge.. Its not bad if theres a bit of drag on upper ball bearing? Theres no preventive heating to expand the cartridge to make room i can see here.. thats a big chunck of cast iron to warm up.

okay that bottom retainer does need to checked... good to know, is it bad if I go in good faith that itll squeeze enough? (I know the correct answer to question) However if you have a way for me check that that'd be great. but the retainer gets trapped when I press the bearings on. I cant slide the retainer on after.

Thanks
 
clean up the hole and see if a old bearing slides in. I agree with Esley...inner are tight ..outer are help by retainer rings. Did the bottom bolt on ring have a paper gasket on it or just sealant? I hand tighten the spanner nut and when it is snug and then using a hook spanner tighten it one more notch on the spanner lock washer. Probably
close to the original bent one or the next one if the washer is a bit smashed.
Here is a some info. SKF Maintenance Products
- YouTube
 
Richard the bottom plate had no sealant or gasket of any kind, I do have the part number book for the mill (shows all the parts to order from Milltronics) and there is no gasket either, my best guess if there was nothing don't do anything? Note: I haven't cleaned up the parts in the pictures I attached, so I assume safe to say there was no sealant either. And what you said for hand tight plus a notch on the washer would seem right to how tight/loose the nut likely was when I disassembled, I'll compare with the previous bent notch and see if it lines up. The only thing I feel I would need to know yet is the bottom retainer, how to tell if it's squeezing enough? then I'll clean everything up and give a go with the old bearings, new ones will arrive in couple days. I'll run through some of the SKF vids tomorrow as well

I really appreciate all the help so far gentlemen, I mostly work with wood machinery so this is new stuff to me.
 
Run down to an auto parts store and buy a small tube of non hardening Permatex or some blue silicone and put on a super thin later of one of them as it will be thin enough to keep out coolants. :-)
 
There should be a labyrinth seal built into the bottom bearing retainer ring. A good spindle will have a face o ring to seal the ring to to body. If not you can use permatex 2 or something but it will affect the amount of squeeze on the bearings so keep that in mind.

Squeeze amount is determined by bearing diameter. Probably .002 or so. The bearing preload is buit into the bearings. You do not, and cannot, adjust it. Just tighten the inner and outer races against each other in their back to back configuration and you are all set.
 
Hey everybody, so... I got side tracked from the mill for a while, however I did get the spindle rebuilt! I went ocd on the clean environment and clean parts, bearings went on slick. I did an 8 hour run in according to information I gathered online. No bearing noise that I can notice, spindle doesn't get hot, I consider it a success! The only thing that scared me is when I put the shaft with bearings into the housing the top ball bearing went a bit harder then I would of liked but I believe everything is fine. I now just have to finish getting the newer yaskawas all up and running and then it'll be time to make chips! I really appreciate the input and help from everybody who chipped in, likely could of flopped otherwise, thanks!
 








 
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