Servicing a High Precision GMN Spindle

[@GMNPaulMueller]

Great job Alex! Many thanks for praising our spindle. Although this is a “simple” spindle from our extensive range of grinding spindles, it is still precisely manufactured with over 90 years of experience. In addition to this model, we also successfully manufacture motor-driven grinding spindles for manual or automatic tool changes as well as milling spindles.

[@anengineersfindings]

Oh wow, many thanks for your kind and encouraging comment! I hope I was at least slightly close to something that you would consider proper GMN spindle service. Is there any chance you can comment on the following items? The viewers would surely appreciate insight on these questions that I cannot provide answers for (I will pin the conversation on top). a) is the amount of grease I used per bearing adequate or too much? b) is the torque of 50Nm I used on the shaft and on the adjusting cartridge adequate? c) is it probable the the spindle was adjusted originally to have almost zero axial play (unlike the 10µm as suggested by the manual)? d) any chance you can tell a rough price of that spindle when it was sold around 1977? Many thanks for your time and effort!

[@BernardSandler]

I imagine those folk who originally assembled the spindle cheering on as it is serviced with such skill and carefully returned to use after so many years. You are extending their investment in time.

[@gyrogearloose1345]

Thanks for this excellent video. I really felt I was there with you to marvel and admire this awesome spindle. And learn some things from your careful work and explanations. Good fortune for you Sir!

[@davidtaylor6124]

It's a real pleasure watching a skilled person doing what they're good at. So yes, it was worth it :) I know what you mean about that fit, the sound of if in the video had me thinking 'that's a great fit'.

[@chrisarmstrong8198]

That was good thinking at 10:30 when you checked for a left-hand thread.

[@benz-share9058]

[Alex does what we've all done and forgets the welding ground clamp] "Thats Classic!" Well, you're only human, but what an expert and entertaining human you are. Thanks for another interesting and enlightening video lesson!

[@paulbyerlee2529]

Great to see you post again. Looking forward to seeing some more content

[@churumusik]

It is an honor to have recorded the intro music for your channel, thank you Alex! And also for the endless nerdy talks we use to have about engineering topics 😅

[@somebodyelse6673]

Good to see all the practical issues of service. Thanks for sharing!

[@camillosteuss]

It was absolutely worth it to service the spindle... I am refusing to use my Schaublin22 which is in near factory state, exactly for the same reason... She has been sitting for over 50 years with OEM grease in the spindle and all other bearings, as well as the spindle gearbox... To use a virgin machine with such lubricant, which has to have had been chemically contaminated, even if it never saw a single revolution of the shafts... Moisture and oxygen get in there and slowly deteriorate the lubricant and it`s properties... Sure, some of these greases can operate far beyond their proscribed service life recommendation, but all in good reason and sensible limits... ``Lubricated for life`` only makes sense to the witless and ignorant... Glad you ran across a lovely machine! Some of my acquisitions have not been as stellar, some have, like the S22, but some will take hell of a lot of effort, altho, that only means loads of material for video-making... All the best and kind regards! Steuss

[@gyrogearloose1345]

Get to work on that Schaublin man!

[@camillosteuss]

@@gyrogearloose1345 yeh, i really should... She is sitting nice and comfy, oiled, wrapped, warm and in dry, but i ain`t got no real space to maneuver the crane and the parts off of her to deal with them... Maybe i`ll make some more room if i manage to... Atm, i`m waiting to sort some financial shit as to build a proper shop that will allow me to both house my machines and restore other machines(any my own before using some of them), so i`ll have to see... Either way, the S22 is happily unmolested and lovingly taken care of for now... Best regards and warmest wishes! Steuss

[@gyrogearloose1345]

@@camillosteuss Well Steuss, I feel your conundrum . . .so many projects and all their requirements, all interconnected in a maze of possibilities . . . I wish you courage, fortitude and good fortune! Cheers Gyro

[@than_vg]

Thanks for taking us along the ride Alex, very nice! (when setting axial play to such specs I prefer to rest the mag base on the spindle housing itself, not the vise, to minimize reading error)

[@gyrogearloose1345]

From what I see, that's exactly what he was doing.

[@DrKnow65]

Alright Alex, my wife has comments... First, she came in this morning just in time for -inserting the spindle-, her comment was "Yes, now I have sex on my mind." She also said that "Everything he said for the next two minutes sounded sexual to me." So thank you for that! :) At the end of the video you asked if it was an improvement and her response was "I don't know, one micron could be a loss of accuracy if it started at perfect". Her favorite quote from you was "The conical end of the spindle very much helped inserting it, yes, it was VERY GOOD". I think she is now also a big fan, as am I.

[@anengineersfindings]

HAHAHA, that's very encouraging, thanks for your comment and greetings to your wife! I hope the discussion had a happy ending.

[@sharkbaitsurfer]

OH my you almost lost your bearing...;) Great video as it was great to be able to see inside the spindle of such a precision machine - thank you, subscribed

[@billdoodson4232]

Great to see you back Alex. That spindle is a superb piece of engineering, the fits and finishes are astounding. I can't wait to see the rest of the refurbishment. Happy New Year to you.

[@ydonl]

Very nice; thanks! I don't know if I will ever rebuild a spindle, but that's not why I watch -- it's not so much school, it's more just the interest!. :-) Well, maybe it is a little bit school. The sound and the results were very satisfying. And when that outer sleeve slid in so nicely... just magical. I will have to go back and watch again to see how loosening the nut reduces the runout; I missed that part, and it continued to confuse me! "Alex! You're going backwards!" :-) But I'm sure I'll find it in there somewhere, when I watch again. Cheers. Happy new year!

[@squelchstuff]

Good question, and it does look counterintuitive at first, but it's probably best understood if you look at the drawing at 5:54. The two bearing races (14) are held captive in the cylinder by the nut (12). The three other races (15) are held captive in the plug/carrier (10) by nut (13). You'll notice that the races in the drawing are inclined up on the left (plug) and down on the right (fixed). Adjusting the plug outward drives the inclines apart, and therefore the balls tighter on the inclines (pre-load). The reason for pulling the two bearing carriers apart as opposed to pushing them is something someone else will have to chime in on. I'm uncertain on the advantages of one compared to the other. HTH and happy new Year.

[@ydonl]

@@squelchstuff I see! Thanks very much; that's quite clear now. These are interesting devices!

[@humanspirit3432]

Really high precision spindle : D Interesting to test it again after some work and with different temperature : D

[@mohabatkhanmalak1161]

A very precise spindle. The one micron runout would be fine as it will take up any thermal expansion in the axial direction when the machine is running. Thanks for posting, enjoyed watching.🐞

[@rickpalechuk4411]

Hi Alex, I think you came up with a new term for fitment: "Speechless Fit" 😁😁 Happy holidays Cheers

[@theromihs]

Very interesting video! Amazing runout on that spindle.

[@jimsvideos7201]

Happy new year Alex! Thank you for showing us your spindle; I can only imagine what it cost new!

[@MrTad99]

Always so much to learn from you Alex, all the best in the new year, and thanks for the video!

[@rickhaass1133]

Great running spindle you have there Alex

[@TheCalvinSkinner]

static friction is usually higher when removing a bolt or nut than the amount of torque used to tighten it.

[@greglaroche1753]

Good job! I hope the spindle of my FP1 is in as good shape when I decide to overhaul it. Happy New Year !

[@sky173]

35:15 - lol... can't wait to see it running. Thanks for sharing.

[@MgBaggg]

Brilliant stuff with excellent results. Looking forward to the next one

[@BronzeAgePuritan]

Why do I love spindle rebuild videos? Am I strange?

[@anengineersfindings]

No, you aren't! 😄

[@wktodd]

When you remove the AC bearings , I was screaming check the radial position. Hardinge lathe spindles are aligned, but I guess this is unimportant on a grinder spindle.

[@anengineersfindings]

Very good point, thanks for your comment. I should have mentioned in the video why I didn't check this. I didn't because the adjusting cartridge rotation makes it quite improbable that the bearings were clocked.

[@philiprogers5772]

It's a beautiful thing.

[@abdelrahmanelmasry9699]

7:30 The difference in the drawing of the spindle's floating bearings from up and down, most spindle manufacturers make 2 models of spindle, the drawing above the centre line is one model and below the centre line is another model , always seems weird to me because if you study engineering drawings you draw only one model on one paper not 2 😵‍💫

[@LikeFactoryMade]

Great video! I had to do a similar operation for 2 grinding spindles I got on an auction. I think it would have helped if you added some grease into the rings labyrinth. That grease in there also helps in catching any dust that might get in there.

[@ED_T]

The heavens have opened and given us a new video to enjoy ❤

[@joell439]

Thank you. Looking forward to more fascinating presentations like this 👍😎👍

[@localele1]

Nice job there Alex. While it is all still clean you could carefully dis-assemble the bearing packs again and re-assemble them with the bearing balls in a different order to get rid of that measurable run-out. Come on ,we know you want to.😂😂😂😂😂😂😂😂😂😂

[@rsemrad2]

33:45 In my shop we would call that a ring fit or a line to line fit.

[@blacksupra10]

such a great channel, equal to any of the rest.

[@c4t4l4n4]

I would cal 1 angstrom the norm. 😋 Happy New Year. Good service!

[@ALSomthin]

Having some experience with German spindle cartriges many of them specificly required Kluber grease not using it resulted in failure.

[@TheMIroslaVbachev]

A dust particle fell on my screen during assembly process and I was like: Oh shit, that thing went right in the lube. I just ruined the repair. 😂

[@be007]

hoi alex, why not drive the spindel outside the machine to check for heat, so you can simply adjust the preload of the bearings when to much/to little play? thanks for sharing your video,s, they are always very interesting to me. happy new year, cheers ben.

[@bigwave_dave8468]

Nicely done!

[@paumasip]

i m wondering if that could be the right amount of play on the spindle while its cold.

[@stonecraft745]

Thanks for showing us this beauty! Kannst du Bücher über Spindeln empfehlen?

[@HaraldFinster]

Excellent! Very interesting.

[@muuce]

I hope to see more from you in the future. I noticed you have your machines up on wood blocks, can you comment on why you did this?

[@anengineersfindings]

Good question. I have my machines raised on blocks because I find it very tiring and probably unhealthy to stand all day with a bent spine, handling the wheels etc. In my opinion, the wheels should be roughly at elbow height. I use wooden blocks because I wanted to avoid damaging the floor tiles. I had no problems so far with machine vibrations. The lathe blocking should be improved though, but there was no desperate need yet.

[@davidtaylor6124]

@@anengineersfindings I tried putting mine up on wood for the same reason but it did not go well. Are they solid wood underneath, or just around the perimeter of the stands? I had lengths of 100 x 100 mm wood (which I'd milled square) going front to back and the machines just wobbled like crazy. Are the machine bases bolted through the wood or something?

[@neffk]

I thought you are meant to spin the bearings to distribute the grease before assembly. Also, is the orientation of the outer bearing race important? I thought there was some trick where the high and low variations in spacers and bearings are alternated to reduce the bending forces on the arbor. Is that a ground glass syringe? Haven't seen one of those in ages.

[@HaraldFinster]

To my (limited) knowledge you should "run in" spindle bearings after re-lubrication, i.e. you do running-pause cycles at low speeds and increase the speed step by step. (Some manufacturers give detailed instructions.) I was surprised that the bearings hadn't any markings showing the optimal angular orientation. But it is well possible that the tolerances of the GMN bearings are so tight that this isn't required. A small question-mark: I have been told by a professional that the mating faces of the bearings should not be lubricated with grease during the installation. Again, I am not an expert. This might not be an issue.

[@naturpudding3361]

Moin, darf ich fragen warum du beim einstellen des Axialspiels kein Fühlhebelmessgerät verwendet hast?

[@AdityaMehendale]

Why is the radial run-out (one micron in your case) so crucial? I can imagine that you run a dressing-stone on your grinding wheel before any operation - would this not correct for run-out? Am I missing something?

[@koharaisevo3666]

You need to balance the grinding stone even after dressing, it's impossible to balance with a runout spindle causing vibration result in poor finish.

[@bobengelhardt856]

Beautiful work, as always. How did your adjustment of the axial play turn out relative to the "original" adjustment? I think that you tightened it beyond where it was at the start?

[@car9167]

Is this an internal grinding spindle?

[@dileeparukshan1696]

Hi Alex, I’ve got a dismantled maximat v13 lathe… with missing parts also. If you can send me some pictures of the apron, gearbox, etc. Then I am grateful…!

[@dizzolve]

nice machine