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How to determine the condition of bearings in a 10ee, and other questions

Your photo of the sliding dog clutch is about as bad as I've seen from a working machine. Great demonstration of which part Monarch intended to be the expendable one! That poor clutch was seriously mistreated for a long time by hacks. With that much crud generated inside what Monarch calls the "back gear" on a 10 EE your plan to replace the output bearings demonstrates sound judgment.

Cutting the keyway can be done with common equipment such as a lathe or turret mill by making a HSS tool of the required width and operating it as a shaper would by making multiple passes through the bore while stepping the tool for a .001-.003 deeper cut on each pass. I used the spindle of a turret mill to make the keyway in the new dog clutch I made. It took about five minutes to set up and cut it, it's on size and works well. The entire part was done in an hour or two, it's a simple part.

It would have taken me longer to weld and reshape the dogs for full engagement. I'm fully equipped and competent with TIG with deep knowledge of metallurgy and weld engineering. My assessment was that path lead to a lower quality repair than a new part. Kicker was a new part was faster too.

I posted in a thread some years back about this method of cutting an internal keyway. Included are photos of tools I made over 50 years ago which I still use for the random occasional internal keyway I need. Sorry, can't find those posts but they're in this Monarch Forum. I've done the job on lathes too in the past, works fine for one offs and it's easy to do, even for keyways for tapered keys. Anyone doing prototype or repair work should have that in their pocket.

Had a huge laugh, thank you!

I was taught how to chip out a keyway with chisels and it works. My grandfather was a millwright in the late 1800s through first half of 1900s. That's the only way they had to do it at large machine installation sites away from machine tools for repair and to correct screw-ups during original installations a hundred years ago. Versa Mill and similar devices didn't exist. The skill level to do it accurately takes years to develop, no way for a newbe one off to have good a result! The required level of layout, gaging, tweaking is insane today.

pbungum has machine tools, no problem.
Bill and Dave - I'm enjoying listening in on the conversation - fun stuff, and interesting.

Dave - I've seen reference to the technique that you've mentioned - maybe even your post. I'll reference that. The thought went through my mind to do that, but for some reason the thought didn't stay IN my head, and instead fell back out and rolled underneath a toolbox. I'll consider that method.

At the moment, I've got some time - I will pull apart the reduction unit more, and think about the best way to tackle that dog clutch. I'll go search for a bearing splitter today.

Here's a question to answer - I see that the output bearing from the reduction unit is often referenced as an angular contact bearing. In trying to find a replacement, all the bearings that seem similar are called deep groove bearings (or something like that). From my poor understanding, it seems that these are different, due to how the ball and the race are positioned relative to each other. Are the N.D. 20209 bearings really angular contact bearings, or deep groove bearings? Will replacing the 20209 with a deep groove bearing cause issues? It would seem the axial load on the bearing in this application isn't really all that large, so the deep groove would be sufficient, but I'm no trained mechanic or engineer.
Ah - good to know. I think I'll just bite the bullet and call General Bearing for the proper replacements. I was hoping to at least find one of them, such as the 7209WNMRBSU (number taken from different thread) inner bearing online, but I can't get all of the suffix to line up. I can find 7209WN SU, but not that middle part. I haven't been able to identify the significance of the MRB portion, (unless that's supposed to be MBR, for the brass retainer). I'm not sure what the brass retainer does, and if it is important, if that's what that portion of the suffix means. I can also find a H420209B, but that doesn't sound quite like what is needed. The "DT" from 420209DTL indicates grinding for mounting in tandem, whereas the 420209B doesn't have that specific grind. I'm assuming that is important. This is as bad as trying to figure out a new carbide insert system! Thanks for setting me straight on that - maybe I'll use the 6209-Ns I bought for bracelets or something -ooh I know - napkin rings! :)
Your dog clutch can be welded and recut although making a new one would be better. I did it on mine as far as bearings are concerned the nachi 6209nse bearings are what I used my back gear is considerably quitter now. The originals in mine were 209 bearings. The front bearing uses the snap ring the rear does not. Bob
I was able to talk to General Bearing and the 7209WN MBR SU was ~ $85. As luck would have it, I was able to find one on eBay for around $40, so I purchased that one. The 420209DTL would have to be custom modified for the groove, for around $150+. I'm considering doing that, However there is also a 420209B (the 4 indicating the snap ring groove) on eBay for considerably less. I'd consider that, but the DTL apparently appears to be specifically for tandem mounting, where as the B is not. I am wondering if I could get away with using a 420209B instead of the DTL, without much penalty. I'm sort of all over the place here, BUT I do feel like I am also learning a bit about bearings (though it is still a bit mystifying). I also have the 6209NSE bearings in hand now, and at least 2 people appear to have them in their gearboxes without trouble. Decisions, decisions!

As another thought - does anyone have a rough idea what a shop would charge to grind the snap ring groove into a 20209DTL? I think I could get one of those for fairly cheap (<$50).
This is how I would go about the dilemma here..

I would buy a 7209 bearing... Just a generic one from a quality manufacturer... I would then get another 7209 with the snap ring... I would not concern myself with what grind it has, whether it was made for universal mounting or anything like that...

I would get both bearings and place the outer ring of one on a parallel spacer on my surface plate.. Remember an angular contact has a correct and incorrect way to install, so you place it on the spacer in the correct orientation as it would be when under load...... Many things can suffice for this job, even another bearing as shown in the photo...

I then get a surface gauge or in my case a height gauge and place a dial test indicator on it... The one I use is in 0.01mm graduations... In the pictures below a deep groove ball bearing is used just as an example..


With the bearing inside ring hanging by gravity, I give it a small turn to bed it in, then with the dial indicator measure the difference in height between the inner and outer ring.... Lets say the inner ring is hanging 0.02mm lower then the outer ring..


I measure the other one and it measures the inner ring is lower by 0.04mm...

So what does this tell us? Well it tells us the spacers between the two bearings have to be sized differently so that when all assembled the bearings are placed under a bit of preload and are not just floating there...

So it the spacer between the outer ring is say 3mm, the spacer between the inner ring needs to be 3mm + 0.02 + 0.04 + a figure you feel will give you some decent preload... Lets say 0.03mm. So the inner spacer will be 3.09mm thick...
Then I would make the spacers to suit...

I had to do this this year when replacing bearings in a G&L borer.... The originals were not precision bearings, but bearings ground with preload in them... I used Japanese bearings with spacers between the two to apply preload..

Hi Richard,

That was very informative! Thanks! I feel like I understand how the preload setting is accomplished now, when I was not clear on that before.

I ended up purchasing the outer 20209DTL prior to seeing your post. I plan to have the snap ring groove ground into it. I previously purchased the inner 7209wnmbrsu. I am hoping to have that done locally - I think that I know of a place that can do that. I will then end up with basically the same factory setup, which I think I will feel best about. I can see where your method would also accomplish a suitable setup, and I will remember that for the future!
Well, the motor is back in place again.

If any one else is going to do maintenance on their Reliance DC motor and hasn't done so before, here's the steps I'd recommend based off of my one time experience:

1) remove the electrical box from the hinges, and set sideways on a 4x4 (as the wires are short) in front and to the side of the machine base.
2) pull the lower sprocket and chain for the speed pot.
3) pull the front right motor mounting plate bolt (that goes through the rubber vibration dampener washer).
4) screw the leveling foot down so that the head is below the motor mounting plate.
Steps 3 and 4 allow the motor to be pulled/reinstalled without disturbing the speed pot, if very careful. Otherwise, this will need to be removed.
5) disconnect the motor from the incoming wires (A1,A2,F1,F2). Remove the wires coming into the box from the electrical panel, not the DC motor.
6) The motor should be able to be slid out from around the speed pot if careful. I was able to move it without assistance from a dolly, etc. but putting it back in, I used a flat pry bar to help ease the process. It's not too bad to do this way, if you lift 1 end of the motor at a time (so you aren't actually lifting the full weight of the motor).

When disassembling the motor, I found it useful to use a 7/8" flat wrench normally used for a radial arm/table saw arbor nut to help unscrew the nuts that hold the DC motor leads that run to the brush ring. Using that to hold the inner nut, I could then use a regular 7/8" combination wrench to screw the outer nut, to release the leads.

I installed the 2 armature bearings by sticking them in the oven, wrapped in tinfoil, and baking them at 250°F for about 30 minutes. They just flopped onto the spindle, piece of cake. I made sure to pull the brushes fully from the brush ring prior to assembling the front motor casting. The brushes and commutator all looked pretty good to my untrained eye. The springs for pushing on the brushes were all firm. I inspected the wiring and replaced one lead that goes to the brush ring. I got the chance to use my new PB Swiss screwdrivers for that, which my wife got me for Christmas - that was a good gift (and they even match my initials!)

I turned on the spindle motor, half expecting some drama (I turned my head and squinted, for extra safety), but there was no drama. There was also no difference in the sound of the motor - it sounded exactly the same as before changing the bearings! My conclusion is, the motor just sounds like that! It's hard to spell a sound, but it is sort of like the sound of a light, higher pitched fly reel "rrrrrrrrrrrrrrrrrrrrrrr" sound. Could that be the brushes clicking over each of the bars on the commutator maybe? There is no visible sparking from the brushes whatsoever.

Question: When I pulled the motor, I noticed that there were some shims, amounting to about 1/4" under each foot of the motor. The shims were not all the same size, and seemed to be somewhat cruder than what I would have expected from Monarch. Was this something that Monarch did (shim motor), or was this likely someone after the fact? I also noticed that the rear vibration dampening mount was a bit blown out, and so I stuck some large fender washers underneath to make the mount more even with the front 2. The screw for the rear plate mount was barely screwed in when I removed the plate, so it stood proud of the plate by a good half inch. I don't know what the significance of that would be, but I wonder if it added to some of the vibration. As a side note, the washers that Monarch used to press against the rubber vibration mounts appears to have been ground flat - maybe it's just me, but that seemed like a bit of overkill! I'd like to get a replacement for that rear vibration mount. I wish I had asked Monarch for that and gaskets for the gearbox prior to buying a complete set of way wipers a few days earlier.

With regard to the gearbox, I was able to remove the bearing from the main output shaft with a bearing splitter. The inner bearing feels rougher than the outer one (the outer one feels pretty dang smooth). I am contemplating leaving the outer angular contact bearing alone, and replacing just the inner one. I'll probably change my mind and replace both of them (as I have ordered both bearings, one in hand currently). In my case, the current ones are a pair of 20209DTLs, with the outer one having been modified for the snap ring. I thought I could have the snap ring groove done locally, but it sounds like I will probably have to send it to Portland to be done.
I welded up the dog clutch teeth today. Took a few minutes to weld, and maybe a half hour or so to shape the teeth. I realized that if I had made the part from scratch, I still would have run into issues with matching the profile of the teeth from each half of the dog clutch unless I had also milled the dog clutch teeth on the bull gear as well. As it were, I hand shaped the teeth with air tools, and a little file touch up. They aren't perfect, but it's a big improvement over how they were. I say it's not perfect, because I know that I don't have full engagement of each tooth face with each corresponding face of the bull gear. The shape would seem to be somewhat complex to match to each tooth, and then to also maintain pressure with each tooth. It would be a serious undertaking that I don't think will be necessary. As it is, it would appear that there is some contact with each face (or close to it).

I realized that the gear box has been previously worked on. One of the shoes that moves the gears back and forth was made from brass, whereas the other 3 were steel. One of the rings that engages with the shoe was made from brass over a steel inner liner. The brass part was pinned to the steel liner, and there is a little wear area around the pin that I'm guessing makes a little click noise when the shoe rides across it. I left it as is - it appears to be well made and functioning. I don't think that gear even turns unless in the gear reduction mode (which I rarely use). Someone also pinned the arms of the shift fork to the shaft (no more screws), which made pulling the upper gear a bit of a head scratcher. I ended up working the jackshaft bearing out the back of the bore by pushing it with the shaft itself (which is stepped), which freed the shaft enough to pivot and allow for the removal of the gear. Might be a useful technique if you wanted to remove the gears but didn't want to disturb the shift fork.
The shape would seem to be somewhat complex to match to each tooth, and then to also maintain pressure with each tooth. It would be a serious undertaking that I don't think will be necessary. As it is, it would appear that there is some contact with each face (or close to it).

If there's any concern you can make sure of the contact with a little bluing and using the grinder to remove the transfer area. 2-3 passes and you'll see very good contact.
Thanks Russ - I think I touched up the contact surfaces to satisfaction.

I assembled the new rear bearing on the output shaft, and assembled the gearbox (using the old front bearing). It felt quite smooth, so I went ahead and reattached the gearbox to the motor. I cut new cork gaskets out, and so it should be fairly straightforward to pull the box apart again should I decide to replace the front bearing. I tested the motor/gearbox without attaching belts, and found that it pretty much sounded the same is it ever has, which is to say noisy! But I've decided that this is just how that section of the drive system sounds. I know that some might say "hey dingus! but you didn't replace the front output bearing so that could be where the noise is coming from!" I've decided though that most of the bearings were probably in decent shape (though I do think that the REAR output bearing was a little worn), and that while worthwhile to have done this maintenance, ultimately none of the bearings were problematic in this area. I think that the sound is largely telegraphed from the motor, with a little noise from the rotation of the bearings, shafts, etc. There's not much difference in sound/volume between high or low speed.

After putting everything back together, I machined a backplate, and then mounted a new to me, barely used 3-jaw Bison 6" scroll chuck. The Buck 6-jaw I normally have mounted is fairly worn, such that it does not accurately repeat consistently. I ran the spindle, and sure enough, there is a definite additional noise (meaning that I don't think the motor or gearbox are the sum total of the noise that the machine makes). I turned 2 short test pieces. The first was a length of 4140, and the second was a piece of 12L14. I replaced the chuck thinking that there was some potential that the surface finishes that I achieve are affected by the workholding. Attached are the photos of the test pieces.

4140 turned at around 2000 rpms, .002"/rev, various doc (final was around .020" IIRC).

12L14, 1500 rpm, .006"/rev

The work appears to maintain size accurately (not surprising with short part lengths), but there is definite vibration that is affecting the surface finish. The photo of the 12L14 appears exagerated - the finish doesn't look THAT bad in "real life". However, the photo is good in that it does make clearly visible the harmonic nature of the surface finish. While I don't perform work that requires immaculate finishes, I'd prefer this be better. Amazingly (to me anyway), the two ends of the test piece, when flipped in the "new" chuck ended up matching up really well. Other than using the Sjogren chuck, I haven't had this type of experience with this machine, as the 3 or 6 jaw chucks have always been well used.

So, I'm thinking I need to address spindle bearings. My first thought is to replace the rear bearings and see if that makes a difference, then address the front bearings if it looks like that will be necessary. At about page 13 of "the wreck update" saga, Harry mentions symptoms that sound similar to my situation. He changed out the rear bearings and remedied the problem. If anyone wants to chime in and give me their $.02, feel free. In the meantime, I'll be scouring the PM archives for spindle bearing related information.

Oh! P.s. when reassembling the gearbox onto the motor, there is a sequence that makes it much easier to do than what I originally had in mind:

0. Tie the tie rod that connects to the shift crank of the gear reduction box up and out of the way. Don't ask me how I figured this out.
1. Remove the key (if not already removed) from the motor shaft that goes into the back of the reduction gearbox.
2. Take the dog clutch half that goes on the motor spindle and slide it onto the shift fork, while the back half of the reduction box housing sits on your lap or some such. Don't worry about the front casting right now.
3. Holding the dog clutch half with your fingers, grab the housing and slide it all onto the motor and motor shaft, using the dowel pins to locate and temporarily keep the housing in place.
4. Rotate the dog clutch half so that the keyway lines up with the keyway on the motor shaft. Install key (mine slid in easily, but not super loosely)
5. Now mount up the front half, with the four mounting bolts.

This strategy is probably obvious to most. It wasn't a big deal to figure out, but it might save someone some time in the future.
Before you order new spindle bearings I would find out where noise is starting from. This is what I would do. Disconnect the feed belt and set the threading dial to off see if it gets better. If not Take a stethoscope available at a automotive parts store or tool store or a long screwdriver put handle end to your ear with lathe running listen to all suspect areas. You should be able to hear where the noise is loudest. Change that bearing first then repeat as necessary. Bob

On my gearbox the output shaft bearings were the cause of my vibration /noise they felt good by hand but made noise under load.
Thanks for the suggestion Bob. Prior to disassembling the machine to do the maintenance on the DC motor and gearbox, I did exactly that (minus the stethoscope part). I also repeated the "build up" of parts, belts, engagement of feed/gear box, to see what caused changes in sound. I have pretty well isolated the spindle... I think. At least that is what makes the most sense to me, logically, based upon removing other potential sources of noise. I had thought for awhile that perhaps the noise was telegraphing through the main drive belts to the spindle, but after spending more and more time listening to the system, It seems most plausible that the noise is originating from the spindle itself. On the plus side, the gear train doesn't seem to contribute any noticeable sound, so it would seem that all that is in good shape.

I will try to do more investigation of the noise with some type of stethoscopic device though, for further verification.

Absolute worst case scenario I've come up with is that I try to remove the spindle, and all the balls from the front and back start bouncing all over the floor, and then a meteor hits the house. Next worse case scenario is, I remove the spindle and drop it on the ground, or some such, and have to replace the front and back bearings. I'd do it if I needed to. BUT I think there's a good chance that the sound is coming from those back bearings, And barring the need for some type of very specialized equipment (which there does not appear to be the need for), I think I can manage to remove the spindle and replace those back bearings, and reinsert the spindle again. At least that's what I'm hoping for.

I should just upload the sound, but IF it really does originate from the spindle area, it's not a sound that I can just leave alone. The machine is telling me it needs help, and when I bought the old thing, I told it I'd take care of it! Sometimes you just have to pay the vet bill.
I think some specialized equipment would b very helpful. Is there any practical way you can access a vibration analyzer (spectrum analyzer, bearing analyzer) and apply it to the machine? Maybe try an online test equipment rental place or GTI Spindle <link>. Defective rolling bearings emit at characteristic frequencies that a spectrum analyzer can find. You can even tell whether a defect is in the inner race, outer race, or balls. If you don't find a spectrum peak belonging to one of those issues, then your bearings may be okay, and you'll have saved yourself serious time, money and effort.
Hmm - that's an interesting thought. I will investigate that a little further. My preliminary search came up with reputable looking ones being a fairly high cost - I can see how one of those would be a useful tool however.

I'll say this - the noise is not subtle. Now that I've spent a fair amount of time trying to figure out where the various noises eminate from, the spindle noise is a quite loud "Brawoooorrrrbrawooorrbrawoorrrr" noise. I can hear it outside the shop. Something clearly isn't right.
Absolute worst case scenario I've come up with is that I try to remove the spindle, and all the balls from the front and back start bouncing all over the floor, ...
Don't worry about that. If any of the balls fall out, the bearing is far beyond shot.

Don't worry about that. If any of the balls fall out, the bearing is far beyond shot.


Oh I was kidding. I just figured that if I'm resigned to the potential of everything being utterly shot, it won't be so bad if I discover that things aren't that bad.