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February 22, 2019, 02:23:19 pm
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B&I Gem Maker making a bad sound

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Author Topic: B&I Gem Maker making a bad sound  (Read 995 times)
mossagatemac
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« on: March 15, 2014, 08:50:42 pm »

Hi Everybody, I'm still fairly new to this so forgive my ignorance....

I just bought a 'refurbished' 10" B&I Gem Maker to get started cutting and polishing some small rocks with.  Got it home last weekend and did a few hours of sawing, things seemed to be working well.  Today, I was doing some grinding and switching out grinding pads on it, turned it on, and it started making a horrible sound.  Sounded like the lap was vibrating really badly, but I couldn't see any sign of a problem.  I played around with it for a while, tried a bunch of different combinations, but can't quite pin down what the noise is. 

The lap plates were all tightened down firmly when this is happening which is what i originally thought the source of the sound was.  I'm not convinced anymore.  The belt doesn't seem to be loose.  There was some squeaking going on when i put the saw blade back on which made me think it needs some grease (how often do these need to be greased?).

Any ideas?  Here's a picture:


* b&i_gem maker.jpg (57.1 KB, 600x392 - viewed 14 times.)

* IMG_20140315_160222 - Copy.jpg (80.38 KB, 980x735 - viewed 6 times.)
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lithicbeads
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« Reply #1 on: March 15, 2014, 10:45:12 pm »

 There should always be the ability to deflect the belt about half an inch . If the bearing has problems an overtight belt will accentuate them . Perhaps the bearing was heavily greased to hide problems . I have trouble imagining needing greasing more than every 40 hours of use unless there is a problem with a seal.
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« Reply #2 on: March 15, 2014, 11:32:58 pm »

Is your pulley loose on the shaft? That will make a loud noise.
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« Reply #3 on: March 16, 2014, 06:30:00 am »

Quick bushing check, grasp threaded spindle in one hand grab step pulley in other try moving side to side up and down should not be any motion or very little. You may need to loosen belt. Do you know when the last grease was applied ? Old grease can dry out and starve the bushings- bearings and sometimes prevent fresh grease from getting to the bearing.

As was already mentioned belt tension should not be over done.


 These things can make a whale of a noise if the bearing gets dry- most were fitted with oilite bronze bushings- though I have been told some late models had ball bearings though I have not seen one of those in person.
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mossagatemac
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« Reply #4 on: March 16, 2014, 02:16:57 pm »

Ok, I greased it up and the noise went away.  Ran for about 20 minutes and the noise started to come back.  Added some more grease, sounded good again.  Repeated that three or four times before I had to leave.  Does this indicate some other problem to you guys?  Something else I should try?  Its not so bad except it slings grease all over after filling it. 

The belt doesn't seem to be too tight.  Pulling side to side on the shaft seems tight.  Pulling up and down has a little give in it but pretty small.
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« Reply #5 on: March 16, 2014, 03:33:22 pm »

Bushings seem good by the description you gave about the motion- sounds like the machine was little dry for lube. As I mentioned in the PM wipe any excess grease that may appear north of the pulley underneath and around the threaded arbor flange. These machines are good at slinging grease if you don't. I know from personal experience also about grease slinging- and when dry can squall like two fighting tom cats.

I will try to pull my machines shaft to take a look at the way the galleries are drilled in the machine to disperse the lube to the bearings. I seem to remember I had one plugged with old dry grease once. Can't recall if it was a six or 8 inch machine.

Keep us all posted-- these are pretty simple machines once you get used to them.
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Bryan
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« Reply #6 on: March 16, 2014, 05:01:25 pm »

If grease fixes the problem for a short time it is a sure indication of a bad bearingl.
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« Reply #7 on: March 16, 2014, 07:28:35 pm »

Very true on ball bearings.

Sometimes the bronze bushes in these take a while as there is quite a bit of air space in these between upper and lower bushings.
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Bryan
mossagatemac
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« Reply #8 on: March 16, 2014, 08:21:49 pm »

Bad news. 

I wiped off the grease so it wouldn't splash and turned it on to grind some rocks.  It made the sound intermittently so I stopped it and added grease.  Whipped off the excess and tried to turn the shaft by hand.  At that point, the shaft won't even turn.  I can move it a little with my hands, but the belt doesn't move it at all. 

Bushing/bearing problem?  Any ideas or where to get replacement parts if needed?  Or what size this thing takes?

I took a video of it right before the last time I turned it off and uploaded to  youtube.  It's at the following: 

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« Reply #9 on: March 16, 2014, 10:10:56 pm »

Sounds like the bearings are shot .
Pull them out they should have a number on them .
Google the number and find a replacement
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« Reply #10 on: March 17, 2014, 08:50:19 am »

OK We have a problem if the shaft wont turn at all bushings galled up or shaft scored, obvious now the lube never got to where it needed to be or previous owner ran it dry for too long. Lets hope its just bushings. I had one once due to dry grease that the upper bush seized because fresh grease could not get there- was able to clean everything out and re grease and it cured that one. But either way this shaft needs pulled for inspection.
You will want a good penetrating oil or wet lube- WD 40 drys up too quick.

When mine does the screech or warble usually one or two pumps of grease and it goes away for 3 to 6 months.

Am willing to pull mine apart and post photo's of the tear down if that will help-- everyone's mechanical skills vary so I will offer that to help.
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« Reply #11 on: March 17, 2014, 08:55:39 am »

That is a very generous offer . If you make  a  tear down repair post I will sticky topic it so it will remain easy to find.
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« Reply #12 on: March 17, 2014, 09:21:00 am »

Go to your local auto parts store and get a can of "PB Blaster". Its the best penetrating fluid that I have ever found. WD-40 is useless.
Bob
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« Reply #13 on: March 17, 2014, 09:28:05 am »

One little word of caution on these if you start tear down before I get the tear down shot and posted.

The set screw in the step pulley almost always leaves a cup shaped burr or dimple on the shaft- these shafts are fairly soft steel. Very carefully file and stone away( I use a hard arkansas slip stone and mill smooth file about a 2 cut ) the burr till even with the shaft surface. Don't damage the shaft. Reason for this is when you drive, pull or push the shaft through the bushing that burr can do un told damage to the bushings/ or hang up on bearings. Anyways it's a much easier removal without that darn burr.
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« Reply #14 on: March 17, 2014, 09:38:39 am »

P B Blaster is good stuff I have used it.

My secret weapon penetrating oil is Aero Kroil only problem is , it's not in stores. Pro use only type of thing.

I learned about this stuff from some aerospace machinist friends. Don't mean to sound like an ad but this stuffs good.

www.kanolabs.com
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mossagatemac
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« Reply #15 on: March 17, 2014, 10:15:11 am »

Quote
Am willing to pull mine apart and post photo's of the tear down if that will help-- everyone's mechanical skills vary so I will offer that to help.

Bryan, That would help a ton.  I've never done anything like this so even the advice you've given so far is a great help.  I can't express how much pictures would help!
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« Reply #16 on: March 17, 2014, 04:46:23 pm »

Bear with me. Am pulling lights and tools together, never did a shoot of a tear down in the shop before. I will keep this as simple as possible I don't think you are in too bad a shape but we will see when we get inside.
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« Reply #17 on: March 17, 2014, 08:45:02 pm »

I had some time tonight and might not later this week so I took a stab at it.  Thanks for the advice about the burr, you were spot on. 

Here are the photos.  I didn't see anything that was obviously wrong at this point (do you guys?).  Is the next step to pull out the brass looking things on the top/bottom?  Those are really tight and didn't budge so I wasn't sure if those should come out or not.  If yes, what's the best way to get those out?


* tear_down_1.jpg (50.24 KB, 653x490 - viewed 8 times.)

* tear_down_2.jpg (54.26 KB, 490x653 - viewed 2 times.)

* tear_down_3.jpg (63.54 KB, 490x653 - viewed 4 times.)

* tear_down_4.jpg (78.91 KB, 490x653 - viewed 5 times.)

* tear_down_5.jpg (44.91 KB, 490x653 - viewed 5 times.)

* tear_down_6.jpg (58.77 KB, 490x653 - viewed 7 times.)
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mossagatemac
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« Reply #18 on: March 17, 2014, 08:46:46 pm »

Here are the rest of the pics.  The last two are pictures of the brass thing that is stuck in there pretty good. 


* tear_down_7.jpg (40.49 KB, 490x653 - viewed 7 times.)

* tear_down_8.jpg (86.45 KB, 490x653 - viewed 23 times.)

* tear_down_9.jpg (48.82 KB, 490x653 - viewed 9 times.)
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« Reply #19 on: March 17, 2014, 10:57:30 pm »

The second photo above shows the wear on the metal. If that is the bottom of the bowl just above the pulley. I would get a 5/8"inside dia x 1/8"thick oil bronze washer and try to install it before I take the bronze bushings out. That may stop the squealing from the pulley rubbing the bottom of the bowl. Just grease all the bearings and washer before reassembling the arbor and give it a try. There is probably more ware on the lower bushing due to v-belt tension than any on the top bushing. It is possible that there was a spacer between the bottom of the bowl and the pulley hub that is missing. When you  put the bronze washer on the shaft and slide the pulley back on. there must be some clearance between the pulley and the bottom of the bowl. You want the shaft to be tight enough that you can't push up on the pulley and the arbor rises in the bowl. If you don't understand what I'm telling you. Let me know what you are not sure about.

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mossagatemac
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« Reply #20 on: March 18, 2014, 06:45:23 am »

Those pictures were of the top.  Here are the pictures of the bottom. 


* bottom_1.jpg (94.73 KB, 653x490 - viewed 3 times.)

* bottom_2.jpg (100.41 KB, 653x490 - viewed 5 times.)
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« Reply #21 on: March 18, 2014, 06:54:11 am »

Good looks like it came apart easy. Thats good

Do you know if any grease appeared between the lower steel arbor flange and the top bronze bushing ? This is kind of important, sometimes there is dry grease in the bore between the upper and lower bushing that will not let new lube flow up to the upper bushing. Clean out the old grease in the space between the upper and lower bush, make yourself a little flag shaped thin plastic tool that will fit down the bore and scrape it out. The upper is the one that usually starves for grease partly gravity I think but you kind of have to make sure lube is getting up there, it's usually the upper one on mine.

The wear pattern on the shaft does not look too bad. Wipe out the top bushing with solvent and a cloth.

Neither of the original two equipment machines I have or any of the  second hand machines had a spacer washer between the pulley and the lower bronze bushing flange. That said it is not a bad idea, I have had to snug up the pulley to the bottom bushing to compensate for wear.
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« Reply #22 on: March 18, 2014, 08:53:00 am »

Photo doesn't indicate whether it was top or bottom. The bronze washer will work on top as well. I was looking at the chadder marks on the bearing surface and that is where your getting the noise from. The dried grease thing is a good thing to check as well.

You would need a special tool to remove the arbor bushings so it would have to most likely be done by a machine shop.

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« Reply #23 on: March 18, 2014, 01:50:57 pm »

Here are a few shots of the top bushing of my machine and some measurements


Top lip of bushing measures .125 Inch



* 017.JPG (45.52 KB, 600x450 - viewed 3 times.)

* 016.JPG (67.42 KB, 600x450 - viewed 7 times.)
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« Reply #24 on: March 18, 2014, 01:59:57 pm »

http://gemstone.smfforfree4.com/index.php?action=dlattach;topic=15708.0;attach=27662

Where is this photo from? I see the wear marks that I think are chadder marks where the metal has not been lubed and got hot. It it is the top of the bowl without the flange bearing installed the bearing may be ok.

Dickb
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« Reply #25 on: March 18, 2014, 02:14:22 pm »

Bushing above from my machine .

Lip of bushing measures .125 inch thick

Bore of bushing measures .750

Shaft in Unworn areas measures .748 inch

Shaft measured in areas where bushing rides.747 inch

Overall length of bushing 1.00 inch

Bushing O D Under flange 1.00 inch

Flange OD 1.50 Inch
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« Reply #26 on: March 18, 2014, 02:16:42 pm »

Shaft of my B& I machine


* 011.JPG (68.91 KB, 600x450 - viewed 5 times.)
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« Reply #27 on: March 18, 2014, 02:23:15 pm »

Hi Dickb  The photo you were asking about is a top shot of mossagatemac's machine, I am not sure but this top bushing looks like it got worn almost to the aluminum arbor body. It might be grease, could sure use a side shot of that top bushing. I think it's worn badly.

I posted mine so we can compare photo's

The photo of the bushing with the grease zerk showing is the bottom of the tub mossagatemacs machine.
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mossagatemac
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« Reply #28 on: March 18, 2014, 07:19:58 pm »

Here's a side picture of the top bushing.  I didn't remove them yet because they are in there pretty good.  The lip measures in at around 1/8th of an inch.  It looks this in the other picture because of the angle and part of it is painted gray. 

On the inside of the top bushing, i can see a spiral pattern which looks like it may be from a previous owner not taking the burr off prior to removing the shaft.  It goes the entire depth of the bushing and goes around the entire inside about once or twice from bottom to top. 


* tear_down_12.jpg (45.65 KB, 490x653 - viewed 4 times.)
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mossagatemac
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« Reply #29 on: March 18, 2014, 07:37:56 pm »

Actually, Bryan, after looking at the top picture of your bushing (pic 017) I think I can see a spiral groove in it similar to the one mine has.  Is that normal?  It's not the most high res picture so I might be mistaken.
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« Reply #30 on: March 18, 2014, 08:10:28 pm »

Yes there is a concentric circle from the flange on the shaft and tends to wear that into the top of the bronze flange. The gray paint fooled me and I thought I was seeing aluminum.

Yes I see the spiral you mentioned must have been from factory assembly, it's not real deep and has not been a problem. I just did not want to add any more from set screw burs most of mine do have that light spiral- should not be a problem.

Is the top of your upper bushing smooth with just a little circular wear? There was grease in the first shot. Dickb thought he saw some chatter marks on it and so did I.

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« Reply #31 on: March 18, 2014, 08:43:51 pm »

Here are some close ups of the top.  It looks like there is some pitting or something on the top near the center.  It feels pretty smooth and didn't look too bad in person, but it really shows up in the picture (even more than just looking at it in person).


* top_wear_1.jpg (193.41 KB, 980x1306 - viewed 4 times.)

* top_wear_2.jpg (193.23 KB, 980x1306 - viewed 3 times.)
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« Reply #32 on: March 18, 2014, 11:03:16 pm »

That surface should be as smooth as the bottom flange. Those cuts in the bearing might be from metal shavings from the spindle flange bearing surface. If the shaft was run without lube for a time then the surfaces may have heated up and galled the spindle flange and embedded metal, Silicone grit, or rock dust into the soft bearing surface. Before tearing it apart, take some emery cloth and smooth both surfaces up then grease the bearings and the flange of the spindle and re assemble the arbor into the pan and give it a try. If it runs quiet for a little while, a bronze washer added to the spindle and greased should get you up and running. Just give it a pump of grease every so often to keep it lubed. There should be very little side to side movement of the shaft and just a slight amount of travel when you push the spindle shaft up from underneath. It should spin in the bearings with no binding or drag when you spin it without the v-belt attached.

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« Reply #33 on: March 18, 2014, 11:15:15 pm »

That spiral groove is most likely a grease grove you need that to deliver grease to all of the bushing.
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« Reply #34 on: March 18, 2014, 11:24:29 pm »

Yes it is and I was talking about the top flange of the bearing. That should be smooth.
I would guess that about 4 pumps of the grease gun should fill the arbor and you should see grease at the top and bottom of the arbor. Once it is full then 1 pump  of grease is all that is needed every so often. That depends on how much you use it. The grease pushes the grit from the bearings and lubes the surfaces.

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« Reply #35 on: March 19, 2014, 10:12:09 am »

Yep top bushing starved for lube. Worth a shot to clean it all out re lube and try it again before we have to get in to re bushing it, though that is not all that tough on these. But lets try the simple first.

On one of my rebuilds I found a small mill cut file 4" drawn across a rough flange like this will also help smooth it up. Use great care to keep the flange flat, they often will lap in ok with running. You can color the top of the flange with a black marker then when you draw file you can see the high areas being removed, this will help keep the surface even. Go slow and use care. Wipe up all metal shavings.

With the shaft being only a couple thousandths smaller that the bushing bore it doesn't leave much room for a lube film and if the spiral is supposed to be a grease groove it's not very deep compared to commercial grease groove bearings. I think this is a design or engineering flaw on these- fixable but a nuisance. In the photo's it seems the grease came out mostly the bottom judging by what is on the pulley. One of my six inch machines does this also and I wind up every few months pulling the shaft and putting a finger full of synthetic in the top bush and flange- very seldom will grease flow out the top as much as it does at the bottom and there is no obstruction or dry grease in the bore. It appears this machine does the same.

On two of the other machines I sometimes push up a little on the pulley while the grease gun is on the fitting that helps on a couple of them to get lube out under the top flange. As always wipe up the excess these are great grease slingers.

Does anybody think a bearing with a larger grease groove is a bad idea for the top bushing? I have other antique machinery here with similar shafts that runs with very little attention but all have larger grease grooves than just a spiral scratch.



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« Reply #36 on: March 19, 2014, 07:06:45 pm »

Good call on the grease groove minkos.  Looked too perfect to be from pulling out the shaft.

Anyway, the saga continues.  I lightly smoothed out the top bushing with some emery cloth, cleaned it up, greased everything and reassembled.  Put a few squirts of grease in until it came out the top, spun it by hand a few times, and turned it on.  No strange noises!  So that's good news, but I only had it on for about 20-30 seconds and the top of the shaft became pretty warm after only that amount of time.  Seems like something isn't quite right and is causing some friction.  I don't remember it getting that warm before taking it apart. 

I then started taking it apart again so that I could inspect what was going on, and then I noticed the bottom bushing was starting to come out.  Keep in mind, i can't even turn this thing by hand, but now it's sticking out 1/8th of and inch or more.  Did I not get enough lube on the bottom bushing, so it got spun out when it was running?  What's the recommendation at this point, pound it back in?  Replace it?  other?


* bottom_bushing.jpg (48.54 KB, 490x653 - viewed 3 times.)
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« Reply #37 on: March 19, 2014, 07:49:08 pm »

I may have replied but I forgot, especially if it was an hour or more ago.....anyway, I had one just like this but it was a sears.  Didn't really know what it was at the time and sold it way to cheap.
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« Reply #38 on: March 19, 2014, 09:24:05 pm »



Does anybody think a bearing with a larger grease groove is a bad idea for the top bushing? I have other antique machinery here with similar shafts that runs with very little attention but all have larger grease grooves than just a spiral scratch.





In my opinion no it is not a bad Idea to have larger grease groves, at work we do this all the time for bushings in large logging equipment also on small bushings for saw mill rollers and many other things.

 
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« Reply #39 on: March 19, 2014, 09:46:45 pm »

  What's the recommendation at this point, pound it back in?  Replace it?  other?

My recommendation at this point is to replace both . I think what has happened is .
1) it got run dry (no grease) heated up and has shrunk the bushing to close to the shaft and is seizing up.
2) now that has shrunk to the shaft that means the O.D. of the bushing has shrunk which now has made the press fit less and is allowing the lower bushing work its way out.

Why I'm saying this is happening with the bushing is that is how we remove Aluminum/Bronze bushings from blind holes. Heat the bushings up they expand against the housing and when it cools it has shrunk to allow to be pulled out. And I think this is what has happened in your situation .

This is my opinion only and I could be totally off base as I have never worked on a machine like this.

   
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« Reply #40 on: March 19, 2014, 11:05:02 pm »

Well now is the time to replace the bushings if you can find replacements. What happened is the grease gun pressure forced the lower bushing out of the arbor. Now, you can either take a wood block and a hammer and tap the lower bearing back into the arbor, or take the lower bearing out of the arbor, then use a wood dowel that is just a bit smaller that the outside diameter of the bushing and stick it into the arbor and tap the upper bearing out as well. What happened is when the lower bearing came out it tighten up the friction of the spindle and pulley rubbing on the bushing flanges and that is what caused the bushings to heat up. That is probably what made the top bushing score the flange surface. Otherwise just tap the bushing in so it's tight to the arbor and re-install the pulley and try the lap again. You now know what to look for next time you lube the lap and what caused your chatter problem.

It may be difficult to find replacement bushings, but you now know how to get the bushings out of the arbor.

Good luck and have fun.  yes

Dickb
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Isotelus
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« Reply #41 on: March 20, 2014, 08:07:57 am »

The Bushing is an SAE 841 Oilite Bronze  FF 1013 your local bearing distributor can look it up, most don't seem to stock this one. The are made by Isostatic Industries but they only sell through a distributor. Motion Industries locally can get them, their cat # 00003868. A word of advice there are very many similar numbers If after the FF sequence there are more than the 4 numbers 1013 its not the right bushing refer to the measurements i posted earlier.

Again:
Bore  ID .750  OD tube 1" Overall length 1" Flange OD 1.5" Flange lip thickness .125  Never install a longer bush than 1" or you will have no grease space and no easy way to get them out in the future.

Luck is on your side the bottom one slid partly out that is where all the lube accumulates this often makes removal easier.
A 3/8" drive socket extension 5 or 6" long will make a acceptable driver, use the female end with the square socket ( the fat end ) it will slide through the top bushing bore and with finger pressure hold it against the side of the bushing bore slide it down gently and you will feel when it gets to the space the grease occupies between the upper and lower bushing. Keep sliding it down till you feel it contact the top edge of the lower bushing. I use about an 18 OZ brass no mar hammer but any will work. Don't hit real hard just a good solid tap will do.

Whatever point you start at think of it as 12 o'clock on a clock dial then go to 6 o'clock position ( another solid tap ) then go to 3 and 9 o'clock positions tap at each. Keep repeating that untill the bushing is driven all the way out. Then flip machine bowl over and repeat the same operation on the upper bushing. I like to set the machine body up on a couple wood blocks for this. Once the lower bush is out clean out any grease, this will help you see up the bore to find the top bushing edge.

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Bryan
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« Reply #42 on: March 20, 2014, 08:42:51 am »

McMaster Carr carries a very good selection of these types of bushings. Their catalog is online. Look under Bronze flanged sleeve bearings.
Bob
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Isotelus
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« Reply #43 on: March 20, 2014, 10:00:59 am »

They ( Mc Master ) do have a good selection, their stock flange OD's only go to 1 1/4" though. Because of this machines steel arbor flange 1 1/2" OD it requires a bush with an 1 1/2 OD flange. I had tried them some years before.

Just watch the measurements folks this one is real easy to get the wrong one there are so many variants.
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Bryan
mossagatemac
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« Reply #44 on: March 20, 2014, 05:08:17 pm »

Quote
SAE 841 Oilite Bronze  FF 1013
I didn't see your post before going to the store and picked up two bushings, so hopefully i got the right ones!  Had two in stock that matched the measurements we discussed earlier.  I brought the one that popped out and the shaft with me to make sure I got the right ones.  I'm going to try and remove the top bushing tonight or tomorrow and will let you know how it goes.
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mossagatemac
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« Reply #45 on: March 20, 2014, 06:38:56 pm »

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SAE 841 Oilite Bronze  FF 1013

Crud.  I'm pretty sure I got the FF-1011-4.  The marker is a little worn off where they wrote it, but pretty sure. 
Is this going to be a big deal?  Here's the differences:

                      ID Max    ID Min        flange OD
FF-1011-4:     0.7505    0.7495       1-7/16
FF-1013   :      0.751    0.75             1-1/2


Everything else is the same.  Same OD, length, etc.  Just a smaller flange by 1/16th of an inch, and 0.0005 inch difference on ID. 
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Isotelus
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« Reply #46 on: March 20, 2014, 06:50:51 pm »

Yes, you need the full diameter bushing flange so the steel flange on you arbor does not wear unevenly. The rest of the specs are acceptable ID Max and Min.

That arbor flange also takes the brunt of the pressure from flat disc grinding which is something these machines are good at. You really don't want to mess up your arbor shaft there is no replacement for them part wise unless you have a machinist friend. That said they are not a real complicated arbor for a machinist.

The stock numbers are a pain with these-- so many variants.

I also have a few on order while my machine is down I am going to add a grease groove to mine to see if I can quit spoon feeding the top bearing grease
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« Reply #47 on: March 20, 2014, 07:27:37 pm »

If you add or enlarge a grease groove, make sure it is in that spiral shape, otherwise the shaft will make the bore egg shaped. A Dremel with a ball bit should do it for you. Just work the spiral from both ends of the bushing. A quarter turn would work but a complete revolution would be best.

Dickb
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Elegance in Jewelry
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GPAA, PLP - Blackhawk G&MC, CVR&MS
Eastern Iowa, Clover SC

mossagatemac
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« Reply #48 on: March 21, 2014, 08:34:49 pm »

ok, got the bushings, cleaned everything out with mineral spirits, and put the new bushings in.  The shaft seems to fit pretty well so I'm excited about that. 

The problem I'm currently facing seems pretty basic compared to the rest.  I'm putting the pulley on, but the little screw that holds it on to the shaft won't screw in.  It seems like I'm cross threading it or something because i get just a little ways in and it stops.  I don't want to force it and am worried I already went too far.  What are my options? 
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« Reply #49 on: March 21, 2014, 09:14:32 pm »

Those pulley's are notorious for cross threading. Take the setscrew out of the pulley.

Stick the allenwrench through the screw hole and slide the setsecrew into the bore of the pulley so you can engage the allen wrench in the setscrew and back the setscrew up into the pulley as the setscrew comes through the screw hole it will re-align the threads in the pulley casting, It's delicate work but if you put a little grease on a stick like a popsickle stick you can position the screw where you can get the wrench into the setscrew then lift up on the stick to start the screw into the threads, that may get you out of trouble.

Dickb
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Elegance in Jewelry
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GPAA, PLP - Blackhawk G&MC, CVR&MS
Eastern Iowa, Clover SC

mossagatemac
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« Reply #50 on: March 21, 2014, 10:29:38 pm »

Great idea dickb! I'll try it in the morning if i can get some time.

Next question -- as I'm reassembling this thing, how do I know if the belt tension is correct?  They way it was set up didn't allow me to change the belt tension so I'm going to rotate the motor 90 degrees which allows me to adjust the tension. 
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« Reply #51 on: March 21, 2014, 11:28:24 pm »

Those bronze bushings don't stand a lot of side load so the tension only needs to be tight enough that the belt doesn't slip under load. You should be able to flex the belt up and down about 1/2" or more at the center between the pulleys. A flat lap should not have the cab pushed down hard enough to slow the lap. Let the grit cut the stone, not burn it off.

Dickb
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Elegance in Jewelry
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GPAA, PLP - Blackhawk G&MC, CVR&MS
Eastern Iowa, Clover SC

mossagatemac
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« Reply #52 on: March 23, 2014, 02:45:41 pm »

Well, that screw was way more of a problem than it should have been.  Long story short, it's where it should be now.

Everything is back together, and I rotated the motor 90 degrees so that the belt tension can be adjusted.  Also replaced the belt because there were a few hard spots on the original; so as long as I went through all of the trouble to replace the bushings i may as well do the belt too.

Just ran it for about 2 hours and things are sounding pretty good.  Not much heat coming off of the shaft and it is running pretty smoothly. 

Thanks for everybody's help! 
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« Reply #53 on: March 23, 2014, 04:30:32 pm »

Glad I could help. Now go have fun!  yes

Dickb
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Elegance in Jewelry
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GPAA, PLP - Blackhawk G&MC, CVR&MS
Eastern Iowa, Clover SC

guest3478
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« Reply #54 on: March 23, 2014, 04:53:21 pm »

i have to replace these bushings in my grinder like this also, im just too lazy to go to my local hardware store and buy the new ones.
McLendons where i used to work has these in stock all the time.
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« Reply #55 on: November 19, 2015, 08:20:34 am »

Memories... my dad ordered me that same machine from Sears and Roebuck over 60 years ago.  I have an agate in my showcase that I flat lapped way back when.
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« Reply #56 on: November 19, 2015, 04:32:52 pm »

I prefer Kroil as well.  It is available directly from the manufacturer or from McMaster.com
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