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3 Phase Lightbulb
08-27-2005, 02:35 PM
My bearings for holding my differential in my buggy arrived.. I ordered the bearings with a bore of 1.625 and they are exactly 1.625... I thought my differential bearing seats were also 1.625 but they are in fact 1.628 so I need to either take off .003 on my differential, or bore out the 1.625 bearings to 1.628..

Normally I would just use an edge finder and bore them out on my Bridgeport, but since I only need to take .003 off, I was wondering f there is an easier way? Could I just heat up the bearings with low heat and expect them to expand from 1.625 to > 1.628?

Here is a picture of them:

http://www.bbssystem.com/buggy/bearings.jpg

-Adrian

tattoomike68
08-27-2005, 02:56 PM
boring a bearing it not that simple, they should be stone hard.

you can do it in a lathe with ceramics, turn it @ 2000 rpm. it will look like the 4th of july.

I would turn the diff.

michaeljt
08-27-2005, 02:57 PM
The bearings a hardend, and would need to be jig bored. Can't you return them and get the correct ones.

3 Phase Lightbulb
08-27-2005, 03:05 PM
I definitely don't want to turn it since I'm taking off so little.. I could probably just wrap some emry cloth/sandpaper around the diff's bearing seat and get it to fit since all I need to remove is .0015.. I'm just not sure how long that will take.

-Adrian

3 Phase Lightbulb
08-27-2005, 03:14 PM
<font face="Verdana, Arial" size="2">Originally posted by michaeljt:
The bearings a hardend, and would need to be jig bored. Can't you return them and get the correct ones. </font>

The bearings are 1.625" and that's what I thought I needed.. The differential needs 1.628" . I quickly measured the diff before buying the bearings and It looked like 1.625.. The next larger size bearings jump 1/16" so I'll just turn down my diff..

I was going to turn a sandpaper flapper inside the bearing bore and see if I could clear another .0015 but I'll go try hand sanding down the diff carrier instead..

-Adrian

Evan
08-27-2005, 04:53 PM
Chuck up the diff in the lathe and use a fine mill file. Run it in reverse and hold the tang/handle in your right hand at the back of the work, left holding the front of the file. This way it can't catch and bite you. Take off a bit and hit it with some emery. Blacken it with a sharpie so you can see what is coming off. Sneak up on it, it's easy to overdo. Use a file with a blind edge toward the shoulder.

[This message has been edited by Evan (edited 08-27-2005).]

hoffman
08-27-2005, 05:00 PM
Maybe you could hone it. Just an idea...

------------------
Deep Sea Tool Salvage

Evan
08-27-2005, 05:32 PM
Hone the bearing IDs? I wouldn't touch them. It's liable to turn out badly.

zl1byz
08-27-2005, 05:46 PM
Sounds like a job for a small tool post grinder on the lathe.

Mount the bearing in the chuck get it running true and take a bit out of the bore with a stone that will fit through the bore.

Take the bearing out of the housing and remove the grub screws (don't loose the grub screws) and chuck up on the extended inner race.

John.

Forrest Addy
08-27-2005, 05:58 PM
0.003" is way too much shrink. You may not crack the inner race but you're sure to take up all the internal clearance and then some vastly shortening the bearing life.

Don't modify the bearings; you might have to replace them. Modify the diff. Chuck the diff up in the lathe and dial in the bearing fits. 0.002 isn't too much to machine/ file/polish off. Do a careful job and mike in a dozen places as you go and you can work down the the bearing fit to allow 0.0008" shrink per inch of diameter.

Heat the bearing up to 300 degrees and drop it on the fit.

CCWKen
08-27-2005, 06:15 PM
I'd just cut the differential to 1.624 and be done with it. If you ever have to replace the bearings, they'll be standard again. The .0005 (.001 total) clearance will still be snug fit. Besides that, don't the bearings have lock/set screws?

Forget trying to rebore bearings. Like everyone said, the carrier is HARD. Stay with a standard size bearing and make the differential fit. Surely you can cut .002 with some accuracy. Right?

Forgot to mention:
With the diff made to fit the bearings, you could make sure your sproket surface is also true to the bearings.

[This message has been edited by CCWKen (edited 08-27-2005).]

3 Phase Lightbulb
08-27-2005, 07:24 PM
I ended up using a vertical belt sander and tried to evenly remove the material while slowly rotating the diff.

It worked, but I get a tiny wobble which I'm not happy about, but I can live with it..

Thanks for everyone's input!

-Adrian

Mcgyver
08-27-2005, 07:37 PM
<font face="Verdana, Arial" size="2">Originally posted by 3 Phase Lightbulb:
I ended up using a vertical belt sander and tried to evenly remove the material while slowly rotating the diff.


</font>

dude you get an A for bravery for disclosing that http://bbs.homeshopmachinist.net//biggrin.gif if the vibration is too much turn the diff shalf concentric again, buy the next larger size of bearing and sleeve the difference.

[This message has been edited by Mcgyver (edited 08-27-2005).]

CCWKen
08-27-2005, 07:50 PM
Geez. Ya just couldn't wait eh?

That's a pretty half-assed way of doing something that's going to be spinning at 3000+rpm. http://bbs.homeshopmachinist.net//rolleyes.gif

IOWOLF
08-27-2005, 08:14 PM
ROFLMAO.

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The tame Wolf !

chkz
08-27-2005, 08:31 PM
I'd weigh-in with CCW Ken and others here...much better to be able to replace 'em with std. brng sizes....

zl1byz
08-27-2005, 08:45 PM
On reflection modifying bearings is not a good option.

Wow! Balls out for telling us how you did solve it Adrian. I don't think I would have let on. http://bbs.homeshopmachinist.net//biggrin.gif http://bbs.homeshopmachinist.net//biggrin.gif

John.

chief
08-27-2005, 09:09 PM
"Measure twice cut once" as they say. Forrest
has the best idea I believe, you won't get the money back for special bearings.

Evan
08-27-2005, 09:19 PM
Well, I have to admit to doing things like that. It's a learning process.

madman
08-28-2005, 08:37 AM
Measure correctly and reorder correct bearings. Dont make mountain outa mole hill.

Peter S
08-28-2005, 11:42 AM
3 Phase,

I am surprised about the bearing ID - normally that type of self aligning bearing is always oversize (compared to a 'normal' bearing. They are made so that off the shelf shafting will be a sliding fit, and they then rely on their locking system to hold the shaft. I would expect that bearing to be 1.626 or 1.6265 (approx, I don't have a book to check)

BTW, when it comes to fixing self-aligning bearings to a shaft, there are 3 options I have used:

Grubscrew locks are the least effective, and also the most difficult when it comes to removing a bearing.

Eccentric collar locking is much better - they lock better and the bearing is much easier to remove because you can file off the grubscrew mark on the shaft. (Normally only recommended for one direction of rotation though). You always tighten eccentric collars in the direction of rotation, give them a good whack using a hammer and centre punch, then lock grubscrew.

The taper sleeve option is better again, but expensive and a bit of a pain.

Oh, and if you want to get those bearings off again in a years time, you must use a moly grease or similar on the shaft and bearing bore, this prevents fretting corrosion. General purpose grease won't prevent this.

[This message has been edited by Peter S (edited 08-28-2005).]

mochinist
08-28-2005, 11:50 AM
<font face="Verdana, Arial" size="2">Originally posted by Peter S:
3 Phase,

I am surprised about the bearing ID - normally that type of self aligning bearing always is oversize (compared to a 'normal' bearing. They are made so that off the shelf shafting will be a sliding fit, and they then rely on their locking system to hold the shaft. I would expect that bearing to be 1.626 or 1.6265 approx.
</font>

For all we know they could have measured that big, if he was using those cheap digital calipers to measure the ID his measurement probably wasnt that accurate.

Mcgyver
08-28-2005, 12:13 PM
<font face="Verdana, Arial" size="2">Originally posted by mochinist:
For all we know they could have measured that big, if he was using those cheap digital calipers to measure the ID his measurement probably wasnt that accurate.</font>

the correct name for that device is a very-near. in fairness, the could be sitting there just to create scale in the picture

3 Phase Lightbulb
08-28-2005, 03:04 PM
My $14 HF digital calipers say the Bearing ID was exactly 1.625 and the Diff's bearing seat OD was exactly 1.628.. I do trust the .003 delta between them more than I trust the measurements.. The diff's bearing seat should be standard, so if anyone knows how to look up the spec for a GM 7.5 & 7.625" rear end bearing seat my chepo HF unit consistantly says it's 1.628"

Taking .0015 off the radius was harder than I thought.. I should have turned it but I figured if I turned it, It would be too easy to take off too much..

The differential gets clamped into both bearings with set screws so unless I had an absolutly perfect fit, there was probably going to be a little bit of wobble due to the set screws anyway..

-Adrian

speedy
08-28-2005, 05:35 PM
Dial calipers? Are you talking about dial vernier calipers? If so, I have always considered them to be a comparater only or an expensive adjustable spanner http://bbs.homeshopmachinist.net//biggrin.gif If needs must they are Ok but a mic is far better IMO.
I wouldn`t have belt sanded the housing http://bbs.homeshopmachinist.net//frown.gif, if you couldn`t machine it, "rock" filing would have been superior for such a small amount of material and a good 'fitting' exercise but still not an ideal option .
My advice; Set it up and machine it true.
Ken

[This message has been edited by speedy (edited 08-28-2005).]

Charlie Rose
08-29-2005, 02:12 AM
Yes, but what does your 1 to 2 micrometer say? Dial calipers good for scale measurments only.

Harold_V
08-30-2005, 03:46 AM
<font face="Verdana, Arial" size="2">Originally posted by 3 Phase Lightbulb:
[B]
My $14 HF digital calipers say the Bearing ID was exactly 1.625 and the Diff's bearing seat OD was exactly 1.628.. I do trust the .003 delta between them more than I trust the measurements.. The diff's bearing seat should be standard, so if anyone knows how to look up the spec for a GM 7.5 & 7.625" rear end bearing seat my chepo HF unit consistantly says it's 1.628"</font>


Regardless of manufacturer, it's not a good idea to trust readings from calipers, be they vernier, dial or digital. The likelihood that the inside and outside jaws agree with one another isn't great, nor is the chance that you'd use a reliable approach to measuring. There are way too many variables in calipers to make them trustworthy for high precision work. Bearing fits should never be accomplished with calipers.


<font face="Verdana, Arial" size="2">Taking .0015 off the radius was harder than I thought.. I should have turned it but I figured if I turned it, It would be too easy to take off too much.. </font>

Yet you trusted a belt sander? By working carefully, in a lathe, you could have made a setup that would have permitted the removal of a couple thou, assuming it was necessary, and then polished for final size. You'd have maintained concentricity and parallelism, and certainly a better fit than you achieved. Besides, it's a part of learning to properly machine. You'd have been proud of the outcome, and added to your arsenal of experience.


<font face="Verdana, Arial" size="2">The differential gets clamped into both bearings with set screws so unless I had an absolutly perfect fit, there was probably going to be a little bit of wobble due to the set screws anyway..</font>

But you'd have kept alignment, something you've most likely lost by using a belt sander. No problem, consider it a learning experience, and use better shop practice in the future. Many of us have learned the hard way. It's often the best teacher.

Good luck with the project.

Harold

3 Phase Lightbulb
08-30-2005, 10:55 AM
The problem I had with the bearing not fitting was not a problem with my $14 calipers. I would have bought the same size bearing regardless how accurately I measured the bearing seat on the differential...

The root cause of the bearing not fitting was because I made a wrong assumption. I thought that bearing sizes and bearing seats were standardized. I thought anything close to 1.625" would be a 1 5/8" bearing. I could have measured the diameter of my differential's bearing seat with a piece of string or the world's most accurate MIC and I would have still bought a 1.625" bearing based on my lack of bearing knowledge.

I don't have any excuses for belt sanding my differential other than I just wanted those bearings on there ASAP so I can take measurements and continue building my buggy's frame.

-Adrian

Mcgyver
08-30-2005, 11:01 AM
<font face="Verdana, Arial" size="2">Originally posted by 3 Phase Lightbulb:

The root cause of the bearing not fitting was because I made a wrong assumption. I thought that bearing sizes and bearing seats were standardized. -Adrian</font>

that's puzzling to me as well - I thought bearings were standardized for the most part, with the most common being metric dimensions. are custom ball bearing sizes common in autos??

what is it from and can you backtrack - dealer's parts dept look up the bearing from one of their exploded views etc.

JPR
08-30-2005, 11:13 AM
I am with the others on turning the differential instead.

Regarding the bearings, I tried something similar for a Dana 60 carrier. For the "setup" bearings, I needed to remove .0045 - .005. I tried honing, but after the first .001, it took about 30 minutes per .0005. I got tired of that real quick and resorted to a dremel tool with a sanding drum and just kept going around in the inside of the race. Then I would hone it and check the fit. It still took one evening to get a good fit with both races. However, these were for setup only, not for permanent use.

[This message has been edited by JPR (edited 08-30-2005).]

3 Phase Lightbulb
08-30-2005, 11:25 AM
<font face="Verdana, Arial" size="2">Originally posted by Mcgyver:
that's puzzling to me as well - I thought bearings were standardized for the most part, with the most common being metric dimensions. are custom ball bearing sizes common in autos??

what is it from and can you backtrack - dealer's parts dept look up the bearing from one of their exploded views etc.

</font>

The differential is a standard GM 7.5 & 7.625" 28-spline. I can't seem to find any specs on the actual carrier bearings. Has anyone else tried to find out the true OD on the bearing seats?

-Adrian

JPR
08-30-2005, 12:20 PM
I checked the od on the Dana 60 carrier that I replaced last year and it is .003" above nominal. The bearings were standard 4T-387A with a bore of 2.2500. My assumption is that they are wanting a press fit to ensure that the bearings do not spin.

[This message has been edited by JPR (edited 08-30-2005).]

3 Phase Lightbulb
08-30-2005, 12:23 PM
I wonder if I should have just pressed my 1.625" bearings over the .003 larger bearing seats with my press?

-Adrian

JPR
08-30-2005, 12:36 PM
You should be able to, just make sure you are pressing on the inside race only.

maxkroeker
08-30-2005, 12:58 PM
The tapered roller bearing normally used in this application is a shrink fit. The ball bearing that you will be using is normally a slip fit. This accounts for the added diameter of the diff carrier.
Max

CCWKen
08-30-2005, 01:59 PM
<font face="Verdana, Arial" size="2">Originally posted by 3 Phase Lightbulb:
I wonder if I should have just pressed my 1.625" bearings over the .003 larger bearing seats with my press?</font>

Heck NO! That would have required some thought, a plan and some precision. No time for that! Just bang 'em on with a sledge hammer.

3 Phase Lightbulb
08-30-2005, 02:09 PM
<font face="Verdana, Arial" size="2">Originally posted by CCWKen:
Heck NO! That would have required some thought, a plan and some precision. No time for that! Just bang 'em on with a sledge hammer.

</font>


You're absolutly correct. I would never finish this project if I got anal over everything.

Joel
08-30-2005, 02:39 PM
Sure you would Adrian, but the Vaseline would need to be kept close by. http://bbs.homeshopmachinist.net//biggrin.gif

I think the point some people were trying to make about the cheap calipers is that you don't know how much of an interference fit there really was. The cheap veneers are great, but the inside and outside measurements don’t always agree. Add this to the mediocre repeatability and resolution of the calipers and it is easy to lose where you are. It’s just too easy to mic everything and get exact numbers, and then proceed with the most logical approach.

3 Phase Lightbulb
08-30-2005, 03:05 PM
<font face="Verdana, Arial" size="2">Originally posted by Joel:
Sure you would Adrian, but the Vaseline would need to be kept close by. http://bbs.homeshopmachinist.net//biggrin.gif

I think the point some people were trying to make about the cheap calipers is that you don't know how much of an interference fit there really was. The cheap veneers are great, but the inside and outside measurements don’t always agree. Add this to the mediocre repeatability and resolution of the calipers and it is easy to lose where you are. It’s just too easy to mic everything and get exact numbers, and then proceed with the most logical approach.</font>


The problem would have been worse for me if I used a MIC and was absolutly sure I needed to find a 1.628" ID flange bearing.. I don't think they exist so I would probably still be looking for them, or even worse I'd have a really expensive pair custom made..

My point was, precision didn't matter in this specific case.. The problem was far more alarming because I had no idea how bearing clearences worked. I'm lucky that I thought it was 1.625".. It could have de-railed/lost interest in my project if I felt I had to wait weeks for a custom set of 1.628" ID bearings. I was lucky and learned something about bearings, and I also learned a new trick on my belt sander http://bbs.homeshopmachinist.net//wink.gif

-Adrian

Joel
08-30-2005, 03:39 PM
For example, say the mic showed the carrier was 1.6272 and the telescopic gauge/mic showed the ID of the bearing at 1.6258 (well within the possible and probable error of the calipers). This would have shown that you had less than half of the difference you thought you had; a reasonable interference fit, or a small enough difference that could have been accurately filed off and the bearing could have been pressed on immediately with confidence of concentricity. If you use a mic with telescopic gauges –or an inside mic, you are using the same measuring tool to get the numbers for both readings. This allows for very accurate comparative measurements.

You do have a set of telescopic gauges or inside mics, and a set of outside mics that read tenths, correct?

3 Phase Lightbulb
08-30-2005, 03:49 PM
<font face="Verdana, Arial" size="2">Originally posted by Joel:
For example, say the mic showed the carrier was 1.6272 and the telescopic gauge/mic showed the ID of the bearing at 1.6258 (well within the possible and probable error of the calipers). This would have shown that you had less than half of the difference you thought you had; a reasonable interference fit, or a small enough difference that could have been accurately filed off and the bearing could have been pressed on immediately with confidence of concentricity. If you use a mic with telescopic gauges –or an inside mic, you are using the same measuring tool to get the numbers for both readings. This allows for very accurate comparative measurements.

You do have a set of telescopic gauges or inside mics, and a set of outside mics that read tenths, correct? </font>

I have several china 0-1" MICs, but not 1-2", or 2-3", etc. I should get a complete set eventually. I've never needed high precision yet but I eventually will. I do have a set of telescopic inside mics and a set of depth mics. I think all from Grizzly.

-Adrian

Joel
08-30-2005, 04:01 PM
Go crazy and get the 0-6" set that reads in tenths. They are cheap and work pretty well. I would still recommend having a good quality 0-1” mic and a good Mitutoyo or B&S caliper as well. I prefer digital on the last 2 items, but to each his own.

Harold_V
08-31-2005, 12:57 AM
<font face="Verdana, Arial" size="2">Originally posted by 3 Phase Lightbulb:

You're absolutly correct. I would never finish this project if I got anal over everything. </font>

Keeping bearings concentric, and running with proper clearance is hardly being anal.

From your comments, I gather you don't have time to do it right, but you'll have all the time you need to do it over when it fails? That's a strange approach to things, at least where I came from.

Bearings don't take too kindly to running out of position. If you're lucky, yours are self aligning and will be forgiving of minor eccentricity. If not, you'll soon understand why you should have done it differently.

Be sure to keep us all advised as to how it ends up. I could be wrong, or you're damned good with a belt sander! :-)

Harold

Harold_V
08-31-2005, 01:06 AM
Sorry for the double posts, group. I'm just getting used to the board and didn't realize my post was appearing on a different page.

I'll do better in the future. Promise!

Harold



[This message has been edited by Harold_V (edited 08-31-2005).]

Harold_V
08-31-2005, 01:10 AM
[This message has been edited by Harold_V (edited 08-31-2005).]

madman
08-31-2005, 09:30 AM
HONEING WITH SMALL HAND HONE, MAYBE

3 Phase Lightbulb
08-31-2005, 09:43 AM
Hopefully I'll start welding up my Sand Belt Buggy's frame tonight and then everything should start comming together quickly. I took some pictures of the frame last week durring construction over here in this thread:

http://bbssystem.com/viewtopic.php?t=397

I'm designing/building as I go so the plan(s) are to have NO plans..

-Adrian

3 Phase Lightbulb
08-31-2005, 10:33 AM
<font face="Verdana, Arial" size="2">Originally posted by CCWKen:
Geez. Ya just couldn't wait eh?

That's a pretty half-assed way of doing something that's going to be spinning at 3000+rpm. http://bbs.homeshopmachinist.net//rolleyes.gif</font>

I'm curious where you got the "3000+rpm" number from because 3000 RPM with small 22" tall rear tires = 196 MPH. 1000 RPM MAX is more realistic.