# WHAT DRILL FOR THIS BEARING INSTALL???



## riversidedan (Jun 30, 2021)

ok guys am doing a project that entails a bearing install at both ends of this bar, being the bearing is flat am assuming  a flat end bottom  mill type drill would work, would that be right??  never using one would also assume I would plunge it into the work, right??


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## mmcmdl (Jun 30, 2021)

Dan , if that was myself , I would put a rather large thru hole thru the shaft if possible . We use tons of rollers very similar looking to your part . Before I arrived , when the bearings went south , they thru the entire rollers out . I started drilling holes thru the shafts and now I can knock the bad bearings out with punches thus saving the rollers . Just a thought .


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## riversidedan (Jun 30, 2021)

already has a thru hole


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## mmcmdl (Jun 30, 2021)

Can you get to the opposite bearing with a punch ? The answer to your original question would be to bore them out to size .


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## riversidedan (Jun 30, 2021)

already has a thru hole and thier will be 1 bearing on each end, so again, what kind of drill would I use?????


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## mmcmdl (Jun 30, 2021)

Bore it out to size .


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## riversidedan (Jun 30, 2021)

the bearings are only installed at the ends


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## mmcmdl (Jun 30, 2021)

riversidedan said:


> the bearings are only installed at the ends


That's assumable . Bore the ends for the bearings and press them in . Where does the problem lie ? I would also assume you want the bearings concentric to the OD of the shaft .


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## ErichKeane (Jun 30, 2021)

To answer the question: any sort of drill bit or end-mill won't be the right thing here, they will end up cutting oversized and you won't be able to press the bearings in.  Use a boring bar in a lathe to get the bottom flag, but most importantly, get the OD of the hole correct.


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## Martin W (Jun 30, 2021)

Hi Dan
i don’t think you could have the accuracy if it I’d drilled. Dave is saying bore it with a boring bar in the lathe.
Cheers
Martin

Sorry Eric was faster typing. Lol


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## riversidedan (Jun 30, 2021)

ok I get it, no drill, boring bar only which I do have just hope its small enuff............below is the project with the bolt going thru the part that rides on the bearings at both ends


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## T Bredehoft (Jun 30, 2021)

Martin's got it. Bearings don't fit well in drilled holes. The hole is too large or too small, the depth can'[t be closely monitored. Drill it .030 undersize and bore it to size, light drive fit on the bearing.  .030 will give a shoulder to seat against.


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## T Bredehoft (Jun 30, 2021)

Use a 3/16 HSS sq tool, grind away all (on one end) except the boring bar that's hiding inside.


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## pacifica (Jun 30, 2021)

riversidedan said:


> ok I get it, no drill, boring bar only which I do have just hope its small enuff............below is the project with the bolt going thru the part that rides on the bearings at both ends


If possible it would be preferable to have the bearings riding on a smooth rod not the crest of the threads.Means you would prolly have to fabricate the rod.


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## markba633csi (Jun 30, 2021)

You are certainly welcome to use an endmill as a boring bar, I do it all the time.  Just use one flute as a cutting edge. You'll need to figure out a way to mount it in your toolpost tho
-Mark


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## homebrewed (Jun 30, 2021)

markba633csi said:


> You are certainly welcome to use an endmill as a boring bar, I do it all the time.  Just use one flute as a cutting edge. You'll need to figure out a way to mount it in your toolpost tho
> -Mark


I've used that approach for boring relatively small holes in softer materials like aluminum and brass.  It works quite well.  I haven't tried it on steel, a little worried about the relatively sharp cutting point -- but it looks like it's worked OK for you.  Good to know!

I have HSS end mills of varying diameters with a 3/8" shank that fit in my boring bar holder, makes it easy.  When I do this I'm usually boring out through-holes so I rotate the holder a few degrees to get a little relief behind the cutting tip.  If you need a flat-bottomed pocket the end mill needs to be parallel to the spindle axis.


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## markba633csi (Jun 30, 2021)

Yes soft metals only, or light cuts in steel.  The one flute will wear faster of course
I have done the same trick with the lip of a twist drill in a pinch


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