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Bonding a sealed bearing to brass?

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TTD

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#1
Probably over-thinking this & worried about nothing, but I need to permanently bond a (steel) sealed bearing inside a brass cylinder & was wondering if Loctite 620 bearing mount/retaining compound would be sufficient? I’ve used 620 a lot in the past for aluminum, steel, or a combination of the two with great success, but have yet to try it with brass (heard that brass can be finicky stuff to bond to).

In case anyone is wondering what the application is for, I’m making a radius turning attachment for my little 7x12 lathe:
m_Ball Turning Attachment.jpg
O/D of bearing will be bonded to tool holder. Bearing pocket will be bored .050” deeper than bearing thickness.
When O/D has fully cured to tool holder, I/D of bearing will be bonded to stub sticking up from .375” thick x 2.5” wide base plate.
Once completed, bottom of tool holder will sit snugly against base plate, yet still be able to rotate easily. Basically making for a one-piece, somewhat sealed unit.

Note - only reason I went with brass round bar for the tool holder is because that is all I currently have on hand that is 2” diameter or larger. If brass won’t cut it (no pun intended) I could always purchase a length of 1144 if need be.

Any advice and/or suggestions are greatly appreciated!
 
F

f350ca

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#2
You could machine the bearing pocket for an interferance fit, then warm the brass part and shrink it onto the bearing. Should never move. The Shaft could simply be a press fit, warm the bearing with a heat gun before pressing it on.

Greg
 

pacifica

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#3
I used loctite 680 (hi strength) on a bearing I used in a router lift assembly and it failed. Not as strong as loctite would have you believe.

Instead I heated the bearing to 220f degrees (check the specs on your bearings) and mounted on a shaft .0015 oversize(put in freezer) and it didn't fail(3/4" shaft).

I believe loctite 242, 270 ,etc is actuated by brass; 680,620 is a methacrylate ester which is a slightly different chemical.

You can paint one surface with activator 7471 and 7649 and use virtually any metal or plastic with the loctite. Loctite has many products and the gap you have will determine which product to use.
 

Latinrascalrg1

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#4
Can you drill and tap a few spots for set screws for the holder to bearing fit then do an expanding type set by drilling and tapping a sinlge hole parallel and into the center on the peg. If you counter sink the top of the hole then cut 3 or So slots from the center threaded area out to the sides going down far enough to give you the needed movement (basically a collet that is threaded completely thru) so that they will spread as you tighten the screw to lock the bearing in place. Not needed but Back this up with loc tite if you desire and you should be good to go without it coming apart on you and if you need to change something out in the future you wont have too much of a problem taking it apart!
 

TakeDeadAim

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#5
The green locktite 620 cures in an anaerobic (no air) environment so if you have a light press or size on size fit it works very well regardless of the material. Unless you know what the temp range is on the bearing's seal AND what kind of cage is inside I would avoid heating any part of the assembly. If you clean the OD of the bearing and ID of the housing with Acetone so there is no trace of oil or cutting fluid on either part the assembly should be very solid for a long, long time.
 

Tozguy

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TTD

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Thank you very much guys for all the tips/advice…much appreciated! :encourage:

My apologies for not answering sooner, life & work are crazy busy right now so don’t get to hang out here as much as I would like to.

As I said earlier, brass certainly wasn’t my first choice of material to use, just what I have readily available at the moment. Having said that though…I have to order in some more metal this week anyways, so I think instead of trying to save a few bucks & make do with what I have, I’ll just add a few feet of 2” o/d 1144 or 12L14 to the order & save the brass for a more appropriate project later on.

While I may (?) end up shrink fitting the tool holder to bearing o/d (never tried shrink-fitting parts together before), I do have the same concerns as @TakeDeadAim regarding heating the bearing i/d enough to slip onto stub. Thinking I will still go with retaining compound for that step.

Thanks again for the help!
 

FanMan

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#8
Bearings are normally press fit on one side and mechanically retained on the other. Which is which depends on the loading. Most bearing manufacturers publish tables of the recommended fits for each side under various loading conditions.
 

Eddyde

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#9
IMHO, for that application, I would skip the ball bearing all together. A sleeve bearing or even no bearing well oiled should work fine.
 

pacifica

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#10
IMHO, for that application, I would skip the ball bearing all together. A sleeve bearing or even no bearing well oiled should work fine.
Ditto on the sleeve bearing; for that application some controlled friction would be preferable. A slight amount of drag like on a fishing reel.
 

P. Waller

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#11
If I understand the drawing correctly you plan on holding a tool in the slot and rotating it to form a radius on the part?

Or is there a tool holder attachment that fits in the slot that will allow you to make both concave and convex radii.
 

TTD

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#12
If I understand the drawing correctly you plan on holding a tool in the slot and rotating it to form a radius on the part?

Or is there a tool holder attachment that fits in the slot that will allow you to make both concave and convex radii.

There will be a tool holder made from 1/2” square bar (CR1018) that slides in the slot to make both concave & convex profiles & 1/4" HSS tool bit for the cutter.

Cutting tip will only have .563” clearance above assembly so max size for ball turning will be 1” while concave profiles will be maxed out somewhere around 1.250” radius. Most of my projects (for now) with the radius tool will be with round bar stock between 1/4” - 3/4” diameter so it should work nicely (I hope).

m_Ball Turning Attachment Tool Holder.jpg
m_Ball Turning Attachment Max Convex.jpg m_Ball Turning Attachment Max Concave.jpg

Everything is still in the designing stage at this point, so after reading the suggestions above from much more experienced fellas than I (thank you once again!), I'm now thinking of just ditching the whole bearing idea....no sense in re-inventing the wheel, huh? lol
 
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