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Author Topic: Holding an 11 mm shaft with non-metric pillow blocks  (Read 1704 times)
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Hello, I've been trying to make a man-powered water purification system and whenever I search for my mechanics questions, the Arduino forum always pops up.  My project isn't quite a robotics project, but I have used Arduino microcontrollers before, and this forum is fantastic!

I basically want to hold an 11 mm jack shaft on two pillow blocks.  I couldn't find 11mm ID pillow blocks, so here's my conundrum:

So from my searching I have gathered that an 11 mm shaft is an oddball shaft size, but I am pretty much forced to use it because the only sprocket I could find that was suitable has an 11 mm inner diameter (it belongs to a scooter), and my water pump also uses a 7/16 shaft, which is pretty close to 11 mm.  Also, I already bought the 11 mm shaft, so I'd like to use it.

From previous posts on this forum, a solution that was recommended was:
Purchase two 7/16 inner diameter, 5/8 outer diameter bronze sleeve bearings.
Purchase two 5/8 inner diameter pillow block bearings.

So now, after having bought those, I have two questions:
1) The bronze sleeve bearing's inner diameter is slightly larger than the 11mm stainless steel shaft and so the bronze ring slides up and down the shaft pretty easily.  How do I connect sleeve to the shaft so that it won't move?

2) My bronze sleeve bearing's outer diameter is exactly 5/8" and the inner diameter of my pillow block is 5/8", so the sleeve bearing won't quite fit into the pillow block.  Do I need to take the sleeve bearing to a machine shop and have them taper the sleeve bearing, or is there something I can do at home to fix this myself?

Sorry for the newb questions- I know they're pretty simple answers, but I'm finding it harder and harder to find relevant search results.  I'm not really well versed in mechanics, so I don't know the vernacular phrase what I'm trying to accomplish.

Thanks!
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My bronze sleeve bearing's outer diameter is exactly 5/8" and the inner diameter of my pillow block is 5/8", so the sleeve bearing won't quite fit into the pillow block.

If you are sure about those dimensions, I would try press fitting the sleeve bearing into the pillow block. This can be done in a vise. You must be sure that the pressure of one jaw of the vise is on the inner race of the pillow block bearing and not on the entire bearing. The easiest way is to use a socket that is the same size as the inner race. You must be sure that the parts are square to each other before applying pressure.

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The bronze sleeve bearing's inner diameter is slightly larger than the 11mm stainless steel shaft and so the bronze ring slides up and down the shaft pretty easily.
After press fitting the sleeve bearing, the inner diameter of the sleeve bearing may be slightly smaller so the shaft may fit more tightly.

- Scotty
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You could try some 1/2" pillow blocks and make a sleeve out of some 16ga steel. Not quite perfect but it might work.

Know anyone with a metal lathe? They could turn the end of the 7/16 shaft down to 11mm. Or you could polish the end of a 17/16 shaft down to 11mm with some emery cloth while spining the shaft in the pillow blocks- IF you have a micrometer to check the size as you go.
Or a machine shop could ream the ID of the sprocket to 7/16. The last is probably the cheapest way.
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Thanks scottyjr, I understand what it is I need to do.

Thanks kf2qd, I will see what an emery cloth can do.

Is there any other way to affix a loose fitting sleeve to the shaft though?

Is it a good idea to drill a hole though the sleeve and the shaft and line the holes up with the hex screw of the pillow block?
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Is there any other way to affix a loose fitting sleeve to the shaft though?

Loktite or JBWeld or some other type of gap filling cement.

Depending on the material of your shaft, Solder may be an option.

I have been known to slit the sleeve with a cut-off wheel in a dremel, then squeeze the sleeve around its shaft with a bunch of stainless steel wire and solder it.  Results poor, but not disastrous.  Works okay if the sleeve is thin like a segment of 3/4 copper pipe or something.

If it was me, i'd go with the JBWeld.  I'd also hone down the outside of the bushing until it gives a friction fit to the pillow block by spinning it in a drill and running 300 grit wet-dry over it.
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Quote
The bronze sleeve bearing's inner diameter is slightly larger than the 11mm stainless steel shaft and so the bronze ring slides up and down the shaft pretty easily.
After press fitting the sleeve bearing, the inner diameter of the sleeve bearing may be slightly smaller so the shaft may fit more tightly.

- Scotty

Nope, a difference of 0.1125mm (7/16" = 11.1125mm) is too large to be significantly altered by the strain of press-fitting
 - some sort of shim material (perhaps even coats of paint?  tape?) might help remove the slack, but the correct solution
is making a proper adapter on a lathe.  Bearing surfaces are cut to high precision.
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Thin shim material (aluminum drink can metal or brass shim stock) might be used to remove the gap. If a small amount of clearance is needed you might spin the shaft with a drill and use emery paper to gradually remove some outer material.
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Or a quick and dirty solution:  glue gun!  [ not a serious suggestion... ]
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For press fit stuff like bearings in housings heating the housing and putting the bearing in a cold environment before assembly would be used depending on circumstances. But has been mentioned just slitting the bronze sleeve (hacksaw or whatever) will allow the sleeve to go into the pillow block. If you are using collars on the shaft or whatever is attached next to the pillow block then that would keep the sleeve from coming out.
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Ok, thanks so much for your replies.  I'll let you all know what worked out.
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This response is for anyone who finds this thread in the future, looking for solutions to this specific problem.

I called a local machine shop (Findlays in LA) and he suggested that I order a 3/8 ID, 5/8 OD plastic sleeve bearing from McMaster.   When that arrives, we're going to bore the inside to 11 mm.

My application is ok with plastic parts, so I lucked out with an cheap and pretty easy (boring through plastic is really nothing!) solution.  Hope this helps someone.

Thanks for all the advice!
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