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Old 11th Nov 2023, 2:10 pm   #1
cooperman
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Default Bearing removal from motor shaft

The bearing on the motor shaft from my Bosch leaf blower needs replacing. Does anyone have a method for pulling the old bearing off the shaft. I don't have a bearing puller and I'm worried that heating the old bearing with a blowtorch is likely to destroy the insulation on the motor windings.
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Old 11th Nov 2023, 2:14 pm   #2
G6Tanuki
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Default Re: Bearing removal from motor shaft

Do you know for sure that it comes off? I have seen plenty of small domestic things where the bearing isn't a separate item but the balls/rollers run directly on an induction-hardened part of the shaft. When they seize, they weld themselves to the shaft, destroying the bearing-surface.

When I've had to replace removable bearings on things in the past I've taken an angle-grinder to the outer race then whacked a chisel into the slot to split it, removed the ball/roller cage, then done the angle-grinder thing again on the bit on the shaft.
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Old 11th Nov 2023, 2:19 pm   #3
cooperman
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Default Re: Bearing removal from motor shaft

It does look as if it comes off. I'll use the angle grinder method if no one comes up with an alternative.
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Old 11th Nov 2023, 2:51 pm   #4
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Default Re: Bearing removal from motor shaft

Bearing pullers are not expensive and designed for the job. They're my first port of call and get used for a lot of work. I'd suggest getting a set. Screwfix have several possibilities which I can vouch for on car work.

Heating could work despite the proximity of the motor windings if you use a heatshield - a piece of metal with a slot in that you can slide over the shaft would probably be sufficient.
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Old 11th Nov 2023, 3:48 pm   #5
barrymagrec
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Default Re: Bearing removal from motor shaft

I`ve used the angle grinder method many times on various types of bearings and shafts. A bearing puller can be good but there is not always space to use it.
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Old 11th Nov 2023, 10:42 pm   #6
The Philpott
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Default Re: Bearing removal from motor shaft

Eye protection, if using a chisel on a bearing.

Dave
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Old 12th Nov 2023, 8:41 am   #7
Malcolm T
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Default Re: Bearing removal from motor shaft

Give us a piccy of the bearing / shaft.
I had a seized bearing on my wood linisher roller shaft ie rusted on but i got it off
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Old 12th Nov 2023, 8:50 am   #8
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Default Re: Bearing removal from motor shaft

I have cut through bearing races with the Dremel cut-off discs. It takes quite a time, and I wore out 2 discs doing it, but it did work.

My experience is they must be genuine Dremel, though. The cheap clones just shatter.

This was a bearing about 3/4" O/D in the fan motor in one of my DEC racks. Before somebody suggests I should have just replaced the fan, I'll point out that an equivalent fan was over £150 at RS, the bearings about £3 each.

I will also agree that an assortment of 2-legged/3-legged/bearing pullers is almost essential if you do mechanical repairs.The controlled force of the screw does a lot less damage than using a hammer, and is a lot more effective.
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Old 12th Nov 2023, 10:08 am   #9
Craig Sawyers
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Default Re: Bearing removal from motor shaft

When I bought my old bandsaw the upper wheel bearing was clearly worn and making a hell of a noise. I drifted out the top wheel by drilling a hole in the case in a measured position, and using a piece of brass bar and a hammer. It came out of the case quite easily. But of course it was tight on the shaft itself.

I bought a new bearing of the same size (cheap). This was quite a big bearing.

I then took the wheel with the old bearing to a local garage. They pulled the old bearing off in seconds, then pressed the new one on. Gave them a tenner. Job done.

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Old 12th Nov 2023, 11:33 am   #10
cooperman
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Default Re: Bearing removal from motor shaft

I've managed to remove the bearing by using a cutting wheel on a Dremel. Not a Dremel wheel - just a clone. Thanks for the various suggestions.

I'm just annoyed that it seems impossible to buy most of the parts for the Bosch leaf blower. Apart from the motor being unobtainable, the impeller fan is too. I'm currently gluing the cracks in that item using JB Weld plastic bonder.
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Old 12th Nov 2023, 11:43 am   #11
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Default Re: Bearing removal from motor shaft

Remember that bearings come in standard sizes and it may be cheaper to buy them from a bearings factor.
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Old 12th Nov 2023, 12:52 pm   #12
G6Tanuki
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Default Re: Bearing removal from motor shaft

I would be careful about trying to repair a cracking rotor, having seen what happened when a spot weld failed on the metal rotor of a vacuum cleaner and one of the vanes got loose... The rotors spin extremely fast and there is a lot of energy stored in them if they decide to self destruct.

Also, a repair is likely to cause imbalance in the rotor making failure of the thing more likely.
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Old 12th Nov 2023, 1:02 pm   #13
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Default Re: Bearing removal from motor shaft

Quote:
Originally Posted by Station X View Post
Remember that bearings come in standard sizes and it may be cheaper to buy them from a bearings factor.
And this is why you may want to read the type number off of the side of one of the tracks before cutting loose with the angle grinder. Murphy will be doing your aiming for you!

Been there, done that.

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Old 12th Nov 2023, 1:03 pm   #14
Uncle Bulgaria
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Default Re: Bearing removal from motor shaft

It may be a standard impeller and available off the shelf with some diligent research. The bearing almost certainly will be.

A rake may be a better long-term solution to the leaves with less chance of catastrophic failure.
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Old 12th Nov 2023, 2:18 pm   #15
Station X
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Default Re: Bearing removal from motor shaft

Or measure it. Internal diameter (shaft diameter), external diameter, thickness and any special features such as "rubber" seals etc.

You can then enter the info on a website such as this to identify the bearing:-

https://www.bearingboys.co.uk/Ball-Bearings-1129-c

Other sellers, eBay etc. are available.


Quote:
Originally Posted by Radio Wrangler View Post
Quote:
Originally Posted by Station X View Post
Remember that bearings come in standard sizes and it may be cheaper to buy them from a bearings factor.
And this is why you may want to read the type number off of the side of one of the tracks before cutting loose with the angle grinder. Murphy will be doing your aiming for you!

Been there, done that.

David
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Old 12th Nov 2023, 7:20 pm   #16
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Default Re: Bearing removal from motor shaft

A friendly owner of a 3d printer may be able to help with the impeller and probably print it in a more resilient plastic. Followed this method myself (with an off brand, 'Power G' hovermower fan) it worked for that: though in my case the person who did the print knew the part was unobtainable and charged accordingly!
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Old 12th Nov 2023, 8:09 pm   #17
cooperman
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Default Re: Bearing removal from motor shaft

I measured the shaft diameter and the outside diameter of the bearing. New one already arrived via Amazon. I had to warm up the new one (and cool down the shaft) get it installed.

I note the comments about impeller imbalance after repairing. I'll see if there appears to be excessive vibration when running. The plastic housing in that area is very thick - it looks like it should contain anything that becomes detached. I'd like to think Bosch would have taken impeller failure into account when designing the housing.
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