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Shafts, bearings, and gaps.


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#1 R Soul

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Posted 20 February 2021 - 16:40

The short version is: How can I fit a 22mm shaft into a 25mm spherical bearing, or what other options are there, without welding or machining? There may be a 22mm spherical bearing out there but so far the prices have been a bit steep so I may be looking in the wrong places.

The full version:
I'm currently designing a sim rig to use with a force feedback wheel motor.

Typical example at the top of this page: https://www.raceanyw...-rigs-pros-cons

I don't have the space for that, or the need for all those motitors, and I want to be able to have a desktop so I can remove the wheel and do other things.

I've designed something much more compact, where the motor is much further back. The motor's reach needs to be extended via a shaft. The shaft design will be similar to this:
https://community.gr...tension/2463/26

I've been asking for advice on a couple of sim racing forums to see what parts are available. It seems that I can use two of these: https://simtag.eu/as...ing-accessories (servo clamping sets) at either end.
According to the creator of the above design, it uses a shaft of 22mm

These motors aren't designed for twisting forces being applied over that kind of distance (the main one being the weight of the wheel), so I plan to support the shaft with a spherical bearing, which could rest on the desk. When detaching the wheel, the bearing assembly would go with it, making the desk available. The wheel motor I'm planning to buy comes with its own quick release so that's not a problem.

I've found these bearings which look suitable:
https://www.igus.co.uk/product/20326
The advantage of spherical bearings is that they can allow for axial misalgnment. The problem is that their bore sizes go up in 5mm, so 25mm is the smallest that I could use.

With a gap of 1.5mm, what could be used to fill it? When looking things up I've learned about tolerance rings, but I'm stuck on what to look for with them.

I've also been searching for 22mm bore spherical bearings but the only ones I've found have quite steep prices, wheras the igus bearing prices are nice and low.

Thanks



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#2 DogEarred

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Posted 20 February 2021 - 17:18

Igus do top hat bearings about the £7 mark.

 

They are on their website.

 

https://www.igus.co.uk/product/64



#3 Greg Locock

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Posted 20 February 2021 - 20:30

Wow, handy for many bodges. Good find. You'll need two.



#4 DogEarred

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Posted 20 February 2021 - 21:07

Formula One and shopping trolleys can’t function without them...

#5 GreenMachine

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Posted 20 February 2021 - 21:47

Pretty sure this (in plain tube form) is what one of the locals used to sleeve the poly bushings in his dual duty road/race car.  Seems to have worked for him.  



#6 Kelpiecross

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Posted 21 February 2021 - 04:46

 A machine shop will machine a suitable sleeve for you in steel, nylon or whatever for a few dollars.  Everybody should have a tame machinist.  



#7 Greg Locock

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Posted 21 February 2021 - 06:28

That is a nicer solution in general, probably better to use a 30 id ball joint in that case. But I dunno, given this is not safety related, and the loads are trivial, $16 on spacers and a bit of loctite is good enough.



#8 DogEarred

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Posted 21 February 2021 - 10:42

If it was made by McLaren, it would be machined to 3 decimal places, inspected, polished, anodised, re-inspected, laser etched and put in a foam lined storage box.

Not much change out of $100 each...

Edited by DogEarred, 21 February 2021 - 10:43.


#9 Greg Locock

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Posted 21 February 2021 - 20:49

Not much change out $100 at a local machine shop. In fact even for me to do it on a borrowed lathe it isn't going to be much less than that. Setup time is the killer.



#10 malbear

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Posted 21 February 2021 - 21:18

Not much change out $100 at a local machine shop. In fact even for me to do it on a borrowed lathe it isn't going to be much less than that. Setup time is the killer.

I charge about 100/hour  and mates rates about 70  or if a few beers are involved free using my home lath not at the business site 

:wave:



#11 R Soul

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Posted 21 February 2021 - 22:22

Thanks for your advice.

Dog earred:

With that top hat sleeve bearing do you mean it slots between the shaft and the spherical bearing, or would that be used on its own?

 

If the former, I made a virtual mockup of how I think it would work based on the dimensions listed on the site/bearing sketch:


Edited by R Soul, 21 February 2021 - 22:23.


#12 DogEarred

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Posted 22 February 2021 - 00:35

Ok, I'll slot my question in here...

In keeping with the SCCA theme, venues. Three past or present Major League Baseball stadia hosted SCCA Regional or National events on courses laid out using parking lots and perimeter roads, which three stadia were these?


Yes exactly.

You obviously filled in the sizes you need in the webpage.

I think the length available were 25 mm or 21.5 mm, which is probably a bit longer than you need but I don’t know the width of your bearing.
But that’s not a problem unless you want it to look neater.
If it were for higher loads though, I would cut down the length and use one either side.

As Greg says, your loads are not high, so your CAD animation is correct.

Igus allow for a push fit (H7) into the ball but you need to verify the o.dia & straightness of your shaft. I think the min. i. dia of the bush is 22.040 from the spec.

Edited by DogEarred, 22 February 2021 - 01:20.


#13 Kelpiecross

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Posted 22 February 2021 - 05:16

I charge about 100/hour  and mates rates about 70  or if a few beers are involved free using my home lath not at the business site 

:wave:

 

 I meant something similar.  A machinist who takes an interest in what you are doing.  My machinist(s)  sometimes would do a job like this  - modifying an  existing bush  maybe or a piece of tubing to suit  as a while-you-wait  job for nothing or maybe $20.  And these two machinists I refer to were not  running a backyard  operation but a business with a turnover of quite a few million dollars a year.   Depends on how lucky you are in finding someone. 



#14 Canuck

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Posted 22 February 2021 - 18:29

When I was at the shop, we had a customer that would pay us doughnuts and coffee for access to the manual lathe. Good deal for everyone involved.