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Which Bushing to Use?

kevin21

Registered User
Aug 30, 2021
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I am in the process of learning to put bushings in by hand. I have disassembled an old Urgos UW47128 movement in order to practice this, as was recommended to me on this forum. I found a hole to bush and went through the process today. I'm pretty happy with it.

Now for my next step. In the last few weeks I have disassembled and cleaned an Urgos UW03051B movement removed from my running grandfather clock. There are at least three holes that need bushings. One of these is the minute wheel's hole on the front plate.

Below is info on the hole:
Original Hole: My estimate is 3.25mm using the non-cutting end of a #30 drill bit I was able to use as a gage pin
Elongated hole: 3.55mm (visual estimate)
Projected bushing hole size minimum: 3.55 - 3.25 = .3, 3.55 + .3 = 3.85mm
Pivot: 3.17mm

I believe my KWM bushing options are:
L80 (or L50, L51 which I don't have but would mean less work to increase the ID)
- Only 1.7mm in height
- Uses V reamer (OD=5.85) so a larger hole would be needed than the option below

L144 (or L145 which I don't have but would mean less work to increase the ID)
- height is 2.7mm, so I'll have to file this down
- Uses IVa reamer (OD=4.66) which I don't have and is $45 at timesavers (not a problem to buy if this is clearly the better option)

So which bushing should I choose since I have both L80 and L144 bushings? Or is there a different option?

Thanks in advance for your advice...
Kevin

p.s. I should tell you that even though I am a newbie, I have inherited all my father-in-law's tools and supplies so I have all kinds of KWM bushings, the reamers, etc. Since he doesn't have a IVa reamer but he had L144 bushings, I assume he just used a broach to size the hole, but I will probably by the tool if that is the right option.
 

POWERSTROKE

Registered User
Jan 11, 2011
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Use the closest size you have and slowly broach it out little by little until it’s correct. Check often. You’ll start running into this more and more.
 

Willie X

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Feb 9, 2008
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When you rebush a hand shaft, or any shaft that extends through the plate, the bushing can usually be left a little long. This is a good thing, as long as the bushing is upright with no interference or binding. Willie X
 

kevin21

Registered User
Aug 30, 2021
16
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Thanks for the replies...

Ok, so I can go with the L144 and either broach to the correct size or by the IVa reamer. WillieX, when you say to leave the bushing a little long on hand shafts, where should the extra length be? I'm thinking you mean centered on the plate. Since I am pressing the bushing in from the inside and using an anvil do I just use an anvil with a hole to get the bushing centered?
 

Willie X

Registered User
Feb 9, 2008
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Yes, over a hole, preferably using a press

A 1.9mm bushing will usually protrude just a little, just the right amount in most cases.

Not centered ... the inside will always need to be flush with the inside of the plate and always needs to have a slight chamfer on the inside edge of the hole.

Willie X
 

kevin21

Registered User
Aug 30, 2021
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Not trying to be a pain...

In my original post I discussed the two bushings I was looking to use. One is 1.7mm in height, the other is 2.7mm in height. I am choosing these because there don't appear to be any KWM bushings for 1.9mm height that have an OD greater than 3.8mm which my hole is.

You mentioned 1.9mm as a perfect amount to "protrude just a little" from the front of the plate (not the inside). So, I assume the best choice for me is to use the 2.7mm height bushing (instead of the 1.7mm height) and file it down to somewhere close to the front of the plate so that it doesn't interfere with the minute wheel height as it sites on the arbor above the plate.
 

wow

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Jun 24, 2008
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Not trying to be a pain...

In my original post I discussed the two bushings I was looking to use. One is 1.7mm in height, the other is 2.7mm in height. I am choosing these because there don't appear to be any KWM bushings for 1.9mm height that have an OD greater than 3.8mm which my hole is.

You mentioned 1.9mm as a perfect amount to "protrude just a little" from the front of the plate (not the inside). So, I assume the best choice for me is to use the 2.7mm height bushing (instead of the 1.7mm height) and file it down to somewhere close to the front of the plate so that it doesn't interfere with the minute wheel height as it sites on the arbor above the plate.
If you use the 1.7 bushing it will only be .2 mm below the plate on the outside. You will not need to file anything and the .2 mm of the plate will become a part of the oil sink already built into the bushing. I would use the 1.7.
 
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kevin21

Registered User
Aug 30, 2021
16
2
3
Country
Thanks to you all for your input. I think I will go the 1.7mm route as Will has suggested. I don't like the idea of filing the 2.7mm bushing even if I don't get it level in support of Willie's thoughts. I also think the the larger difference between the OD and ID that the L80 bushing provides is better for a longer lasting bushing, though I have no technical knowledge to base that on, I am just guessing.
 

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