Preachers Tool for bushing centre location

[Nitrous]

Hi folks,

I am gradually building up my nerve to take a clock carcass and replace a few pivots with bushings.
One of the things I want to clarify is the role of the 3-point preachers tool for bushing centering.

I understand the role of the two points in establishing an external reference point for the centre of the 'soon to be replaced' pivot. What I'm not sure about is how this benefits you in inserting the bushing into the worn hole. Specifically, if there is a centered hole in the bushing, and it doesn't align with the 3rd point of the Preachers Tool... don't you still have to enlarge the hole to the make it coincident with the 3rd leg of the tool?

If the inserted bushing was actually solid, then the divot made in the bushing could then be drilled and be perfectly centered. But that adds an extra setup step, doesn't it?

I suspect I'm missing the point all together - but thought I'd ask.

Thanks folks,
Doug

 

[R. Croswell]

You do not need a preacher for bushing installation.

RC

 

[Nitrous]

I understand I don't "need" on, but is it helpful, and what advantage does it offer, if any?
Thanks for replying
Doug

 

[Jim DuBois]

The so-called preacher tool is a complete waste of time. It has no purpose when doing repair work. It is at best an inefficient crutch that only complicates repairs and solves nothing. It has been written about here multiple times in other threads. It has strong advocates that I suspect most have never repaired a clock. And pretty much to a competent repairman, those with knowledge and skills, refute its need or its use. The only time it might be of use is if you effectively mark the remaining center accurately, make the divots in the plates, completely fill the old bushing hole with a solid insert, then remark, using the preacher, and drill the new center of the solid bushing. IMO, if you get in that much trouble you need a proper tool and that would be a depthing tool.

 

[JayKosta]

The tool is used to 'identify' the center if its position gets lost in the process of reaming the enlarged round hole for the new bushing.

 

[Nitrous]

The so-called preacher tool is a complete waste of time. It has no purpose when doing repair work. It is at best an inefficient crutch that only complicates repairs and solves nothing. It has been written about here multiple times in other threads. It has strong advocates that I suspect most have never repaired a clock. And pretty much to a competent repairman, those with knowledge and skills, refute its need or its use. The only time it might be of use is if you effectively mark the remaining center accurately, make the divots in the plates, completely fill the old bushing hole with a solid insert, then remark, using the preacher, and drill the new center of the solid bushing. IMO, if you get in that much trouble you need a proper tool and that would be a depthing tool.

Thank you Jim,
The actual answer to all my questions about the tool rests toward the end of your response. Except in terms of filling the pivot with solid brass, and then drilling the bushing out to the 'actual' center that was determined by the preacher tool, it really offers no advantage. If I understand the depthing tool correctly, it could be a nightmare trying to determine the actual pivot location for multiple, worn bushings using a depthing tool.

So, would it be reasonable to think that getting a set of broaches/reamers and some bushing material would be a good start to have a go at repairing bushings (in a trashed movement, of course!)?

Thanks again for responding,
Doug

 

[Jim DuBois]

Doug,
Bushings only wear in one direction on one side of the bushing. It is quite easy to determine where the wear has occurred so it is also pretty easy to center up a cutter where the bushing hole started life, retain the plate in position, and use a properly sized reamer to ream the recess for the new bushing. Over many years and more than a few bushing replacements, I have only messed it up a couple of times. I use either an old and sloppy drill press or an El-cheapo Chinese small mill to cut the new bushing recesses. I have also done some number by hand but prefer the speed and accuracy the machines provide. I have and use both Burgeon as well as KMW bushings, depending on what falls into hand.

It is not rocket science to re-bush clock movements. I showed my 14-year-old daughter how to bush on one bushing. She did all the other required bushings on that movement and they were all properly done, and the movement ran fine when she was finished. She did them on my drill press, under power. Then she discovered boys, and the rest is history.

And depthing tools are not often required, but I own 3 sizes of them and they are a lifesaver on building new clocks, or replacing botched-up wheels/pinions, and they would work fine on re-centering bushings too. I used one that way a couple of months back. Somebody had replaced some parts, no original parts left, so depthing of the replacement parts became critical. And that included the bushings, Uncle Fix-it had put in an eccentric bushing just to make life interesting. When you don't know where the correct center is, depthing tools become critical. But, as you are just staring the process you don't need one of those.

 

[R. Croswell]

I understand I don't "need" on, but is it helpful, and what advantage does it offer, if any?
Thanks for replying
Doug

If the original hole has not been bushed, you have no need for a preacher. if the hole has been previously bushed incorrectly the center has already been lost and a preacher will be useless.

 

[JayKosta]

When doing hand reaming, are there typical methods of marking the desired center location?
e.g. + crosshair marks on OD of new hole location, OD circle marks around the location, etc.

 

[disciple_dan]

Hello all, I use my preacher for checking the accuracy of whatever bushing technique I use. I set a point in an unbushed bearing hole as accurately as possible and make my marks. I ream and install the bushing. Then I set a point in the new bearing and see how well the other points line up.
Here are some pics of the method.
This is the original hole being marked.


Checking the accuracy, it seems to line up perfectly. I can live with that.

Thanks, Danny

 

[Chris.K]

I found out long ago that a "Preachers tool" is a worthless gizmo that just complicates the bushing process. I do a "self-centering" style of hand bushing. If the bushing is worn at the 11-5 o-clock position, place the back side of your reamer toward the worn area and cut from 12 o-clock to 4 o-clock only cutting on the "meaty" side of the bushing. After 4 or 5 cuts do a complete cut and repeat until reamer is through the plate. By doing this style you are re-constructing the original hole where the bushing went. Then all you have to do is broach to pivot size, smooth broach and done. Over the years I have only had to re-do 3 or 4 bushings and that was due to being tired or having one too many canned adult beverages. Hope this is of help.. Chris..

 

[disciple_dan]

I don't use the preacher on every bushing. I do that on one hole every couple of months just to renew my confidence in my bushing skills. It makes me feel like I'm doing good, quality work.
Thanks, Danny

 

[R. Croswell]

The p

I don't use the preacher on every bushing. I do that on one hole every couple of months just to renew my confidence in my bushing skills. It makes me feel like I'm doing good, quality work.
Thanks, Danny

Preacher does absolutely nothing to help install the bushing. The only thing it can do is tell you if you screwed up after the job is done. I would argue that if you are installing bushings properly you already know if the bushing is properly located. But if it makes you feel better do it.
RC

 

[disciple_dan]

It does make me feel better and so does your approval. Thank you, Danny

 

[Tim Orr]

Good afternoon, all!

Not too far off topic, I hope: Why is it called a "preacher"?

Thanks!

Best regards!

Tim Orr

 

[disciple_dan]

I think it would be because Preachers tell the truth about what really is. ( Well, the ones faithful to the truth do.)

 

[Simon Holt]

If the original hole has not been bushed, you have no need for a preacher. if the hole has been previously bushed incorrectly the center has already been lost and a preacher will be useless.

I seem to remember reading that you can set up the preacher using the pivot holes on the opposite plate then transfer the measurements to the plate needing bushing. Would that be a valid use of the tool?

Simon

 

[JayKosta]

I seem to remember reading that you can set up the preacher using the pivot holes on the opposite plate then transfer the measurements to the plate needing bushing. Would that be a valid use of the tool?

Simon

That should work - IF 'good center' for all three holes in the other plate can be located, AND the two 'reference holes' in the working plate have good center.

 

[R. Croswell]

I seem to remember reading that you can set up the preacher using the pivot holes on the opposite plate then transfer the measurements to the plate needing bushing. Would that be a valid use of the tool?

Simon

A standard 3-point preacher like the one shown in post #10 will not work to transfer pivot hole locations from the opposite plate. This tool works by placing one point in the reference pivot hole and making a mark on the plate at the other two points. Obviously the two required reference marks will not be available on the plate where the location is being transferred to. A while back someone posted a picture of an adjustable preacher with two slotted adjustable arms. With that device, the preacher can be referenced from two adjacent pivot holes instead of the usual marks on the plate. At least in theory such an adjustable preacher could be used to locate a pivot hole from the location of the corresponding pivot hole on the opposite plate. Assuming that the pivot holes in the opposite plate are also worn (have egg-shaped holes) aligning all three points of the preacher to the unworn end of each hole will require some care. Likewise positioning the preacher on the plate to be bushed using two worn pivot holes will also require care.

One can also just measure the distances between adjacent holes (2 or more) on the opposite plate using the inside measurement points of a digital, dial, or vernier caliper, and using layout dye or blue magic marker, layout where the new pivot hole will be drilled on the old plugged hole. A depthing tool of high quality would seem to be the tool of choice here. (search for depthing using a mill, Jerry K. describes a neat technique that is probably the best and most accurate possible).

I've installed hundreds of bushings and I can count on one hand the number of times that I had to locate a new pivot hole on a blank bushing. I never bothered to make a preacher, but if I wanted another seldom used gadget to accomplish that I can do with tools I already have, I would consider making an adjustable one. You will probably never use it but making it and bragging about it will be fun.

RC