pivot hole center locator

[Willie X]

Not sure who wanted this but will try to post a couple of pictures of these very hany little tools. Bodies are 3/8" aluminum with 3/32" and 1/8" spindles. Central holes are drilled slightly undersize and lapped in for a tight slide fit. Scribner is tapped in a tight hole and sharpened, in place, with a Dremel or Fordam tool.

Willie X

 

[Willie X]

There is a second picture showing the scriber ends but you have to click on the plain picture and then hit prev or next button. I am a slow study when it comes to computers so please be patient with me.

Willie X

 

[Jay Fortner]

I'm with you on that,seems I can seize and crash one quite easily. You lost me on the use of these tools,are you using them to mark a radius?

 

[Willie X]

Yes,

The tiny circle made by the scriber encircles the old center. Very helpful when relocating a severely worn over hole. The smaller 3/32" one is the one I use most.

Willie X

 

[moe1942]

Willie I'm sorry but I can't visualize how your tool would help locate center better than the bushing tool center finder. I like new gadgets. Maybe a little more explanation would help me.

 

[bangster]

Willie I'm sorry but I can't visualize how your tool would help locate center better than the bushing tool center finder. I like new gadgets. Maybe a little more explanation would help me.

Willie's tools actually scribe a circle concentric with the original hole. Bushing tool center finder doesn't.

 

[moe1942]

Yes that part is apparent. I don't see how it would help me any more than what I do now. Willies tool physically locates center before scribing a circle. So does my bushing tool center finder. What further benefit is the scribed circle? Don't mean to nit pick. Trying to understand..

 

[shutterbug]

I had the same questions, Moe. I'm sure you are representing several others as well

 

[moe1942]

Well Bug I really want to understand its use but I'm not there yet. I don't want Willie thinking I'm trashing his idea. I am all for a new tool to make a job easier..

 

[R. Croswell]

I having a similar problem understanding. If the original hole is worn elongated, how is this tool going to "know" where the original hole was and what's to keep the center point from drifting to the other end of the worn hole? Seems to me it would just scribe a circle around an average of the worn hole or it would scribe an ovel to match the worn hole.

RC

 

[David S]

It seems to me that in order to work effectively you would force the center against the unworn side of the hole and then scribe a circle. The circle scribed acts as an aid as you work the cutting broach to make sure you are center. Does this sound reasonable? I think I could use this as I do rebushing manually.
David

 

[shutterbug]

Yeah, that makes sense, David. For bushing by hand I can see it's advantages. The taper in the point will help hold center too. The place where I and some others are having difficulty seeing is the advantage over a typical bushing machine. In fact, when first seeing it I misunderstood it to be a center locator for pivot replacement. I'm sure it will be all cleared up soon

 

[Willie X]

how is this tool going to "know" where the original hole was and what's to keep the center point from drifting to the other end of the worn hole? Seems to me it would just scribe a circle around an average of the worn hole or it would scribe an ovel to match the worn hole.

RC

The tool's highly tapered spindle is held centered exactly in what is/was the center of the old hole. When you scribe the circle you then have a permanent reference as to where the hole was and where the new hole needs to be. Now you know exactly what needs to be done to center the new hole, whether by fileing or nibbling over with the bushing tool.

If you are simply centering your bushing tool in the old unworn part of the hole and depending on the center to be kept, well that just doesn't happen. The hole will be off (toward the wear by 20 to 30 thou) this is very significant.

A good test would be to scribe the inside of the plate using the centering tool and then cut the bushing hole without 'nibbling over' or fileing the elongated hole. When you check your work you will easily see that the hole cut with the bushing hole is way off center. A milling machine is the only tool that will hold a predetermined center. This was discussed to some degree in a recent thread.

There are several methods of doing the reference marking. One uses a plastic overlay or reticule, one uses north/south and east/west cross-hair marks and there are probably others. This was covered at length on one of the older list several years ago. There was much exchange of ideas, blueprints, drawings, etc. I settled on the pictured circle making method. Bangs, thanks for the word "concentric" to describe the circle.

The smaller pictured scribe makes a 3mm circle. This works out nicely with my most used 2.7 mm KWM cutter. It's easy, with practice, to put a badly worn hole dead in the center and you know it's on center because the reference circle is still there, but barely viable around the edge of the new bushing hole.

Without good reference marks, the old center is lost with the first stroke of the file or first turn of the cutter. The idea of making accurate reference marks to maintain the original center would probably be a good topic to rehash.

Willie X

 

[bangster]

An excellent tool, Willie. Where can I get one?

 

[shutterbug]

Hmmm. I'm not sure you could spot a .002" error during the filing process either, so I'm still not totally convinced it's worth the trouble to make one of those critters
If I had a mill (still on my wish list) it wouldn't be needed, and since I don't, I'm not sure I'd get any closer than the 2 to 3 thousands you mention as being part of the disadvantage of a bushing machine. I'm not totally convinced I'm getting that much error, but have no way to refute that right now.

 

[Willie X]

Bugs,

Agreed, 2 or 3 thou would be good. But I said 20 to 30 thou off, that's not good ...

Bang, they are easy to make. A 3/32" piece of piano wire, or tool steel, and about 2 1/2" of brass or aluminum rod will do it. Takes a while to grind and sand the long straight taper on the spindle. The hole through the rod does not have to be exactly in the center, so you don't have to use a lathe. The hole does need to be a tight slide fit though, so bore it slightly undersize and lap it in with fine valve grinding compound. The scriber needs to be a light drive fit in its hole which is slanted at about 20 degrees inward toward the hole. I think that my scriber hole was made with a #58 drill but it could be a little bigger. Use a 2" length of hard wire with a very slight taper made to the base by barely touching the end to the side of a bench grinder's wheel while spinning it between your fingers. This will give the base of the scriber a bit of 'tooth' to grip in the undersize hole. Tap it in, just like a re-pivot, and cut it off sharp it with a Dremel. Pay close attention when you sharpen because the size of the circle will depend on the length of the scriber pin and also how you sharpen it. The circle needs to be just slightly bigger than the bushing, about 1/2 mm bigger is good.

Once you use this center marker on a hole that is badly worn over, you will wish that you had this little baby from the start.

Willie X

 

[Willie X]

It seems to me that in order to work effectively you would force the center against the unworn side of the hole and then scribe a circle. The circle scribed acts as an aid as you work the cutting broach to make sure you are center. Does this sound reasonable? I think I could use this as I do rebushing manually.
David

David,

Yes, the reason I use such a long taper is to allow a good bit of the spindle to go through the plate. This lets you keep steady pressure against the tip using your thumb nail, as you make the scribe.

Yes, it will help. The worse the hole is worn over, the more help the 'circle of truth' will be.

I didn't invent this and don't know who did but I think I will name it the"

" WILLIE'S CIRCLE OF TRUTH" Ha!

Best wishes, Willie X

 

[shutterbug]

Bugs,

Agreed, 2 or 3 thou would be good. But I said 20 to 30 thou off, that's not good ...

Ooops. So 2 or 3 hundreds. I'm going to have to find a way to measure my results, but I just can't believe I'm making that much error in my bushing work

 

[dAz57]

I generally use the oil sink to guide me to where the pivot hole should be, if its really bad I use the preacher tool to mark the original centre, bore and plug the hole with a solid bush, remark the pivot hole with the preacher tool and drill to size.

this tools has merits, but I am so used to doing things by eye that I never had a real need for something like it.

 

[harold bain]

I generally use the oil sink to guide me to where the pivot hole should be, if its really bad I use the preacher tool to mark the original centre, bore and plug the hole with a solid bush, remark the pivot hole with the preacher tool and drill to size.

this tools has merits, but I am so used to doing things by eye that I never had a real need for something like it.

On many American movements there never were bushings/oil sinks. The plates just had drilled holes. On these you have to carefully determine what direction the wear is to maintain the original hole's location. It's not always obvious.

 

[Willie X]

I generally use the oil sink to guide me to where the pivot hole should be, if its really bad I use the preacher tool to mark the original centre, bore and plug the hole with a solid bush, remark the pivot hole with the preacher tool and drill to size.

this tools has merits, but I am so used to doing things by eye that I never had a real need for something like it.

Daz,

Some things to consider: Bushings are intended to go in from the back, they have a slight taper and are designed to be driven (or pressed) in from the back of the plate. Also, the little rings around the holes, are often way off center, they are very close on most of the 1900s S-T clocks though. Most others, not. Preachers are very good but not a permanent or visual indicator of the original center, IMO not necessary except in some very rare occasions.

Try it, you might like it.

Willie X

 

[dAz57]

maybe, maybe not

I don't own a bushing machine, just use a drill press, don't even use the cutters, just a set of specially modded metric drills from 1mm to 10mm in 0.1mm steps, even have some in between sizes like 1.95, 2.05 etc, I drill in from the oil sink side generally, so yes I always check to see if the oil sink is concentric to the pivot hole, on most modern movements is not a problem, americans with the stamped oil sinks are normally ok too, on french movements extra care has to be taken because often the oil sink is off centre.

if the bush is in the wrong place usually from a previous repairer then I will use the depthing tool.

 

[Len Lataille]

By coincidence, today, I was going through old copies of Horological Times (Nov 2004). There is an article by Laurie Penman describing a new bushing system. He describes a new bushing tool that he developed. It is somewhat similar to the tool mentioned in this thread in that it marks a circle on the plate around the bearing hole. This makes the location of the wear much more evident, because the long tapered finder is only 9 degrees or so.

I would not use this method in a valuable clock as it does mark the plate. I'm also not sure that the additional accuracy would make much difference from using my Bergeon bushing machine.

 

[shutterbug]

I would not use this method in a valuable clock as it does mark the plate. I'm also not sure that the additional accuracy would make much difference from using my Bergeon bushing machine.

That's where I'm at, Len. Can't imagine Bergeon selling a machine that has a reputation of being 20 to 30 thousands off from original center! I've yet to see a depthing problem on a replaced bushing from mine, but I haven't done that many really small movements, where such a thing would really be obvious

 

[Willie X]

Can't imagine Bergeon selling a machine that has a reputation of being 20 to 30 thousands off from original center!

Don't intend to be offensive or defensive to anyone ... (where's th new smiley face buttons?). But, it is really hard to believe that folks seriously repairing clocks actually think that the bushing tool is strong enough to hold a center on its on! Put a dial indicator on the spindle tip and finger pressure will give you about 20 thou combination flex and slop. Running a tapered cutter round and round into a severely worn over hole, with brass on one side and air on the other, and you will add at least 10 thou more, depending on how much the old hole was worn over. Learning how to "nibble" with your bushing cutter is mandatory.

To the scratch worriers. The scribe can be easily removed but who would want to remove the circle when it is totally invisible and also a permanent record of the original center

Oh well, I was just trying to help,

Found the smiley buttons.

Over and out on this one.

Willie X

 

[dAz57]

But, it is really hard to believe that folks seriously repairing clocks actually think that the bushing tool is strong enough to hold a center on its on! Put a dial indicator on the spindle tip and finger pressure will give you about 20 thou combination flex and slop. Running a tapered cutter round and round into a severely worn over hole, with brass on one side and air on the other, and you will add at least 10 thou more, depending on how much the old hole was worn over. Learning how to "nibble" with your bushing cutter is mandatory.

absolutely, as you say there is enough flex to cause the cutter to follow the easiest path, the fellow that serviced this little french clock before me did use a bushing machine, the rear centre wheel pivot was so off centre that the clock jammed, in this particular clock which is 8day the barrel meshes straight to the centre pinion which has 8 leaves, the teeth were butting, had it been a bit more over the barrel could have been easily stripped

this was a depthing tool job but I got it to run properly, this is a french tictac escapement with a double escape wheel and the pallets look like a half round disc.

 

[shutterbug]

Don't intend to be offensive or defensive to anyone ... (where's th new smiley face buttons?). But, it is really hard to believe that folks seriously repairing clocks actually think that the bushing tool is strong enough to hold a center on its on! Put a dial indicator on the spindle tip and finger pressure will give you about 20 thou combination flex and slop. Running a tapered cutter round and round into a severely worn over hole, with brass on one side and air on the other, and you will add at least 10 thou more, depending on how much the old hole was worn over. Learning how to "nibble" with your bushing cutter is mandatory.

To the scratch worriers. The scribe can be easily removed but who would want to remove the circle when it is totally invisible and also a permanent record of the original center

Oh well, I was just trying to help,

Found the smiley buttons.

Over and out on this one.

Willie X

Don't be sensitive, Willie. No one is condemning you or your tool, just trying to fully understand it's value. I enjoy these types of conversations and always learn something or at least have something to think about. I'm sure you're right about the bushing machines, and like you said, you have to know how to use them effectively. I tend to play devils advocate, and hope I didn't over step! I respect your opinions here, and acknowledge your expertise!

 

[moe1942]

Willie thanks for further clarification. I just finished an upgrade to my Bergeon bushing tool. I don't want to hijack this thread by rehashing details but will only say that in my particular case I only have a few thousands runout in the business end using a Starrett last word indicator. I am confident that I can accurately place a bushing hole if I take care in setting up for the reamer.

I now can see where your tool would help in bushing by hand. I prefer to use my bushing tool. I have a mill but would rather use my bushing tool for greater feel and control.

 

[bangster]

Bugs,

Agreed, 2 or 3 thou would be good. But I said 20 to 30 thou off, that's not good ...

Bang, they are easy to make. A 3/32" piece of piano wire, or tool steel, and about 2 1/2" of brass or aluminum rod will do it. Takes a while to grind and sand the long straight taper on the spindle. The hole through the rod does not have to be exactly in the center, so you don't have to use a lathe. The hole does need to be a tight slide fit though, so bore it slightly undersize and lap it in with fine valve grinding compound. The scriber needs to be a light drive fit in its hole which is slanted at about 20 degrees inward toward the hole. I think that my scriber hole was made with a #58 drill but it could be a little bigger. Use a 2" length of hard wire with a very slight taper made to the base by barely touching the end to the side of a bench grinder's wheel while spinning it between your fingers. This will give the base of the scriber a bit of 'tooth' to grip in the undersize hole. Tap it in, just like a re-pivot, and cut it off sharp it with a Dremel. Pay close attention when you sharpen because the size of the circle will depend on the length of the scriber pin and also how you sharpen it. The circle needs to be just slightly bigger than the bushing, about 1/2 mm bigger is good.

Once you use this center marker on a hole that is badly worn over, you will wish that you had this little baby from the start.

Willie X

Me no skilled with lathe.
You make me one.
Me pay you.
Hokay?

 

[R. Croswell]

I have a Bergeon bushing tool and I have no confidence that it will hold a true center in the end of an elongated pivot hole. There are also times when, due to the design of the tool, that a plate can only be held by one clamp which definitely will not hold the plate secure enough to locate in an elongated hole. I prefer to “round up and center” the hole by hand before using the Bergeon tool. That way I only rely on the tool to ensure that the hole is perpendicular to the plate with parallel sides that are not “wallowed out” by my less than true hand motion. I can see how the Circle of Truth could help as long at the locator point can be held at the correct position. For most American plates, I just use a fine line “Sharpie” pen to mark where I need to nibble with a small hand-held Bergeon reamer. Then I use the “machine” to ream the final hole. Whatever gets the job done easiest is worth a try. I welcome everyone’s new ideas and innovative contraptions. I like trying things even if I don’t end up using all of them.

RC

 

[moe1942]

Willie, I believe your thread has some life left in it.. Looking at you tool dredged up something I've thought about over the years but never got around to trying. I think a more acute angle on a center finder would more accurately locate center of a worn hole. I may try it now that I have my chuck mounted on the bushing tool. There is a lot of clearance between the reamer arbors and the tool spindle. No telling how much of an error that trasmits to the reamed hole. My chuck eliminates almost all of that error.

So Willie I will make a center finder with the taper on you tool and use a small pivot drill to start the hole. I think that will give me a well placed hole.

 

[Len Lataille]

"Nibbling" at an oval hole with my Bergeon is how I learned and how the guy that I learned from did his rebushing. He had a very successful repair shop long before I touched a clock.

My Bergeon has worked for me for nearly 25 years, and it must work for many others, as they are still around.

I will admit that there are better bushing types available (KWM), but when I started Bergeon was what I could afford and nearly the best available at the time. Like any tool, any bushing machine has to be used properly.

Too old and not about to change. WFM.

As for accuracy, most of the clocks that I work on are sloppy enough to accept some error in bushing placement. I dont see much in "precision" quality clocks.