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Help understanding a depthing tool

ChrisCam

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Hi Guys,
Whilst I understand what a depthing tool basically does in that it allows you to accurately find the centre positions of gear arbors I have a hole in my knowledge.

As we all know clock pivot and arbors come in various sizes. How then can a depthing tool cope with all these different sizes. If you make your own depthing tool you still have the same issue.

Can someone explain how av depthing tool copes with the many different sizes of pivot / arbors out there. Is the gear / pinion held by its pivot or arbor etc and do you need to machine add on for different sizes?

Regards
Chris
 

gmorse

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Hi Chris,

The traditional depthing tools have female cone runners which accept a range of pivot sizes. The tools themselves are made in sizes to suit both watches and clocks, although the clock sizes tend to be expensive now. If the tool is an appropriate size for the job, you shouldn't need to machine anything.

Depthing Tool.JPG DSCF6536.JPG

Regards,

Graham
 

ChrisCam

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Hi Chris,

The traditional depthing tools have female cone runners which accept a range of pivot sizes. The tools themselves are made in sizes to suit both watches and clocks, although the clock sizes tend to be expensive now. If the tool is an appropriate size for the job, you shouldn't need to machine anything.

View attachment 619161 View attachment 619164

Regards,

Graham
Nice to hear from you Graham,
So the females are tapered and accommodate a range of pivots / arbor sizes?
Chris
 

ChrisCam

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Thanks Graham I intend making a simple jig. There is an issue of different arbor sizes...possibly brass bushes but will do some more thinking and poking about. Maybe the v cut will Suffice for a fair range.
Regards
Chris
 
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gmorse

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Hi Chris,

The female cones are hardened steel and ensure that the pivot tips are always centred. They also remove the need for many different sized runners.

Regards,

Graham
 
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John MacArthur

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Chris - Here are some pics of my fixture.
27 depthing1.jpg 27 depthing3.jpg 45.6 after all three grades.jpg
I have quite a variety of bushings and studs to fit wheel and pallet holes, and various sizes of arbors. I also have pointed scribes which fit into the two holes, so it can be used to scribe arcs for locating pivot holes. Now I just measure the center distance ((ID + OD)/2) and lay out holes by geometry and the DRO on the mill. I suspect this is the sort of thing you are thinking of.
Good luck,
Johnny
 
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ChrisCam

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Chris - Here are some pics of my fixture.
View attachment 619376 View attachment 619380 View attachment 619382
I have quite a variety of bushings and studs to fit wheel and pallet holes, and various sizes of arbors. I also have pointed scribes which fit into the two holes, so it can be used to scribe arcs for locating pivot holes. Now I just measure the center distance ((ID + OD)/2) and lay out holes by geometry and the DRO on the mill. I suspect this is the sort of thing you are thinking of.
Good luck,
Johnny
Appreciate post Johnny, will study it in detail later.

many thanks
Chris
 

gmorse

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Hi Johnny,

Is it just the picture, or is the arbor on the right in the first image out of upright?

Regards,

Graham
 

John MacArthur

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Good spot Graham, but it is just the distortion of the picture. If you look closely the plate appears slightlycurved too. The bushings for the arbors are actually tubes that extend through the fixed end, and are fairly snug.
Johnny
 

gmorse

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Hi Johnny,

Thanks, I did wonder; wide angle lenses can produce some odd effects!

Regards,

Graham
 

Dr. Jon

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I am working on a depthing tool and making the pivots. I chose bronze as the material. It is harder than brass, used for bushings, easy to machine and does not require heat treatment. The downside is that the smallest stock is 3/8 diameter and I had to machine away a lot of bronze. There was some benefit in that I have kept the shavings. I use them to hold steel I in bluing pan.

What i have discovered since them is that aluminum bronze is available a TiG welding rod in small sizes 1/8" diameter and 1/16. I think this is a very good material for making these and I amy try it. The down side is that it comes in 36" lengths but it costs about the same as bronze rod stock.
 

ChrisCam

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I am working on a depthing tool and making the pivots. I chose bronze as the material. It is harder than brass, used for bushings, easy to machine and does not require heat treatment. The downside is that the smallest stock is 3/8 diameter and I had to machine away a lot of bronze. There was some benefit in that I have kept the shavings. I use them to hold steel I in bluing pan.

What i have discovered since them is that aluminum bronze is available a TiG welding rod in small sizes 1/8" diameter and 1/16. I think this is a very good material for making these and I amy try it. The down side is that it comes in 36" lengths but it costs about the same as bronze rod stock.
Hi, thanks for posting I would be interested in how it turns out
Regards
Chris
 

ChrisCam

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Graham, pictures can often lack dimensions. In side the cone is what looks like a centre hole, possibly a start point for a 60 degree centre drill or something similar. If there is a hole there would not small pivot enter the hole and the arbor be supported by the cone?
What i am trying to work out is; is it alright to support the wheel by the arbor rather than the pinion?

Regards
Chris

conepic.jpg
 
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gmorse

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Hi Chris,

pictures can often lack dimensions. In side the cone is what looks like a centre hole, possibly a start point for a 60 degree centre drill or something similar. If there is a hole there would not small pivot enter the hole and the arbor be supported by the cone?
What i am trying to work out is; is it alright to support the wheel by the arbor rather than the pinion?
This picture is of a watch sized tool which measures 96 mm tip to tip; each runner is 46 mm long and 1.5 mm in diameter. The OD of each tip is 0.7 mm. There is a slight depression in the centre of each cone which is hard to measure, but I estimate that it's between 0.15 and 0.2 mm.

If you can be certain that the pivot is concentric with the arbor, (not necessarily always the case), then you could support the wheel by the arbor rather than the pivot. It depends on the quality of the work and its condition. All the examples I've seen of these tools in the watch sizes have been designed to support the pivots.

Regards,

Graham
 

ChrisCam

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Hi Chris,



This picture is of a watch sized tool which measures 96 mm tip to tip; each runner is 46 mm long and 1.5 mm in diameter. The OD of each tip is 0.7 mm. There is a slight depression in the centre of each cone which is hard to measure, but I estimate that it's between 0.15 and 0.2 mm.

If you can be certain that the pivot is concentric with the arbor, (not necessarily always the case), then you could support the wheel by the arbor rather than the pivot. It depends on the quality of the work and its condition. All the examples I've seen of these tools in the watch sizes have been designed to support the pivots.

Regards,

Graham
Thanks Graham for replying,
I have come across an old (1985 AWCI) drawing for a do it yourself but decent depthing tool. The 60 degree cone has an internal start point diameter so it again points me to using a centre drill. If there is this centre drill on a 6mm rod it will leave at least 2mm start diameter. Needless to say many pivots would go into this leaving the arbor supported by the cone.
Further my research suggests many folk believe depthing tools inaccurate. Am I trying to achieve if not the impossible the very unlikely in no error by using the depthing tool. There are several places a few thou error can creep in. That is not to say you should not use a depthing tool, in some way or other achieve correct depth. I suspect on many wheels and pinions a few (e.g <5 ) thou might be expected from inaccuracies of the tool,wheel,arbor, pinion, bushing it is only when that few thou is on the wrong side of the fence it may be of serious consequence.
Regards
Chris
 

Jerry Kieffer

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Chris
As others have mentioned, only pivots should be used as a reference point when depthing.

In addition, the safest runner female "V" cavity will be pointed at the bottom center per the attached sketch. This assures that the pivot will always be the reference point and centered in the runner.

A "V" with a sharp pointed center can be machined to any desired angle and size using a boring bar per the attached photos. The photos show a micro size since small size is a concern and part of the discussion.
The size shown would handle sizes smaller than found in Horology thus illustrating the size of a pivot need not be a concern.

The setup shown was a 5 minute setup with boring for illustration only where exact accuracy was purposely avoided. To get a sharp point at the bottom of the "V" the boring bar cutting tip must be centered to center of the spindle rotation. The boring bar used has been ground and has lost its factory ground center, thus the yellow shim seen under the tool post to compensate. If you look very closely, you will see a tiny "tit" at the bottom of the .25mm OD "V" requiring probably an additional .015mm tool post shim for the boring bar to remove it.

Jerry Kieffer

fullsizeoutput_72c.jpeg fullsizeoutput_72b.jpeg fullsizeoutput_72a.jpeg
 

ChrisCam

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Dec 9, 2017
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Chris
As others have mentioned, only pivots should be used as a reference point when depthing.

In addition, the safest runner female "V" cavity will be pointed at the bottom center per the attached sketch. This assures that the pivot will always be the reference point and centered in the runner.

A "V" with a sharp pointed center can be machined to any desired angle and size using a boring bar per the attached photos. The photos show a micro size since small size is a concern and part of the discussion.
The size shown would handle sizes smaller than found in Horology thus illustrating the size of a pivot need not be a concern.

The setup shown was a 5 minute setup with boring for illustration only where exact accuracy was purposely avoided. To get a sharp point at the bottom of the "V" the boring bar cutting tip must be centered to center of the spindle rotation. The boring bar used has been ground and has lost its factory ground center, thus the yellow shim seen under the tool post to compensate. If you look very closely, you will see a tiny "tit" at the bottom of the .25mm OD "V" requiring probably an additional .015mm tool post shim for the boring bar to remove it.

Jerry Kieffer

View attachment 620044 View attachment 620045 View attachment 620046
Jerry,
Thanks for post. I never even thought of using a boring bar. That said can i use a spot drill or end mill chamfer to achieve my goal as I now am owners of such?
Regards
Chris
 

ChrisCam

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Jerry,
Thanks for post. I never even thought of using a boring bar. That said can i use a spot drill or end mill chamfer to achieve my goal as I now am owners of such?
Regards
Chris
Update Jerry had advised me the use of a suitable spotting drill is also fine. I would add ref Laurie Penman that some old clock pivots were crudely rounded with a file thus these may be difficult to impossible to run as they stand on a depthing tool. As always listen to others but prepared to think for for your self, a lesson I am learning loud and clear. Note all alternatives..someday you may at some point need them.

Chris
 

part-timer

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Jun 27, 2017
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Pardon me for butting in...
Jerry, what is the object with the green grip in your center picture? It appears to be a ballpoint pen, but of course it can't be. The tip shown in the third picture seems to be a lens - so is it a camera? If so, where did you obtain such a marvelous tool?

Chris
As others have mentioned, only pivots should be used as a reference point when depthing.

In addition, the safest runner female "V" cavity will be pointed at the bottom center per the attached sketch. This assures that the pivot will always be the reference point and centered in the runner.

A "V" with a sharp pointed center can be machined to any desired angle and size using a boring bar per the attached photos. The photos show a micro size since small size is a concern and part of the discussion.
The size shown would handle sizes smaller than found in Horology thus illustrating the size of a pivot need not be a concern.

The setup shown was a 5 minute setup with boring for illustration only where exact accuracy was purposely avoided. To get a sharp point at the bottom of the "V" the boring bar cutting tip must be centered to center of the spindle rotation. The boring bar used has been ground and has lost its factory ground center, thus the yellow shim seen under the tool post to compensate. If you look very closely, you will see a tiny "tit" at the bottom of the .25mm OD "V" requiring probably an additional .015mm tool post shim for the boring bar to remove it.

Jerry Kieffer

View attachment 620044 View attachment 620045 View attachment 620046
 

Jerry Kieffer

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Pardon me for butting in...
Jerry, what is the object with the green grip in your center picture? It appears to be a ballpoint pen, but of course it can't be. The tip shown in the third picture seems to be a lens - so is it a camera? If so, where did you obtain such a marvelous tool?
Part-timer

Chris the OP of this thread mentioned the value of dimensions with photos earlier that I am often guilty of not supplying.

The green thing is indeed a ball point pen from the local bank per attached photos. Ball diameters of ball point pens seem to be about .3mm to .7mm with the one in the photo at .5mm that seems to be the most common typically encountered. As such, it was used as a size reference.

Actually it is truly amazing how small cameras can be and how they can be utilized now that you mentioned it..

About three years ago Discover Channel filmed at my house for a day regarding a model engineering model that contains parts half the size of the smallest watch parts. They placed micro cameras in tight areas that allowed views from the inside out of assembles and other specific areas. At any rate it was a unforgettable experience.

Jerry Kieffer fullsizeoutput_734.jpeg fullsizeoutput_732.jpeg
 
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part-timer

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Jerry,
Aaahhhh... it's just a pen, and not a camera! Alright, everything in your post is suddenly "pulled into focus"... it was merely a way to indicate scale. Thank you for clarifying. My gosh, that certainly is a tiny boring bar.

Part-timer

Chris the OP of this thread mentioned the value of dimensions with photos earlier that I am often guilty of not supplying.

The green thing is indeed a ball point pen from the local bank per attached photos. Ball diameters of ball point pens seem to be about .3mm to .7mm with the one in the photo at .5mm that seems to be the most common typically encountered. As such, it was used as a size reference.

Actually it is truly amazing how small cameras can be and how they can be utilized now that you mentioned it..

About three years ago Discover Channel filmed at my house for a day regarding a model engineering model that contains parts half the size of the smallest watch parts. They placed micro cameras in tight areas that allowed views from the inside out of assembles and other specific areas. At any rate it was a unforgettable experience.

Jerry Kieffer View attachment 621429 View attachment 621430
 

motormaker

Registered User
Apr 5, 2010
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Here is a tool designed for making such "V" shaped pivot holes...I need to resharpen it...

20191221_172212lathe.jpg 20191221_172458lathe.jpg
 

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