Bull's Foot

bangster

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Is there a way to make a bull's foot file out of an ordinary small flat file?

bangster
 

Lynne Gillette

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Yes, but more work than buying one. Heat the selected file to soften. Form end to desired shape by bending and grinding. Heat treat and clean .

Lynne
 

bangster

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Yes, but more work than buying one. Heat the selected file to soften. Form end to desired shape by bending and grinding. Heat treat and clean .

Lynne
Buying one is an unlikely option, given the paucity of sources. Of course, I don't believe in diamond "files", so that limits my opportunities.

bangster
 

lkjjkl

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What is a bull's foot? I'd like to know how this is different from a crow's foot or if it is.
 

Jerry Kieffer

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If you own a small accurate Milling Machine or a Lathe with a sturdy accurate milling column, Functional Bulls Foot files are easily constructed.

First either round or square stock of the desired size is selected and mounted in the Mill with a vise or Lathe Chuck. Then a slot is machined down the center to a slip fit of the file to be used. The slot is also machined about .005"-.010" deeper than the thickness of the file. For this type application I use parallel cutting surface Pillar files of the desired width. Next the piece of file is cut to length and glued in the File body slot. For this I use Super Glue because it is very thin and allows accurate mounting of the file under headstock clamping tension. The file body remains in the mill mounting to assure accurate machining and grinding until the project is completed. When the mounting/gluing process has cured the body is then ground to the proper depth (Just above the file)to assure proper function. To achieve this I first press a thin moist strip of paper into the file with my finger. I then mount a 4" cup wheel in the mill spindle to grind the body. When the stone just touches the paper I know I am very close and take one or two more very light passes. This results in the body being about .0005" higher than the file to protect surrounding surfaces. At this point the file is complete.

To accurately do this work the mill should be properly trammed. Also if the Pillar File cutting surfaces are not parallel one side can be ground using the process above. Personally for Horological use I have found Bulls Foot file handles to be of no use and do not use them. However they are easily added to any constructed file.

I have attached a photo of a completed File and the Pillar file that a section was removed from for the construction.

Jerry Kieffer
 

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Old Codger

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Bangs, if you just need a file for removing high bushings etc, its an easy job to grind/polish a ski slope on the end of a fine file, this will minimise any marking of the plate you are working on. The last bulls foot file i owned was given to a NAWCC member FOC, they are an old fashioned idea that should be permanently put in the rubbish bin and have no place in good clock repair, OC UK
 

Tony Ambruso

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Good discussion. I was thinking this might be a useful tool to have. I was thinking that one with a handle might be easier to steady and avoid accidentally hitting the plate surface. But so far, the posts are suggesting my thinking is wrong.
 

bangster

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Bangs, if you just need a file for removing high bushings etc, its an easy job to grind/polish a ski slope on the end of a fine file, this will minimise any marking of the plate you are working on. The last bulls foot file i owned was given to a NAWCC member FOC, they are an old fashioned idea that should be permanently put in the rubbish bin and have no place in good clock repair, OC UK
Explain a little more about that grinding job. Sounds interesting.

bangster
 

Jerry Kieffer

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Tony
A properly designed Bulls foot file will not damage a surrounding flat surface since the file body (sides) will not allow the file to touch that surface. This will be regardless of how the file is held. No disrespect to others but personally I am not a big fan of grinding/shaping the end of a file to help decrease damage for this type work. The file must be skillfully controlled if damage is to be avoided. For this tool a handle may very well increase file control. While this tool may be inexpensive and helpful in some cases it will rarely produce the same quality result as a properly designed Bulls foot.

When needed my personal preference is the true bulls Foot since it avoids issues without skill or concern rather than just decreasing the chance of damage. At least for myself it is much easier to use the Bulls Foot with my fingers for smaller Horological work rather than with a handle. It also gives much greater feel for the work being done.

Jerry Kieffer
 

bangster

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What about using a riffler file? They seem to be more available than bullfoots.

bangster
 

Tony Ambruso

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Tony
A properly designed Bulls foot file will not damage a surrounding flat surface since the file body (sides) will not allow the file to touch that surface. This will be regardless of how the file is held. Jerry Kieffer
Thanks for the clarification, Jerry. It DOES sound like a useful tool to me. Now I have another tool project on a list that's already too long.:D
 

Old Codger

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Hello Bangster, most of the bulls foot files i have seen from the material dealers are too coarse for the purpose they are intended for and have ragged edges that need grinding and polishing to avoid marking the plates so why not cut out the dealers and make your own. A few minutes on the grinder and polishing should only take about 30 minutes and then you have the ski slope, you then have a tool that should last for years. You mentioned riffler files, i also use these for the same job and dont forget to use old film negatives as a mask against marking the plates, ( an old trick that does work), OC UK
 

shutterbug

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I think Grobet may have the finer styles, if you want to buy one. I think they call them 'spoon' files. Look under Optical.
 
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