Building a Depthing Tool

Discussion in 'Horological Tools' started by Raynerd, Oct 19, 2016.

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  1. Raynerd

    Raynerd Registered User

    Apr 11, 2004
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    I`ve wanted a good size depthing tool for years. I`ve got a few of the simple John Wilding designs that work well, but I`ve always fancied a more traditional hinged design. I`ve actually got large castings from Malcolm Wild but never dared put tool to metal as I`m just not confident of getting everything true and parallel!

    Anyway, I`ve started with an attempt to build a large depthing tool made from brass plates but using a ball bearing as a hinge and ball bearings to hold the runners true. If this works, the design will be quite useful in the home workshop as you only need to ensure each row of holes is drilled on the same run and with the plates pinned together, everything should be parallel.

    Let me know if you have any thoughts, suggestions or concerns!

    [video=youtube;22DjjXPdmaE]https://www.youtube.com/watch?v=22DjjXPdmaE[/video]
     
  2. Raynerd

    Raynerd Registered User

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    Appreciate I got no comments on this but for anyone that was interested how it turned out, I have finally finished it! The concept works and the project is finally finished. Appreciate the video may not be to everyone's taste but I enjoy putting them together and each to their own. Certainly shows the build and final product!

    [video=youtube;1SQ-2T6ExeA]https://www.youtube.com/watch?v=1SQ-2T6ExeA[/video]
     
  3. Dick Feldman

    Dick Feldman Registered User

    Sep 1, 2000
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    Although nobody responded to your posting, many have looked.
    (2492 views as of now).
    Thank you for the great videos
    You have done a great job and the tool should service you well.
    With the time required to set up the jobs, you could have made 4 or 5 more to sell with little more time involved.


    Best Regards,

    Dick Feldman
     
  4. karlmansson

    karlmansson Registered User

    Apr 20, 2013
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    I can't believe i didn't respond to this. Great work! I wasn't aware that this thread existed. I've been having a project such as this in mind for some time now and I've tried to work out the most precise way to make a hinge without having to waste a massive amount of stock in the process. The ball bearings are very clever.

    Seeing as it's been a while since you posted this I understand if I won't get a reply but it almost looks like the ball bearings that are supporting the runners are of two different materials. Or at least finishes. What did you use on the ones that appear brushed or even white?

    Best regards
    Karl
     
  5. doc_fields

    doc_fields Registered User

    Sep 29, 2004
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    Good job! I tried a time or two to build one but had some machining problems (umm....mistakes) and got discouraged. I ended up getting a nice one in exchange for some work. Keep up the good work!.....................doc
     
  6. FDelGreco

    FDelGreco Registered User
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    I think you did a great job and were creative in using ball bearings the way you did. I've been meaning to make a depthing tool myself, but since I work on tower clocks, it will be a lot bigger -- like 18" long and a lot deeper. I'll use your design but make the plates from steel, as sheets of thick brass that large are too expensive. I, too, would like to know why some of the ball bearings appear to be made of steel, and some are white -- ceramic?

    Best regards,
    Frank
     
  7. Raynerd

    Raynerd Registered User

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    Good morning, thank you for the replies!

    Dick, I am now definitely going to run off a few additional frames now I know they work. At the time of creating this, I was not
    convinced it was going to be successful but now I'm happy with it, I am going to build a few for sale.

    Karlmansson - yes, I was experimenting with standard steel balls and nylon bearings. The nylon stay in the whole better but in retrospect I think this is because the edge of the hole is cutting into the nylon which is t a good thing. I'm going to stick with steel and look at securing them, either using resin, solder of adhesive.

    Frank, I'm pleased you are considering the design to build one. I too considered steel plate but managed to get this brass at a good price. I wondered if any future ones I created for sale should be made in steel but was concerned it would put people off buying if not in traditional brass! I guess if it works people don't mind.

    Anyway, thanks again for the replies. I appreciate it.

    chris
     
  8. MartinM

    MartinM Registered User
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    I'm unclear as to just how the balls that contact the runners work.
    Are they slightly offset from the centerline of the runners, so that the runners impact them on the side of the bearing and not the top?
    If so, how did you create the pockets for the balls?
    I'm guessing they were drilled on the mill, as any variance, at all, would throw off the geometry/parallelism of the runners.
     
  9. Raynerd

    Raynerd Registered User

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    Martin, that is exactly the point! I looked for months about machining a depthing tool. I even have some lovely brass castings I purchased but don't dare to put tool to metal for fear of losing parallelism. With this design, each row of holes is drilled at a time on the mill, moving onto the next line. This means all holes are parallel drilled on the mill.
     
  10. FDelGreco

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    Chris:

    I'm thinking of using steel and then blueing it. It should look good.

    Frank
     
  11. karlmansson

    karlmansson Registered User

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    A problem with it still is the depth of the ball bearings. The holes need to be exactly the same size with no burrs or the runners will be off angle. Maybe milling with a V cutter would be better? If you don't have a way of depth setting the ball bearings in plates it will be hard to get repeatable results of the brass under the balls deforms under load for instance.
     
  12. David S

    David S Registered User
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    If I understand this method. The ball bearing holes are through holes, both plates at the same time. The balls are larger diameter than the holes, so the alignment should be pretty good.

    David
     
  13. karlmansson

    karlmansson Registered User

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    That's my understanding as well. But I think "pretty good" wouldn't be good enough for this application. The balls seem to be only an inch apart or so and any difference in their resting position in the hole will be amplified through the runners. Does the hole have a burr? Out of alignment. Do you deburr the hole ever so slightly more on one of the holes? Out of alignment. I think the balls work well for the hinge, although the same issue should be present there. That affects the whole frame though and not individual runners.

    I think a jam nut for the depthing would be a good addition too! It is after all the only variable that really needs to be kept constant after you have done your tests.
     
  14. FDelGreco

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    Perhaps chamfering each hole to the same depth would fix that problem. After chamfering, you could put the ball in its place and with a mic measured the thickness from the other side of the ball to the back side of the plate. When all are the same, you are done.

    Frank
     
  15. gmorse

    gmorse Registered User
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    Hi Frank,

    Surely it's the front side of the plate that's critical, unless you can be sure that the two sides are exactly parallel. After all, the ball bearings forming the hinge are planted in the fronts of the plates.

    Regards,

    Graham
     
  16. MartinM

    MartinM Registered User
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    Cool.
    When people were first discussing the bearings, I thought they were referencing the hinge balls.
    In both instances, you've shown a great mind for creative engineering solutions.
     
  17. David S

    David S Registered User
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    Let's hope Raynerd comes back with more details.

    As I understand it, if you pin both plates together, reference off one side in the mill and do all of the machining of the bearing holes, when you open the plates like a book, the holes have to be exactly in the same location on both plates. Where as trying to machine V grooves in each plate would require separate set ups for each plate, and for a home hobbyist I think that would be an accuracy challenge as well.

    It will be interesting to hear if Raynerd has managed to perform some sort of alignment test.

    David
     
  18. karlmansson

    karlmansson Registered User

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    That's true. If your mill has a large enough envelope you could machine them in one run though. Align them axially on the table and go to town.
     
  19. Raynerd

    Raynerd Registered User

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    Good morning,

    I am interested in all your feedback and constructive criticism. I considered a number of ways of machining a depthing tool, as I said, including purchasing large brass castings which cost me a fortune. However, the issue with the runners being parallel always caused the concern. Of all the methods I considered in machining, this seemed to give the least number of variables to go wrong!

    I think this has been clarified but for those asking, yes the bearings are close enough together to form a groove that the runner sits in.

    Most of this has been discussed but to confirm, this was drilled in the mill. The two plates were clamped together, taper pinned together and drilled together (something that could not have be done with a conventional tool). All holes are therefore aligned. The plates were clamped in the machine vice on the mill. The holes were then drilled and reamed, a row at a time. By row, I am referring to the adjacent holes in which the runners sit as this is crucial for the runners to sit parallel. So the top 4 holes were done, then the bottom 4 and then finally the bottom two. It was my understanding that it was also critical that the bottom two holes for the hinge bearings were parallel with the bar runner bearings.

    It it was also mentioned above by David that the holes were drilled referenced off one side. Using this method, providing all three rows of holes were drilled one after the other without removing the plates, it does not matter if the plates are not square or if the vice is out of alignment as surely the hinged bearing holes are still parallel to the runner holes - the critical part. I see this as another advantage of this design.

    I do fully agree that a disadvantage is how the ball sits in the groove - debur, not to debur etc. I do also wonder weather steel would be a better material for this being more hardwearing although for such infrequent and gentle use of such a tool, I doubt brass holes would wear. The holes were reamed and I then gently rubbed the plate on a surface plate with 1800 grit to clean the hole. There is a sharp edge on the hole and I can feel the nylon bearings digging in which isn't good and why they are now all steel.

    I guess this this could be done with v groves. However for 200mm depthing tool you'd be looking at 400mm x travel on the milling machine, past the limits of mine.

    I have really enjoyed reading the comments and it's got me thinking a lot! Thank you.
     
  20. karlmansson

    karlmansson Registered User

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    Sounds like you really thought this through! Nice work.
     
  21. David S

    David S Registered User
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    Thanks for the update Raynerd. I have thought about your approach considerably and with the limited work envelop that I have this is the only way it would make sense for me. With one set up I am not sure how you could be more accurate. I do understand the concerns around the steel to brass hole interface. I guess if one was really ####, they could install oversize steel plugs in all of the hole locations and then proceed to drill and ream all the bearing holes.

    Thanks again.

    David
     
  22. karlmansson

    karlmansson Registered User

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    Or you could make tapered buttons made out of steel to fit the holes. That way you could turn them as you detect any wear in their surface.

    But I do like the simplicity of the ball bearings, so long as you can make it work.
     
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