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A Versatile Dividing Head

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  • Pherdie
    replied
    Hello Svend and thanks for your complements. Sorry for my delay in responding as I don't visit this site as often as I used to.

    Yes, I did apply the worm helix angle to the spur gear teeth. I also turned both worms on my lathe with single point tools I made.

    As discussed in previous postings, the gears are not in a true worm gear engagement. While the worm will rotate the spur, no real power can be transmitted, just rotation between stops, which fails to allow milling while rotating. However, the simple engagement system also allows for significant errors in gear construction and engagement, which means give those gears a go in your shop!!! You'll probably enjoy success with minimal effort.

    As hazy as my memory is of constructing this item, I also recall referencing Ivan Laws' Gears and Cutting, so you're on a good path with that book. I offer that building items from Geo. Thomas' Workshop Techniques gave me some of the greatest knowledge, pleasure and satisfaction I have received from this hobby. I hope you find the same.

    Please feel free to email me via the site with any further questions and I'll do my best to answer them.

    Fred

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  • svenko
    replied
    Hi Pherdie,
    I'm new here and posted to this thread, it occurred to me that you may not be notified unless I'm replying to one of your post, could you please take a look at my prior post.

    Thanks, Svend

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  • rock_breaker
    replied
    Great work!!

    Ray

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  • svenko
    replied
    I'm new on this forum and I hope Pherdie still monitors this thread. First of all let me express my admiration for the beautiful work done on this VDH. I recently received my castings and both of George Thomas' books from Martin Models and actually arrived at this thread from the link on their web site. I must say that I was somewhat disappointed, not with the castings which are fine but the fact that the instructions in the book basically assumes that the worms and the gears would be purchased ready made which takes most of the challenge out of this project. Not that I'm an expert, far from it, but I hope to gain some more experience with each project. Would you please share, if you still remember after all these years, what you did for the machining of the gears and the worms, i.e. did you apply the helix angle to the straight teeth on the spur gears and were you able to get the correct gear train for the worms (I have a gear box on my lathe which complicates the setup). I'm trying to assess my chances of getting a decent and usable project if I attempt the gears and worms on my own, or if I should just suck it up, dig deep and buy them from Hemmingway. That would turn this in to a simple turning and boring project. I also have the book by Ivan Law that you mentioned in the post, so if you are still willing to answer questions I'll probably have a good deal of them if I decide to do it in house.

    Svend

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  • boslab
    replied
    Beautiful work, well made, I saw one in the model engineer exhibition in London in the 70s, I'm not certain but GT was there with it, the quorn on the stand was brilliant too, class
    Mark

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  • Kd0afk
    replied
    I'm getting this at the end of the month.

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  • Daveb
    replied
    Originally posted by EVguru View Post
    A wrinkle finish paint would really set it off nicely.
    All my machines have a smooth finish, I have the wrinkled finish.
    Dave

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  • thaiguzzi
    replied
    Originally posted by dp View Post
    Looks like a milling adapter on a lathe would get the job done on the castings but you need a way to make gears or buy ready-made gears. LMA has dividing plates assuming you make the worm to suit.
    http://littlemachineshop.com/product...1801&category=
    If you guys in the US can stump the postage, Hemmingway Kits in the UK have been doing this kit and other G.H Thomas stuff for years. The VDH from Hemmingway comes with all the difficult stuff ie gears etc, ready made. Not cheap, but then quality never is.
    Regards,
    Mike.

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  • Pherdie
    replied
    Originally posted by Kd0afk View Post
    Also, what is the height to the center of the spindle?
    2 1/16"

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  • Kd0afk
    replied
    Also, what is the height to the center of the spindle?

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  • gbritnell
    replied
    Outstanding work on a very useful tool. For the things I do in my shop I don't know how I could get along without one.
    gbritnell

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  • Pherdie
    replied
    Originally posted by J. R. Williams View Post
    The finished product looks like they are running a worm on a straight gear and not on a correct worm gear.
    This is absolutely true. The rational for this approach is addressed in detail within the Workshop Techniques book. I followed the author's suggestions in construction.

    Leave a comment:


  • Pherdie
    replied
    When I built this unit, I purchased the castings, the ER-32 straight shaft chuck (about $100) I optioned for, and some screws, so maybe I have about $300 total into this project. The ER-32 chuck serves additional purpose on other machinery such as my lathe which helps amortize the cost. If I recall correctly, everything else (plates, gears, shafts,etc.) were made from on hand bar stock. Incidentally. I've seen some fine looking versions made totally out of bar stock alone. The Workshop Techniques book has detailed construction information, including pictures of construction on a lathe (no mill needed but I used mine extensively). I would judge this project to be suited to someone with a couple of years of home shop construction projects under their belt.

    If saving money to acquire a dividing head is your goal, this is not the way. The Versatile Dividing Head is one of a series of brilliantly designed tools by George Thomas, intended to complement each other. The head is small (for "model engineering") and best suited for light work. One very important feature is the head incorporates the ability to do differential dividing, something not found on semi-universal dividing heads that are commonly found in home shops. This means you can create new dividing plates with all sorts of unique prime number divisions, including the 127 hole division plate which may be utilized to make metric conversion gears for lathes. Of course there are other methods of generating "non-standard" hole plates such as electronic, CAD templates and mechanical division.

    If I can answer any further questions, please feel free to ask. Thanks for your interest.
    Last edited by Pherdie; 01-05-2014, 12:52 AM. Reason: Grammer

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  • dp
    replied
    Originally posted by Kd0afk View Post
    So all of the gears and dividing plates and hardware has to be bought elsewhere? Does one need a mill to build it? I fell in love with this tool from day one and I want one.
    How much does it wind up costing to build?
    Looks like a milling adapter on a lathe would get the job done on the castings but you need a way to make gears or buy ready-made gears. LMA has dividing plates assuming you make the worm to suit.
    http://littlemachineshop.com/product...1801&category=

    Leave a comment:


  • J. R. Williams
    replied
    The finished product looks like they are running a worm on a straight gear and not on a correct worm gear.

    Leave a comment:

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