Page 2 of 2 FirstFirst 12
Results 16 to 19 of 19

Thread: Threads on Vicmarc chucks

  1. #16
    Hmm, my AB is 10 or so years old, with the 3 speed ranges in the headstock. Also, the lock down on the headstock was a wrench rather than the lever operated one that is now standard. No problems at all with any of my Vic chucks, some of which are 20 years old, and one set that is less than a year old..... No clue as to why others are having problems...

    robo hippy

  2. #17
    Join Date
    Sep 2015
    Location
    San Diego, Ca
    Posts
    1,273
    On the Grizzly G0766, I worked with Griz on getting a better spindle than the one that it originally came with. The original one had threads that were undersized. It didn't affect the lock up and run out, but I had a concern that long-term it might create a wear issue. Perhaps the size was a mistake on their part or perhaps it was intentional to help guarantee that a chuck wouldn't get stuck (as others have commented above relating to using a tap or die to reshape). Working from memory, I recall that the thread was a classic 60 degree Vee but the OD was only 1.232 or so and the leading edge had a sharp whisker. I cleaned up the whisker with a jeweler's file and rounded it slightly.

    If you look in the Machinery's Handbook, you will see that American Vee threads do not come to a sharp point at the outer (major) diameter of a male thread. Instead there is a short "flat". I suspect that if I had not softened the leading edge that it would have been somewhat more prone to cross threading.

    I eventually was supplied with a spindle with good looking threads and with a major OD of around 1.244 or so - - perfectly within national thread tolerance.

    BTW, someone commented earlier that the spindles and chucks come with really tough steel. When I check steel for hardness, I use a small file or a non-critical location and see if it digs in or "skitters" off. I checked 5 of my chucks (two of which are for a metal lathe, One is a Nova and two are Grizzly) and also checked the spindle on my wood lathe. The steel is not hardened. I then checked the jaws and found that only the two for my metal lathe have hardened jaws. The others are unhardened. Also, reflecting back on early comments of running a tap through a chuck or putting a die on a spindle - - the steel would probably need to be unhardened in order to chase the threads.

  3. #18
    Join Date
    Jun 2004
    Location
    Orangevale, CA
    Posts
    110
    As the originator of this thread, I thought I'd give an update. I received the tap from McMaster. I tried without success getting the tap started. I am not a machinist and didn't want to mess it up, so I took it to a skilled machinist. The problem was that for the first quarter inch or so there are no threads and the tap had to cut very shallow threads until it reached the "real" threads. There was considerable resistance for this first quarter inch. When it reached the "real" threads there was less resistance, but it was still cutting into the existing threads. Unless the tap I paid $80 for was not machined properly, this tells me that Vicmarc threads are not to correct specs and tolerances. The machinist was able to successfully tap my four Vicmarc chucks, even the one that buggered up my Robust spindle threads. I can now go back to mak'n shavings.

    David Peters: Thanks for your post. I am very disappointed in Vicmarc's response.

  4. #19
    Join Date
    Sep 2015
    Location
    San Diego, Ca
    Posts
    1,273
    Tom, thanks for the update.

    Whenever I need to either tap or cut threads on a lathe, I grab my Machinery's handbook. It is kind of a machinist's bible. From your description, yes, it seems like Vicmarc miscut the threads. It sounds like the ID was too small and that the tap was being forced to make it the right size. Since you were essentially "chasing" the existing threads, it should have threaded much easier and very little material should have needed to be removed, especially at the first 1/4 inch.

    I looked up the specs for "Recommended hole size limits before tapping unified threads (Class 1A and 1B). If someone had your problem and used a caliper to measure the ID of the Vicmarc threads, they should measure between 1.134 and 1.146". If I had this Vicmarc problem and it measured less than 1.134", I think that I would first (carefully) run a drill or a boring bar (with a metal lathe) through to open it up to 1.134" (or maybe a tad less) and then run the tap through.

    It's good that this problem is now behind you. Happy shaving making.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •