Threads on Vicmarc chucks

[Tom Hoffman]

Has anyone out there with Vicmarc chucks had any problems with the 1 1/4 x 8 threads? I have a Robust American Beauty and it seems like my Vicmarc chucks don't thread easily. One was so bad I ruined the male spindle threads which required factory replacement I also have a Nova G3 and a Grizzly chuck and have had no problems with the threads on those.

[Steve Nix]

While I was in a class at Arrowmont in July one of the Robust AB has the same issue with a Vicmarc chuck.We like to never got it off. I’ve had no problems with the two older Vicmarcs on my AB.

[Joe Bradshaw]

I had the same problem with my Robust Liberty. It seems that Robust machines the spindle threads to very close tolerances. I used a 1 1/4 x 8 tap and chased the threads on my chucks(Oneway Talons). Also on faceplates and other odds and ends. Everything threads on nicely now.

[Eugene Dixon]

I had the same problem with my Robust Liberty. It seems that Robust machines the spindle threads to very close tolerances. I used a 1 1/4 x 8 tap and chased the threads on my chucks(Oneway Talons). Also on faceplates and other odds and ends. Everything threads on nicely now.

Same thing for me and my Talon/AB. I now have two 1-1.4X8 taps. One available if someone would like to make a donation to retirement fund. I had to chase the spindle threads and so I have a matching thread die.

[Reed Gray]

I have 6 or so Vicmarc chucks, and never had any problems getting them on my AB or Liberty. Even have one of the old Vics that opens and closes in the 'other' direction. Also have one that is 6 months old.

robo hippy

[Phil Rose]

I have not experienced any issues with my AB with my Vicmarc chuck (VM 120, direct thread)

[Tom Hoffman]

Eugene: I'm interested in donating to your retirement fund. How much?

[robert baccus]

1&1/4" x 8" threads are the "almost" standard thread on wood lathe's these days, but not universal in the machining world. There are other thread shapes out there. I have seen this problem years ago and was solved by figureing out the correct thread shape on the pieces involved. If it required a thread chaser this was probably the case. one of several reasons Nova makes inserts.

[Tom Hoffman]

Thanks to all who responded. I ordered a tap from McMaster Carr today and will run it through all my Vicmarc chucks.

[Alex Zeller]

I think the key is to be very careful not to cross thread the chuck when trying to screw it on. If it feels sort of rough when installing/ removing it then either use a tap on the chuck and anything else (like a face plate) and a die or very thin file to make sure the spindle.

[robert baccus]

The steel in spindles and chucks is extremely tough and hard steel. I doubt if you can cross thread one without super effort and tools--and it would show.

[Bill Boehme]

I have three Vicmarc chucks and they thread beautifully on my Robust AB. It should go without saying that you need to have the chuck straight and not cocked off to the side. It is also a lot easier if you turn the handwheel to screw the chuck on rather than turning the chuck.

The thing that I really dislike is the antiquated LH/RH cross threads that Oneway insists on using on their 1¼ X 8 inserts. Those things just love to go on crooked given even the slightest bit of encouragement.

[Paul Winer]

Brent English, Robust president, gave a presentation on lathe maintenance to our woodturning club this spring. He made some comments about maintaining the spindle thread and talked about Vicmark chucks. He stated that he had more complaints about Vickmark chucks then any other brand, even though they were excellent chucks. After looking into the issue they bought all of the well known accessories and chucks to determine how to adjust their thread form to fit. He said the problem was that they strictly followed the standard and a lot of companies, including Vicmark, did not. The different results may be due to manufacturing date of the lathe. If he stated when the change was made, I do not remember it.

[Eugene Dixon]

Eugene: I'm interested in donating to your retirement fund. How much?

Tom, sorry for the delay in responding. I was on a road trip to the south-left coast. PM'd you before I saw you second post. Brent at Robust suggested the McMaster Carr tap and die that I used.

[David M Peters]

I can confirm that Vicmarc's newer 1-1/4" chuck adapters are problematic, I had the same issue on my AB. The 6 or so other 1-1/4" female accessories I have have always worked just fine on my lathe.

Here's a message I sent to Vicmarc and their response:



Hello!

I'm writing to let you know about a thread sizing problem I've experienced with three VM100 1-1/4" chuck inserts. My lathe is a Robust American Beauty.


The internal 1-1/4" x 8TPI threads were far too tight to thread onto my lathe's spindle. Two of the inserts would only thread on about one turn before grinding to a halt. The third insert was better, able to be threaded on about halfway before stopping. I was able to correct the threading on the third adapter with a thread tap, now it hand-threads on just fine.


I hope you find this message useful. My suppliers (Packard and Craft Supplies) were helpful in dealing with this problem but it was still a frustrating experience.


Regards,
David Peters



Hi David,

All of our threads are tested with CE approved gauges, however there may be slight tolerance differences.

Many thanks,



I griped about this to Brent and he echoed the comment about Vicmarc tolerances being a bit wacky.

[Reed Gray]

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

[Brice Rogers]

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.

[Tom Hoffman]

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.

[Brice Rogers]

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.