Bad chuck insert?

[Roger Wiegand]

Unpleasant experience yesterday, for the second time. Wondering if my chuck insert is mis-macnined.

Chuck is a Vicmarc 150 with a 1-1/4 x 8 TPI insert. Lathe is a Robust AB. After coring a big bowl blank I tried to remove the chuck from the lathe. It turned maybe a tenth of a turn and then stopped. I could turn it back and forth that small distance, but it wouldn't unwind. With more force I could get it to turn farther, pushing it back and forth I could gain a few degrees each time, the chuck still rotating about an eighth of a turn. Applying a pipe wrench I was able to increase the amount I could turn it, ultimately taking pretty much all my strength to make progress. After I had forced it about two turns it loosened up and I was able to unscrew it. There were a scary amount of metal filings on the shaft and in the insert.

The lathe thread itself doesn't appear to be damaged, and my other chucks spin on and off easily. This is the second time this has happened with this particular chuck, the first time not so severe.

I'm thinking that I will replace the insert; I don't want to do this again. But I'm wondering why it's happening and whether there was anything I could have done to prevent it.

 

[Clifton C]

Unpleasant would be an understatement... Not sure why it happened but you are not the first. This was also on an AB with a Vicmarc insert. Same symptoms.
I was there for the aftermath, after all the wrangling with a pipe wrench, the spindle lock was bent and had to be replaced. This happened during relatively light turning. The interesting thing, as you noted was that it would "turn" in that small range with no resistance. The other thing, in our case, was that when it stopped, it was a hard stop, not mushy, but dead stop.



We replaced the insert....

 

[Kevin Jenness]

Unpleasant would be an understatement... Not sure why it happened but you are not the first. This was also on an AB with a Vicmarc insert. Same symptoms.
I was there for the aftermath, after all the wrangling with a pipe wrench, the spindle lock was bent and had to be replaced. This happened during relatively light turning. The interesting thing, as you noted was that it would "turn" in that small range with no resistance. The other thing, in our case, was that when it stopped, it was a hard stop, not mushy, but dead stop.

View attachment 44294

We replaced the insert....

That's ugly. How was the insert cut and pried apart without damaging the lathe spindle?

 

[Clifton C]

Part way thru, then beat to death... You can see the split/cracked steel close to the inner threads where the cut stops. Spindle wasn't damaged (much) but as I said, the spindle lock pin was bent and had to be replaced.
Roger, we couldn't figure it out. Forensics after the fact was near impossible. The fact that it could turn with no resistance in that one little spot ???
I had visions in my mind of how a pin drive works, except in this case, the pin was a shard of metal (or more) jamming up the works.

 

[robo hippy]

Hmm, never experienced this. I consider both Vicmark and Robust to be top of the line when it comes to tooling. I do have one Vicmark chuck where the jaws tighten and loosen in the opposite direction than the others, but no other problems. Think I have 4 of them, purchased maybe 20 years apart... I would contact who ever you got the chuck from and see what they say. Only problem I ever had with any of their chucks is that with one chuck, for reasons unknow,, I broke teeth off of the pinion gears, a couple of times. Sent it back to Craft Supplies, which they asked me to do, and they sent me another one. No problems since then.

robo hippy

 

[Tom Gall]

Never heard of anything like that happening. Probably not the case .... but, did you have a grub/set screw tightened down for reverse turning? Or maybe a grub screw holding the insert?

 

[Marvin Jones]

Unpleasant experience yesterday, for the second time. Wondering if my chuck insert is mis-macnined.

Chuck is a Vicmarc 150 with a 1-1/4 x 8 TPI insert. Lathe is a Robust AB. After coring a big bowl blank I tried to remove the chuck from the lathe. It turned maybe a tenth of a turn and then stopped. I could turn it back and forth that small distance, but it wouldn't unwind. With more force I could get it to turn farther, pushing it back and forth I could gain a few degrees each time, the chuck still rotating about an eighth of a turn. Applying a pipe wrench I was able to increase the amount I could turn it, ultimately taking pretty much all my strength to make progress. After I had forced it about two turns it loosened up and I was able to unscrew it. There were a scary amount of metal filings on the shaft and in the insert.

The lathe thread itself doesn't appear to be damaged, and my other chucks spin on and off easily. This is the second time this has happened with this particular chuck, the first time not so severe.

I'm thinking that I will replace the insert; I don't want to do this again. But I'm wondering why it's happening and whether there was anything I could have done to prevent it.

With the amount of filings you found, any galling evidence would be destroyed but the face of the insert to threads could be checked by a good machinist.

 

[john lucas]

receive. Experienced it on my lathes an over the years have had 8 different chucks. Now own 5 chucks 3 are vicmarcs. I did help a student with a Nova chuck and Nova lathe and stuck insert. Turns out the tolerances were just too close. The inserts worked on my lathe and my inserts worked on his lathe but his insert would not work on his lathe. I filed his sindle threads very lightly and all was fine. Since Nova makes fine tools the only thing I could figure was the insert must have been on the negative side of the tolerance and the spindle on the positive side. So they were just too snug.

 

[Roger Wiegand]

Unpleasant would be an understatement... Not sure why it happened but you are not the first. This was also on an AB with a Vicmarc insert. Same symptoms.
I was there for the aftermath, after all the wrangling with a pipe wrench, the spindle lock was bent and had to be replaced. This happened during relatively light turning. The interesting thing, as you noted was that it would "turn" in that small range with no resistance. The other thing, in our case, was that when it stopped, it was a hard stop, not mushy, but dead stop.

View attachment 44294

We replaced the insert....

Well, I guess it could have been worse. Not much consolation in that!

I guess I'll write to the Vicmarc folks and see if they want to look at it. Having had the problem twice I'm not going to screw it back on the lathe!

In answer to another question, no grub screws in this chuck or insert.

 

[Mark Jundanian]

I wonder if anyone else does this, I put a drop of oil on the spindle threads before I install a chuck. Seems counterintuitive, but it was in the manufacturer's instructions. It's worked well in as much as I've not had difficulty removing the insert/chuck from the spindle -- and it's always the insert that releases from the spindle. I haven't had a chuck come off unexpectedly, either (I do use the set screw). Not saying that this would have prevented your problem.

 

[Marvin Jones]

When I was working, I turned some green wood then left the chuck on the spindle for two or three weeks before trying to remove it. I now have a slight bend in the locking pin. Other than that I've never had an issue with my three Vicmarc chucks, would be nice if Vicmarc would check it out and they might...might find a defect and replace it.

 

[Dean Center]

Reading John L's note, I recall a problem screwing my Nova chuck with insert onto the spindle of my 3520A Powermatic. The lathe was obtained used, and probably abused, and the chuck with insert was brand new. My recollection is that folks on this forum said this happened sometimes due to not quite cleanly cut threads. I used a triangle file to very slightly clean up the spindle threads, and everything has worked fine ever since. I suspect the issue was actually with the insert, but getting inside to deal with threads wasn't feasible. Back in my mental cobwebs is an image of a spiral scratch on the flat of the spindle, between the shoulder and the first turn of thread, suggesting the insert had at least one section of insert thread that was cut too tall.

 

[Tom Lucas]

I have a direct thread Vicmarc. I've noticed the threads are cut real sharp. If I put my finger in it, there's a better than 50/50 chance I'll get cut. It's also finicky about starting; has to be perfectly straight or it'll bind and won't go on. This is both with my lathe's drive spindle and a tailstock adapter. Once on, if anything, it's loose. I have to watch it and not turn the lathe off aburptly at high speeds or it sometimes over spins loose. I probably should file them a bit, I guess.

 

[Doug Freeman]

I have a direct thread Vicmarc. I've noticed the threads are cut real sharp. If I put my finger in it, there's a better than 50/50 chance I'll get cut. It's also finicky about starting; has to be perfectly straight or it'll bind and won't go on. This is both with my lathe's drive spindle and a tailstock adapter. Once on, if anything, it's loose. I have to watch it and not turn the lathe off aburptly at high speeds or it sometimes over spins loose. I probably should file them a bit, I guess.

I suspect something along this train of thought. Any small burr can cause what Roger described. With close inspection something is visible, with that type of force applied. I have SS brushes of various sizes that are great for deburring internal threads. I have had a couple of inserts over time that required a bit of cleaning up to prevent such events.

 

[Brent@TurnRobust]

I've attached a file that you can also download from our website. It is not brand specific, and relates to most lathes. There is a section on spindle maintenance. The take-away is I advise that everybody have at least a tap that matches their lathe spindle threads. Run this through your chucks, faceplates, etc. frequently to keep them clean and "booger free". If there is bad damage to the spindle, you may need a die to clean up your spindle threads. A number of clubs have used this document to lead lathe maintenance discussions at their meetings. I welcome anyone that can use it to help themselves. Roger, if you'd like specific advise on your AB, please contact me directly.

 

[Michael Hirsch]

Unpleasant would be an understatement... Not sure why it happened but you are not the first. This was also on an AB with a Vicmarc insert. Same symptoms.
I was there for the aftermath, after all the wrangling with a pipe wrench, the spindle lock was bent and had to be replaced. This happened during relatively light turning. The interesting thing, as you noted was that it would "turn" in that small range with no resistance. The other thing, in our case, was that when it stopped, it was a hard stop, not mushy, but dead stop.

View attachment 44294

We replaced the insert....

It would help me evaluate the cause of I could see a photograph of the threads that mated with the spindle. I am gusting the threads had so material spall which trapped in the threads made underwriting the chuck almost impossible. This could have been caused by the plating process, metallurgical issues of the insert, or damage caused during installation. The thread inspection will help resolve the cause.

 

[Bill Boehme]

I have a couple of horror stories with chuck inserts. Oneway inserts for 1" and 1¼" spindles are all RH/LH threaded. On one of my 1 X 8 adapters, they somehow neglected to counterbore the end of the insert where the set screws go. The intersection between the threaded holes of the setscrews with RH and LH threads resulted in some really sharp jagged edges. I learned rather quickly not to stick my fingers into the adapter. It was also very tricky threading the chuck onto the lathe spindle and was rather aggressive about digging into the spindle threads if not lined up just right. I didn't want to go through the trouble of removing the adapter because of the risk of breaking a screw so I just used a die grinder to grind down the threads and sharp edges at the back of the adapter. Fortunately, that was an easy fix that worked out quite well.

The other incident was my fault. The setscrews that I used in the spindle adapter of another chuck were just a tad too short and one of them fell through as I was locking the chuck onto the spindle. If the setscrew had been slightly shorter it wouldn't have been a problem, but the length while being too short was also too long so instead of just falling through it wedged at an angle between the spindle and the bottom of the screw hole. This looked like a disaster with no easy recovery, but it was unbelievable good luck that I was able to get a hex key into the screw socket and carefully aligned it with the threads in the hole so that it could be backed out.

 

[Roger Wiegand]

It would help me evaluate the cause of I could see a photograph of the threads that mated with the spindle. I am gusting the threads had so material spall which trapped in the threads made underwriting the chuck almost impossible. This could have been caused by the plating process, metallurgical issues of the insert, or damage caused during installation. The thread inspection will help resolve the cause.

Here you go:

 

[Roger Wiegand]

So, an interesting, if somewhat odd, response from Vicmarc. "We use expensive go/no go test gauges to test all our threads"

They attached a picture of said expensive gauge and offered to send a video of it in use. Then went on to say that "Unfortunately many lathe makers do not purchase these". I'll leave that one for Brent to react to ;-)

They suggested that the problem could be, as mentioned here, parts respectively at the high and low end of tolerances.

Speaking of which, I see prices on 1-1/4 x 8 TPI taps running from $50-$250 I'm guessing that the cheapest ones should be avoided, but are the $100 ones from the likes of McMaster Carr likely to be OK? I know virtually nothing about metal working tools.

 

[Mark Jundanian]

Roger, just to clarify, have you been using this chuck on this lathe many times and for a while, and have experienced this problem a couple of times? Or is either the lathe or chuck insert a relatively new element in the equation?

 

[Bill Boehme]

So, an interesting, if somewhat odd, response from Vicmarc. "We use expensive go/no go test gauges to test all our threads"

They attached a picture of said expensive gauge and offered to send a video of it in use. Then went on to say that "Unfortunately many lathe makers do not purchase these". I'll leave that one for Brent to react to ;-)

They suggested that the problem could be, as mentioned here, parts respectively at the high and low end of tolerances.

Speaking of which, I see prices on 1-1/4 x 8 TPI taps running from $50-$250 I'm guessing that the cheapest ones should be avoided, but are the $100 ones from the likes of McMaster Carr likely to be OK? I know virtually nothing about metal working tools.

Their response sounds a bit snooty. Perhaps they should have their “expensive” gauge sent to a calibration lab. Being “expensive“ doesn’t necessarily correlate to being “accurate“. My former employer required every measurement tool to have an up-to-date calibration certificate before it could be used to measure anything. Legend had it that our cal lab even had a calibrated anvil whose certificate was directly traceable to NIST.

 

[Roger Wiegand]

Roger, just to clarify, have you been using this chuck on this lathe many times and for a while, and have experienced this problem a couple of times? Or is either the lathe or chuck insert a relatively new element in the equation?

It's relatively new and my least-used chuck. Probably used it no more than two dozen times. The first time I had this problem I assumed I had been careless about cleaning the threads before putting it on, so didn't worry about it too much-- though it did take a pipe wrench to get it off. I probably used it 5-10 times without issue between the times when it jammed. It never threaded on as smoothly as the other chucks that will go a turn or two with a spin.

I have two VM120's as well, also with inserts rather than direct thread, that are in continuous use. The 120's pre-date this lathe, the 150 came when I got this lathe, though I bought all three inserts at the same time-- my old lathe had a bigger spindle.

 

[Bill Boehme]

Is there a possibility that you have a mislabeled M33 adapter? The difference in thread pitch is only 0.012795 inch. With the slightly larger diameter I don’t know how many turns the chuck could be turned before jamming.

 

[Doug Freeman]

Their response sounds a bit snooty. Perhaps they should have their “expensive” gauge sent to a calibration lab. Being “expensive“ doesn’t necessarily correlate to being “accurate“. My former employer required every measurement tool to have an up-to-date calibration certificate before it could be used to measure anything. Legend had it that our cal lab even had a calibrated anvil whose certificate was directly traceable to NIST.

I have almost 40 yrs exp in engineering areas of mfg. Any legit mfr has a calibration system in place for all gauges, frequency based upon many variables, but usually 1/yr min. All traceable to NIST.

 

[Doug Freeman]

It's relatively new and my least-used chuck. Probably used it no more than two dozen times. The first time I had this problem I assumed I had been careless about cleaning the threads before putting it on, so didn't worry about it too much-- though it did take a pipe wrench to get it off. I probably used it 5-10 times without issue between the times when it jammed. It never threaded on as smoothly as the other chucks that will go a turn or two with a spin.

I have two VM120's as well, also with inserts rather than direct thread, that are in continuous use. The 120's pre-date this lathe, the 150 came when I got this lathe, though I bought all three inserts at the same time-- my old lathe had a bigger spindle.

Based on these comments and the pics, I suspect the root cause is more poor thread forming, causing some galling and burrs on the insert threads. The fact that you used it several times without issue says the threads are likely sized correctly. Some debris can be raised or scraped off causing binding when dont hold your tongue just right when screwing on/off.

A tap might help, but this is why I use a stiff wire short “bottle brush” to clean and polish threads with rough surface finish.

 

[Marc Banka]

It’s too bad this happened.

These things must be difficult for manufacturers. So many variables outside their control—they don’t know you or how you work. The crap about thread gauges is just that. I’m sure they don’t check all the threads on all of their products.

Kind of sounds like there were some burrs on the insert threads, a bit of which scrubbed off on that fateful mounting of the chuck. Bits get caught to start the gaulling, metal transfer. After that, more metal gets caught and the whole thing jams.

Avoid cleaning or straightening the threads with taps or dies. They’re too sharp for this application. Use a thread chaser, which is designed to push any bent threads, to massage things, not cutting away. As has been suggested, a stiff bottle brush for female threads, a wire brush on a drill would be perfect. And a thread file, or even jewelers files to clean up any burrs on the spindle.

Did you have any washer between the chuck and lathe when this happened?

I really like my Vicmarc chuck, only have one 120. One thing I’ve noticed (and they mention in the booklet that comes with the chuck) that the tolerances are tighter than most chucks. That a notchy feel is normal, and will break in. Maybe their machining of the adapters is the same. Still, deburring the threads would have been nice. Shouldn’t cut your finger on them!

 

[Tom Lucas]

Could a Beal tap be used to clean up the threads on a chuck?

 

[Brent@TurnRobust]

Could a Beal tap be used to clean up the threads on a chuck?

The Beal tap is great for tapping wood, but it has quite a lead in (taper) on the threads, so it won't fully clean a thread at the end of the insert. You want what is known as a bottoming tap so that you can get full threads to the end of the insert. You can find them cheaper, but here is an example: https://www.mcmaster.com/2597A72/

 

[Ron Boulton]

Hi Roger
The Vicmarc factory is in Brisbane where I live. The Vicmarc brand has a high profile in Australia and is very respected for the design and manufacturing quality of their lathes and chucks.
Yesterday I went to the factory to buy some accessories for my lathe. My lathe is not a Vicmarc but they make many accessories to fit other lathes. One of the items purchased was a150mm Vacuum Chuck which requires a Vm100 chuck adapter to fit the vacuum chuck to my lathe spindle. My lathe has the defacto Australian Metric Standard of M30x3.5 rather than the international M33. (Vicmarc make many accessories with the M30 direct thread for Australia).

Because of the issue you had with your chuck adapter I very carefully inspected the adapter they supplied. I am happy to say that the adapter is close to perfect. No sharp threads and very smooth surfaces on the threads both internal and external. It screws onto and off my spindle smoothly without any slop.

I also purchased a 200mm steel faceplate and a 3 in 1 Screw chuck both of which were supplied direct threaded M30. Again the internal M30 threads are smooth, not sharp and thread onto my spindle without issue.

I am not sure why you had a problem. Are you sure your chuck adapter was made by Vicmarc and not some third party. Some time ago Nova chucks had a lot of problems wit adapter inserts but these turned out to all be with unofficial 3rd party adapters
.
Get a new genuine Vicmarc adapter and I think you will solve your problem.
Cheers from down under.
Ron

 

[Roger Wiegand]

.
Get a new genuine Vicmarc adapter and I think you will solve your problem.
Cheers from down under.
Ron

I've got three Vicmarc chucks, six or seven sets of jaws, and five inserts so far, so obviously I'm a fan. There is, for better or worse, pretty much no way to know whether one is buying the real thing of a knock-off of almost any manufactured product. These were bought from a reputable seller, priced, packaged and labeled as the real thing, and look like the pictures on the web site. Someone would have had to have gone to a lot of trouble to copy a very niche product, but apparently it happens.

I bought three at the same time, the other two have been trouble-free. A new one just arrived in the mail, I can compare them.

 

[Doug Freeman]

One has to pay attention to ads. It can be easy to overlook that an ad says “for Vicmarc”but doesnt say mfd by Vicmarc, or whatever company. Many ads are not lying, just being tricky with how the product is described.

 

[Brian Nowak-Thompson]

There is, for better or worse, pretty much no way to know whether one is buying the real thing of a knock-off of almost any manufactured product. These were bought from a reputable seller, priced, packaged and labeled as the real thing

I had something similar happen with a Nova chuck insert. I didn't realize I bought a knock off until I moved it to another chuck where you could visually see the runout and then replaced it with a new insert that actually came in a Teknatool box. The differences were subtle, like their length and the letter stamped one the nut face. Nearly identical except, of course, for the runout, which kind of defeats the purpose.

 

[Ron Boulton]

Roger I hope the new insert solves your problem. Can I offer you a little temptation.

When I started turning many many years ago I started off using the original Technatool Nova chucks made in NZ. Subsequently tried Vicmarc which are very nice chucks and definitely a step up. However a year or two ago I had the opportunity to purchase an Axminster Evolution SK114 chuck with an M30 thread. I thought this chuck was even better than Vicmarc which is saying something I never expected . It was so good I eventually purchased 3 more and an almost complete set of jaws.
The chucks are made from SS, CNC machined to an incredible fit and finish and the jaw carriers transfer from one chuck to another perfectly. To top it off Axminster make a serious range of jaws to fit. Particularly like the O’Donnel jaws.
There might be two issues for some people, they are not cheap and they are direct threaded so you have to order the correct chuck body to fit your spindle.
From my point of view here in Au there is another problem in that they have stopped making the M30 version ( this is not common in the rest of the world) but I was lucky enough to import another 3 from existing stock. Dont think I will have to buy another chuck before I die.
Cheers
Ron