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Stronghold chuck.....ever have this happen?

Odie

Odie

Panning for Montana gold, with Betsy, the mule!
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This afternoon, I had a fairly small Bocote bowl chucked up on my Stronghold chuck. At about 1200 rpm the #2 jaws were backing off. This happened several times, and after I heard a "ticking" sound, I shut off the power and sure enough, the jaws had backed off just slightly. This only happened at the 1200rpm setting, as I did some sanding at around 400-500rpm and no problem there.

Looks to me there is no way to lock the jaws in place.....only provision for using a set screw to lock the chuck to the spindle.

Got any ideas about this? Has it happened to you?

otis of cologne
 
Some sort of resonance struck there.

Could it be affected by rotation? I use Novas, which expand when rotated CCW, think the Stronghold contracts. So if you were using a tenon rather than a mortise, it shouldn't have bothered you.

There would have to be some extremely loose gearing to allow that. Or maybe just some loose jaw screws? Sometimes I don't get the jaws firm against the bottom of the mortise or the shoulder of the tenon before I tighten. They always seem to work loose later, though. Reason why I have a zero tolerance on runout conditions on re-mounts. If it's not "there" it's because I haven't fitted the chuck properly.

Might be what happened.
 
Barbara Gill said:
Odie, the set screw holds the chuck on. Are you saying the chuck backed off or are you saying the #2 jaws opened slightly?
Click to expand...

Barbara,,,,,,

The jaws opened slightly. MM's suggestion that there was some sort of resonance condition might be possible. If CCW rotational direction is when looking directly at the spindle from the tailstock, then it was CCW......or the normal direction. It was a mortise, or recess application......not tenon. It's a mystery to me, because this has never happened before. I haven't checked this morning, but I don't believe the jaw screws were loose.

Thanks

otis of cologne
 
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I never have had the jaws back off of either the Stronghold or the Talon. I have had the grip loosen slightly as the wood gets compressed, especially with green or easily compressed wood. I rarely use the chuck in the recess application.
 
Odie, I also have a Stronghold and a Talon, and have had a problem as MM described, loose jaw or two. I now have a brass "tooth brush" that is used to quickly clean the mortise on the chuck and the back of the jaws before installing. This method, as well as paying more attention to installation, seems to have addressed the problem.
 
Jake Debski said:
Odie, I also have a Stronghold and a Talon, and have had a problem as MM described, loose jaw or two. I now have a brass "tooth brush" that is used to quickly clean the mortise on the chuck and the back of the jaws before installing. This method, as well as paying more attention to installation, seems to have addressed the problem.
Click to expand...

Jake......

OK, I guess I'm going to have to pay more attention to the installation of the jaws than I have been. Your input seems like a very likely scenario. I'll check under the jaws and see if there's any dust or crud under there.......but, I won't be able to for the next few days.

thanks

otis of cologne
 
John Jordan said:
You need to lubricate the gears and moving parts. Blow the dust out, and spray it with WD-40. Problem solved.🙂

John
Click to expand...

Thanks for the "heads up" John......I'll give that a shot.

BTW: I have a VHS video of yours, purchased in the early 1990's......this is back when you had hair, and was turning on a Woodfast lathe! It's a great video, and one that I refer to now and then. Thanks. I'm still using my Woodfast, and am one of your early admirers!

otis of cologne
 
Cleaning and lubrication will help. But on most scroll chucks, there are two or more sockets for tightening the jaws. Use both (or all) of them, same as with Jacobs drill chucks, to reduce unbalanced purchase. Yes, there's a debate about whether this is necessary or advisable; it works for me.

Joe
 
I have not had a chuck loosen in the way described. Is it really the chuck that is at fault? Most blanks that I mount in a chuck, I find after a short time are loose, indicated by the fact that it is possible to farther tighten the chuck. Clearly, this is something one should make a practice of always doing.

Malcolm Smith.
 
Hi Odie, I would suggest cleaning out the gear mechanism, it may be full of dust and debris. Also check that all jaws are tightening in unison. Back off the screws securing the jaws, tighten the jaws lightly, and retighten the jaws. I had this happen to a student; the bowl he was turning kept popping out of the chuck no matter how tightly he secured the bowl. After cleaning thoroughly, the problem was solved.
 
Thanks for all the helpful suggestions.

I took the jaws off my three Stronghold chucks, and found no dirt or crud between the jaws and slides.....gave the mating surfaces a shot of air before reinstalling the jaws. All of the jaw mounting screws were tight.

I opened all three chucks, and squirted some WD40 into the scroll works. After doing this, the jaws were opened and closed 3-4 times apiece. At this moment, I have not given any of the chucks the "ultimate" test.......will try to do that soon, but it looks like it might be after Monday.

Thank you sincerely for trying to help me with this, to all of you who responded.....

otis of cologne
 
Happy you are so carefull!
About 6 months ago a 40 cm diameter piece of oak escaped from the stronghold chuck with a fastness of 4,6 meter / sec ... It flow straight in my face ... my headprotection saved my eye and doctors says I have a lot of luck that I'm still alive.
I'll recover, because I'm a strong nature, but still I'm not able to work a whole day!
so, folks, be very very carefull.
Squirrel
 
squirrel said:
Happy you are so carefull!
About 6 months ago a 40 cm diameter piece of oak escaped from the stronghold chuck with a fastness of 4,6 meter / sec ... It flow straight in my face ... my headprotection saved my eye and doctors says I have a lot of luck that I'm still alive.
I'll recover, because I'm a strong nature, but still I'm not able to work a whole day!
so, folks, be very very carefull.
Squirrel
Click to expand...

This is one set of posts everyone should note. There's no mention as to the rotation speed and if it was appropriate, but even if it was, injury is a possibility. I don't know why people turn without face protection not to mention dust protection. Most of us have had a block come loose and most of us feel grateful that it went in some other direction.

I have five of the Stronghold chucks and have not encountered any problem with them. As for loose screws, when the chuck is tightened, the screws would be locked in place. Perhaps in that situation not all the jaws are applying equal force. With the number of chucks I have, I don't often change the jaws. When I do, I clean all the surfaces before assembly.

I typically use the chucks in compression mode. The time a block came loose, the chuck was in expansion mode. The block split when I had a catch. The likelyhood is that I had overtightened the chuck and that there wasn't enough wood where the chuck expanded.

I've mentioned this before on the forum but it's worth repeating. If one is twice turning, it's very important that the wood be re-turned to round before it is mounted in the chuck. I realize this adds a time consuming step but for safety sake, it should be done. Also, the tightness of the chuck shortly after turning commences should be checked and this should be occasionally repeated. This is not a failure of the chuck but rather a reaction of the wood drying and compressing. If one stops for lunch or leaves a bowl mounted over night, be sure and tighten the chuck BEFORE starting to turn.

One person's experience but I hope this helps. A facial injury can be very severe.

Malcolm Smith.
 
Malcolm Smith said:
This is one set of posts everyone should note. There's no mention as to the rotation speed and if it was appropriate, but even if it was, injury is a possibility..
Click to expand...

Very well put Malcolm and things we should all remember - to note though - actually he does mention speed - 4,6 meters per second - however maybe someone can convert that to rpm
 
Wipedout said:
Very well put Malcolm and things we should all remember - to note though - actually he does mention speed - 4,6 meters per second - however maybe someone can convert that to rpm
Click to expand...

Pick one. He indicates a sixteen inch (Diameter?) piece, but the edge is moving at a much higher rate of speed than the center at any RPM.

The first thing one should do to protect themselves is to stay out of the throw/disintegration zone. Learn to use tools that allow you to stand away as you move the tool along the rest.

Second thing is to get the rest up close, and on the outside of a bowl, a bit above centerline so that the piece can't climb out from behind the barrier.

Both of these help in another way, since they keep you from stuffing the nose up into the rotation and dismounting like the man in the Laguna video might easily have done had he not been working above center.

If you knock the piece a few times, even short of a catch, you can potentially shift the jaws against loose screws or dent the wood, leading to flop and potential failure. Follow the feedback you're getting through your hands, which supposes that you're not stuffing and ripping so recklessly that you couldn't distinguish the first flop from your "muscling." Check for snug once in a while even if the piece is behaving.

True cowards like yours truly keep the tailstock engaged until the bowl is at its lightest and best balance, and check for snug before they retract it.
 
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should have, could have, your choice

True cowards like yours truly keep the tailstock engaged until the bowl is at its lightest and best balance, and check for snug before they retract it.
Click to expand...

here is another chicken, i use the tailstock as much as possibe, i use a steady rest with my hf"S till i reverse to clean up the foot, and then i use the tailstock again
 
folks,

I always do everything you mention.
But I was in a hurry and for one time I did not retighten ... but this kind of damn Southfrench oak was still distorting and ... I have a shortbed graduate so, I'm never on 'the wrong place' when I'm turning but ... I just picked up something from the ground near to the lathe when the piece got away: bad luck for me to be on the wrong place at the wrong moment .... that is all.
I learned:
- always to wear a mask which can be tightened under my cheeks (until now I just had a mask and headprotection but the woodstrike made it fly off of my head and gave me, falling down out of consciousness, a second injury at the back of my head) I flow over the table 2,5 meter further, down on the ground.
- always check the chuck, even when you are in a hurry or sure there is no necessity to do so.
- don't use the chuck unless the piece is almost hollowed out and absolutely stable.
- use chucks which can hold at least 3 cm wood for diameter 16 inch
- don't turn too fast !!!! I was in a hurry and turned too fast.

I'm strong but still had a lot of luck because if the piece had hit my head 2 cm further, I definitively would be dead now.

So, take care!

Squirrel
 
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