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Jammed keyless chuck

I did the same as you a week or so ago, driving a 2" hole saw in 1" aluminum, got mine apart (after making a pin spanner !). Threads are buggered on the internal screw that opens / closes the jaws - basically ruined it.
Mine was a Rohm, don't remember what I paid for it but I don't think it was cheap.
Those are nice / convenient chucks, especially for tailstock of the lathe but I've come to the conclusion that they're not meant (not capable) of heavy duty work. Try to run a hole saw or a big drill in hard material and they seem to just wind themselves tighter and tighter until they strip / gall the threads of that internal screw.
One more lesson learned the hard way !:(
 
cuslog said:
I did the same as you a week or so ago, driving a 2" hole saw in 1" aluminum, got mine apart (after making a pin spanner !). Threads are buggered on the internal screw that opens / closes the jaws - basically ruined it.
Mine was a Rohm, don't remember what I paid for it but I don't think it was cheap.
Those are nice / convenient chucks, especially for tailstock of the lathe but I've come to the conclusion that they're not meant (not capable) of heavy duty work. Try to run a hole saw or a big drill in hard material and they seem to just wind themselves tighter and tighter until they strip / gall the threads of that internal screw.
One more lesson learned the hard way !:(
Click to expand...
Huh, sounds exactly like my problem. There was a small rubber washer on the bottom of the internal threads that was partly chewed up but I am thinking right now the internal threads may be the buggered ones on mine. I'll clean it up and see. 20210417_120618.jpg
 
For those that may not have seen the internals of a keyless chuck before.
The collar and ball bearings in the parts tray go on the central shaft just below the black locking collar that is on the top/right.

The internal/female threads are the problem on this chuck.
 
Too late now but I never run a bit larger than 1/2” in my keyless chuck.
 
I had a expensive keyless chuck that broke the moving jaws while i was drilling a large hole on the lathe. Didn't slip in the tailstock just went crunch and the jaws came out in pieces. Lesson learned, drill small hole and use boring bar to make bigger.
 
cuslog said:
I did the same as you a week or so ago, driving a 2" hole saw in 1" aluminum, got mine apart (after making a pin spanner !). Threads are buggered on the internal screw that opens / closes the jaws - basically ruined it.
Mine was a Rohm, don't remember what I paid for it but I don't think it was cheap.
Those are nice / convenient chucks, especially for tailstock of the lathe but I've come to the conclusion that they're not meant (not capable) of heavy duty work. Try to run a hole saw or a big drill in hard material and they seem to just wind themselves tighter and tighter until they strip / gall the threads of that internal screw.
One more lesson learned the hard way !:(
Click to expand...
Interesting to hear you had the same experience with an expensive brand name chuck. My chuck was a non branded Chinese version and was relatively cheap ( I don't remember exactly how much) . I was always quite impressed with it and thought it was of quite high quality. It was also much more accurate than the keyed chuck that came with my drill press.
 
I guess everything has its limits. I've read of similar incidents when people have inadvertently jammed a drill on a keyless & like you had a devil of a time un-tightening & discovering damage. Maybe why some people dislike them over keyed. But the trade-off is convenience & tool change speed. I keep my (high runout) 5/8 key chuck for 'special occasions' like rougher duty. I've also had shanks slip on the those jaws when loaded & it either chowders the tool or is hard on the jaws/fit so I guess choose your poison. Some of the hole saws I've seen have hex shanks maybe so you don't have to gronk radially as much. Hole sawing can be a tricky endeavor at the best of times because I think they can require substantial torque with all those high pitch teeth & simultaneously engaged. I'm surprised they work so well in metal. From the saw perspective, its not much different that a bandsaw blade working away at a chunk of metal. Drill press speeds are probably ok for hardwood but high for metal.
 
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Previous owner of my SM1340 was making parts for the oil field industry in some special plastic they use on “pipeline pigs”. He used a keyless chuck with a whole saw in the TS. The arbour was the hex type. He gave me the whole thing - chuck, starrett saw&arbour. He had tried to get it apart with pipe wrenches - the marks are still there - no joy. I finally got it open with a purpose made pin spanner and a long cheater bar. It now has a ”funky spot” when tightening - much like the OP is reporting. I have not investigated further, but probably the threads are mashed in that spot.

I made the same mistake with a new import keyless chuck and a hole saw in the mill. Had to use the spanner wrench again.

Then I learned the lesson: anything with hex drive does not belong into a keyless chuck (in my opinion). So I got some decent quality Jacobs ball bearing keyed chucks for the heavy grunt work. The biggest hole saw I have run in metal so far was 3” in 1/4 mild steel and 2.25” in 1/4” 304 SS with the keyed chuck.

0A527B1E-2696-409B-A25F-F48D9D562510.jpeg
 
I think the message here is : keyless chucks are nice and convenient - especially for lighter duty work but for heavier duty work, "you need to have another think" and maybe choose another tool.
 
RobinHood said:
Previous owner of my SM1340 was making parts for the oil field industry in some special plastic they use on “pipeline pigs”. He used a keyless chuck with a whole saw in the TS. The arbour was the hex type. He gave me the whole thing - chuck, starrett saw&arbour. He had tried to get it apart with pipe wrenches - the marks are still there - no joy. I finally got it open with a purpose made pin spanner and a long cheater bar. It now has a ”funky spot” when tightening - much like the OP is reporting. I have not investigated further, but probably the threads are mashed in that spot.

I made the same mistake with a new import keyless chuck and a hole saw in the mill. Had to use the spanner wrench again.

Then I learned the lesson: anything with hex drive does not belong into a keyless chuck (in my opinion). So I got some decent quality Jacobs ball bearing keyed chucks for the heavy grunt work. The biggest hole saw I have run in metal so far was 3” in 1/4 mild steel and 2.25” in 1/4” 304 SS with the keyed chuck.

View attachment 14256
Click to expand...
So do you feel that anything with a hex drive does not belong in a keyless chuck because it won't slip when it jams? I hate to see a tool spin in the jaws but like Peter mentioned above "pick your poison".

FWIW. I was using a 3.25" hole saw with a hex shank and cutting sheet metal that was sandwiched in between some osb board. I had the drill press at lowest rpm and had lots of torque. The chuck spun out of the Jacob's taper a couple of times.
I won't be using a hole saw in a keyless chuck again.
 
Yes, I feel hex driven tools overpower keyless chucks. Especially if there is enough drive torque behind it - like a milling machine turning at 60 rpm or a lathe at 40 rpm. Even though my mill only has 1.5hp, it has a lot of torque down low. The lathe has even more, being a 3hp motor.

As @PeterT pointed out: hole saws work surprisingly well in metal, but are deceptively hard on the driving machine.

I am now looking into coring drills and even trepanning cutters in a boring head iso large hole saws to reduce the wear and tear.

I think hole saws work well as long as the chips can evacuate freely. Once they start jamming up in the cut, bad things happen really fast.
 
I like annular cutters, but they get spendy in big sizes.
I would think trepanning tool would be good because you just have one cutting surface to contend with & infinite diameter set. Many modern ones look kind of gimicky, at least for metalworking. But you see ones they used back in the day, they were beefy & meant business

1618708922498.webp
 
I called the annular cutters “coring drills” in my post #32. I think “coring“ is a term more frequently used in the concrete/masonry field. The metalworking folks prefer the term annular cutter.
 
RobinHood said:
I called the annular cutters “coring drills” in my post #32. I think “coring“ is a term more frequently used in the concrete/masonry field. The metalworking folks prefer the term annular cutter.
Click to expand...
Big annular cutters must take huge torque also? The thing I "like" about annualr cutters and holesaws is that they aren't as grabby as a trepanning bit especially if not perfectly perpendicular to the surface being cut. And there really is nothing I "like" about hole saws, at least the way I use them.
 
The big design advantage of the annular cutter are the flutes which extend out of the cut to aid in chip evacuation. Once the gullets on a hole saw are full of chips, the saw starts to jam in the cut and needs to be raised to clean the gullets.

I can’t comment on torque requirements, as I don’t have any annular cutters.
 
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