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Woodturning (rec.crafts.woodturning) To discuss tools, techniques, styles, materials, shows and competitions, education and educational materials related to woodturning. All skill levels are welcome, from art turners to production turners, beginners to masters. |
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#1
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Adjustable pen mandrel quality
My advice on adjustable pen mandrels: Don't buy one!
As a followup to my earlier post regarding 0.012" runout on, not one, but two of these: (Recall that this mandrel consists of the rod itself in a 1/4" collet on a #2 MT.) Before returning the second one to Craft Supplies, I took it to Woodcraft to test it in their Jet mini. Same problem (i.e. the morse taper fit was poor, and noticeable runout at the collet). Then, I tried a Woodcraft adjustable mandrel (same design, different finish), and though the morse taper fit was a little better, the runout was visible by eye. So now it seems to me that the poor quality is in the collet itself, which is not too surprising when you look at it. You can't expect those 4 short tangs to compress equally. And, when you compare it to, say, Beall's 1/4" collet (at $80) you can see where the improvement is! Lee Valley sells an adjustable mandrel which, rather than a collet, clamps the rod with a set screw in the MT. This has possibilities so long as the hole for the rod is drilled slightly off-axis to allow for the set screw pushing it to one side. If not, whatever tolerance there is in the hole diameter will equate directly to runout. For now, I use a replacement mandrel (rod only) in my Jacobs chuck. No measureable runout. Regards, Tom |
#2
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Adjustable pen mandrel quality
Just measured my LV adjustable pen mandrel and it has 0.0005" (half-thou)
runout max. I wouldn't even get excited if it were 5-10 times worse since we are dealing with wood, a relatively sloppy hole drilled down the "center" by my old drill press and then stuck onto a brass tube with some kind of glue. I know I have never checked to see if the tailstock which supports the other end of the mandrel lines up within that degree of tolerance. Billh "T. J. Miller" wrote in message ... My advice on adjustable pen mandrels: Don't buy one! As a followup to my earlier post regarding 0.012" runout on, not one, but two of these: (Recall that this mandrel consists of the rod itself in a 1/4" collet on a #2 MT.) Before returning the second one to Craft Supplies, I took it to Woodcraft to test it in their Jet mini. Same problem (i.e. the morse taper fit was poor, and noticeable runout at the collet). Then, I tried a Woodcraft adjustable mandrel (same design, different finish), and though the morse taper fit was a little better, the runout was visible by eye. So now it seems to me that the poor quality is in the collet itself, which is not too surprising when you look at it. You can't expect those 4 short tangs to compress equally. And, when you compare it to, say, Beall's 1/4" collet (at $80) you can see where the improvement is! Lee Valley sells an adjustable mandrel which, rather than a collet, clamps the rod with a set screw in the MT. This has possibilities so long as the hole for the rod is drilled slightly off-axis to allow for the set screw pushing it to one side. If not, whatever tolerance there is in the hole diameter will equate directly to runout. For now, I use a replacement mandrel (rod only) in my Jacobs chuck. No measureable runout. Regards, Tom |
#3
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Adjustable pen mandrel quality
"billh" wrote in message
. .. Just measured my LV adjustable pen mandrel and it has 0.0005" (half-thou) runout max. Excellent! I think I'll try that one after all. I wouldn't even get excited if it were 5-10 times worse Agreed. But when it approaches 25 to 30 times worse, it's a problem! since we are dealing with wood, a relatively sloppy hole drilled down the "center" by my old drill press and then stuck onto a brass tube with some kind of glue. I know I have never checked to see if the tailstock which supports the other end of the mandrel lines up within that degree of tolerance. Actually, a sloppily drilled hole and an off-axis tailstock (within reason) won't show up in the final product the way runout will. Billh Thanks for the info! Tom "T. J. Miller" wrote in message ... My advice on adjustable pen mandrels: Don't buy one! As a followup to my earlier post regarding 0.012" runout on, not one, but two of these: (Recall that this mandrel consists of the rod itself in a 1/4" collet on a #2 MT.) Before returning the second one to Craft Supplies, I took it to Woodcraft to test it in their Jet mini. Same problem (i.e. the morse taper fit was poor, and noticeable runout at the collet). Then, I tried a Woodcraft adjustable mandrel (same design, different finish), and though the morse taper fit was a little better, the runout was visible by eye. So now it seems to me that the poor quality is in the collet itself, which is not too surprising when you look at it. You can't expect those 4 short tangs to compress equally. And, when you compare it to, say, Beall's 1/4" collet (at $80) you can see where the improvement is! Lee Valley sells an adjustable mandrel which, rather than a collet, clamps the rod with a set screw in the MT. This has possibilities so long as the hole for the rod is drilled slightly off-axis to allow for the set screw pushing it to one side. If not, whatever tolerance there is in the hole diameter will equate directly to runout. For now, I use a replacement mandrel (rod only) in my Jacobs chuck. No measureable runout. Regards, Tom |
#4
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Adjustable pen mandrel quality
Lee Valley sells an adjustable mandrel which, rather than a collet, clamps the rod with a set screw in the MT. This has possibilities so long as the hole for the rod is drilled slightly off-axis to allow for the set screw pushing it to one side. If not, whatever tolerance there is in the hole diameter will equate directly to runout. I have the Lee Valley adjustable mandrel. It works fine although I have never measured the runout. I have never noticed any out of round whatsoever. It is made in the UK and is 5-6 dollars less expensive than the fareast versions sold by everyone else. Charlie Romano |
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