Dan Hintz
Member
...or if I didn't, it darn near feels like it. All in the name of lathe accuracy.
So, the story goes... I took possession of a robust American Beauty with all of the trimmings about a year and a half ago, give or take. It has worked wonderfully for bowls and such, but now that I've been turning a lot of pens, I wanted to dial it in for such use. Although I have a nice drill press (Delta 18-900L), I try to keep all of my work at one station (I may rethink that because of the constant retooling, but that's neither here nor there for this story). So I started drilling on the lathe.
I use tower jaws to hold the blank. I would see a tiny amount of wobble in the bit as it first touched the blank, and by the time it was about ready to pop through the other side of a 3" length, the wobble was so bad I thought the bit was sure to break any day now. I finally decided to see if my axis was aligned... 60deg dead center in head, 60deg live center in tail, bring together, aaaaand... hmmmm. Looks pretty good, for a wood lathe, but I want to know just how much it really is, so out come the calipers.
I estimated about a 25mil difference between points. Check quill... nope, same fully extended. Rotate live and dead centers... nope, same thing. Okay, it's the head that's out of wack. Verify with my CNC's laser alignment tool. Yep... 60 mil diff in location at 14" of movement. Miniscule for a bowl, but HUGE for drilling pen blanks, evidently. So out comes the file.
Of course, for those who have ever worked on a Robust, you'll know the headstock weight is massive (100+ pounds?). During my first attempt at removing it from the bed, I wasn't properly prepared for the shift in weight, so I slammed the head into the bed, with my finger acting as a buffer. So, writhing in pain, I managed to keep hold of the head until I could gently place it on the ground.
Lucky for me, the wife keeps those ready-made daiquiri packs in the freezer, so I used one of those to sooth my pain (I used it as a compress, but I'm seriously considering imbibing it, too).
After 4 filing sessions with the head's tenon, with me putting the head back on for test fits each time (yeah, now my back is killing me, too), I'm happy to say I can now drill a blank from end to end with no noticeable bit wobble... and the hole is square to the blank at both ends
I can finally do celtic knots and other similar blanks without worrying about the knot looking like a 2 year old tied it :wink:
Maybe it'll cut down on some of the chatter I've seen from time to time far from the head.
Excuse me while I go get drunk to dull the pain...
So, the story goes... I took possession of a robust American Beauty with all of the trimmings about a year and a half ago, give or take. It has worked wonderfully for bowls and such, but now that I've been turning a lot of pens, I wanted to dial it in for such use. Although I have a nice drill press (Delta 18-900L), I try to keep all of my work at one station (I may rethink that because of the constant retooling, but that's neither here nor there for this story). So I started drilling on the lathe.
I use tower jaws to hold the blank. I would see a tiny amount of wobble in the bit as it first touched the blank, and by the time it was about ready to pop through the other side of a 3" length, the wobble was so bad I thought the bit was sure to break any day now. I finally decided to see if my axis was aligned... 60deg dead center in head, 60deg live center in tail, bring together, aaaaand... hmmmm. Looks pretty good, for a wood lathe, but I want to know just how much it really is, so out come the calipers.
I estimated about a 25mil difference between points. Check quill... nope, same fully extended. Rotate live and dead centers... nope, same thing. Okay, it's the head that's out of wack. Verify with my CNC's laser alignment tool. Yep... 60 mil diff in location at 14" of movement. Miniscule for a bowl, but HUGE for drilling pen blanks, evidently. So out comes the file.
Of course, for those who have ever worked on a Robust, you'll know the headstock weight is massive (100+ pounds?). During my first attempt at removing it from the bed, I wasn't properly prepared for the shift in weight, so I slammed the head into the bed, with my finger acting as a buffer. So, writhing in pain, I managed to keep hold of the head until I could gently place it on the ground.
Lucky for me, the wife keeps those ready-made daiquiri packs in the freezer, so I used one of those to sooth my pain (I used it as a compress, but I'm seriously considering imbibing it, too).
After 4 filing sessions with the head's tenon, with me putting the head back on for test fits each time (yeah, now my back is killing me, too), I'm happy to say I can now drill a blank from end to end with no noticeable bit wobble... and the hole is square to the blank at both ends
I can finally do celtic knots and other similar blanks without worrying about the knot looking like a 2 year old tied it :wink:Maybe it'll cut down on some of the chatter I've seen from time to time far from the head.
Excuse me while I go get drunk to dull the pain...
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