About a year ago , after reading about Mr. Jerry Howell plans and looking at the website for a while , I purchased 3 sets of plans . The " Farm Boy" IC engine , the" Sensitive Drill Press" , and his plans for a ball turner . There are many plans floating around on the web for ball turners , but none that I have seen as complex as his . The plans give the user the ability to index the tool bit in the X , Y , Z plane with locks to make it secure . Some would say it is overkill , but I had the plans and decided to go with them . As with his other plans , I learned a lot ! All sliding parts were dove tailed . Having made some tool holders for the QCTP , I thought no problem . Well , lets say I found out that those were easy compared to the one shown in the plans .Things had to fit much closer . There was no sliding wedge to take up the slack like the QCTP set up and they had a unique locking system to hold them in place . A very good design . All the pieces were milled down to size from some 2" sq. 4140 bar stock that I had . Used carbide cutters and a 90º insert face mill w/ the exception of the machining of the dovetails . The adapter to the compound was my design , as his was set up for a different lathe . Another machining consideration was the movement of the metal during the cutting process , so all cuts were rotated during their cuts to prevent them from warping .
Had not cut this long of dove tails . Used the 2 rounds in the V for measuring the fit . They got me surprisingly close with only a little bit of hand fitting . Still had to take it slow w/ the 60º cutter
The locks for the dovetails were10x32 SHCS that were fitted for length . The slots were , IIRC , .032" and had a very sold lock up to prevent any movement . Also pics of the adjustment screw . The REX AAA toolbit is 1/4"x1/4"x3" The first grind wasn't to good , the second one did good . I had to shim it to get it on center ... 005" high .
All assembled .
The turner will do convex cutting by setting on the out board side of the swivel pin and concave cutter by setting on the inboard side . Pretty tricky . Still have to play with it some more to get the diameters where I can predict what they are going to be . These first two came out as more elliptical than round .
By keeping fits to tolerances in the plans the the tool feels very solid and gave no indications of the dreaded chatter that could come with this type . A very learned man and the plans were excellent .
J . Howell Ball Turner
Moderator: Harold_V
- coal miner
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J . Howell Ball Turner
The more I learn , The more I don't know !
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Re: J . Howell Ball Turner
Nice work.
- warmstrong1955
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Re: J . Howell Ball Turner
Nice job!
I've got info on various ball turners I've found on the web, and rigidity has always been something that concerned me.
Interesting design.... added your pics to my ball turner folder of my "Gotta get around to it' file.
Bill
I've got info on various ball turners I've found on the web, and rigidity has always been something that concerned me.
Interesting design.... added your pics to my ball turner folder of my "Gotta get around to it' file.
Bill
Today's solutions are tomorrow's problems.
Re: J . Howell Ball Turner
Ah Bill, the ever elusive "round tuit", bane of my life.
Re: J . Howell Ball Turner
I saw this thread when you first posted it and didn't have time to really read it, and then forgot to come back to it.coal miner wrote: Still have to play with it some more to get the diameters where I can predict what they are going to be . These first two came out as more elliptical than round.
Nice work, as usual, and lots of it!
I see there is a hole in the center of the pivot point. Perhaps you could make a pin that dropped into the hole and you could measure from the pin to the tool tip to determine the radius it would cut. That would work for a convex radius, but a bit of head scratching may uncover a similar method for a concave radius.
On a radius dresser for a grinding wheel, if the diamond tip is not perfectly centered from left to right over the pivot point, it can swing a really odd radius that's not a true radius. I imagine this would be the same, but it may require further investigation.
Some day I need to break down and make some sort of radius turning setup as well!
Glenn
Operating machines is perfectly safe......until you forget how dangerous it really is!
Operating machines is perfectly safe......until you forget how dangerous it really is!
Re: J . Howell Ball Turner
I hadn't seen this thread earlier. That dovetail lock design sure was a test. So well presented and informative in that the way dovetails lock in 3 planes when done as close as was required.