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Collet block fine tuning

DPittman

DPittman

Ultra Member
I made these collets blocks when any milling had to be done on my lathe and the only collets I owned were OZ25 collets, which I also used on the lathe. I made the collet holders out of aluminum and fitted them to square and hex shaft. They work ok but of course the square and hex shaft were not perfect in their dimensions nor did I likely get them perfectly centered with the collet holders I made.

Now that I have real milling capabilities, I am wondering if I could improve them. I'm thinking of placing a round shaft in the collet and then chuck the other end of the shaft in a dividing head chuck on the milling machine. I then would then mill the square and hex blocks around the axis of the collet holder and do the simple indexing with the dividing head.

Thoughts or suggestions?
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Thats what I did when I had a surface grinder, I would setup the DTI on my surface gauge and flip each flat and see the difference. Then simply grind accordingly. In you case mill accordingly.

Nice work on the lathe!
 
Proxule said:
Thats what I did when I had a surface grinder, I would setup the DTI on my surface gauge and flip each flat and see the difference. Then simply grind accordingly. In you case mill accordingly.

Nice work on the lathe!
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Yes a surface grinder finish would be nice!
I'm thinking I just need to get the surfaces in the right plane with the dividing head and mill away. I think how much I take off each side doesn't matter as long as it's equal on all sides. ??
 
Don did you press fit the aluminium into the steel ? - looks good to me. What made you think to do it that way as opposed to an all aluminium or all steel single part?
I guess you answered that already - you didn't have a mill!
 
Actually I like the round shoulder sticking out as it makes a nice surface to rest and align the collet against a vise jaw.
 
Janger said:
Don did you press fit the aluminium into the steel ? - looks good to me. What made you think to do it that way as opposed to an all aluminium or all steel single part?
I guess you answered that already - you didn't have a mill!
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It was a sliding fit and I used permanent loctite to fasten.
Yes one piece would have been nice.
The material selection was based largely on what I had and on my limited skills at the time. I had square and hex steel shaft and I figured the aluminum would be easiest for me to get the right matching inside taper for the collets and good threads to match the commercially made collet holder nut.
 
So this is the setup I'm thinking will work. I don't have a 4 jaw chuck for my dividing head, so I guess there will be the inherent discrepancies with the 3 jaw but because the entire milling operation will be done without having to remove the work from the chuck, the newly milled surfaces should be in line and true with the collet axis?? Is that right thinking?
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I think with a tailstock support and a little time fooling with some shim stock in any jaws that might be a tad out, and I think that should work.... The devil is in the details during the set up to eliminate as much runout and deflection as possible.
Another possible idea that may or may not work, would be to turn a custom adapter, mt2 on the one end, and a short stub for your collet on the other, then you could eliminate the chuck.........
Looking forward to seeing how it turns out.
 
DPittman said:
the newly milled surfaces should be in line and true with the collet axis?? Is that right thinking?
Click to expand...

Only if the chuck is true to the axis of the dividing head and both are at a right angle to the spindle. . Most are pretty good. You should be able to check it with an indicator rod if you have one and if not then with the shaft of a broken end mill. The latter isn't perfect, but better that than nothing. Don't forget to check it at several distances not just where the part leaves the Jaws.

Edit - I agree with @140mower too.
 
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140mower said:
Another possible idea that may or may not work, would be to turn a custom adapter, mt2 on the one end, and a short stub for your collet on the other, then you could eliminate the chuck.........
Click to expand...
I have to mull over that idea.


140mower said:
I think with a tailstock support and a little time fooling with some shim stock in any jaws that might be a tad out, and I think that should work...
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Tailstock support is possible with the one holder as it is cetera drilled, the other holder I have a pass through home in it.
 
140mower said:
I think with a tailstock support and a little time fooling with some shim stock in any jaws that might be a tad out, and I think that should work.... The devil is in the details during the set up to eliminate as much runout and deflection as possible.
Another possible idea that may or may not work, would be to turn a custom adapter, mt2 on the one end, and a short stub for your collet on the other, then you could eliminate the chuck.........
Looking forward to seeing how it turns out.
Click to expand...
You've got me thinking now but I still need help.
I need to figure out how the center dog works as I have never used one with a dividing head before.

As mentioned above the one collet block (on mill table in pic) has a through hole in it and I am wondering how I could support that with the foot/tailstock end?
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140mower said:
You could put a light chamfer on it and use a bullnose center....
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But my foot/tail stock doesn't have a MT to it. It only holds the dead center that came with it. I don't know how I would hold my mt live center on that end.
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I think I figured out the drive dog business on the spindle end....I was thinking what I have is a center dog but it is a DRIVE plate that works in conjunction with a lathe dog. The problem now appears that my lathe dogs do not fit the drive plate but I'm thinking that may have solutions also.
 
DPittman said:
You've got me thinking now but I still need help.
I need to figure out how the center dog works as I have never used one with a dividing head before.

As mentioned above the one collet block (on mill table in pic) has a through hole in it and I am wondering how I could support that with the foot/tailstock end?
View attachment 30768
Click to expand...
Can the bar you are using in the collet be extended through the hole and put the tailstock into the end of that?
 
Well I bored holes in the end of the collet blocks and made sure they were dead nuts centered with the axis of the collet so I could use a support shaft through the collet block so I could mill between centers.
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I had to make a dog to work with the divider head drive plate. Design by Harold Hall.
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Started milling the block and found that the drive plate and dog do not hold the shaft adequately for milling. A flat spot on the shaft would help with the dog but the drive plate is only secured with a bolt onto a round collar on the dead center.
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I guess I'll go back to holding the one end in the dividing head 3 jaw chuck.

Have I seen dead centers with a flat spot for a dog bolt ??? And if there is such a thing would that be enough to hold thi gs secure enough for milling?
 
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