Source of runout on chuck

I have a 5c collet chuck that had the same issue of the taper on the chuck being to small and not being able to fully seat against the face of the head stock.

It took me awhile to figure out why there was so much runout.

Just keep eliminating things that may be causing the problem.

Joe Hynes
 
TRA said:
Check the pins. I'd bet the pins are too long. Bison is known for that. If the pins are too long the chuck will never pull up tight to the face of the spindle. This ain't rocket science, guys.

Take the pins out one at a time and check them in their proper hole and see if the locking cam turns past the register marks. If it does not, then the pin is too long.

The adapter registers on the taper and is tight to the large surface of the spindle, not the front surface of the spindle taper. Usually there is a gap between the taper nose and the recess in the chuck. If there is no gap and the chuck is bottoming out on the spindle taper nose, you have other problems.
Click to expand...

When you say that the pins are "too long" are you referring to their physical length or how far they are screwed into the plate? I'm assuming you meant the latter. I spent some time yesterday adjusting the pins one at a time to get them to lock with the index on the bolt midway between the V's. This left the plate with a .005 gap between it and the spindle for more than half the circumference. So far I have not seen the plate contact the large surface of the spindle. At lunch today I'm going to see if anyone had a lathe with a D1-4 mount available to see if this adapter will fit. When I was checking the registration of the plate using Prussian blue I saw no indication that the plate was contacting the spindle nose.
 
Went through several cycles of adjusting and testing the pin depth setting until I've got it as good as it can be. I still had a gap around .005 on part of the circumference. So I started going around mounting and dismounting the plate but starting with a different pin each time. I noted that there was no gap adjacent to the starting pin but ended up about .005 opposite. I tried partially tightening the pins going around the plate but that didn't make any difference. I always ended up with a .005 gap somewhere. At this point I have to think that the inside of the recess in the plate is a bit under size. I have no idea how to take it out evenly as I assume it would involve the complete taper. I think it must be less than a thou because the plate is so close to mating now. However, it still leaves me with .008 run out on the face. Makes me want to grab a Dremel but I resist the temptation.
 
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adamsgt said:
When you say that the pins are "too long" are you referring to their physical length or how far they are screwed into the plate? I'm assuming you meant the latter. I spent some time yesterday adjusting the pins one at a time to get them to lock with the index on the bolt midway between the V's. This left the plate with a .005 gap between it and the spindle for more than half the circumference. So far I have not seen the plate contact the large surface of the spindle. At lunch today I'm going to see if anyone had a lathe with a D1-4 mount available to see if this adapter will fit. When I was checking the registration of the plate using Prussian blue I saw no indication that the plate was contacting the spindle nose.
Click to expand...

I'm referring to the amount or length of pin outside the chuck. From the chuck surface to the end of the pin. It's not uncommon for those pins to be too long and that causes them to bottom out in the cam lock bore. Could just be from not enough chamfer. When that pin hits the bottom of the bore you think it is tight when it is actually holding the chuck away from the face of the spindle. The pin and cam lock will appear to be tight.
 
TRA said:
I'm referring to the amount or length of pin outside the chuck. From the chuck surface to the end of the pin. It's not uncommon for those pins to be too long and that causes them to bottom out in the cam lock bore. Could just be from not enough chamfer. When that pin hits the bottom of the bore you think it is tight when it is actually holding the chuck away from the face of the spindle. The pin and cam lock will appear to be tight.
Click to expand...

I understand, thank you I'll check that out.
 
TRA said:
I'm referring to the amount or length of pin outside the chuck. From the chuck surface to the end of the pin. It's not uncommon for those pins to be too long and that causes them to bottom out in the cam lock bore. Could just be from not enough chamfer. When that pin hits the bottom of the bore you think it is tight when it is actually holding the chuck away from the face of the spindle. The pin and cam lock will appear to be tight.
Click to expand...

As I go merrily along looking for straws to grasp I mounted the original 3 jaw again and it was flush all around the spindle. So I took it off and measured the height of the pins. I got 1.223, 1.221, 1.218. I then measured the pins on the Bison plate and got 1.294, 1.285, 1.305. So they are definitely longer but is it enough to cause the problem. I re-read your earlier post where you said "Take the pins out one at a time and check them in their proper hole and see if the locking cam turns past the register marks. If it does not, then the pin is too long. " I missed the intent and significance of that the first time. I will try that next. Now if they do turn out to be too long, is the solution to grind down the top of the pin.?
 
Cam Lock Studs

If your cam lock studs have a groove around the OD, this must be installed until the groove is flush with the mounting face. If the timing on the thread does not allow this, try slightly above and below the mounting face. The front face should have a indicator reading that matches or is close to thickness of any out of parallel condition. If the studs don't lock properly no amount of adjustment or machining will remedy the problem. Proper installation will produce a repeatable indicator reading. Once this is achieved a light facing cut for clean up and a similar stock removal on the pilot that the adjusting screws tighten against.

If the cam lock studs do not have the marking groove, get a location from a working chuck adapter to the beginning of the milled radius slot to the face of the mounting plate. Match this dimension for the new studs +-.040" and install anti rotation screw in slot. The location of this surface is critical to performance and then follow the machining procedure I discussed previously.
 
TRA said:
Check the pins. I'd bet the pins are too long. Bison is known for that. If the pins are too long the chuck will never pull up tight to the face of the spindle. This ain't rocket science, guys.

Take the pins out one at a time and check them in their proper hole and see if the locking cam turns past the register marks. If it does not, then the pin is too long.

The adapter registers on the taper and is tight to the large surface of the spindle, not the front surface of the spindle taper. Usually there is a gap between the taper nose and the recess in the chuck. If there is no gap and the chuck is bottoming out on the spindle taper nose, you have other problems.
Click to expand...

I checked all the pins per your suggestion and they all turn past the register marks.
 
Randy Perkowski said:
If your cam lock studs have a groove around the OD, this must be installed until the groove is flush with the mounting face. If the timing on the thread does not allow this, try slightly above and below the mounting face. The front face should have a indicator reading that matches or is close to thickness of any out of parallel condition. If the studs don't lock properly no amount of adjustment or machining will remedy the problem. Proper installation will produce a repeatable indicator reading. Once this is achieved a light facing cut for clean up and a similar stock removal on the pilot that the adjusting screws tighten against.

If the cam lock studs do not have the marking groove, get a location from a working chuck adapter to the beginning of the milled radius slot to the face of the mounting plate. Match this dimension for the new studs +-.040" and install anti rotation screw in slot. The location of this surface is critical to performance and then follow the machining procedure I discussed previously.
Click to expand...

The studs do not have a groove. I checked the dimension you specified from a 3 jaw that fits properly to the Bison adapter plate and they are all within tolerance. At this point I was thinking about just buying a new adapter plate until the best price I could come up with was $300.
 
adamsgt said:
The studs do not have a groove. I checked the dimension you specified from a 3 jaw that fits properly to the Bison adapter plate and they are all within tolerance. At this point I was thinking about just buying a new adapter plate until the best price I could come up with was $300.
Click to expand...

Try Industryrecycles on EBay. I have purchased Genuine Buck backplates for 1/4 of the new price. Worth a call as they have new stock all the time. Sometimes they are missing the cam studs, but you can get these at www.macit.com
Michael
 
Almost there

Taking longer than I planned due to some family trips. However, I'm getting close. Started with about 11 thou run out on the adapter and I'm now down to about three tenths. Randy Perkowski gave me a good suggestion to put the adapter in the three jaw and use abrasive to take off the excess. I cut some pieces of 1/2 dowel and wrapped some 240 grit cloth around it and ran the lathe at about 70 rpm. Tedious but it's getting me there. One more session should do it.
 
Butch Lambert said:
Jerry,
You lost me on this.
Click to expand...

Well, I was lost for a while too, Butch. Basically the taper on the adapter for the Set-Tru chuck was a little too small to allow the adapter to seat against the face of the lathe spindle. So, it tilted slightly when the cam lock was tightened. I didn't have the means to set up the adapter to take a small cut on the taper. So, I just grabbed the reverse side of it in the 3 jaw and just used abrasive cloth to take off the 4 to 5 tenths needed to get the adapter to meet the face of the spindle. I felt I could maintain the 7 degree taper better this way. As I'm pretty close now I'm going to shift to 320 grit to get the last 3 tenths of run out gone.
 
Success

Now there is no discernible run out on the adapter. Mounted the chuck on the adapter. So I now have to learn how to use the set-tru feature. Shouldn't take too long. Just a little different in that the adjusting screws aren't 90 degrees apart and the screws pull rather than push.
 
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