Need Help!- Chuck miss-alignmet

[yatz]

Hi,
i own a tri-power bridgemill,cnc, and i set it up almost two years ago and havent
worked very much in it, im a student, well the problem is that when i checked if the lathe chuck was running true, with a dial indicator, it wasnt!...it has a deviation of about .010"!!...does anyone knows how to correct this?...can some help me, ill appreciate it very much...thanks, in advanceXD

[smallblock]

Originally Posted by yatz Hi, i own a tri-power bridgemill,cnc, and i set it up almost two years ago and havent worked very much in it, im a student, well the problem is that when i checked if the lathe chuck was running true, with a dial indicator, it wasnt!...it has a deviation of about .010"!!...does anyone knows how to correct this?...can some help me, ill appreciate it very much...thanks, in advanceXD

Hi-
Where are you measuring?
At the spindle flange, the chuck body or on a piece held in the jaws?

[dgapilot]

It all depends on what you are measuring. That said, I'd check the spindle flange first. Pull the chuck off and do a check for runout on both the flange face and the outside and inside diameter. If these run true, then the error is either in the chuck or the way it is being mounted. Clean the mounting face and look for any burrs before remounting it. Chuck up a piece of drill rod and see what you have. If there is any clearance between the mounting flange and the ID on the back of the chuck, you may be able to loosen it and tap it into position.

[TomB]

Originally Posted by yatz Hi, i own a tri-power bridgemill,cnc, and i set it up almost two years ago and havent worked very much in it, im a student, well the problem is that when i checked if the lathe chuck was running true, with a dial indicator, it wasnt!...it has a deviation of about .010"!!...does anyone knows how to correct this?...can some help me, ill appreciate it very much...thanks, in advanceXD

I seem to remember that several years ago there was a problem with the 3 or 4 screws that mount the chuck to the spindle flange being just a bit too long. They were bottoming out before the chuck was pulled tight. I think I replaced the screws on mine at the time. I don't remember if the problem was runout but it might have been. I may also be recalling a problem that happened on a different lathe, i.e. senior moments are always a possibility for me.

Tom

[yatz]

hi smallblock, i apologize if i didnt answer earlier, but i mailed shoptask and they didnt answered me, that was a dissapointment for me......
Well im measuring the chuck body and a stock rod held by the jaws...the chuck body has a small deviation, but still is to much, such as, that when a put a piece on it the deviation becomes wider.....

[yatz]

and also, im sorry if im asking to much, how can i remove the chuck?...there are some bolts behind the chuck but there is not enough room to take them out because of the column that supports the gears and all that....any advice?

[TomB]

The screws you need to remove are the set that I said might be too long. To get then out you need to make a very short allen wrench. I took one that measured just under 1/4" (.230") across the flats, clamped it in a vice and cut of the short end to leave about 1/4" measured on the inside of the bend. I cut it off with a cut off wheel running on a portable Dewalt 4" grinder but it probably could be done with most any grinder. I would not recomend a hack saw.

They may make these short throw allen wrenchs comercially as I found out after I made one for the Shopmaster that the wrench that came in a plastic sleeve with an old guitar also fits perfectly and it does not show signs of being home made. That wrench is a 6 mm wrench according the label and it does fit better.

Tom

[yatz]

thanks TomB, i couldnt believe it was that way....why make a bolt in wich u cant insert a wrench...well thanks for the tip, ill guess ill start looking for one and if i dont find any ill follow ur suggestion...once again thanks

[smallblock]

Originally Posted by yatz thanks TomB, i couldnt believe it was that way....why make a bolt in wich u cant insert a wrench...well thanks for the tip, ill guess ill start looking for one and if i dont find any ill follow ur suggestion...once again thanks

Yatz-
Which jaw set are you using? Post a picture of your setup. I spoke to JT before about the chuck bolts, and he said it was a factory foul up- apparently they decided it was faster to put the chuck on the spindle before installing it in the machine, not thinking about removing the bolts. After you take them out, just replace them with regular cap screws.

[dahui]

I had the chuck bolts that are too long problem as well. The shoptask will teach you a lot about machining AND your problem solving skills you can check out my site, I documented a lot of my work with the shoptask. Welcome to The Alchemist

Take a look at "fixes/chuck fix" link. Once I had a short Allen wrench on hand i just cut down the screws and kept using them as-is.

[yatz]

hi...well thank you guys for the help!!...im sorry i didnt answered earlier, but i was finishing my semester at my university....i managed to take out the chuck from the "spindle flange" i realize that the chuck is miss aligned, but it has been very dificult for me to align it by setting the three bolts behind the chuck, if i screw one bolt too tight it wont be running true...any ideas?...maybe using a torquemeter?...that way ill be tighting it equally?...by the way, the spindle flange runs amazingly trueXD....thankz

[smallblock]

Originally Posted by yatz hi...well thank you guys for the help!!...im sorry i didnt answered earlier, but i was finishing my semester at my university....i managed to take out the chuck from the "spindle flange" i realize that the chuck is miss aligned, but it has been very dificult for me to align it by setting the three bolts behind the chuck, if i screw one bolt too tight it wont be running true...any ideas?...maybe using a torquemeter?...that way ill be tighting it equally?...by the way, the spindle flange runs amazingly trueXD....thankz

Check the depth of the recess in the back of the chuck compared to the height of the shoulder on the spindle flange. If the recess is not deep enough, it will bottom out and then when you tighten the bolts, it will pull the chuck out of alignment. If this is the problem, a simple skim cut across the face of the spindle will solve it.