Another obligatory New PM-833TV and PM-1340GT Ordered!

davidpbest said:
Put your indicator on the face of the spindle nose and also on the outer diameter of the nose (as shown in this photo) and run the machine slowly again to see if either of those surfaces show runout. A camlock chuck should register to those surfaces, not the surface that the indicator is currently against in this photo.

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I’ve done that. All good there.
 
Christianstark said:
I’ve done that. All good there.
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Ok. This may sound weird, but have you indicated to the center of the clamping surface of the chuck jaws and swept the on Z-axis by moving the cross slide in/out toward the headstock?
 
davidpbest said:
Ok. This may sound weird, but have you indicated to the center of the clamping surface of the chuck jaws and swept the on Z-axis by moving the cross slide in/out toward the headstock?
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If all that checks out then I agree that the cross slide is not moving close enough to perpendicular to the spindle axis. In that case, I would start focusing on the cross slide. This could be a gib problem. If the gib taper doesn’t cause both surfaces of the saddle to ride against the dovetail of the carriage, then the saddle can shift position as it’s moved across the X-axis. Total PITA, but blue up the gib and check the imprint to the dovetail. I assume you have already removed the apron-to-saddle gib and stoned it to remove burrs and check for flatness. If not, then do that.
 
davidpbest said:
Ok. This may sound weird, but have you indicated to the center of the clamping surface of the chuck jaws and swept the on Z-axis by moving the cross slide in/out toward the headstock?
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I would think that that points to the taper, but not to the face that the cross slide is moving away from the chuck as I crank in.

Since re-leveling and tramming, I have done Rolle's Dad and found no taper.

I will check the cross slide gib for flatness next. I will also look at attempting to mount a DTI on the spindle, and testing distance to the spindle side dovetails. but I am not sure there is a good way to measure that.
 
Christianstark said:
I would think that that points to the taper, but not to the face that the cross slide is moving away from the chuck as I crank in.

Since re-leveling and tramming, I have done Rolle's Dad and found no taper.

I will check the cross slide gib for flatness next. I will also look at attempting to mount a DTI on the spindle, and testing distance to the spindle side dovetails. but I am not sure there is a good way to measure that.
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I can certainly understand how the carriage could drift away from the spindle as it's advanced if the gib isn't fitting and adjusted properly.
 
In terms of Gib straightness, how straight is straight? My gib seems to have the sliding surface with a bulge in the center, and a more slight dish on the non sliding side.

If I put the non sliding side on my surface plate, I can slide a .0015 feeler gage under in the center.

If I put the sliding side down on my surface plate, it clicks if I touch the ends Holding down one end allows me to slide a .006 feeler gage under the opposite end
 
The headstock side of the carriage is fixed, the gibs are on the tail stock side, if you can get access to the gib lock and can lock it on either side of the spindle to do your measurements, then alignment would be dictated by the front dovetail. In addition if you can mount a round flat plate in a chuck and sweep front to back and the taper is progressive (past the center point of the spindle) then it would indicate that the cross slide dovetail is not parallel to the head. You certainly have gone above and beyond trying to determine the problem, but at this point I would contact the manufacturer to move forward to resolve this problem.
 
mksj said:
The headstock side of the carriage is fixed, the gibs are on the tail stock side, if you can get access to the gib lock and can lock it on either side of the spindle to do your measurements, then alignment would be dictated by the front dovetail. In addition if you can mount a round flat plate in a chuck and sweep front to back and the taper is progressive (past the center point of the spindle) then it would indicate that the cross slide dovetail is not parallel to the head. You certainly have gone above and beyond trying to determine the problem, but at this point I would contact the manufacturer to move forward to resolve this problem.
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Locking the cross slide gib in both measuring positions, I am getting just over 1 thou difference in a CONVEX cutting bias.
 
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