I'm currently using my PM-25MV to make BXA QCTP tool holders for my PM-1236. I am making 14 new tool holders. I have cut all of the long slots for the the tools and all of the dovetails. The dovetails fit great and I have had no issues in the process until now. It should be noted that I also used this machine to make AXA tool holders for my South Bend Model C lathe so I am not unfamiliar with the process. I now need to drill the 5 threaded screw holes in each tool holder.
I have nearly completed 7 tool holders thus far with all the holes drilled and threaded, but not without issues. I'll explain my process. I proceeded with caution, making sure (hopefully) that I wasn't making a mistake because it's been awhile since I made the AXA tool holders. First I did X-Y edge finding and brought by tool to the first hole location, marked as X0,Y0, and SDM 1. I was using a spotting drill and made a tiny pin prick mark at that location and double checked its accuracy against a steel rule. It looked fine so I went on to SDM 2, X.750, Y0. I made the pin prick mark and measured again. All looked well and I repeated this process for SDM 3 & 4, completing all four holes used for tool lockdown. I then moved to the counterpoint on the X and offset SDM 5 by .186, and all was well against the rule.
From this point I spot drilled SDM 5 and in reverse order, SDM 4-1. All was well and all 5 holes were drilled and tapped without issue. For the next tool holder, again being cautious, I repeated the same process, using all SDM setting that were saved and measured again against the rule. All was well and I spot drilled as I went.
After spotting SDM 5, I changed to a Letter Q drill and drilled 5/8" deep, then tapped for 3/8-24. No problems. I went to back SDM 4, but something looked off. The DRO was slightly off, and I mean slightly, from the spotted location. Using the DRO to determine any error I re-positioned the cutting tool location about .007 to the right, in the X axis. Not much so I didn't worry. I drilled through with a Letter F drill for a 5/16-18 thread to be done after holes SDM-1-4 were drilled. I moved on to SDM 3. Now the DRO was off about .030 from the spotted location and the work/tool had to be adjusted in the X-axis again to line up with the spot. (Y axis was locked). SDM 2 was off about .023 and SDM 1 was off about .007. Drilling and threading was done by eyeballing the tool line up with either the spot or the drilled hole. I could not trust the DRO.
I had been using a vise stop to work against so I removed it. For all toolholders after that I went through the edge finding process and found the X0, Y0 location for SDM 1. But in experimenting I found that the saved SDM location were always accurate when going from SDM 1 to SDM 5. However, when going in reverse 5-1, and using DRO readings, the DRO placed the tool and various dimensions, always off to the left, such that if you drilled a hole using DRO readouts it would be to the left of the spot.
I have brought 7 tool holders to the point where all holes are drilled and tapped. The holes were all spot drilled using the SDM saved dimensions going SDM1 to 5, in that order. All holes were drilled and tapped by eyeballing in reverse order 5-1. Dimension errors were not always the same. What was previously an error of .007 might be a .012 error the next time. Errors ranged from .005 to .042.
It should be noted here that last year I found that the X-axis lead screw nut had come loose ( after suggestions from members herein) and I fixed that. The machine has not been a problem until now. In addition, I recently installed an X-axis power feed from Precision Matthews, but I was not using it due to the short distance between hole locations.
Any ideas as to what might be causing this. Sorry for the long explanation but I felt it necessary in case anyone could spot an error in my process. Thank you.
Denny
I have nearly completed 7 tool holders thus far with all the holes drilled and threaded, but not without issues. I'll explain my process. I proceeded with caution, making sure (hopefully) that I wasn't making a mistake because it's been awhile since I made the AXA tool holders. First I did X-Y edge finding and brought by tool to the first hole location, marked as X0,Y0, and SDM 1. I was using a spotting drill and made a tiny pin prick mark at that location and double checked its accuracy against a steel rule. It looked fine so I went on to SDM 2, X.750, Y0. I made the pin prick mark and measured again. All looked well and I repeated this process for SDM 3 & 4, completing all four holes used for tool lockdown. I then moved to the counterpoint on the X and offset SDM 5 by .186, and all was well against the rule.
From this point I spot drilled SDM 5 and in reverse order, SDM 4-1. All was well and all 5 holes were drilled and tapped without issue. For the next tool holder, again being cautious, I repeated the same process, using all SDM setting that were saved and measured again against the rule. All was well and I spot drilled as I went.
After spotting SDM 5, I changed to a Letter Q drill and drilled 5/8" deep, then tapped for 3/8-24. No problems. I went to back SDM 4, but something looked off. The DRO was slightly off, and I mean slightly, from the spotted location. Using the DRO to determine any error I re-positioned the cutting tool location about .007 to the right, in the X axis. Not much so I didn't worry. I drilled through with a Letter F drill for a 5/16-18 thread to be done after holes SDM-1-4 were drilled. I moved on to SDM 3. Now the DRO was off about .030 from the spotted location and the work/tool had to be adjusted in the X-axis again to line up with the spot. (Y axis was locked). SDM 2 was off about .023 and SDM 1 was off about .007. Drilling and threading was done by eyeballing the tool line up with either the spot or the drilled hole. I could not trust the DRO.
I had been using a vise stop to work against so I removed it. For all toolholders after that I went through the edge finding process and found the X0, Y0 location for SDM 1. But in experimenting I found that the saved SDM location were always accurate when going from SDM 1 to SDM 5. However, when going in reverse 5-1, and using DRO readings, the DRO placed the tool and various dimensions, always off to the left, such that if you drilled a hole using DRO readouts it would be to the left of the spot.
I have brought 7 tool holders to the point where all holes are drilled and tapped. The holes were all spot drilled using the SDM saved dimensions going SDM1 to 5, in that order. All holes were drilled and tapped by eyeballing in reverse order 5-1. Dimension errors were not always the same. What was previously an error of .007 might be a .012 error the next time. Errors ranged from .005 to .042.
It should be noted here that last year I found that the X-axis lead screw nut had come loose ( after suggestions from members herein) and I fixed that. The machine has not been a problem until now. In addition, I recently installed an X-axis power feed from Precision Matthews, but I was not using it due to the short distance between hole locations.
Any ideas as to what might be causing this. Sorry for the long explanation but I felt it necessary in case anyone could spot an error in my process. Thank you.
Denny
Put one in a vise up against a stop and spot drill. Remove and do 14 more . Drill all same way . Tap all same way 15 times . Do all 5 holes this way . Your machine will only be moved 5 times and you won't have to pick up all these locations . You're spending more time moving the table than machining the holders . I know isnt solving the initial question , but rather a order of operations improvement . 
