Hi all,
So I’ve created this as a new thread rather than carrying on hijacking other people’s!
So, the drill is all clean and in really nice condition with original switch, stickers, paint, motor, etc and hardly any damage to the table. But, I’m having some issues with runout...
I’m thinking there might be some damage, maybe even a small manufacturing fault on the JT6 spindle taper near to the bottom/end. Put the dial indicator on two points near the middle, and lower middle of the male JT6 spindle taper and getting around 0.02mm runout which I would consider in tolerance for a drill of this age. However near to the bottom of the taper, the final 3mm or so, I’m getting around 0.20mm total runout - 0.10mm either way from the high to low spots. I’m assuming it might have been squashed at some point, as opposed to it having been hit as the metal has no scratches, or indentations - where it’s indicating the highest readings it has some “shiny” spots which im thinking may be where it’s been squashed by something causing it to no longer be perfectly round. Perhaps someone put a drill chuck on that had some damage in the female taper, and when they compressed it onto the male taper of the spindle it transferred this damage and compressed the metal at the end causing the runout?
Now I don’t know if it’s the runout at the very end of the spindle causing it, or because the Jacobs chuck I have isn’t concentric and is old, but when I mount it on the spindle and indicate the top of a new drill bit I’m getting 0.30mm runoout which is visible to the naked eye and too out of tolerance for me - would prefer 0.1mm or less.
To narrow down the possibilities I’ve ordered a new precision Rohm chuck to see if it’s just the old Jacobs chuck that’s at fault, but the possibility is that despite the majority of the spindle having very little runout the damage to the end is causing whatever chuck is put on there to not seat perfectly and in turn causing causing the runout - the question is how can this be corrected if it is the case?
My only idea would be to grind a bevel into the lower portion of the taper that has the runout so that it’s no longer in contact with the female taper of the chuck, and instead the chuck is only touching/held on by the section of the spindle taper that has indicated very little runout. Other option would be to completely cut off the lower 3mm of the spindle taper where the runout is, and this would leave only the perfectly round section remaining for the chuck to mount to.
Here’s some videos of the indication readings for reference to hopefully explain the issue:
Runout towards the top of the spindle taper:
Runout towards the middle of the spindle taper:
Runout towards at the lower/bottom section of the spindle taper:
So I’ve created this as a new thread rather than carrying on hijacking other people’s!
So, the drill is all clean and in really nice condition with original switch, stickers, paint, motor, etc and hardly any damage to the table. But, I’m having some issues with runout...
I’m thinking there might be some damage, maybe even a small manufacturing fault on the JT6 spindle taper near to the bottom/end. Put the dial indicator on two points near the middle, and lower middle of the male JT6 spindle taper and getting around 0.02mm runout which I would consider in tolerance for a drill of this age. However near to the bottom of the taper, the final 3mm or so, I’m getting around 0.20mm total runout - 0.10mm either way from the high to low spots. I’m assuming it might have been squashed at some point, as opposed to it having been hit as the metal has no scratches, or indentations - where it’s indicating the highest readings it has some “shiny” spots which im thinking may be where it’s been squashed by something causing it to no longer be perfectly round. Perhaps someone put a drill chuck on that had some damage in the female taper, and when they compressed it onto the male taper of the spindle it transferred this damage and compressed the metal at the end causing the runout?
Now I don’t know if it’s the runout at the very end of the spindle causing it, or because the Jacobs chuck I have isn’t concentric and is old, but when I mount it on the spindle and indicate the top of a new drill bit I’m getting 0.30mm runoout which is visible to the naked eye and too out of tolerance for me - would prefer 0.1mm or less.
To narrow down the possibilities I’ve ordered a new precision Rohm chuck to see if it’s just the old Jacobs chuck that’s at fault, but the possibility is that despite the majority of the spindle having very little runout the damage to the end is causing whatever chuck is put on there to not seat perfectly and in turn causing causing the runout - the question is how can this be corrected if it is the case?
My only idea would be to grind a bevel into the lower portion of the taper that has the runout so that it’s no longer in contact with the female taper of the chuck, and instead the chuck is only touching/held on by the section of the spindle taper that has indicated very little runout. Other option would be to completely cut off the lower 3mm of the spindle taper where the runout is, and this would leave only the perfectly round section remaining for the chuck to mount to.
Here’s some videos of the indication readings for reference to hopefully explain the issue:
Runout towards the top of the spindle taper:
Runout towards the middle of the spindle taper:
Runout towards at the lower/bottom section of the spindle taper: