burlywoodpecker
Member
I have been facing an issue whenever I turn kitless pens where the cap doesn't perfectly line up with the body.
These images are an exaggeration of the problem. The actual offset is about 0.1mm and is only slightly noticeable to the eye.
Previously I only had a wood lathe and made the assumption that his was inevitable due to the poor tolerances of the lathe. now, however, I have gotten a metal lathe and am experiencing the same problem. The only two possible explanations that I can think of is either that the mandrels I use are not centered, or somewhere during the threading operations I am threading off center. I have tried to see if I could address these issues but nothing I did worked to a satisfactory extent.
Firstly I tried several different styles of mandrels to see if a certain method of holding the blank caused it to become lopsided.
For mandrel A the blank came to a stop by hitting the shoulder and for mandrel B the blank came to a stop by running out of threads. A has worked better for me than B and I suspect this is because as the threads run out it pulls the blank in a certain direction...???
Secondly I tried changing my order of operations to see if I could improve the alignment. I noticed that when I mount the body onto the mandrel by the internal threads (for the section) the external threads (for the cap) don't run smoothly, they wobble (the wobble you get when something isn't centered). I can tell by the flat spot behind the threads which doesn't run smoothly and seems to be spinning slightly out of axis. To me this implied that my tapping operation must be going into the blank at an angle, but maybe it is something else.
I have tried tapping first, then mounting it on a mandrel to re-round the blank. after which I put the blank back in my collet chuck to thread it. I haven't had the chance to look into this more, and the one attempt I did this for also came out slightly lopsided.
I find this an extremely annoying am hoping one of you has some suggestion as to why this is happening and how I could solve it.
These images are an exaggeration of the problem. The actual offset is about 0.1mm and is only slightly noticeable to the eye.
Previously I only had a wood lathe and made the assumption that his was inevitable due to the poor tolerances of the lathe. now, however, I have gotten a metal lathe and am experiencing the same problem. The only two possible explanations that I can think of is either that the mandrels I use are not centered, or somewhere during the threading operations I am threading off center. I have tried to see if I could address these issues but nothing I did worked to a satisfactory extent.
Firstly I tried several different styles of mandrels to see if a certain method of holding the blank caused it to become lopsided.
For mandrel A the blank came to a stop by hitting the shoulder and for mandrel B the blank came to a stop by running out of threads. A has worked better for me than B and I suspect this is because as the threads run out it pulls the blank in a certain direction...???
Secondly I tried changing my order of operations to see if I could improve the alignment. I noticed that when I mount the body onto the mandrel by the internal threads (for the section) the external threads (for the cap) don't run smoothly, they wobble (the wobble you get when something isn't centered). I can tell by the flat spot behind the threads which doesn't run smoothly and seems to be spinning slightly out of axis. To me this implied that my tapping operation must be going into the blank at an angle, but maybe it is something else.
I have tried tapping first, then mounting it on a mandrel to re-round the blank. after which I put the blank back in my collet chuck to thread it. I haven't had the chance to look into this more, and the one attempt I did this for also came out slightly lopsided.
I find this an extremely annoying am hoping one of you has some suggestion as to why this is happening and how I could solve it.