Tempering mandrel

[alxe24]

I notice with the pen I've being turning lately that soon after I start turning the barrels, the rod starts to wobble like it had flex not a whole lot but enough to bother anyone who cares about a concentric fit.

I thought about tempering the rod to make it stronger and less prone to bend. The idea would be to heat the rod as red as I can and put under water right away. Once or twice.

I have the right taper on the live center; I do not over tight the tail stock nor the rod knob. As a matter of fact I could be borderline loose on the err of caution. I really take light cuts so it is not excess force or catches. What is weird is tha it starts true and it starts with the deflection soon after.

Thanks for your insights.

 

[Paul in OKC]

It could still be the nut tightening while you are turning. With the size of the mandrels no tsure if tempering would help. It would be like heat treating it. Let us know how it works if you try it.

 

[skiprat]

Alex, I don't know if this will help or not, but it may point you in the right direction.

Mount the mandrel but without any blanks, bushes, spacers or even the nut. Don't bring up the tail stock yet. Rotate the headstock by hand and watch the threaded end of the mandrel, is it reasonably straight?. You could also remove the rod from the mandrel and roll it on a flat surface to check straightness.
Next, bring up the tailstock and tighten the live center as much as you normally do, while looking at the mandrel rod. Is it bending?
I don't know what everyone else feels, but after I've tightened mine I can still turn the live center without too much effort.
Next, with the lathe running on slow, press with your fingers in the middle of the rod and look at the deflection relative to the pressure you apply. Also look at the point where the live center holds the end of the rod, is there any movement? Mine moves a lot. the dimple in the rod is fine but my live centre has(had) developed a thin pencil lead like tip. I just dressed it up with a file.

Finally, when you mount the blanks and respective bushes, do you adjust the mandrel length to suit or do you do like me and fill it up with spacers? I did this for a while to accomodate my tool rest.

Hope you find the answer, but I don't think tempering it will help. In fact I think they're pretty hard already. Good luck

 

[Penmonkey]

I think it will work as long as you can keep it from bending as you heat it.

 

[its_virgil]

I hate to ask this, but I will. How sharp are your tools? Dull tools means we push harder which means the mandrel deflects. Just a thought...it was a problem I had when I first started. I also agree with Paul...the brass nut can be overtightenend as can the tailstock. the nut bows the blanks and the tailstock can cause a bow in the mandrel and they compound the problem when in tandem. I'm ducking now....[]

Do a good turn daily!
Don

Originally posted by alxe24
<br />I notice with the pen I've being turning lately that soon after I start turning the barrels, the rod starts to wobble like it had flex not a whole lot but enough to bother anyone who cares about a concentric fit.

I thought about tempering the rod to make it stronger and less prone to bend. The idea would be to heat the rod as red as I can and put under water right away. Once or twice.

I have the right taper on the live center; I do not over tight the tail stock nor the rod knob. As a matter of fact I could be borderline loose on the err of caution. I really take light cuts so it is not excess force or catches. What is weird is tha it starts true and it starts with the deflection soon after.

Thanks for your insights.

 

[alxe24]

I will change the lathe. This is a good axcuse to upgrade. Also I'll get a couple of new rods and a beal chuck (is that how you call it).
End of story.
Ah trust me the tools are vrey sharp. I sharp the tool every time I turn a pen. Wolverine makes it easy.
Thanks

 

[alxe24]

Sorry for all the typos. Next time I'll check the post before I send [][][]