What speed are you turning at?
As per my response to Cindy:
"I'm also can't tell you lathe speed for certain either. I have a total shop, and the speed adjuster thingy (scientific name) broke a while back. Again, if I had to guess, I would say probably 1500-2000 rpm."
When turning why not turn with the tailstock for support??? Now if you are breaking when sanding then you have a serious problem with heavyhandedness. Need to lighten up some.
I am using the tailstock for support. I only remove it to do the final shaping on the end after everything else is done. Definitely not happening during sanding. I only use enough pressure to let the sand paper do it's job.
If it is the mandrel for the stoppers that are long that come from Woodcraft then I would make sure that the back piece is all the way into the chuck or whatever is holding it due to is only being approximately 1/4" stock. I use a mandrel that I got from Ruth Niles. It is the best mandrel that I have ever used on BS because it is on a morse taper and is very solid as it is in the headstock when turning and very thick. I now only turn stoppers that are stainless steel as I have had the other corrode from contact with acid materials in wine, vinegar, etc. You could only have gotten hold of a couple of mandrels that have fatigued metal.
They are the thinner, 1/4 in ones from Woodcraft. I mkae sure I slide it all the way in to the jacobs chuck. Unfortunately, I can't use mosre taper stuff in my headstock, as I have a Total Shop, and it uses 5/8 in slide on pieces. :frown:
So the broken mandrel fractured at the end of the 3/8" threaded stud?
How old was the mandrel? Could this have been a stress fracture that built up over time? How does (did, now) the stud join the mandrel body - was it a solid piece of steel or was the stud braised on?
I use a PSI mandrel - a very robust steel fitting that threads onto the spindle. I also support the end of the blank with the tail stock during roughing so that I minimize stress on the mandrel and blank, and then remove the tailstock only to finish the end. But considering the repetitive shocks that a blank/mandrel incurs as it is being initially rounded off, I could imagine that eventually something might give.
Everything eventually will wear out - some things just last longer than others.
No, they were actually the 1/4 in mandrels from Woodcraft. I guess I should have mentioned that, but I didn't think about it. It looks to be one piece of steel. I had turned 3 stoppers on the first one that bent, and the other two were brand new.
Seems to me near impossible to break one of those mandrels. How are you chucking the mandrel? Are you using the tail stock for support? No tail stock is definitely the wrong way to do it, which would cause levered stress on the mandrel, multiplied by the force of your chisel, then I suppose with no tailstock in play you could bend a mandrel, but otherwise it seems near impossible.
I'm chucking the mandrel, fully seated, into a jacobs chuck. I am using the tail stock for support for all but the very final shaping on the end. When I am doing that shaping, I try to be very light handed, as I know there is a lot of stress on the mandrel at the point.
Okay, I think I answered everything. Let me know if I missed something. Thanks for the replies!
