more fun with chucks....

[Johnny4]

Hey all,

I wasn't sure if this needed to be a new thread, or if I should have put this under the old one (help with chucks), but here goes....

The spur center was pretty firmly lodged in there, and I couldn't expose enough thread to measure an entire inch to get the thread diameter. So....I gave it some WD-40 love, and was able to tap it out with a little persuasion the next morning. The diameter is 7/8". I don't have a full inch of thread, but at the 1/2" mark, I counted 7 threads. Is it logical to assume it's 14 over 1 inch, making the thread a 7/8" 14? The outboard side has a completely different thread pattern than the inboard....is that normal?

When I went to put the center back in, it didn't want to stay in. I have had experience with Morse taper, and basically black magic holds it in....you just kind of push it and the Dark lord does the rest. This thing was really loose in there. It also looked kinda crudded up. It was not a smooth, clean taper. Additionally, there was some small bar running across the inside of what i will call the cylinder the spur goes into. It looked like it was supposed to be in the lathe. It lives about 4 inches inside the lathe. Is this making sense? Am I doing it wrong, or do I probably need a new spur center?

The lathe is making me work for its love. I like knowing how tools go together, and thus how to fix them.

Thanks again for all the help.

 

[Marmotjr]

You lost me on the thread thing...

But for the MT, clean that puppy.  Both the taper and the bore need to be baby butt smooth for the dark lord to do his thing. 

If there's a bar blocking insertion now, then something is wonky and you need to figure out what.  Crack the hood a take a look. 

[wtnhighlander]

Not sure I am picturing this correctly, but could that bar you see be the part that locks the head stock from spinning? Holds it still for attaching faceplates and such. My cheapo lathe has a knob on the pully side that I pull and twist to lock / unlock the head.

FWIW, the motor and drive belt do NOT like being turned on with that bar still in place ....

[Mark J]

As to the thread count the spundle adapters  come in specfic discrete sizes.  You could look at Teknatool's (Nova) web site at the adapters they have for sale.  I know you will see 8 TPI and 16 TPI.  I don't recall seeing 14 TPI.  See what size adapter your measurements are closest to, then find a nut with the same measurements as that adapter and try the nut on your spindle.