Rethreading question

[clemwixted]

I would like to know if a 1-1/4" x 8 TPI (female) to 33mm x 3.5mm (male) spindle adapter can be rethreaded on the 33mm male threads to 1 X 8 inch?

Is there enough metal on the 33mm threaded male end to allow it to be reduced and threaded to 1 inch by 8 threads to use on my wood lathe?

Thanks,

Clem

[Doug_C]

Clem,

There should be plenty of OD there. The next issue would be over all length to give strength in the step down. If need be, the 1"-8 could be somewhat short. The 33mm will have a minor diameter not less than 1.125"? . That could be easily checked with a pair of calipers to verify the root of the thread end.

I just made couple of this type adapter last week for a retired guy down the street from me. I know the runout on mine was net zero since the ID thread and the OD were turned in one setup. On his swiss wood lathe, the adapter had at least .02 runout? I brought it back to my shop and placed it on a 1- 1/4-8 test mandrel I had made and it spun within .001.

I know we cannot apply the same standard of machine tool to a wood lathe, but I would expect the threads machined on a nice electronic swiss wood lathe to be better than .02 on spindle center.

I did my parts right, but I cannot control what is already there. I'm just glad he was still happy with the parts.

Like this link to Craft Supplies USA



DC

[clemwixted]

Thanks Doug,

That's what I was hoping for.

Sounds like you do good work.

I'm a retired guy and I wished you lived down the street from me!

Clem

[Victor_R]

Clem,

I think you will have enough meat to re-thread. Looking in the H28 manual, the major diameter for a 33-3.5mm thread (which is a standard size) is 1.300. (.0394x33=1.300) This is a double depth of .300 over a one inch diameter or .150 per side. The depth of an 8 pitch thread in less then .100 inch. The OD will not limit you, but the ID might if it is hollow. And try to make a radius at the shoulder for strength if possible.

[clemwixted]

Thanks Victor,

I hadn't thought about the inside but I checked and it is solid.

Thanks,

Clem