# 1.625 x 8 Mounting Plate for 3 Jaw Chuck



## Chuck K (Jun 22, 2013)

I had a friend call today and ask if I could bore and thread a mounting plate for a small 3 jaw chuck.  The lathe is a small Hardinge with 1.625 x 8 tpi spindle.  I explained to him that I could do that for him, but he should check around and see if he could just buy one that was already threaded.  I checked the usual places and didn't find anything.  I have to think that with all the Hardinge lathes out there someone must be selling mounting plates for them.  Anyone know of dealer selling plates that size?  Thanks

Chuck


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## ScrapMetal (Jun 22, 2013)

Oddy enough my SB 11" spindle is also 1 5/8" - 8.  The bad news is that no, there doesn't seem to be anything available.  I have been keeping my eyes open as well as actively searching for the last couple of years and have found nothing.

What I generally recommend is that one get a 1 1/2" - 8 backplate, bore it out, and re-thread it.

Sorry I couldn't offer anything better,

-Ron


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## Chuck K (Jun 23, 2013)

Ron, Thanks for the reply.  I don't remember ever seeing that size listed, but I thought maybe somebody was selling them.  I don't think he has the machine or ability to bore and thread one, so I will probably be doing it for him.  I was wondering if the bore dia. for 1.625 would clean up the existing threads in a plate with 1 1/2-8 threads in it.  Seems like it would be close.

Chuck


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## ScrapMetal (Jun 23, 2013)

Chuck K said:


> Ron, Thanks for the reply.  I don't remember ever seeing that size listed, but I thought maybe somebody was selling them.  I don't think he has the machine or ability to bore and thread one, so I will probably be doing it for him.  I was wondering if the bore dia. for 1.625 would clean up the existing threads in a plate with 1 1/2-8 threads in it.  Seems like it would be close.
> 
> Chuck



It actually works out fairly well.  The minor radius of the 1 5/8" - 8 works out to be right about 1 1/2" so you can pretty much just wipe the threads so that you have a 1 1/2" hole then start threading them for the 1 5/8" - 8.

Hope that helps,

-Ron


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## Chuck K (Jun 24, 2013)

Ron, Thanks for the info.  He told me that he had purchased a plate with 1-1/2-8 threads thinking that was the size he needed, so I guess that will work as well as a blank.

Chuck


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