ER32 Collet Chuck thread issues

[aquilla]

HI All,
a long while ago I purchased an ER32 collet chuck for my SB9B, it was brand new and listed on a popular auction site as for a boxford but looked to be the right thread, it is all one piece not a backplate and bolt on type (the same as the link below), my questions is, it only seems to thread on about a half turn then binds up, I have read that it may be the wrong pitch, which I will try to check tomorrow when I can get to it (any suggestions for checking the internal thread pitch?), but is there anything I can do if it is? anything else I should try to get it to fit? and has anyone else used one of these with any success?

Redirect Notice

 

[Erich]

8 tpi. Each thread should be 1/8 inch apart. Stick an Imperial (English to us colonials) scale down the bore and see what the threads pitch measures. The points should line up nicely on every 1/8 inch mark.

 

[Ken-Bergen]

From http://www.lathes.co.uk/boxford/

An interesting note in the Company's records states that: From Serial 1360 all machines have an 8 t.p.i. Whitworth form spindle nose - a reference to the fact that the first batch must have had an exact copy of the South Bend fitting with its American 60° thread angle (the Whitworth is 55°).

 

[Blob]

If it's a 55 degree Whitworth thread in 8 tpi, you could dress the threads with a 60 degree tool so it will fit. That's what I'd try if it was mine - might take some work with a magnifier to get the threads lined up with the tool, but after that it shouldn't be a big deal.

 

[Mark Rand]

That would be a foolish thing to do on a UK made Boxford.

Better to slightly open up the collet chuck's thread with a 55° tool, if needed

 

[Blob]

That would be a foolish thing to do on a UK made Boxford.

Better to slightly open up the collet chuck's thread with a 55° tool, if needed

I thought the OP said he had a SB 9 and the ER chuck was for a Boxford? My suggestion was certainly not to modify a Boxford lathe spindle, I was talking about the chuck. I agree it would be beyond foolish to mess with a boxford lathe.

 

[Ken-Bergen]

There are likely one or nine Boxford lathes still operational in the UK so why not just sell what you mistakenly bought and go shopping for something that fits?

 

[SteveM]

There are likely one or nine Boxford lathes still operational in the UK so why not just sell what you mistakenly bought and go shopping for something that fits?

Yes and list it as:

RARE!!!! ER32 Spindle Chuck for Boxford Lathes with Whitworth spindle threads. RARE, RARE, RARE!!!!

using the word RARE as many times as will fit and all those caps and exclamation points because, as everyone knows, caps and exclamation points bring higher prices!

Steve

 

[traditional-tools]

Oh crap, I guess per Mark's message the lathe is a SB...I can't read either. I was just following the conversation here...

Make one yourself if you need to...you can thread on the SB, and true it up after, so that it runs right on your lathe. Same if you buy a threaded back plate, which cost about as much as a happy meal...the answers are out there...some of them sitting in front of you.

 

[Mark Rand]

I thought the OP said he had a SB 9 and the ER chuck was for a Boxford? My suggestion was certainly not to modify a Boxford lathe spindle, I was talking about the chuck. I agree it would be beyond foolish to mess with a boxford lathe.

Bugger! I didn't have my thinking head on when I wrote the post. Saw the OP was in the UK and automatically assumed that the lathe was a Boxford.

 

[aquilla]

Hi All,
thanks for the responses, so I checked my spindle pitch and it is indeed 60 degrees. however I tried threading the collet chuck onto a chuck arbor I have for my rotary table (also 60°) and it threaded onto that just fine with no slop, I tried threading it slowly onto the spindle again and it looks like the un-threaded part of the spindle is contacting against the un threaded back of the chuck before it can thread on fully. I checked with a caliper and this seems to be the case. Can I just open up the back of the collet chuck? what should stop the chuck from threading further?

I am quite willing to buy a new one/ try making one, but learning where this one is wrong seems like an important step towards that

 

[iwananew10K]

yes, just open up the unthreaded part of the collet chuck a bit.

Easy way- chuck up a scrap bar in a death grip with your 3 or 4jaw chuck, with a couple inches sticking out and turn it the size of your biggest ER32 collet(3/4" or so presumably)
Now you have a dead nut mandrel...do not move it...snap collet into ER nut,slip it on t your turned mandrel and carefully tighten the collet nut to the ER chuck...sharp boring bar and turn the inner register to a nice slip fit on your lathe spinde register...easy peasy and it will be dead on.

 

[aquilla]

yes, just open up the unthreaded part of the collet chuck a bit.

Easy way- chuck up a scrap bar in a death grip with your 3 or 4jaw chuck, with a couple inches sticking out and turn it the size of your biggest ER32 collet(1" or 26mm presumably)

Now you have a dead nut mandrel...do not move it...snap collet into ER nut,slip it on t your turned mandrel and carefully tighten the collet nut to the ER chuck...sharp boring bar and turn the inner register to a nice slip fit on your lathe spinde register...easy peasy and it will be dead on.

That makes a lot of sense, thanks! I'll give it a go next time I have a little time to spare. Thanks again!

 

[Ken-Bergen]

Hi All,
thanks for the responses, so I checked my spindle pitch and it is indeed 60 degrees. however I tried threading the collet chuck onto a chuck arbor I have for my rotary table (also 60°) and it threaded onto that just fine with no slop, I tried threading it slowly onto the spindle again and it looks like the un-threaded part of the spindle is contacting against the un threaded back of the chuck before it can thread on fully. I checked with a caliper and this seems to be the case. Can I just open up the back of the collet chuck? what should stop the chuck from threading further?

I am quite willing to buy a new one/ try making one, but learning where this one is wrong seems like an important step towards that

Have you verified that the chuck is also a 60° thread?

 

[aquilla]

Have you verified that the chuck is also a 60° thread?

I am kind of assuming I guess, since it threads onto the 60° threaded arbor, it doesn't seem to be binding or have any slop, so I assumed it must match the thread pitch... is that safe to assume?

 

[Ken-Bergen]

I am kind of assuming I guess, since it threads onto the 60° threaded arbor, it doesn't seem to be binding or have any slop, so I assumed it must match the thread pitch... is that safe to assume?

Have you measured the spindle thread and the arbour thread? The three wire method comes to mind.