Re: Drawbar Question - too short
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Hi Peter I have Dalton as well as SB and Hardinge 3C collets.? They only vary a couple of thousands?in outside?thread diameter but that is not the critical dimension.? The?pitch diameter?of the thread? is what counts, not the outside diameter.? If your collets slide in and out of the threaded end of the draw tube this is very odd.? It may indicate that the thread in the draw tube is totally?worn out as I have seen this on a couple of SB draw tubes.? Especially?on the lever operated collet closer as they can exert way more force than a hand wheel draw bar. As to lever operated Dalton draw bar setups they are very rare.? I have one for a Lot 6 and Dalton 9 inch but do not have one for the smaller lathe.? I only know of one that is owned by a guy near Chicago and he loaned it to me when we exhibited?at the NAMEs model engineering show in 2016.? Ralph also has many other Dalton accessories we only see in catalogs. Pictures attached were taken when Ralph loans?me his lever operated collet closer.? Just some information guys.
Well... I've got a problem.? I ordered a 3C Collet Draw Bar from Ebay
that is a bit longer than the Dalton draw bar I have.? I chose to do
this because I didn't want to butcher the Dalton draw bar for more
extension.
I received the draw bar but when I went to screw in the Dalton collet it
just slid right in. No thread engagement at all.? I looked up 3C collet
dimensions and as you would expect there are more than one dimension
documents that don't appear to match.
South Bend collet dimensions for a #3 collet which is claimed to be
compatible with 3-C collets shows an overall length of 2 7/16 which
matches my Dalton collet.? The diameter of the collet shaft is .6495 on
the chart and my Dalton collet diameter is .645, a difference of .0045.?
The thread length on the chart for a 3-C is .750 and the Dalton collet
thread length is .600.? The thread diameter on the South Bend chart is
.642 which is very close to the Dalton collet thread diameter.
The inside diameter of the draw bar where threaded is .654 which allows
my Dalton collets to slide in and out.
Before I ask to return this draw bar I want to make sure that it is not
3-C as advertised.? I can't find a thread diameter on the SB chart that
matches it so it may be a metric draw bar.
I was under the impression that 3-C was a hard standard but if mistaken
please set me straight.
I want to make sure that I am correct before I ask to a return the draw bar.
Thanks,
Peter
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Dennis Turk
