D1-3 lathe chuck

[Sandman north]

So my Modern Standard 12 x 30 lathe has a good 6 "- 3 jaw. A crappy 8" -4 jaw

I was trying to get a 6" or 8" independent 4 jaw, then run into a problem of getting a backing plate that was not way too expensive 500 + dollars.

My best guess is I have a D1- 3 tapered spindle but it is just a bit smaller @ 2.1015 rather that the 2.125 the chart says it should be
my taper is 0.024 smaller at the largest point

Is this still a D1-3 ?

Any backing plated have a bore but the do not mention a taper.

Confused how do I get this all to work ?

Thanks Sandman

[whateg0]

Where are you measuring the taper? How are you measuring the taper? What size are the studs?

Everything I see online for modern standard machines shows them using D1-4 spindles. Of course, that's subject to change over the years and maybe your model isn't shown anywhere. You didn't mention the model number, so not sure what it was spec'd with.

[GlennW]

Spindle type and size guide.

https://www.toolmex.com/blog/325/spindl ... size-guide

D1-3 pins are 9/16" diameter and D1-4 are 5/8"

[Sandman north]

Thanks
The pins are as .0562 so, 9/16 this is a Utilathe serial # 458-18

I measured the taper with digital calipers at the base of the taper

I did find this on line from Shars I think it will work? but not sure?

https://www.shars.com/6-d1-3-fully-mach ... dent-chuck

[Harold_V]

<snip>

I measured the taper with digital calipers at the base of the taper

I suspect that the measurement does not reflect the true size, as there's generally a generous undercut. If you find your spindle has one, imagine projecting the taper to the face, which would be a true measure of the size.

I have to assume that you understand that calipers of any description do not yield reliable readings. I'm not suggesting that the use of one for this instance isn't acceptable, for it is. Just don't consider readings from calipers as being absolute. There's too many places for error to be introduced for them to be reliable.

H

[whateg0]

A more reliable, though "somewhat" less convenient way to measure the size of something like that would be to measure across a set of dowels nestled in the corner of the taper and the face. A little trig, or a CAD drawing, will give you a very accurate measurement. Certainly, for the difference in your measurement and the spec for a D1-3, with a rough measurement, I could believe it to be that.

Dave

[choprboy]

If it is a D1-3, you can get a backing plate for a lot less than $500. You can pickup a nice Bison from KBC for about $250. Or pick up a cheap generic D1-3 plate from Shars for as little as $65 (depending on size/finish). See also: Grizzly, AllIndustrial ($40 ???), AjaxToolSupply.

[whateg0]

I think I paid right under $100 for an 8" D1-3 from Shars. Grizzly didn't have any that big in D1-3. Plain back chucks are far more readily available.

[Glenn Brooks]

I had a 1950 Utilathe 12 x48. I also thought I had a D-1-3 spindle, because of measurements. But, it wasn't. Bought a D1-4 and if fit perfectly.

Iam 98% certain you will find it is a d-1-4...

Also, FWIW, Racer Machinery is the Standard Modern manufacturer and spare parts supplier in Canada.

http://www.standardmodernlathes.com/spareparts.html

They know everything there is to know about the older Standard Modern Utilathes. They provide unobtainium parts (they make them one off for you when you call), and thenowner seems to be able to recall every model and part from memory.


Glenn

[whateg0]

Everything I've seen online agrees with your D1-4 experience. However, OP said his studs are 9/16", which would be for D1-3. We may never know what he has.

Dave

[Glenn Brooks]

Dave, this goes back a few years, but I seem to recall, my original 3 jaw chuck on the Utilathe had 9/16” studs, and was identified on some paperwork as a d-1-3. When I decided to buy a new chuck, I went through a verified action process and decided it actually should be a D-1-4. So bought that instead, and installed. Worked fine. Iam now wondering if the OP may be looking at a similar set of circumstances.


Glenn

[Sandman north]

Ok I bought a D1-3 backing plate from shars
I guess in a few days we will know!

Thanks everone Sandman