Collets for a non-5C lathe: R8 and other sundry alternatives

I've been reading the archives about lathe collets for those of us that don't have spindles set up for 5C, e.g., the thread from this
post:
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&selm=8spri4%24bof%241%40nnrp1.deja.com
I have a later model Logan/Powermatic "10 inch" (actually 11 1/8" swing) w/ a 1.0" spindle hole and 1 1/2" - 8 nose. I'm thinking through some ways to put collets on this lathe and would appreciate the collective wisdom of Those More Experienced.
In increasing order of $ and/or effort...
1) Adapt R8 collets using a hollow 7/16" drawbar. Very easy, but only gives ~1/4" thru capacity. Does not give the square and hex holding of 5C.
2) Adapt R8 collets via annealing and drilling out the threaded end of each collet, then threading the OD of each collet and ID of drawbar. 7/8" thru capacity, but only rounds. Time-consuming to mod each collet.
3) Buy or make a 5C collet chuck, 5C collets, and nose adapter. Hangs the collets out there--as accurate? Either a lot of work or a lot of $? Anyone made a 5C collet chuck?
4) For my lathe and maybe a few others, and maybe this is a Really Bad Idea: my spindle tube is huge (1" ID but 1.75-1.95" OD--I am guessing the same blank was used to make the larger 2 1/4"-8 and L00 spindles on the "11 inch" Logan/Powermatics.) Drill out the spindle to 1 3/8", removing the nose thread but leaving a 2.625 OD x .500 thick disk that was the chuck mounting shoulder. Next, - machine a new nose blank of 1045 bar stock to fit over the 2.625" shoulder, - secure the new nose using drive pins/bolts and silver braze, - machine the chuck mounting surfaces of the new nose w/ 2 1/4"-8 thread (or L00), shoulder, and 5C taper right in place and running on my lathe--guaranteed concentricity. I think I am tempted to do this one mainly bc that 1 1/2-8 thread looks *totally* out of place on the massive spindle tube. Ads: 1 3/8" thru hole, 5C collets, properly sized spindle thread, low $. Disads: a lot of work (that's a loooong 1 3/8" hole to drill!), risk of trashing the spindle, what else?
5) Buy a true 11" Logan headstock w/ 5C capacity. Much easier than #4 and I know it will work. Unknown $ / availability.
What do y'all think?
Thanks, David
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Anyone made a 5C collet chuck?

Metal Lathe Accessories has a 5C collet kit which is adaptable to almost anything from 1-1/2-8 to 2-1/4-8.
I use a Hardinge-Sjogren, purchased on eBay.
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On 30 Jun 2004 21:09:44 -0700, snipped-for-privacy@ku.edu (David Malicky) wrote:

4C collet has a .950" OD., 3/4" capacity if you can live with that. Would require a bushing and grinding the taper in the front of the spindle. Could possibly be made from a taper sleeve that fits the existing spindle taper. Maybe harder to find, but not especially rare. Square and Hex are available. Something to think about. Lennie the Lurker
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* * Posted and E-Mailed * *
On 30 Jun 2004 21:09:44 -0700, snipped-for-privacy@ku.edu (David Malicky) wrote:

An incredibly stupid design move on the part of Powermatic/Houdaille. This lathe *IS* an 11" lathe with a different spindle, see below.

I would not recommend this. Diminished through capacity, and R-8 collets are "sprung" undersized (or should be). This is so they will tend to hold the tool (they are designed for Bridgeport vertical mills and similar) when released, so your end mill doesn't drop to the table. OTOH, workholding collets, such as 5-C, 3-C, 3-AT etc, are sprung oversized. When released, they will tend to spring to an oversized condition, allowing easier stock change or movement.

And I don't think you are likely to find square or hex shaped R-8 Collets.

We carry these. See http://lathe.safeshopper.com/newitem.htm
Contact me and we can discuss which unit would be best for your lathe and your needs.

I would not recommend this course of action.

Actually, consider just replacing the spindle itself. I have not done it myself, but I have talked to people who have changed out the spindle from a 10" Powermatic for a spindle from an 11" Powermatic.
It appears that this is the only difference between the two machines. Remember that this ONLY applies to the Powermatic 10" lathe that is actually an 11" swing. I would also do some serious checking of dimensions before plunking down very much money.
OTOH, you might find a good deal on a spindle on eBay.
Also, I *THINK* you could use a spindle off any Logan 11" Lathe. According to the diagrams and cross-references, the Logan 11" used the same spindle as the Powermatic 11". According to the P/M parts list, the only difference between the 10" and 11" *POWERMATIC* headstock is the spindle itself. The headstock casting, pulley, bull gear, bearings etc., etc., etc. are all the same. This would indicate to me that the outside profile of the two spindles is identical.
Of course, it does mean you would not be able to use the same spindle mounted accessories as you do now, such as your chucks or faceplates.
Good luck!
--
+--------------------------------------------+
| Scott Logan - ssl "at" lathe.com |
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How about an easier alternative. I recently bought an adjust true 4 inch Bison 6 jaw chuck for my Myford. I adjusted it at one diameter and checked it at several other diameters. The runout was less than 1 thou in all cases. Not quite as good as a collet, but maybe good enough, at least for many things.
chuck
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* Posted and Emailed *
Thanks, Scott, for the great tips!

That is interesting. I am guessing it was driven by marketing/price point/commonality of parts, but it sure does seem like a dumb design when I look at the thing. And I feel kinda cheated out of a proper spindle when I know it couldn't have cost them $5 to make it right.

This sounds like a great idea. And RCM comes (hopefully) to the rescue via Bill Fill's post. I sent him the dims and pics of my spindle so he can check it against what he has. I'm emailing them to you, too, if you would know by looking what the compatibility is. I won't try an ascii dimensioned drwg.
One thing I'm confused about is that my "Logan Operators Instructions & Parts List" for the Powermatic 10 and 11, p. 20 (Headstock exploded view), shows 4 spindles. Mine looks like the one in the upper right corner: 2 keyways, long center section. The 3 spindles at the bottom of the page have 3 keyways and a different profile.
Hopefully this spindle swap will work out and I'll have a real "11 inch" lathe (short of the serial number).
Thanks again, David
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David Malicky wrote:

http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&selm=8spri4%24bof%241%40nnrp1.deja.com
The cheapest thing you can do that is sort of collet-like is to find a mint Jacobs 58B headstock chuck that threads onto your 1-8 spindle nose.
Another alternative I don't often see mentioned is to go with a non-lathe collet setup. The last few years I've been using an ER-40 collet set in my shop with various holders and homemade drawbars, on several machines. On my 9" South Bend, for example, I use an ER-40 holder with a 3MT shank. That gives me collet accuracy but without the pass-through capability of real lathe collets. I have used it to turn 1" drill rod. An ER-40 setup isn't cheap new, but there are the usual workarounds (ebay, import clones). I also use these collets on my tool & cutter grinder and can use them on the mill and my bigger lathe too, but haven't yet.
Grant Erwin Kirkland, Washington
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David-
I have quite a few used Logan spindles in decent condition, including several with the larger spindle bore.
-Bill Fill snipped-for-privacy@msn.com Olympia, WA
...>

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The Bison collet chucks are very rigid so unless you want to take monster cuts the overhang isn't a factor. I like the Bison chucks but I would avoid their collets (the collets themselves, not the collet chucks).
Going with the 5C collet size gives you access to other low cost tooling, such as 5C collet blocks and indexers. I use these all the time on my mill, way more than I thought I would before I added collets to my lathe setup.
I'd go with a Bison collet chuck or make my own collet nose that extends far enough from the lathe spindle for the 5C's to fit. I'd use 3-1/2" or 4" cold rolled bar stock for the nose to make it nice and stiff. Then make a custom drawbar with 5C female threads on one end that necks down to a smaller size tubing that fits through the spindle. On the far end, use a quick release pin to allow the handle to come on and off quickly. The drawbar is then inserted through the front of the spindle and the handle is then pinned on the back end. Since you'll cut the 5C taper with the nose mounted right on the spindle it will have very low runout, likely better than the Bison chuck.
Good luck-
Paul T.
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Thanks, everyone, for your excellent advice. Even more alternatives, and the spindle swap looks like the best one for my case. Thanks again, David
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