Mounting a "plain back" Lathe chuck (My way!!)

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GlennW
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Mounting a "plain back" Lathe chuck (My way!!)

Post by GlennW » Sat Oct 10, 2009 9:19 pm

I had a little free time this afternoon, so I figured I’d mount up another chuck for the lathe. It is a spare, used, “plain back” 6 inch three jaw chuck from my old lathe that I occasionally use n my rotary table. The subject of mounting plain back chucks pops up occasionally sop I thought I would post this.

My lathe of choice has a D1-5 Camlock spindle so I purchased an appropriate $58.00 6” cast iron adapter plate from Shars

Adapter plate on the left, chuck body on the right as I had already disassembled the chuck for cleaning and lubing.

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Next step was to place a few dots of Prussian Blue on the taper and face of the adapter plate and then mount the adapter plate on my spindle and check the face runout and marked the high spot. I then removed it and found that it had excellent contact with the spindle as evidenced by the Blue. I installed it again and checked the face runout once more and found it to be the same so the adapter plate is seated properly. If you have a threaded spindle lathe just make sure everything is clean and screw the adapter plate on and check the runout, remove it, inspect it for any dirt that may have kept it from seating properly and install it again. If the runout is the same, you’re good to go. I always make an index mark on the adapter plate that corresponds with the index mark on the spindle and tighten the camlocks in the same order each time for repeatability.

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Next is to make a facing cut to just clean up the surface. Not really necessary, but I do it.

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This is what a “plain back” chuck looks like on the backside (side that mates up to the adapter plate. Note that it has a recessed area about ¾” in from the OD. This recess is what will locate the chuck so that it will be coaxial with the spindle axis.

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The object of the game is to machine the adapter plate so there is a register that fits snugly into the recess on the back of the chuck. I prefer to make make it a .0005” to .001” press fit.

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Now the fun part. As can be seen in the pic of the back of the chuck, there are six mounting holes that are tapped for 10mm bolts. When using a threaded spindle adapter plate you would drill the adapter plate for 10mm bolts and then install the bolts through the plate into the chuck to secure it. With my Camlock spindle having a larger OD, I prefer a different method as I would have to counterbore the adapter plate for the bolt heads so they would not interfere with the spindle. Therefore I choose to “front mount” the chuck which means that the adapter plate will be drilled and tapped for mounting bolts and the chuck will be drilled to allow the bolts to me installed from the front side of the chuck.

First I centered the Super Spacer under the spindle and zeroed the dials.

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Then since the existing bolt pattern on the chuck was 140mm I moved the Y axis 70mm (I hate Metric) I then chucked up the chuck, located the existing hole and through drilled the chuck for 5/16” 18 socket head cap screws since I don’t have any Metric drills, counterbores, or cap screws. (I don’t do Metric) The 5/16” through holes do not interfere with the 10mm threaded holes so the chuck could still be used on my old lathe if needed.

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I then flipped the chuck over and used my 5/16 Cap Screw Counterbore to counterbore for the heads of the cap screws. Chamfer the edges of the holes and it’s ready to go.

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Next was to chuck up the adapter plate in the Super Spacer (handiest thing I own!) :D :D and drill and tap it for the Cap Screws to secure the chuck to it.

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And here is the chuck bolted to the adapter plate with aluminum soft jaws installed and the whole deal mounted to the spindle.

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Now I have a dedicated soft jaw chuck, as with the Camlock spindle I can change chucks quicker than I can change jaws! I also picked up a set of aluminum pie jaws machined from round bar for it, both from US Shop Tools at a good price!

Now that the chuck is front mounting, it makes it easier to bolt to my rotary table as I can leave the adapter plate centered and mounted to the table and install the chuck when needed.
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

Jose Rivera
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Post by Jose Rivera » Sat Oct 10, 2009 10:18 pm

Nice job Glenn !!! 8) 8) 8)
There are no problems, only solutions.
--------------
Retired journeyman machinist and 3D CAD mechanical designer - hobbyist - grandpa

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Frank Ford
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Post by Frank Ford » Sun Oct 11, 2009 5:36 pm

I did a front-mount one like that myself earlier this year, using one of those cheap 4" chucks from CDCO. I also cut down the hardened set of outside jaws to make little shorty ones. It's now dedicated to working on screw ends, and other things that need to be held close, but which have heads or other large features that keep them from being gripped in regular chucks:

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It fits right over my lathe's 5C collet nose, so I can use a rod in the collet as a work stop for repetitive cuts.

I'm currently assembling the full set of photos to post on Home Shop Tech.
Cheers,

Frank Ford

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GlennW
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Post by GlennW » Sun Oct 11, 2009 5:50 pm

Good stuff Frank!

I've got two 4" chucks lined up on the bench right now. One will be a 5C mount and one will be a D1-5 adapter plate mount. Both will be converted to be adjustable and front mount. I don't like spinning a chuck any larger than it needs to be to hold the work as I'm one of those "speed demons" that could never ave enough spindle speed!

Collets are great.....as long as the stock fits in them! Things like small diameter cast bronze bar and 4140 pre hard don't like to be stuffed inro collets, hence the small chucks.
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

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Frank Ford
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Post by Frank Ford » Sun Oct 11, 2009 7:57 pm

Yep. I'm with you, Glenn. Can't have too many chux! I just counted and I have nine for my Hardinge clone at this point, many from eBay. I found that things like the six-jaw set-tru Buck will sell for about half price if it has only one set of jaws, so I buy chucks that are missing a set, then find the matching ones missing the other set. So instead of changing out jaws, I pop one chuck off and another on in about five seconds.

I also converted one of those CDCO 3" chucks to set-tru for use on my tiny Rambold turret lathe. Took a bit of doing, but it was a fun project:



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Unlike the Buck, mine is tightened from the back:

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As usual, here's the whole story:

http://www.frets.com/HomeShopTech/Proje ... chuck.html

And yet another chuck mounting adventure:

http://www.frets.com/HomeShopTech/Proje ... bison.html



I think I've become a bit addicted to making tools for my tools. . .
Cheers,

Frank Ford

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GlennW
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Post by GlennW » Sun Oct 11, 2009 8:06 pm

Frank Ford wrote: I think I've become a bit addicted to making tools for my tools. . .
I refer to that as having to work my way to work!
Frank Ford wrote: I also converted one of those CDCO 3" chucks to set-tru for use on my tiny Rambold turret lathe. Took a bit of doing, but it was a fun project:
.
I've got an adapter drawn up in ACad to make those little fellas adjustable, but just havn't gotten around to turning one out and mounting it!

One of the 4" chucks is for a T&C Grinder and will be set up to fit my Dividing Head.

Thanks Frank!
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

Harold_V
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Post by Harold_V » Sun Oct 11, 2009 11:36 pm

Glenn Wegman wrote:Collets are great.....as long as the stock fits in them! Things like small diameter cast bronze bar and 4140 pre hard don't like to be stuffed inro collets
That's where the Jacob's Rubberflex collets shine. Sadly, I believe they are no longer made. Not great for gripping short objects, but they work quite well otherwise.

Harold

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GlennW
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Post by GlennW » Mon Oct 12, 2009 7:05 am

And then there are the Pie Jaws.

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I need them to hold a part by it's I.D. so I needed a way to pre-load the jaws prior to machining them to accomodate the part. I spun out a ring from a slice of large aluminum tube and tapped it for three adjusting screws.

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It fits in the dimples that I cut in the jaws with a ball end mill. I dimpled the standard soft jaws too.

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Now I can easily pre-load them prior to machining them to accomodate the part!
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

nealdraper
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Chucks

Post by nealdraper » Wed Oct 14, 2009 1:55 pm

Glenn and Frank,

Beautiful work! You gentlemen, and many others here as well, are an inspiration to newbie wanna-be machinists such as my self. The vast amount of knowledge and professionalism here are truely amazing.

I am very happy to have found this site, and hope to see many more projects such as these, and to be able to continue to learn from everyone here.

Neal (both awed and inspired).

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GlennW
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Post by GlennW » Wed Oct 14, 2009 3:11 pm

Hopefully these posts will inspire or aid someone, as that was the purpose of it. :)

Thank you Neal!
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

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