View Full Version : RT/Chuck Mod.

A.K. Boomer
04-12-2008, 11:27 AM
Well I gave up, I was gonna design some chuck jaws that slipped right into the RT table and did there thing, turns out it would have took some doing as I wanted to use the table as is and not modify --- I also wanted to utilize the tables slots as the jaw slots and not just bolt some massive adapter to them that held the jaws and tightening mechanism,

So anyways --- its kinda small but I took my R8 chuck and mounted it to a face plate I built that then mounts to the RT table, I modified an MT3 JT6 arbor -- the arbor is designed to fit into the rotary table -- the JT6 end is machined down to self align the chuck to the table, it can also be left out if I want to do eccentrics, Also if its a light duty task I can just use the center to tighten it all down as I drilled through the arbor, I have always installed a "floating" nut that I machined down that fits into the bottom of my RT table before I clamp it to the mills table (I actually put my largest stud on it and use it to lift the RT onto the mills table anyways --- then just undo the stud and let the nut float --- sometimes its nice to mount things this way from the center) As one of my main goals when designing something is whenever your opening other doors of opportunities up try not to close any windows behind you ;>}

First Pic shows the stock R8 chuck mounted to the mills spindle and the faceplate on RT table with the modified arbor.


This pic shows the swap (only three bolts) And also the arbor in with center stud for quick mounts.


And this pic shows it mounted using the outer flanges


The shop foreman gave her approval (after she awoke)


04-12-2008, 11:57 AM
Very nice, a good idea with lots of future possibilitys too. About the chuck? is it a plain back? How about the r8 adapter, factory made or home made? JIM

04-12-2008, 01:19 PM
Why the hell would you mount a lathe chuck to an R-8 arbor?!?


A.K. Boomer
04-12-2008, 01:25 PM
Thanks Jim, Im not sure about the chuck as I dont know what "plain back" is, its got a recess for alignment and stability purposes ---- ? The R8 chuck is a total factory unit that you can buy for about a hundred bucks, I use the hell out of it cuz I aint got no lathe...

A.K. Boomer
04-12-2008, 01:36 PM
Why the hell would you mount a lathe chuck to an R-8 arbor?!?


Same reason I mount this where you see the rotary table, cuz it saved me from buying a lathe that I dont need --- cuz a hardinge super precision is just 4 blocks away :D (this set-up gets me by on those late nights when im drinking too much wine and dont want to shut-er-down fer nuthin... just flop the head down on the hoe, lock the quill knob and you would not believe how stable.


Paul Alciatore
04-12-2008, 03:28 PM
I like the floating nut idea. I assume it has a back that fits in the table slot to prevent rotation.

I used an even simpler method of attaching a chuck to my RT. I bought a import, plain back, four jaw for a really reasonable price. Four jaw to allow precise centering as three jaws are always a bit off as we all know. The outside 3/4" or so of the chuck's main casting is solid CI except where the jaws fit so I drilled three long 3/8" holes completely through the chuck in this area to match the 120 degree spacing of the RT's slots (mine has six but it would work for four also). Three long 3/8" grade 5 bolts, washers, and three standard tee nuts and the chuck is mounted. Nothing could be simpler.

I do a rough centering with a square set to gauge the distance from the OD of the table to the OD of the chuck. I can easily get it +/- 0.010 this way and that is all that is needed as the work will be properly centered using the four jaws. I have written down the setting so this does not take long.

This avoids any mounting plates so the chuck sits as low as possible. This would be an advantage for any tall jobs. But a MT plug could be made to quickly center the chuck if desired.

I do have a MT plug with a 0.400" reamed hole in the center that I use for centering the table below the spindle. A 0.200" edge finder fits nicely in this hole and it takes only a couple of minutes to find the precise position. I added a tapped hole below the 0.400" section to screw in a puller (bolt with sliding weight) for easy removal.

A.K. Boomer
04-12-2008, 05:34 PM
I like the floating nut idea. I assume it has a back that fits in the table slot to prevent rotation.

Good stuff Paul, the nut fits up into a recess and has a shoulder on it, its basically all round and all I do to get it started is push the stud down while turning, then I pull the stud up -load it while turning, this allows me to keep track of how many threads are in, then I put the top nut on and it usually spins on without the stud moving further in, if that starts to happen I just side load it some and it usually works.

I added a tapped hole below the 0.400" section to screw in a puller (bolt with sliding weight) for easy removal.

Bingo, I dont have a tap the right size but this is the last thing I need to do, right now I cant use the center align and bolt it down because then I will have to remove the table to punch out the MT3, I can fake it with just placing it in there and using the outer bolts though its not going to be as accurate because the taper is not seated properly --- Good stuff from a guy who's already been there (you:) ) And yes I was planning on using my slide hammer also although a little spacer with a bolt through might due nicely, It should be a nice addition as iv missed this and know it will come in handy.

Edit; One unforeseeable (on my part anyways) Now my chuck key wont work as its a stubby with a locked T-lock handle, so Now I have to build one thats longer so it clears the table top, no big whoop.

04-12-2008, 08:38 PM
Hmmm... Ok, looks workable. A little outside the box, but then again, I do a lot of stuff like that too. I have seen lathes chucks on horz mills doing the same kind of thing. Could be just the thing for that odd sized job. I would not go as far as to say it is Hardinge precision, but I won't knock it till I try it. I have seen the ebay seller 800watt selling them, and always wondered what they were for. I just thought people were holding tooling with them who did not know the right way. I like the R/T.


A.K. Boomer
04-12-2008, 08:58 PM
Doozer Its been quite awhile but I believe thats the seller I got it from (800watt)

My comment about the Hardinge SP was not a joke, its my friends who lets me use it whenever, (thats why its kinda hard for me to invest in a "real" lathe)

04-12-2008, 09:12 PM
Good onya Boomer.

A great exercise in "lateral thinking" and "thinking outside the box/square".

The "precision lather-levelers" are going to be frantic and may well "freak out" - you might well have a lot to answer for!!!

I like it - really.

And if you tilt the head you have a damn fine taper-turning attachment with a good "fine feed" built in and a speed that will be lower that many lathes can get to as well.

04-12-2008, 09:44 PM
Tilting the head and feeding the knee will make a taper.
Tilting the head and feeding the quill will not make a taper.


04-12-2008, 09:47 PM

04-12-2008, 09:50 PM
Pretty slick.
Nice lookin pooch too. I think I have her twin?

04-12-2008, 10:01 PM
Tilting the head and feeding the knee will make a taper.
Tilting the head and feeding the quill will not make a taper.


Oops - sorry Doozer.

I didn't think my reply right through - as I should have. Thanks for picking me up on that.

You are quite right - mostly - particularly if it is a round column mill and if the "left-right swing" cannot be eliminated.

My mill is an RF-45 square column mill with a "Z" dove-tail and so my down-feed on that axis is "usable" but not as good as the fine feed on the quill on the mill head.

I jumped in too quickly there.

When I did do it, I bolted an angle plate to the mill table and fixed a simulated top-slide to the angle plate and used the "top-slide" "feed". It was a bit of a "Heath Robinson" (UK/OZ) or "Rube Goldberg" machine, that worked - just.

(For use as "HSM trivia" items??).

A.K. Boomer
04-12-2008, 10:45 PM
I dont feed with the knee, I feed with the X and Y depending on whether im facing boring or turning, I only use the knee to dial in proper tool hight and then everything in my quick change is pre-set.
My mills got a right and left head position swing -- I throw the head down 90 degree's to the left to mimmick lathe function, Tiffer is actually correct (and so are you for what you were saying) as in this position if I had a head tilt knuckle (a fore and aft) then I could create a taper with it -- but my mill does not have this knuckle --- It is however a turret mill in which the entire upper mass swivels --- So I can indeed create a taper if needed --- I have not had to and dont EVER move the turret because I have it dialed perfectly for the lathe mode and its dead nuts on...

I have to add that I cant thread and also cant use a tailstock, but most all of what i do is small hub work and it suits me fine as my friend has two great lathes not far away...

04-12-2008, 11:25 PM
Well hell yeah Im liking it Boomer!!!! :))

First off, good pics. Second, great machining work. And finally I am envious of folks that can think up work arounds for their needs. That is the machinists mentality!!! Great job!!!!! JR

A.K. Boomer
04-13-2008, 10:00 AM
Thanks fella's, Even a blind pig finds an acorn once in awhile (one of my pops olds sayings:) )

08-13-2008, 10:57 AM
Bridgeport used to make an attachment for turning their mill into a lathe. Lay down the head,indicate it in true with a special test bar.Came with a lathe cross slide and compound,and a tailstock. I'd hate to have to go to the trouble to change the mill,re tram it in before and afterwards,etc.,just to have a non screw cutting lathe. plus,the attachments cost a lot.You could have bought a lathe. Unless onboard a ship with no space,I don't see the point. Most ships' primary machine is a lathe with a milling attachment.