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Shop Built "Adjust True"

johnoder

Diamond
Joined
Jul 16, 2004
Location
Houston, TX USA
Had a real good K&T DH and a good chuck, so added studs to chuck and made oversize adapter that would allow set screws to push on sides of studs and adjust chucked piece dead nuts.

Photo below shows me putting flats on side of studs so set screws have a seat.
DCP_0763.jpg


Photo below shows parts. Maybe you can make out the bright ends on the set screws - surface ground them flat.
DCP_0764.jpg


Photo below shows putting the adapter on the DH. These K&Ts have #50, but with three tapped holes instead of the four found on a mill spindle.
DCP_0765.jpg


Photo below shows chuck installed on adapter, and with set screws installed. Took a little care to gets washers and nuts on studs in confined area.
DCP_0766.jpg


Last photo shows nuts and washers in the space I provided.
DCP_0767.jpg


John
 
Wow John, nicely done in a tight space!

I always wondered why dividing heads were not issued with 4-jaw chucks, that way the gear could be disengaged and the workpiece indicated concentrically before work begins rather than relying on the scroll in the 3-jaw chuck.

-Matt
 
John,

Pretty slick and ingenious idea using the chuck studs as part of the adjustru mechanism! I would have never thought of that. Nice job.

I did a similar thing. I modified a standard Bison 5" non-adjustu 3-jaw chuck & backplate into an adjustru chuck for my 6" L-W dividing head.

I machined a cast iron ring that had an .0005-.0010 interference fit to the recess on the back of the chuck. And modified the standard Bison backing plate to accept this ring. Then tapped the backplate 4 places w/ 5/16-24 set screws to bear against the ring, thereby moving the chuck during adjustment.

I still have the cad drawings I used to design and execute this. It has worked very well. The bison chuck had about .005 runout the fist couple times I used it. I made the adjustru feature when I had a need to get runout to minimum.

Here is the ring...
adjustru-ring%20.jpg


Here is a section view of the modified bison backplate...
modified-backplate.jpg


Here is a section view of the chuck, the ring, and the backplate...
adjustru-assy.jpg


Some additional detail on the assy cross section...
adjustru-assy-detailview.jpg


And a picture of the div head itself...
L-W_div-hd.jpg


It works great. I was worried about perhaps weakening the back plate but it seems quite stiff. I modified the original bison backplate. If I was making one from scratch I think I would thicken it up just a tad to be certain its quite stiff. But in practial use I'm able to get runout down to around .0005 or so and am quite happy with the results. As I'm sure you are with yours also.

Mark
 
Thanks all for kind comments.

Stu: Should work on any chuck. I did make the studs from fairly tough stuff (1990 Toyota Cressida cyl. head bolts), and I did use Loctite 271 to put them in the chuck body before milling the seats on the sides of the studs for the set screws to bear on. This way I knew the seats were perpendicular to the axis of the set screws. I have a total of .020" adjustment.

Mark: Thanks for sharing great drawings - very nice and compact. The extra piece is worth it. What software did you use on drawings and are they saved as jpegs? I know Solidworks models can be saved as jpegs.

John
 
Mark: Thanks for sharing great drawings - very nice and compact. The extra piece is worth it. What software did you use on drawings and are they saved as jpegs? I know Solidworks models can be saved as jpegs.

John

Well John I'll answer your question now... 6 years later. This is John--> :toetap:

Just kidding. I drew the models in AutoCAD Mechanical Desktop. An obsoletedCAD program superceded by Inventor.

The original .jpg's I exported were lost when I changed ISP's. I Still have the CAD files. They open in Solidworks w/ errors. But enough of the views show that the idea can be conveyed.

I have been pinged a few times by various folks for the images but they are long gone. Someone recently pinged me again, and I got motivated to capture some images in powerpoint and I made a .pdf. See the link below.

Link to PDF images
 
Here are the photo's of the adjust true.
The od is 6" and the main plate is .750 thick. The adjust plate is a light press fit to the chuck back and is about .5" thick.
I didn't even remove the bluing before setting it up the first time. It works very well if I do say so myself.

The main plate is recessed about .300 to slip over the DH spindle. You can see the large mounting bolts quite clearly, should be pretty strong.

I should probably mill some flats for the adjustment screws. I am not sure what the best solution is to allow the plate to move while doing the adjustment, normal setscrews seem to bite too much and resist slipping as you get tighter and tighter.
I will also number the setscrews and enjoy it every time I need to dial something in perfectly.

It's quite nice to now be able to use the spindle hole. The old chuck was mounted with a 40 taper L style mount. It stuck out really far and was not a good solution given all the work it took for someone to make the whole thing.


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IMG_2412.jpg
 
Here are the five non PB photos related to this thread and Post #1
 

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I can see your images in post #1 just fine - but I installed the photobucket fix in my Firefox browser. But I know not everyone has it. I need to repost my images now lost from post #6 & #9. Been through 2 ISP's since that orig post...
 
I like it, I went to the trouble of making a ring to bolt on the back of the chuck with 4 setscrews through the ring so it works like a real set tru chuck. Your solution looks great.
 
My dividing head came with a new chuck with .003" runout, which was unacceptable to me.

I turned the register boss on the back plate that centers the chuck down just over 1/2 the runout smaller and drill/tapped 8 setcrew hole through the outside rear of the chuck so that 2 setscrews impinge close to each other every 90 degrees, done this way because the register boss was too narrow for larger screws.
In use I loosen the three socket bolts that hole the chuck to the back plate and tighten/loosen the 8 setscrews to force the chuck to center, and am very happy with how it works. This dividing head's chuck now has less than 1/2 thousandth runout from close to the chuck face up to 4" out.
If the scroll is not perfect and the runout returns at different work piece material sizes I can readjust it in a few minutes.

I've often wondered if anyone else had done anything like that, because it's such an obvious fix. Because it' so obvious I started thinking there must be something wrong with the idea that I wouldn't see until it was too late.

But then I thought making a new back plate isn't a big project so I could make it back to where it was easy enough.
 








 
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