New Project. Chuck Back Plate.

[Xnerd]

If you don't mind how it looks you could just turn it down intersecting the extra holes. Most back plates match the diameter of the chuck but this is not mandatory. The back plate can be a little smaller or even theoretically larger. The registration boss is the critical diameter.
Robert

Thank you very much for the fast response.

I assumed that was the case as I tend to overthink everything. However being so new to Machining I figured I better get a qualified response from someone that knows more than me. The funny thing is I have for other Chucks and every single one of them the backplate is noticeably smaller then the Chuck itself. That should have been my first clue LOL.

The Chuck should be here anytime now I'm getting very excited LOL. I just got done meticulously measuring the intrinsic runout on my spindle which was barely readable perhaps one ten thousandths if that. I don't know if that's really high or low before a lathe built in 1946 I'll take it.

This will be my second backplate that I've ever made but again the last one was unsuccessful because the scroll itself ended up being the problem. So I guess I can't really say that I failed at making the backplate it just did not solve the problem LOL

Thank you for allowing me to briefly hijack this thread

Jeff

Can I junk phone in and ask a related question?

I have a 3 jaw Chuck coming ups in the morning.
I have a 7.25" used backplate that was a failed attempt to fix very old chucks runout issue.

I would like to use this for the little 6 inch chuck that is coming as it is still new, unmarked and.. .80 thick over all.

My problem is that the old mounting holes will indicate up being right at the edge of the new chuck. Just barely!
Csn I turn this backplate down 100 thou smaller then the new chuck? I looked at all of my chucks and it seems like every one of them is a little larger than thier mated back plate...

Is this the way it is done typically?

I really don't want to wait to get another new blank BP and trash this one simple because there is a 16th inch over lap with the old mounting holes.


Anyone?

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[Xnerd]

If you don't mind how it looks you could just turn it down intersecting the extra holes. Most back plates match the diameter of the chuck but this is not mandatory. The back plate can be a little smaller or even theoretically larger. The registration boss is the critical diameter. Just plan out where the new mounting holes will fall. You don't want a counterbore extending through the O.D. of the back plate. If you look at my pic above you will see how close the counterbore is to the edge. Counterbore is not mandatory but it is safer to have the screw heads recessed.
Robert

Here's another quick question. I jumped into this Chuck rather hastily before researching a great deal. I needed a 3 jaw badly so I just went ahead and purchased it. I chose the one with the removable two piece Jaws. Everyone says you'll be glad you did. But I want to know why what is the advantage of these other than quick inverting?

Thanks in advance

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[brino]

I chose the one with the removable two piece Jaws. Everyone says you'll be glad you did. But I want to know why what is the advantage of these other than quick inverting?

With two piece jaws you can make your own sacrificial soft jaws to hold weird shaped items and simply cut right into them when machining the work piece. Good choice.

-brino

 

[Xnerd]

Does money post repeat like 12 times to everyone else I hate the software this tab touch software I am going to uninstall it for the second time the only thing is if I use a browser this forum is unacceptable to me it is nothing but advertisements that fill the text boxes so you can type in them it's some kind of weird forum bug. It was so bad on my desktop PC I did it clean install of Windows to see if it could have been a virus or something but nope same thing anyway I apologize if my post actually did repeat this many times

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[brino]

Does money post repeat like 12 times to everyone else

I only see a single copy of your post.
I have only ever used Firefox on Win7 to view and post here........and it works great!
-brino

 

[Xnerd]

Here's another question please forgive me alright I'll turn the radius perfectly and by the way those old bullet holes just disappear at the perfect size so it worked out good. But if I go to turn the back of the backplate the part that faces the headstock of course it will not thread in all the way because the spindle nose runs out of threads before it gets all the way up to the head. So how do you get that inherent wobble from the threads out of there I cannot bottom it out is typical when you put it Chuck it will buy them outright at the lathe click. And any thread has an inherent wobble to it so if I turn the thing facing the lathe it's going to have a wobble in it if I turn that wobble out its artificial do I just leave the back of the backplate alone?. I did not even think about this the first time I made one.

There's a ton of meat around the part of the backplate that protrudes with a threading in it and there's about three quarters of an inch not threaded

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[Fortis64]

Good job ..... I was nervous as hell doing mine ,and i did muck it up a wee bit . Good learning experience all the same .

Sean

Presto!
All done and mounted. The side body of the chuck near the back plate run-out is .001". I can get a 3/4" end mill to run at .0005" run-out. Hoowweeeveer... on the face of the chuck I have a .007 run-out. I will have to go back through everything and find that. It causes a mild vibration. Gotta find and eliminate it. I assume it might be a chip or a burr somewhere in my backplate bolt holes. Because when I metered out the back plate after the last pass it's run-out was negligible.

Having never used a 4 jaw chuck before it appears there is definitely an art to centering a piece in 4 independent jaws. Took me a few mins to remember whether I need to screw in or out specific jaws to obtain a reading I desire.

Slacken your lows tighten your highs ... and set the jaws by measuring the work piece and get the jaws near size ..

 

[JR49]

But if I go to turn the back of the backplate the part that faces the headstock of course it will not thread in all the way because the spindle nose runs out of threads before it gets all the way up to the head

Find a short piece of pipe with an ID big enough to fit over the spindle threads and butt against the vertical part of the spindle register, and just long enough to butt the chuck up against it before running out of threads. (a spacer) The pipe doesn't have to be a tight fit radially (spelling?) but the ends must be perfectly concentric. Hope this helps, and hope I used the word concentric correctly, JR49

 

[Xnerd]

Find a short piece of pipe with an ID big enough to fit over the spindle threads and butt against the vertical part of the spindle register, and just long enough to butt the chuck up against it before running out of threads. (a spacer) The pipe doesn't have to be a tight fit radially (spelling?) but the ends must be perfectly concentric. Hope this helps, and hope I used the word concentric correctly, JR49

I was thinking about doing that very thing and I was thinking of my head where is there a space you're big enough around here I'll probably have to make one. But the thing is I was thinking it doesn't matter if there's a face wobble in the back side of the backplate as long as it part that is connected to the truck is absolutely perfectly flat and parallel to the axis Centerline. So what I'm going to do to prove my theory is I'm going to complete the chuck with the wobble in the bag played in the perfectly flat front I'll make sure that I don't use the back as reference for anything going forward and then if I have wobble in the end I will back up. I'll make a spacer square off the back of the backplate reface the front of the thing and call it good.

Thank you for the help.

By the way I think concentric is when two cylinders or cylindrical objects are in perfect alignment I'm on the same plane? Please correct me if I'm wrong someone.

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[brino]

The pipe doesn't have to be a tight fit radially (spelling?) but the ends must be perfectly concentric.

I think you mean square.

By the way I think concentric is when two cylinders or cylindrical objects are in perfect alignment I'm on the same plane? Please correct me if I'm wrong someone.

Really, it's when two circular features have the same centre.

-brino