Adapter Plate to Chuck Question

[JR49]

I will soon be buying a new import 8" 4 jaw independant chuck for my 12" logan. I plan to also get a threaded adapter plate for the 2 1/4 by 8 tpi spindle. I realize that, other than the threads being cut, the rest of the machining to fit chuck to adapter will be done by me. I'm pretty comfortable with that, (thanks to the info I gotten here), except for one thing. I was recently told by a supplier that some models of Logans have a very slightly larger OD spindle register, than most of the other 2 1/4 by 8 spindles (Southbend, for example). He said that wasn't hard " just take a few thou. off the ID of the plate register" Here is my problem. How do I mount the adapter plate BACKWARDS so that I can "take a few thou.off the register" PS. All I have now is a 6" 3 jaw. Thanks, JR49

 

[Don B]

Don't take this for the gospel truth, but they probably meant with the back plate mounted (threaded on) the spindle but I'm not familiar with the lathe, best to post a picture when you receive it someone will be better able to advise you then.

 

[110octane]

If it becomes necessary to do this, (As Don B posted, please wait and see if the register needs a little boring), you can take a suitable piece of pipe or tubing and using it as a spacer, thread the adapter plate on "backwards" to bore the register. Just make sure the slice of tubing you chose or make allows the register bore of the adapter plate to "stand proud" of the threads on the spindle so you can work to the shoulder without damaging the spindle threads. If you have another chuck you can square up the spacer. If not, just making as square as possible saw cuts should work just so long as the spindle threads are not exposed to the boring tool.
Work carefully (of, course) you don't want to cut into the spindle.

Regards, Geoff

 

[retmac]

If it becomes necessary to do this, (As Don B posted, please wait and see if the register needs a little boring), you can take a suitable piece of pipe or tubing and using it as a spacer, thread the adapter plate on "backwards" to bore the register. Just make sure the slice of tubing you chose or make allows the register bore of the adapter plate to "stand proud" of the threads on the spindle so you can work to the shoulder without damaging the spindle threads. If you have another chuck you can square up the spacer. If not, just making as square as possible saw cuts should work just so long as the spindle threads are not exposed to the boring tool.
Work carefully (of, course) you don't want to cut into the spindle.

Regards, Geoff

If you have a face plate clamp it to the face plate indicate it true and bore to size required.

 

[GarageGuy]

I'm just guessing, but I know on my Logan 820 there is about 3/16" of smooth spindle shaft (register?) on the head stock side before the threads start. Maybe he is referring to this? If so, you would just use a small spacer like 110octane suggested, and then turn a small shoulder inside on the head stock side. I made some spindle thread protectors, and have done this on all of them. It is quick and easy. Here is a photo of the relief on the inside.



The flare from the flash makes it a little hard to see, but there are two steps before the threads start when looking at the back side. I can take a better photo if it would help. Hope this helps!

GG

 

[JR49]

Guys, all great answers, thanks. I had considered screwing it on BACKWARDS as 110octane suggested, BUT, I have read many times "it is not the spindle threads that holds the chuck or ? true to the spindle IT IS THE REGISTER". So, I am afraid that, with the plate being on backwards, and not on the spindle register, it won't turn true enough to bore the new plate register perfectly, (and after all ""THE REGISTER IS WHAT KEEPS EVERYTHING TRUE AND CONCENTRIC"". if that is actually correct?) I also thought about buying a faceplate, but I'm afraid I'll have the same situation with a threaded faceplate. You may think I'm being premature, worrying about this (yes, I'm anal), but I have a reason! I actually have a spindle thread protector (garage sale 5 bucks) that was used on a Southbend lathe that looks just like the picture in GarageGuy's post. And yes, what I'm calling the register is the smooth area before the threads. It screws on my logan spindle perfectly, BUT STOPS, when it gets to the "smooth area"/ register of the spindle (ID too small). Hence, the questions. Please help me sleep better, this is driving me nuts! Thanks JR49

 

[Don B]

Hence, the questions. Please help me sleep better, this is driving me nuts! Thanks JR49

Your driving yourself crazy for nothing, LOL, until you get it and take a few measurements and do some indicating there's no sense worrying, if it's threaded and bored then you have something to indicate to regardless if it's on backwards or not, and that should be a good indicator as to where you should go from there, if the front is rough that might make it sit a little cockeyed, you may need to thread it on the proper direction first (even though it doesn't go all the way) and take a light truing cut on the face to get things parallel, then flip it around and work from there, but until you get it and see what your working with there's a thousand scenarios and you might be worrying about the wrong ones, put your feet up have a beer and wait for the UPS guy.)

 

[JimDawson]

Guys, all great answers, thanks. I had considered screwing it on BACKWARDS as 110octane suggested, BUT, I have read many times "it is not the spindle threads that holds the chuck or ? true to the spindle IT IS THE REGISTER". So, I am afraid that, with the plate being on backwards, and not on the spindle register, it won't turn true enough to bore the new plate register perfectly, (and after all ""THE REGISTER IS WHAT KEEPS EVERYTHING TRUE AND CONCENTRIC"". if that is actually correct?) I also thought about buying a faceplate, but I'm afraid I'll have the same situation with a threaded faceplate. You may think I'm being premature, worrying about this (yes, I'm anal), but I have a reason! I actually have a spindle thread protector (garage sale 5 bucks) that was used on a Southbend lathe that looks just like the picture in GarageGuy's post. And yes, what I'm calling the register is the smooth area before the threads. It screws on my logan spindle perfectly, BUT STOPS, when it gets to the "smooth area"/ register of the spindle (ID too small). Hence, the questions. Please help me sleep better, this is driving me nuts! Thanks JR49

With the face plate it really doesn't matter that much as long as it is not ridiculously out of square and round. The first thing you do with a new faceplate is take a truing cut on the face to align it with your lathe.

Since you are installing a 4 jaw with a new back plate, the above applies also. Before you mount the chuck, you are going to true up the backplate, and also turn the register flange to fit the chuck.

As a side note, there is medication for that.:roflmao:

 

[JR49]

With the face plate it really doesn't matter that much as long as it is not ridiculously out of square and round. The first thing you do with a new faceplate is take a truing cut on the face to align it with your lathe.

Since you are installing a 4 jaw with a new back plate, the above applies also. Before you mount the chuck, you are going to true up the backplate, and also turn the register flange to fit the chuck.

Jim, or anyone, see: first paragraph-last sentence above. HOW do I "take a truing cut" if the faceplate will not screw completely up on to the spindle register ?? see: second paragraph. HOW do I do either of the 2 things mentioned without FIRST machining the backside of the backplate to fit on to the spindle register?? Maybe my original question should have been: If I screw the new backplate on to the spindle BACKWARDS (chuck side of backplate facing the headstock) will it turn true enough being just on the spindle threads, not on the register, to be able to bore about 10 thou. of the ID of the backplate register ? Hoping for an answer, JR49

 

[JimDawson]

With the face plate it really doesn't matter that much as long as it is not ridiculously out of square and round. The first thing you do with a new faceplate is take a truing cut on the face to align it with your lathe.

Since you are installing a 4 jaw with a new back plate, the above applies also. Before you mount the chuck, you are going to true up the backplate, and also turn the register flange to fit the chuck.

Jim, or anyone, see: first paragraph-last sentence above. HOW do I "take a truing cut" if the faceplate will not screw completely up on to the spindle register ?? see: second paragraph. HOW do I do either of the 2 things mentioned without FIRST machining the backside of the backplate to fit on to the spindle register?? Maybe my original question should have been: If I screw the new backplate on to the spindle BACKWARDS (chuck side of backplate facing the headstock) will it turn true enough being just on the spindle threads, not on the register, to be able to bore about 10 thou. of the ID of the backplate register ? Hoping for an answer, JR49

I was suggesting that if you decide to use a faceplate that it is a lot more forgiving than the chuck backplate. I don't think I was clear on that point. Agreed that you may have to take a cut on the register, but it is not that critical. It will still mount the same way every time. Once you can screw it on in it's normal orientation, even if the has some axial runout, you can fix this with a facing cut. Also you might want to take a cut on the OD just to make it run true in the radial plane.

Once you have the face plate running true, then mount the chuck back plate on the face plate and size the register to fit.

EDIT: To answer your last question, you really won't know until you get the backplate, screw it onto the spindle backwards, and then put an indicator on the register surfaces to see what the runout is. If the runout is less than what you have to bore, I would say there is no problem. You have to machine the chuck mounting surface(s) when you turn it around anyway.