Spindle Adapter

Ken S

Ken S

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I recently acquired a dividing head at the Grizzly tool sale in Springfield. I would like to use my lathe chuck on it but my lathe spindle is larger than the dividing head spindle. I thought about making a bushing but my threading skills aren't too good yet and I'll need to make a boring bar. I haven't tried to thread internally yet so I expect I'll making more than one of these before I get it right.
My question for you guys is, will a bushing work (assuming I get it threaded right) or should I just forget it and buy a another chuck? I don't want to end up with something that might never be accurate but I'm cheap enough and dumb enough to try it.

The dividing head had a threaded backplate that I could turn to fit my lathe chuck but the one in the chuck now is pressed in and something tells me it's a bad idea to try to continually press these in and out of the chuck every time I want to use the dividing head. I'm not that cheap.

Ken
 
Thread the ID and OD and faces in the same setup and it will be as concentric as possible.
 
There are several threads on this very subject on H-M. Do a little searching and reading. This is where you need to get your feet wet. There are several varieties of boring bars out there to consider buying. Rather is is an insert type of boring bar or one that accepts "square" shank tool bits, they are out there. Since Grizzly is near you go do some shopping for tooling. Also look for a insert boring bar that holds a threading insert so you can cut threads with. Grizzly show them in their catalog and they should have them in stock at Springfield.
Feel free to ask more questions if you need help, that's what we are here for.
 
Thanks guys, I searched for an answer to this question before I posted this and found nothing and just tried again with no results. Maybe I'm asking the wrong question. I really just want some assurance that using a bushing to fit a chuck to a smaller spindle is something that is commonly done and does work out well.
 
We call them back plates. The word "bushing" maybe confusing many of us. But that's ok, you're learning. And yes, this is commonly done and standard with most chucks out there. Try searching using the word "back plate" and see if you get something. If still no luck, let us know. Ken
 
4gsr said:
We call them back plates. The word "bushing" maybe confusing many of us. But that's ok, you're learning. And yes, this is commonly done and standard with most chucks out there. Try searching using the word "back plate" and see if you get something. If still no luck, let us know. Ken[/QUO


Thanks Ken, I found the posts.
Click to expand...
 
Please don't slap me around for this but I still don't find anything related to my question. I found these adapter bushings on e-bay that are sold for wood lathes. I just can't find one for metal lathes and that is why I'm questioning whether it is done on metalworking machinery. I know I can eventually produce a bushing to fit but I want to know if others have done it and if there is any loss of precision through the use of a bushing.

http://www.ebay.com/itm/PSI-Woodwor...le-Adapter-for-a-1-Inch-by-8TPI-/152133924119

There was a threaded back plate that came on the dividing head but what I read says it needs to be turned for a press fit. I would rather be able to use a bushing than have to press back plates out and in every time I want to use my chuck on the dividing head. It seems doable to spin my chuck off the lathe spindle, insert threaded reducer bushing, and spin it on the dividing head spindle.
 
Ken,
As long as the threads are a close fit and any shoulders are square to both you should be ok.
 
Hi Ken
I think I understand what you are trying to find and accomplish. Yes, this is quite doable and should be a good solution if made accurately.
In order to make the bushing/adapter as accurate as possible, using some form of a sequence of operations is necessary. If you read through the various descriptions about making back plates, you should notice a pattern. The first thing done is to get the rough stock mounted as concentric as possible, followed by facing, drilling, boring, and threading the spindle hole as necessary to thread onto the lathe spindle, all in one setup. Then, thread the adapter onto the spindle just as it will be used once completed. With it mounted this way, you can perform any operations needed to make it fit the chuck and the resulting work will be as accurate as your lathe is capable of producing.
Provided that you get good fits in each step, you should get a good overall result in mounting your chuck.
By the way, this is called the friendly machinist forum for a reason. We like to help each other and will NOT slap you around for asking questions and trying to understand what you are doing.
Good luck and if anything is unclear, just ask! :D
 
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