# Lathe Lead Screw Bearing Support Question



## rfdes (Jan 6, 2015)

I was wondering if someone has direct knowledge regarding the lead screw support bearing using the square block, pinned against a mounting plate like Atlas used on the newer 12" lathes.  The older, cast Zamak, bearing was built to break away when a collision would occur with the carriage and headstock.  Looking at the pictorial, how is this style bearing meant to provide a similar protection?  I need to make a replacement bearing for my 10F lathe and want to use this design.  I also see two thrust bearings which I am a bit confused about, I wouldn't think that they would necessary.  It's likely I'm missing something here.  If someone would please give me some additional insight, it would be appreciated.

Thanks
Jim


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## Rob (Jan 6, 2015)

The newer QCGB had a clutch on the output.  There is a procedure for adjusting it so if you did have a issue it would slip.  I will post some pics later of one that I made for my lathe.


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## Rob (Jan 6, 2015)

rfdes said:


> I was wondering if someone has direct knowledge regarding the lead screw support bearing using the square block, pinned against a mounting plate like Atlas used on the newer 12" lathes.  The older, cast Zamak, bearing was built to break away when a collision would occur with the carriage and headstock.  Looking at the pictorial, how is this style bearing meant to provide a similar protection?  I need to make a replacement bearing for my 10F lathe and want to use this design.  I also see two thrust bearings which I am a bit confused about, I wouldn't think that they would necessary.  It's likely I'm missing something here.  If someone would please give me some additional insight, it would be appreciated.
> 
> Thanks
> Jim
> ...



As I said earlier this one is made for use with a newer QCGB with a clutch on the output.  The thrust bearings would make it so you could tighten the lead screw nuts tighter to remove some backlash.  

Here are some pictures on what I made for my 12 inch Craftsman.  I made with flanged bushings pressed into a larger bushing.  The large bushing is 1" OD and 3/4" ID and the 2 flanged bushing is 3/4" OD and 1/2" ID. I made the bracket from CRS. The bushings are held in by aluminum screws, this gives the brake away feature.  This made the outside diameter larger than the washers on the lead screw allowing the lead screw with nuts and washers to push the bushing out of the bracket should a problem arise.


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## Mondo (Jan 7, 2015)

Rob:

Have you ever tested this bearing to see if it works and how much force it take to push it apart?


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## Rob (Jan 7, 2015)

Spiral_Chips said:


> Rob:
> 
> Have you ever tested this bearing to see if it works and how much force it take to push it apart?



No, I have not tested other than to make sure the bearing would slip out of the bracket easly. I wasn't sure of using 1 or 2 screws to hold it in but went with 2 as I have twisted other aluminum screws in half without much force.


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