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Sheldon Qcgb Gears

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Hardtack

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#1
Hi everyone. Im hoping I can get some advice on what I should do. I have a EXL-46-B. Im hoping to remove the QCGB and replace 3 gears. First, I want to ask if there are any sticking points or steps during the removal of the QCGB I should know about? I do see a roll pin on the bottom of the box near the bolt heads. Also, once I remove the gear box, I need to change out 3 gears inside. Are there any stumbling blocks to that process I should know about? Im sorry I don't know what those gears are called, but they are the 2 largest gears furthest to the right side when facing the gear box. Also directly underneath those 2 larger gears is another gear that is on the shaft that connects to the lead screw. I would like to replace those 3 gears. Does anyone know where I might be able to purchase those gears? Any advice you can offer me is so much appreciated. Thank you so much.
 

CraigB1960

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#2
Your QCGB should have the two levers, if so, you got to remove the lead screw's roll pin at the gearbox and slide it off the gearbox shaft. Next, I remove the left side end gears/banjo to reduce the weight. The last step is there are 3 bolts holding the box to the lathe, two on top and 1 on the bottom (1/2" head).

A picture would help me visualize which gears you are talking about or reference the link that has the diagram and part name.

There is not a ready source for replacement gears. Most folks look on eBay and buy a complete QCGB when they become available. Do you have the parts manual? It will show the exploded view of the gear box.

I have provided a link to my dropbox with the pages to the left side end gearing and QCGB. It should help you disassembling it. (There are some collars with set-screws and small snap rings that have to be removed).

https://www.dropbox.com/s/mhvka7gzlevui7f/QCGB.pdf?dl=0
 

Hardtack

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#3
Thanks so much Craig for the exploded view link. It was very helpful. The parts I hope I can eventually find include;
#33 L-1624--28 Tooth Gear
#23 L-1614--28 Tooth Cluster Gear
#47 L-1683--32 Tooth Cluster Gear
If anyone knows where I might be able to locate these, it would be much appreciated. Thanks.
 

Gene1934

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#4
Did you find those gears yet? Because the compound on my 11x36 wasn't repairable, and the crossfeed nut was nearly striped from a poorly done previous repair attempt I have begun the process of CNC'ing it as I've already done 3 other machines.

So, last week I excised all the gears below the headstock, and removed that QCGB along with the drive screw and the apron and lead screw bearing, total wight about 100 lbs. I have begun building a new apron carrying the motor that will drive the crossfeed, and have already put a ball screw in to replace the OEM screw and nut that are everything but stripped, backlash in the nut is 0.085".

There are no broken parts in the entire parts list removed. But the drive clutch in the apron needs adjusted as it slips easily. If some of that would be helpful, and I suspect this QCGB is interchangeable with yours. It shouldn't be too hard to drive out that coupling pin locking the screw into it & you could just change the whole thing.

Make me an offer. gheskett AT shentel DOT net.
 
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