1340 GT crash! ! !

RandallsRaceShop said:
It’s most definitely in the qcgb. It’s gear #1 on the right hand side of the box (labeled as 1-8). I ran it in every other gear & everything is normal. Run it in #1 & I get the rotational noise.
I just cannot see the damage looking from underneath. I’m thinking at least get the front cover off of it, that way I can see what happened to it.
Thank you for the well wishes too, I appreciate it.

Randall
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Sorry for my ramble, I missed the part in your original post that the other gears in the qc gearbox were ok. If PM can’t get the gear in a timely manner, you can try Maedler Gears, they have a good selection of quality metric gears. www.maedlernorthamerica.com

I have been threading away from the chuck for a bit now and like that method a lot, so much less stress when threading. I am using a Mesa Tools gooseneck toolholder using vertical on edge style inserts. It works well and I can use my AR Warner HSS inserts or carbide. The carbide insert it came with is working fine, so haven’t switched to the HSS one yet.

I also built a proximity sensor stop, if you have a VFD on your lathe, that is an option. Since I already had tools to thread away from the chuck, I still do external away and internal with the proximity stop with my lay down insert tools. One of these days I will settle on which I like better.
 
Well, I just got home from work a little while ago. I took the front cover off of the gearbox to get a good look.
I’m a little surprised & puzzled at the same time. Not even a mark on any of the gears that were engaged at the time of the crash (C, 1, lead screw, power feed/lead screw selector gear & 2 gears on each handle).

I honestly don’t know what to think now. There’s most definitely a rotational noise in C/1/lead screw that was not there prior.

Maybe the gear is cracked & I just can’t see it.?.?.?
Maybe the little key on the shaft is damaged allowing the gear to dance around a little.?.?.?

I’m going to see about getting the shaft out that holds gears 1-8. Then I can get a better look at the keys, gears & the shaft.

I’ll report back.
 
OTmachine said:
Bent shaft?
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That’s possible. I would like to get it out to take a look, roll it on the surface plate, set it up in a couple v blocks…something. It seems it may be pressed into a bearing on the exterior of the gear box. Trying to come up with a good idea to get it out of there. I may have to put the gear box back together & turn something to get onto the outer race of that bearing.
 
OTmachine said:
And install a softer, more easily breakable shear pin. Might want to check with manufacturer about this.
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They (Precision Matthews) recommend a 5/32” brass rod in the event the shear pin is broken.
 
RandallsRaceShop said:
That’s possible. I would like to get it out to take a look, roll it on the surface plate, set it up in a couple v blocks…something. It seems it may be pressed into a bearing on the exterior of the gear box. Trying to come up with a good idea to get it out of there. I may have to put the gear box back together & turn something to get onto the outer race of that bearing.
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You could disengage the end gears. Run a DTI over the gear teeth tops without disassembly, perhaps?
 
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