Gibraltar Import 15” 6-jaw chuck

[GT-6 Racer]

So I acquired a new to me 6 jaw set-true D1-6 used chuck. It’s a big chunk of steel at 285 lbs. A little surface rust and full of chips as usual. So first order of business was disassembly cleaning and inspection.


Once I removed the backing plate and cleaned it up, tone for a test fit on my 18x48 Monarch series 60. The backplate didn’t seat on the spindle. So back off and a blue check. This revealed the taper was wrong and too small a diameter. A thin blue line around the middle of the taper. So some measurements. The back plate was a mess. Faces out of parallel by 0.007” taper not at the required 7 deg, 7min, 30 s. Bore and outer diameter not concentric by 0.005”. Took a whole day to get it back to useable. First I made a D1-6 gage replicating the spindle nose turning between centers on the 10EE. for both lathes I set the compound to the required angle by sweeping the spindle nose with a 1/10’s DTI.




Then set up the back plate in my 15” Cushman 4 jaw concentric to the parallel bore of the center hole and best fit to the back face.




Then I faced the back off just enough to get flat. Then a light cut on the taper, just enough to get the surface clean. Of course now the taper is too big, so alternating face cuts and blue checks with my gage to get it tuned in without going over. All the while, knowing that I need to stay less than the 0.040“ of 1 turn of the cam lock pins. Once I got that done I installed the back plate on the spindle. Perfect fit. This would have been almost impossible without the gage to do blue checks. Now it was a simple facing operation and a skim off the OD to bring it all in.

More pictures to come, it was late when I finished last night and I didn’t get a final photo.

Hopefully the chuck body has better accuracy than the backplate did.

stay tuned.

 

[GT-6 Racer]

So after a thorough cleaning and stoning of the sliding bits it’s back together and mounted on the lathe. I used a 2“ diameter 8” long hardened die shoe post to check it. The post between centers had about 0.0005” runout or out of round, I can’t tell but it’s small. Chucked it up and adjusted the set true to about the 0.0005” I saw between centers at the end farthest from the chuck. Checking the shaft close to the jaws I get 0.002” runout. So a jaw grind will be next up. Since I can’t find specs on this I only spun it up to 762 rpm. Balance seems quite good.

even clean and freshly lubricated, its still a bit gritty. It’s easy to tell it’s an import, but should work pretty well for general use.

 

[Dabbler]

nice!!!!

 

[3strucking]

I would love to have that lathe. Did you rebuild it?

 

[GT-6 Racer]

I didn’t do the scraping. Saddle, cross, and compound were done by a pro, I bought it as a basket case and reassembled it. New parts where necessary. It was previously rebuilt by Monarch in 58. I replaced all the electrical parts when I reassembled it. Massively powerful and rigid. It’s the high speed version too. Only thing left is a clutch rebuild. There’s worn rollers and pins need to make and replace. Maybe a better paint job someday.

 

[3strucking]

I have looked at several but passed them by because they need rebuilding. I just dont have the time to put in to one.

 

[GT-6 Racer]

They are an incredible machine when working properly. Heavy and rigid. But many are pretty neglected. Keep looking though there are some nice ones out there and usually are pretty cheap as they are too big for the average hobby enthusiast. I turned a 3” piece of A36 last night for an adapter. 150 thou depth of cut was easily taken in stride. Big wnmg insert tool.

 

[Dabbler]

18X48 is a nice size - and a Monarch to boot! I have a 15X60 which takes up a lot more room...

 

[GT-6 Racer]

Yep mine is just under 11 feet long. A little over 4 deep. Takes up a good bit of space. I’d not want to give up much more floor space. However I also wouldn’t want to be without a big lathe. Seems there’s always something that doesn’t fit in the EE