Metric threading on 12x36 import lathe (Grizzly G4003) Options

Oct 14, 2008 4 Replies

Back in May I published exhaustive change-gear tables for the Enco, Harbor Freight, and Grizzly 12 x 36 lathes. I've updated the Grizzly version to include its 86/91 step gear idler option:



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These are for the Grizzly G4003, not the G4003G "gunsmith" version.



Original thread:



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I don't know if you've visited the yahoo group dedicated to these lathes:

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might appreciate this information as well.

Any particular reason to believe that the G4003G (gunsmith) lathe would be different from the G4003 ? Per their respective manuals, both include a mounted 86/91 idler, a mounted 60T change gear, and the same selection of accessory change gears. The metric threading charts in the manuals appear to be the same.

David Merrill

Yes. It looked to me on casual inspection of the respective manuals that on the G4003G either of the F and G gears could engage either of the 86 or 91 tooth idler (that is, 4 possible combinations), while on the G4003 that F was always on 91 while G could engage either 86 or 91 (that is, 2 possible combinations).

On the Enco and Harbor Freight versions there is no step on the idler, just one possible engagement 80T for both F and G, that is, a unity ratio.

Thus the Enco/HF idler provides no additional possible ratios, the G4003 idler doubles them, and the G4003G quadruples them.

Yes, now that you remind me about that.

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