# Imperial or maybe Metric ? New lathe from Harbor Freight.



## TQA222 (Feb 11, 2019)

Just about ready to pull the trigger on ordering a 7 x 12 mini lathe from Harbor Freight when I realised that it might be metric. I am an old dog and I have worked with imperial measurements all m life. The nice young lad I spoke to at Harbor Freight could not confirm one way or the other even after making some calls. 

I had thought it would come in imperial with imperial divisions on the handwheels.

My understanding is that if it comes with an imperial leadscrew I can lathe cut imperial threads with out an issue and using combinations of change wheels can cut most metric threads [ close enough for government work anyway ] 

But what happens if it comes in metric with a metric leadscrew?

Anyone help or reassure me. Perhaps it does not matter as long as I have an imperial ruler and micrometer.


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## markba633csi (Feb 11, 2019)

I believe the machine is metric with a metric leadscrew but comes with the proper gears to cut some imperial threads as well as metric ones
Check it out carefully before you haul one home- possibly the info is on the HF website?
Mark


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## RJSakowski (Feb 11, 2019)

TQA222 said:


> Just about ready to pull the trigger on ordering a 7 x 12 mini lathe from Harbor Freight when I realised that it might be metric. I am an old dog and I have worked with imperial measurements all m life. The nice young lad I spoke to at Harbor Freight could not confirm one way or the other even after making some calls.
> 
> I had thought it would come in imperial with imperial divisions on the handwheels.
> 
> ...



You should be able to download the user manual from the HF website.


			https://manuals.harborfreight.com/manuals/93000-93999/93799.pdf
		

The manual makes no mention of metric threads.
Given that it has a thread dial and sort of mentioned how to use it.  You can't use a threading dial to cut Imperial threads with a metric lead screw so it would be safe to say that the lead screw is an Imperial thread.
However, many of the chinese lathes use metric cross feed, compound and tailstock lead screws using the approximation that 1mm = .03937" ~ .040" or 1.5mm =.059055" ~ .060".


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## Ulma Doctor (Feb 11, 2019)

i had a 7x12,
the threads on the longitudinal leadscrew were imperial V form threads
the dials are approximate 
the lathe threads imperial, but with a few change gears- metric screws can be cut.
you must keep the half nuts engaged,as RJ mentioned, the thread dial is useless

being that you purchased it outside the USA, you may have metric screws


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## chips&more (Feb 12, 2019)

With some “unknown” amount of effort. You can make the lathe cut whatever thread you want with the correct change gears. Your pitch result can be right on or so close that the error is negligible. I just did this universal thread cutting set-up to a lathe. Be prepared to do a lot of math and gear cutting! But then you could have a really handy capability in your hobby shop when done! Good Luck...Dave


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## Larry42 (Feb 12, 2019)

I would bet it is metric if it is sold outside of the US. I sure wish the US was metric. A much better system.
Perhaps you could buy an imperial lead screw and retro fit.


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## RJSakowski (Feb 12, 2019)

From the manual, the HF 7 x 12 lathe has a 16 tpi lead screw.  With two additional gears, a 51 tooth and 81 tooth, most of the common metric threads could be cut.  Here is a chart of the available threads, using the 51 and 81 gears in positions b and c respectively.






Not having the lathe to make measurements, it is possible that some combinations aren't possible due to physical interference.  A rough check of suitability can be made using the stock 50 tooth or 55 tooth and an 80 tooth gear as stand ins.
34 tooth and 54 tooth gears will result in the same thread chart.


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## TQA222 (Feb 13, 2019)

Yes it will be bought in the USA from Harbor Freight and at least the leadscrew is imperial. at 20 TPI  Apparently the cross slide is metric at 1 mm per rev as is the compound.

Imperial leadscrew and metric cross slide and compound, who would have thunk. 

No wonder I got confused. 

Thanks for the help everyone who answered and lead me gently to wards the light.


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## DAT510 (Feb 13, 2019)

Little Machine Shop does sell imperial cross slide lead screws, so that may be an option, if you want to change it at some point.









						Feed Screw Parts, 20 TPI, Mini Lathe 2383
					

Lathe Conversion Kits 2383 These parts change Grizzly, Harbor Freight, Homier, and Cummins mini lathes to 20 thread per inch feed screws on the cross ...




					littlemachineshop.com


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