HF grinder nut question

[®smpr_fi_mac®]

I have the HF 8" bench grinder, model 39798.

I lost the arbor nut for the right side. It's a right hand thread bur I don't know what size it is. A 3/4" nut starts threading, but jams, so I think it's a metric thread.

Any help?

[sweensdv2]

It's a Harbor Freight product, of course it's metric.
Maybe a M18 or M20.

[Cooler]

Write to them.  The address is on the last page of the owners manual.  The part is shown in the exploded diagram so you won't have trouble identifying it.

https://manuals.harborfreight.com/manual.../39797.pdf

[Stwood_]

I have the HF 8" bench grinder, model 39798.

I lost the arbor nut for the right side.   It's a right hand thread bur I don't know what size it is.  A 3/4" nut starts threading, but jams, so I think it's a metric thread.

Any help?

Take one off the other side and make 1 trip to the hardware store.
Then 2 more trips for other stuff you really needed.

[castguy2003]

It's a Harbor Freight product, of course it's metric.
 Maybe a M18 or M20.

I would agree it's probably a 20mm nut. Problem is, if you get a hardware store variety the face of the nut may not be perpendicular to the threads. That would put uneven pressure on the grinding wheel. Not a good thing.

[Stwood_]

But would the HF manufacturer, actually face those nuts.........

[®smpr_fi_mac®]

I called. It's a 1/2-13.

[Stwood_]

I called.  It's a 1/2-13.

[daddo]

You can tell if a nut has been properly faced and trued to the threads. Usually done on a nut chuck, One side of the nut will have a definite flat surface, sometimes with a small circular extended ridge.

[Roly]

I have the HF 8" bench grinder, model 39798.

I lost the arbor nut for the right side.   It's a right hand thread bur I don't know what size it is.  A 3/4" nut starts threading, but jams, so I think it's a metric thread.

 Is what you are calling a 3/4" nut, the bore or wrench size ?  I can see where a 1/2"x13 nut would start threading on a M12 thread but a 3/4" bore would fall on.  The manual says model 39798 is a 8" grinder which lists a 5/8" bore for the grinding wheels.   A 3/4" wrench will fit a 1/2x13 nut,   3/4" &19mm are very close in size which will fit a M12 nut.
 Yes I am confused.  Roly