# Threading On A Grizzly G0602



## RJSakowski (Apr 2, 2015)

On March 19th, I replied to a thread begun by Cody Killgore entitled "Threading, Something Went Wrong Here" (post #19) where I show evidence of an problem with the threading dial on my Grizzly G0602.  I had determined that the dial markings were not concentric with the gear shaft, creating an error of almost a half of a thread on the lead screw.  This created the possibility of closing the half nuts one thread off on certain thread pitches which would have disastrous consequences for the thread being cut.  

I had measured the carriage positions as each of the twelve threading dial marks lined up with the index mark and plotted out the difference between adjacent positions a the solid lines in the graph below.  While there was variation in the readings, there was a clear sinusoidal pattern which would be predicted by eccentric dial markings.

I designed a new dial, using SolidWorks and turned it on the lathe.  The dial was engraved on the Tormach using a 45 degree carbide engraving tool.  The stationary mark left a lot to be desired as well as it was hard to read and moved around easily so that was redesigned and machined on the Tormach.  The engravings were filled with flat black enamel and the surfaces wet sanded with 400 grit sandpaper.  The stationary plate has a dropped lip along the straight edges to prevent movement which is why it overhangs the threading dial housing.

The position measurements were repeated with the new dial shown as the broken lines in the graph.  As can be seen, the sinusoidal variation has disappeared and the readability has improved as well, permitting visual positioning to better than +/- .005" maximum.  This is accurate enough that the half nuts engage smoothly on all marks whereas before they would sometimes hang up due to mis-registration.

Bob


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## tmarks11 (Apr 2, 2015)

Beautiful job.  Now post it on the 10x22 yahoo lathe site, and offer to sell them on eBay....


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## RJSakowski (Apr 2, 2015)

tmarks11 said:


> Beautiful job.  Now post it on the 10x22 yahoo lathe site, and offer to sell them on eBay....


Thanks for the compliment.

Sorry, selling them means I'm working and I retired so I won't have to work any more.  I do subscribe to the Yahoo site though and might post it there as well.

It is actually a fairly simple project and I would urge anyone who owns the lathe to check their dials.  It could save them  from ruining a project in the future.  ( I would hope that I happened to get the one defective dial in the lot but somehow....)

Bob


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## WRMorrison (Apr 3, 2015)

Bookmarked for future reference; thanks for the info!

-WRM


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## GunsOfNavarone (Jun 23, 2019)

As I am a metric guy....I really need this dial to be accurate/useful. I could use some direction on this one. Now I haven't done the whole measure at different points or make a graph, but just trying to hit the marks is useless as they either but we'll before or well after....I'd like it to be pretty much spot on, i could manage to hit that, but before after feels wrong.


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## RJSakowski (Jun 23, 2019)

GunsOfNavarone said:


> As I am a metric guy....I really need this dial to be accurate/useful. I could use some direction on this one. Now I haven't done the whole measure at different points or make a graph, but just trying to hit the marks is useless as they either but we'll before or well after....I'd like it to be pretty much spot on, i could manage to hit that, but before after feels wrong.


Unfortunately, the thread dial is of no use when cutting metric threads on a 602.  Unless the lathe has a metric lead screw, the half nuts must remain engaged for the entire thread cut.  Tom Lipton on OxTools shows a method where you can disengage the half nuts to stop carriage and re-engage to run the carriage back for another pass.  This is useful when threading to a shoulder as you don't have to worry about the momentum of the drive train crashing into the shoulder. Another option is to run the lathe in reverse and thread away from the headstock.  The threading tool has to be either mounted upside down or at5 the back of the lathe to do so.


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