Lead screw or thread dial not right?

Then maybe the new threading dial is a metric version. You could count the teeth on the new vs the old thread dial gear.
 
I didn't realize you replaced the lead screw. I thought it was only the cross slide..
 
Just to know for sure, why not measure the lead screw pitch? Measure over 10 threads and divide by 10. Once you measure it, then you know it for certain. One less variable in the puzzle. Instead of 4tpi, it could be 6mm? At first glance, they look similar.
 
WobblyHand said:
Just to know for sure, why not measure the lead screw pitch? Measure over 10 threads and divide by 10. Once you measure it, then you know it for certain. One less variable in the puzzle. Instead of 4tpi, it could be 6mm? At first glance, they look similar.
Click to expand...
I will do that tonight after work. I was going to do it yesterday, but had prior obligations.
 
A metric lead screw will not cut Imperial threads unless a transposing gear set is used. You can rule out the lead screw as the problem by cutting the thread with the half nuts engaged.I If the thread is the correct tpi, the ;ead screw is good, If you are cutting good 24 tpi threads when using the same thread dial number but not when using alternative numbers, the implication is either the wrong gear on the thread dial or possible the dial is slipping. The thread dial gear will have a multiple no. of teeth relative to the lead screw pitch. You can determine the number of teeth either by counting or by measuring the distance required to make one complete revolution of the dial. It would most likely be 4" for 16 teeth but could be 2"for 8 teeth or less likely 5" for 12 teeth. These intermediate teeth provide additional points of engagement for the half nuts. If the dial has slipped relative to the gear, it is possible to engage the half nut slightly ahead of the mark on one pass and then slightly behind the mark on the second pass which will cause the type of problem you described.

Another possibility, one that I had with my Grizzly 602 was that the dial marks weren't concentric with the gear which made it nearly impossible to correctly engage the half nuts using alternative marks. In my case, the dial wasn't machined correctly. I made a new dial which solved the problem. In your case, the accident that you had could have bent the shaft enough to cause misregistration. Here is the post on my problem and the solution.
www.hobby-machinist.com

Threading On A Grizzly G0602

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...
www.hobby-machinist.com www.hobby-machinist.com
 
Ok, checked lead-screw and dial, I did not measure distances per revolution. It is 1/4” per thread - so 4tpi?

Here is a vid from doing some testing.

 
jareese said:
Ok, checked lead-screw and dial, I did not measure distances per revolution. It is 1/4” per thread - so 4tpi?

Here is a vid from doing some testing.

Click to expand...
Is your half nut handle traveling the same distance every time?

If the half nut gets worn just right (just wrong?) it can engage on the top of the threads well enough to cut a thread out of synch.

Has this been cleaned and inspected for damage, wear or debris?
 
RaisedByWolves said:
Is your half nut handle traveling the same distance every time?

If the half nut gets worn just right (just wrong?) it can engage on the top of the threads well enough to cut a thread out of synch.

Has this been cleaned and inspected for damage, wear or debris?
Click to expand...
same each time, New machine - had a faceplant, but all parts needing replacement have been replaced. Half Nut clamp is good, dial gear is good, new lead screw same TPI (measured)
 
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