I am replacing my northern tool plastic stuffer gears with the hardened gears from LEM.... All was looking good till I went to thread the larger gear to the acme threaded rod and it wont screw all the way on. I get it to screw on the shaft about 1 inch and it locks up. Either my shaft and rod are different thread size or the Lem metal gear is defective and the threads have changed during the hardening process.... I have seen this before when hardening...... I am going to stop by a local machine shop and see what they can do. I don't have an acme tap and they are anywhere from 40 to 100 bucks. I hope they will be able to run a tap through the hardened gear..... its a little dicey... If that don't work I'll have to return the gears to LEM..... From what I have read here the LEM gears fit the northern tool stuffer's and I don't believe there is a metric acme thread.
It also may be in the acme threaded rod.. It not a high quality rod and does have burs and dings and a poor zinc coating. The northern tool gear is super loose and even wobbles on the shaft due to the lack of precision machining.. I will head to my Buddy's shop down the street and clean up the shaft before I head to the machine shop
I also bored out my home made snack stick tube to 7/16Th's Inside diameter.. finished with a reamer... that turned out well.
be back with some results
Thanks for looking