> I took a 3/8-11 pin from a broken Rick Howard to school today,and was told by Jeff my instructor that it shouldn't be called an Acme thread because the threads don't have a flat on them. I told him that it's usually referred to as a modified Acme,and he said it makes more sense.
The frustration is coming from a MUCH larger Acme screw. The threads are only 2" long,but it's 1.375-4,with a pitch of .250. The single depth of the thread is .135,and this thing is KILLING me
. I've had to scrap 4 of them so far during the threading phase alone,the one today went bad when I was .022 from finished depth 
.
My only guess is I dialed in my .003 depth of cut twice. I engaged the threading lever,and after it got 1/2 way down the length of the threads,it started to dig in and despite me having it as tight in the chuck as I could physically get it,it spun in the chuck. Naturally,my HSS threading tool went haywire and ruined it. Another 4 hours of work for NOTHING.
At the rate I'm going,no one will hire me even after I graduate. Tommy D.
The frustration is coming from a MUCH larger Acme screw. The threads are only 2" long,but it's 1.375-4,with a pitch of .250. The single depth of the thread is .135,and this thing is KILLING me
. I've had to scrap 4 of them so far during the threading phase alone,the one today went bad when I was .022 from finished depth . My only guess is I dialed in my .003 depth of cut twice. I engaged the threading lever,and after it got 1/2 way down the length of the threads,it started to dig in and despite me having it as tight in the chuck as I could physically get it,it spun in the chuck. Naturally,my HSS threading tool went haywire and ruined it. Another 4 hours of work for NOTHING
.At the rate I'm going,no one will hire me even after I graduate. Tommy D.
