9X20 Chuck

[mikey]

Look what I just found in the manual...I guess I wasn't too far off in my .020" cuts? Alum alloys says rough feed rate should be between .015" to .030". It'll probably do more especially with carbide but this is what they recommend.

Stioc, are we talking about depth of cut when we refer to the 0.020" cuts or are we discussing speeds and feeds? Your chart refers to cutting speeds and feeds. It lists, for example, a cutting speed of 200 SFM for aluminum when roughing and 300 SFM for finishing. It cuts finishing feeds to 1/3 that used for roughing, which is fine. What this says is that for a 1" diameter piece of 6061, you would rough at 200 X 3.82 / 1 = 764 rpm and 300 X 3.82 / 1 = 1146 rpm to finish. You would feed at whatever your gearing dictates. This has nothing to do with the DOC you use, right?

 

[stioc]

Stioc, are we talking about depth of cut when we refer to the 0.020" cuts or are we discussing speeds and feeds? Your chart refers to cutting speeds and feeds. It lists, for example, a cutting speed of 200 SFM for aluminum when roughing and 300 SFM for finishing. It cuts finishing feeds to 1/3 that used for roughing, which is fine. What this says is that for a 1" diameter piece of 6061, you would rough at 200 X 3.82 / 1 = 764 rpm and 300 X 3.82 / 1 = 1146 rpm to finish. You would feed at whatever your gearing dictates. This has nothing to do with the DOC you use, right?

You're right! I meant DOC initially but didn't realize the chart was for feed rate.

 

[stioc]

OK spent the weekend cleaning the lathe and looking things over to see why I haven't been able to take deeper cuts and I think I've found the problem (more on that below). I also put the 4-jaw chuck on and got this round stock dialed to .001" after about 10mins of fiddling. However, if I moved the dial indicator down the length it would show more like a .010" out of concentric.



OK so looks like the problem has always been that I can't seem to tighten the tool post down well. If I take a deeper cut the whole toolpost rotates. I've been working around it by just taking shallow cuts never thinking about how to fix that. The reason why I can't tighten the LMS QCTP is that the tool post stud that came with the lathe doesn't seem to have a locating pin nor splines nor any other kind of a stop https://www.grizzly.com/parts/Grizzly-TOOL-POST-STUD/P4000908 so as I tighten the toolpost nut down it starts to spin the whole stud. Upon doing research it seems the older versions of the 9x20s came with bottom of the stud splined. Not anymore

To fix this I'm thinking of cutting a flat slot across the bottom of the toolpost stud and a matching slot on the compound body underneath then welding a section of a drill bit into the slot on the stud to sort of make a T. That will prevent the stud from turning once the drill bit section finds the matching slot in the compound body. Never welded a hardened drill bit before but should weld like any other steel with mig?

 

[mikey]

Okay, that is a problem. Rather than burying this issue at the bottom of this thread where the 9X20 guys can't see it, why not start a new thread and label it to draw their attention? You'll get a better response and then we can see what the other 9X guys did to deal with this issue.

 

[stioc]

Okay, that is a problem. Rather than burying this issue at the bottom of this thread where the 9X20 guys can't see it, why not start a new thread and label it to draw their attention? You'll get a better response and then we can see what the other 9X guys did to deal with this issue.

Yeah good idea, I'll do that. Thanks.