Grizzley 4003G lathe, threading tool questions

D

DOUG DOTY

Guest
I am needing to chase the threads up further on a long shanked but very specialized bolt and just can't figure out what kind of tooling I need. The bolt is a 3/4 16 fine. Am I making this too complicated ?? I see the threading tool holders and cutting tips in the griz. cataloge but what about differant size threads and fines and coarses, I expected to see specialized cutters for various bolt sizes.
 
I use an insert type tool for threading. MSC or any other tool house will have them available. The inserts in my tool will cut threads from 16 to 32 TPI, I think. If your threads were originaly cut with a tool that was ground at 60 degree's you can use any other tool ground on 60 degrees. Just follow the steps for picking up threads and you'll be fine.
 
DOUG DOTY said:
I am needing to chase the threads up further on a long shanked but very specialized bolt and just can't figure out what kind of tooling I need. The bolt is a 3/4 16 fine. Am I making this too complicated ?? I see the threading tool holders and cutting tips in the griz. cataloge but what about differant size threads and fines and coarses, I expected to see specialized cutters for various bolt sizes.
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Grind a 60 degree threading tool with starret threading gauge,put it in your holder, like you would to thread anything. indicate the piece in a 4 jaw, or between centers if it is centered on the ends. Set your lathe to 16 TPI, compound to 30 degrees, and about 50 rpms, and time the tool into the threads.

You time it in by engaging the half nut, and traveling along the bolt, but back a few turns. Stop the lathe, but leave the half nut engaged, and use the cross and compound feed to dial the tool right into the threads.

Start shallow, don't try to cut them in 1 pass. go .010 or so for several passes, with cutting oil, and then .005 for the latter passes, and do one once in a while with no advance.

Hope this helps

Ben
 
Sorry to be so much of a rookie but I am just learning on the lathe can you explain the 30 degree compound and in which direction, I understand the rest just fine. 1st. time threading here. Even when ready i will make a test hit on a common piece.

Thanks for understanding my novice.

Using the Grizzley G4003G
 
Here is where you set the compound to 30 or 29.5 degrees for threading on a G4003G. I use the 29.5 degree setting.

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That is the real answer i know but I am trying to learn to run the lathe so I have been over using it to do so.
 
DOUG DOTY said:
That is the real answer i know but I am trying to learn to run the lathe so I have been over using it to do so.
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Doug, get yourself a "machinist shop practice", volume 1 and 2 by Moltrecht and read the basics on threading, indicating, tool making.

Chuck up a piece of steel, and learn to machine a diameter, undercut, and thread to a shoulder.

You have to practice on scrap before you can thread a barrel or something precision. I suggest practicing straight threading, then to thread to a shoulder, threading into an undercut (some types of barrels) And then timing into existing threads after that. Calculating depth of threads, using a thread micrometer etc.

Indicating a work piece into a 4 jaw chuck is a very important fundemental you need to learn also.

Get the books, and then, you can come back, and the guys on here will be able to answer any advanced questions you have.

Ben
 
Try Try Again

Doug,
I would do what Ben said, try cutting your threads on a piece of scrap and see if it comes out right. Do this until you fill confident everything is right then go to your work and cut your threads. Do it the same as you did you test piece.
jdmc
 
dipper said:
Run a die on it??

Rich
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Considering the work piece is a "very specialized bolt" and Doug's statement "1st time threading here"............I'm with you Rich............a die is in order. As a matter of fact, most of us would probably go the die route. BTW, before I'd do it either way I'd test to see if the material can be cut reasonably easily with a mill file; if not, your'e not going to have any fun threading it.

-Dave-:)
 
Dave Short said:
Considering the work piece is a "very specialized bolt" and Doug's statement "1st time threading here"............I'm with you Rich............a die is in order. As a matter of fact, most of us would probably go the die route. BTW, before I'd do it either way I'd test to see if the material can be cut reasonably easily with a mill file; if not, your'e not going to have any fun threading it.

-Dave-:)
Click to expand...

Good point dave, if it's heat treated, this will end in tears.
 
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