“Practice" does not make perfect you Jackass…..Only “perfect practice” makes perfect!!!!

[Runs With Scissors]

Thats what my Senior Drill Instructor kept telling us about “drilling” (the marching kind, not the “drill a hole” kind)

So I have been trying to make a “plug” for the end of my SSQA contraption.

But I keep getting “steps” in my thread(s) when I am single point threading, and the threads to appear “tapered”.

EDIT: when I say “tapered", I am referring to the “V” in the threads, it appears that one side of the “V” is longer than the other…..I am not referring to the taper of a NPT style fitting from end to end. (hope this clarification helps)



I really “screwed the pooch” on my first attempt (who the hell came up with that saying? )

Here is the first attempt.



Threading seems to be my “White Whale” when it comes to machining things, so I have ordered a ‘Big Ass Tap and Die” in order to complete the project.

Basically, I can’t/won’t let my pride get in the way of finishing this project, and I need to make some progress.

HOWEVER, I still want to try and learn what I am doing wrong.

Here are some of my other attempts, but I must be doing something “systematically wrong” cause they keep having the same “steps” and “sloping” problem.




Lastly, in general, the finish of my threads absolutely sucks….

I decided to try threading in “reverse” because it really made a huge difference in my “parting off” abilities. (I used to dread parting off, now it’s kinda fun)

So I bought one of these a few months back, and it looks cool, but I clearly have not “grasped the concept” of it, cause my threads still suck.







I am thinking that those “little steps” in my threads are some sort of indicator, but i can’t quite figure it out.

Any suggestions?

 

[PHPaul]

Disclaimer: I am NOT a machinist.

Now that we have that out of the way, my first thought is that your tool is not set up right. I believe standard threads are 60° and the tool (cutter) has to be at 90° to the work. They make a little gauge for checking that:

 

[Paul Allwood]

Can you post a pic from above showing the angle of your top slide and the angle of the tool ?

What is the thread angle that you're trying to cut ?

 

[GreensvilleJay]

Aside from pride, any reason to not just BUY a plug from the hardware store?
curious as to the 'SSQA contraption'.

 

[ken erickson]

Basic question. Are you using the half nut and tread dial to engage the half nut , not the feed clutch , to cut the threads, in a race track pattern? Engaging the half nut on the proper even or odd line depending on threads per inch ?

From your pictures I assume your cutting a 60 degree thread, if so , are you setting the compound to 29.5 degrees?

How many threads per inch are you cutting?

I single pointed my share of rifle barrel blanks to receivers and the threads had to be cut accurate and to the correct depth for the receiver I was working on. I got in the habit of only engaging my threading dial on the same line no matter what book said, and I also did not like turning the lathe off until I finished the job. I used the racetrack pattern method. Engage half nut, turn out the cross slide quickly as the cutter finished the run, left the lathe run, moved the carriage back to the starting position, run the cross slide back to zero, move my compound in however many thousands per cut, engage the half nut on the same line. Rinse and repeat till I was full depth . OF course then I would have to turn the lathe off to trial fit the receiver.

 

[Workerbee]

My first thought on the finish issue would be that youre not using a correct lubricant, but I rather doubt that you wouldnt know whats correct.

 

[ken erickson]

I decided to try threading in “reverse” because it really made a huge difference in my “parting off” abilities. (I used to dread parting off, now it’s kinda fun)

I do not see the benefit of threading in "reverse" . I assume that is what your showing in the pictures is the holder for that operation? Can you show your set-up for standard rotation, single point thread cutting? I would want to see the top of the cutter as the thread is cut. Important for the cutter to be ground properly and set accurately on center of the work piece.

I normally used a surfer based dark thread cutting fluid for single point work, back gear or slowest spindle speed, paying attention to a rigid set-up.

 

[Lil Foot]

Wow.
As stated above, I'd like to see pics showing everything in place ready to cut threads- tool, tool holder, compound setting, machine settings....
I'm not sure how I would produce "threads" that look like that....

 

[lynnmor]

Mount the cutting tool on the bottom angle of the holder. Set the compound to 29 or 29.5 degrees. Always return to the zero on the cross slide and advance the cuts on the compound. Until we know the TPI, engage the half nuts at the same number. Take light cuts, especially near the finish size.