VIDEO of cutting a thread on 4th axis of my Bridgeport Interact CNC mill with LinuxCNC

And here's the subroutine, released under GPL v3
(Makes a thread on a round part rotated in my fourth axis) (Uses a 60 degree end mill)
O sub # = #1 (X0, left side) # = #2 (X1, right side) # = #3 (Y, middle of the top edge of the round) # = #4 (Z, top of the edge of the round) # = #5 (Safe Z for rapids) # = #6 (Z Step, positive) # = #7 (Step Per Revolution, Also determines Total Depth) # = #8 (Depth of thread, positive, determined automatically if 0 based on 60 degree thread.) # = #9 (Diameter of the round, needed for calculations of feed rate) # = #10 (feed rate based on surface speed) # = #11 (Set to 1 if left handed)
# = [#/3.1415/#] # = [#*#] # = [#/5] # = [ 360 * [#-#]/# ]
(Set negative total angle if left handed thread) O if [# NE 0] # = [-#] O endif
O if [# EQ 0] ;# = [#*1.73205/2] (depth = spr * sqrt 3 / 2 )
; # = [#*0.64952] (depth = spr * sqrt 3 / 2 ) O endif
O call [#] G0 A0 (go to 0 degree) G0 X[#] Y[#] Z[#]
( Start drilling down to Z0, I could rapid, ) ( but slow is safer, will not break end mill ) G1 Z[#] F[#] # = 1 (1 is right, 2 is left) # = #
O while [ 1 ] # = [# - #] O if [# LT [# - #] ] # = [# - #] O endif
G1 Z[#] F[#]
(Depending on direction, we go to X1 on the right and turn total_angle,) (or go to X0 on the left and go back to ZERO angle)
O if [# EQ 1 ] # = 0 G1 X[#] A[#] F[#] O else # = 1 G1 X[#] A0 F[#] O endif
O if [ # LE [# - #] ] O break O endif
O endwhile
O call [#] G0 X[#]
G0 A0 (go to 0 degree)
O endsub
M2

Nice - to bad you can't use a hob ? I think that what thread cutters are or Cob... They have cutters a foot long and 6" in diameter - coated and all - here in Lufkin - the foundry at Lufkin Industries has to do it all. Massive gears and massive bolts and nuts.
The traditional donkey that pumps out oil is twice as long as those made by Lufkin. Their custom way saves space and when in buildings (hiding the pump) it becomes important.
Martin

Nice, but haven't you found a thread mill for $1 yet?

Yes, to do it properly, I would need to orient the rotary table at angle to axis X. Too difficult for me to do it. I will mess with making threads to see how geometry affects fit and how I can compensate by fudging the diameter.
i

I have not! But I should start looking.
i

twice now, the auctioneer has called them taps. Makes for a really good deal, I got one lot of 30 "taps" for $100. Even overheard one guy saying that guy was crazy bidding $100 on taps.
Karl

So you have some extras to sell?

For a 1MM pitch, a hand ground, single point hss threading tool probably would have worked just as well and would also have produced the correct root geometry.

Yep, definitely fun to listen to comments like thhis!

Unlike iggy, I'm not good at selling things. I do plan to have the best estate auction anybody has ever seen. I think, he who dies with the most toys, wins.
karl

But you sold me something once, some great stuff, 11018 welding rod I think.
i

Well there you go, precedent has been set. I seem to recall shipping some variacs too :)

Buying stuff for nothing is a skill. Maybe not the same as your skills, but a skill never the less.
Dan

Thanks.
Converting a Bridgeport milling machine to Linux is also a skill.
And yapping on forums about "having access to a friend's shop" is not a skill.
As for single point threading, my current problem is that the spindle has to be on brake. However, spindle brake right now is tied to estop. It only activates when the mill is e-stopped, and deactivates when the mill is out of estop. Fixing that requires me to spend a considerable time writing emc2 logic statements (to interlock brake and estop and spindle running safely). I do not have time for this right now.
i

I have the knack for buying at 5% of value but unfortunately never acquired the salesman skills to sell for much more than that. jsw

And I do it with a kind word.
Exactly, and lately, scrap metal.
Yes, and there are plenty og great people to talk to.
This CNC conversion project, was not exactly a machine building project. It was mostly about figuring things out, logic, wiring, etc.
i

Any five-finger discounts in that, as I assume?

No, it doesn't.

That's great!
I guess it would also work to make rifling guides, like 1 revolution in 9 inches or so?
RogerN