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

My guy asked me to cut a 1mm pitch thread on a custom shaft.
I could not do it on my lathe, so I finally bit the bullet and wrote a
subroutine to do threading with my 4th axis rotary table. I use a 60
degree chamfering end mill.
Now I can cut any thread, any pitch, right or left handed, and if the
thread is very coarse, the subroutine does it in several passes.
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I am afraid that it does not create a 100% correct thread geometry,
but I hope that I can do enough things with it to be useful with some
adjustments to diameter.
i
Reply to
Ignoramus3931
Loading thread data ...
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 )
;
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# = [#*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
Reply to
Ignoramus3931
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
Reply to
Martin Eastburn
Nice, but haven't you found a thread mill for $1 yet?
Reply to
Pete C.
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
Reply to
Ignoramus3931
I have not! But I should start looking.
i
Reply to
Ignoramus3931
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
Reply to
Karl Townsend
So you have some extras to sell?
Reply to
Pete C.
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.
Reply to
PrecisionmachinisT
Yep, definitely fun to listen to comments like thhis!
Reply to
Ignoramus6048
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
Reply to
Karl Townsend
But you sold me something once, some great stuff, 11018 welding rod I think.
i
Reply to
Ignoramus6048
Well there you go, precedent has been set. I seem to recall shipping some variacs too :)
Reply to
Pete C.
Buying stuff for nothing is a skill. Maybe not the same as your skills, but a skill never the less.
Dan
Reply to
dcaster
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
Reply to
Ignoramus6048
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
Reply to
Jim Wilkins
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
Reply to
Ignoramus28776
Any five-finger discounts in that, as I assume?
Reply to
Transition Zone
No, it doesn't.
Reply to
PrecisionmachinisT
That's great!
I guess it would also work to make rifling guides, like 1 revolution in 9 inches or so?
RogerN
Reply to
RogerN

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