Is it possible to cut 53-400 threads on my mill

[SkyMoBot]

I have a tormach 1100 with a 4th axis and was trying to wrap my head around how I might cut 53-400 threads in some blocks.  I need to make some fixtures to hold bottles (think of the old idea of nailing mason jar lids to the underside of a shelf to hold jars of screws and such).

I'm sure it's possible, but I have no idea of how to go about it.

[ArtF]

I would think its just a matter of the right tool and the right Gcode.. Wouldnt one single spiral down onto a flat face
of the block work? No 4th axis required?

Art

[SkyMoBot]

It's not a "normal" thread.  It's for a jar so it's kinda rounded.

[Wod]

I found the specs for your thread at plastcaps.com/spi-neck-finish-specifications-for-standard-closures-2-4.htm. If I were going to try to cut this thread, first I would grind a single point tool that would fit in a boring bar. Then you'll need to determine the actual diameter that it will cut. Put the bar in a V block and use a height gage to determine the cutting diameter. Here's an example of a thread milling code that I've used on a Haas machining center. I've tried to annotate it so that you can kinda maybe follow what the program is doing. It really doesn't take much code to cut a thread. I'd start with the D value for my tool a little oversized and sneak up on the first thread until I got the fit I wanted. After that the rest of them could be cut pretty quickly. I hope this helps. If you have any questions about the code, let me know.
Wiley

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O01111;
(Thread mill 56 tpi);
(X=0 Y=0 is the center of the shaft);
(Z=0 is the top of the shaft);
(Major dia. is 0.215);
(Minor dia. is 0.199);
G00 G20 G90 G80 G40 G17 G94 G110;
(This is just my standard safety code before I start a program);
(Set the machine in Imperial dims., Absolute positioning,);
(Cancel canned cycle, cancel cutter comp., Circular motion X/Y plane);
(Set the machine in Feed per minute, activate my work coordinate system);
T5 M06;
(T5=Thd milling tool);
S3000 M03;
(Set the RPM to 3000 CW rotation);
G43 H05;
(Use the height setting for tool 5);
M08;
(Turn on the coolant);

G00 X0.0000 Y0.0000;
(move to the center of the hole in X/Y0;
G00 Z0.2000;
(bring the Z down to a clearance position);
G01 Z-0.25 F15.;
(feed Z to the bottom of the hole);
G41 X0.1075 Y0.0000 D05 F20.;
(set cutter comp left and move X to the major diameter using the tool diameter for tool 5);
G91 G03 X0.0000 Y0.0000 I-0.1075 J0.0000 Z0.0178 F25. L18;
(Change to incremental programming);
(Cut a CCW circle at X=0 Y=0);
(I is your Major Thread Radius);
(J is 0 since you're only moving in the X);
(Z is the pitch of the thread);
(F is the feedrate);
(L is how many loops are necessary to get the tool out of the part);
G90 G40 G01 X0.0000 Y0.0000;
(Change back to absolute coords, shut off cutter comp, and move to X=0 Y=0);
G00 Z0.2500;
(Move the Z up out of the way);
M09;
(Turn off the coolant);

G28 G91 Z0.0000;
G28 G91 Y0.0000 M05;
G49 G90;
(This block just moves the Z up, the X and Y out, and cancels tool length compensation);
M30;
(End the program);
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