left hand thread im mx5

[cherokeechief79]

can i get a left hand thread to simulate properly in verify?

i can do it going from the back of the part to the front but i would like to see it coming from the front to Z-.

thanks

mark

[crazy^millman]

I do not see why not, just make sure you have the correct tool defined and the spindle direction set up according to that tool.

[The_kid]

left hand threads are machined z- to z+ least far as i know.

[cherokeechief79]

^{ok i got it.i had to run one tool on the upper dia of the part and one tool on the lower dia.i could not start from the back forward because it is a multi lead thread and the undercut would have to be crazy wide.what im actually trying to do is simulate thread "knurling". i have 35 leads going in one direction and 35 leads going in the other. when they cross it forms the knurl and looks great on the screen. as far as if it can be done on the machine is another story!}

[crazy^millman]

The Kid no sir Left hand Threads can be machine just like Right hand threads with the correct tool. What you are thinking of it using a Right Hand Tool to cut a Left hand Thread and in that case yes you are correct, but with the correct (Notice I did not say right ) tool then you can cut left hand threads from Z+ to Z- just need to reverse the spindle direction and good to go.

 

HTH

[cherokeechief79]

• im cutting this now.lookin pretty good so far but i really need a pitch of about 3 in per revolution which the machine will not handle at all.im using 38 leads and 1.5 in per rev.
  

[The_kid]

Crazy, that was implied... you can use right hand tool upside down and spindle opp way. but is it a good idea?

 

Are you trying to do a multi lead thread? cause i'm not real sure what you're trying to do...

[Bob W.]

I used to build target rifles and I would thread barrels with the tool upside down starting at the shoulder. This allowed me to run the machine at 500 rpm when threading which was pretty fast for a manual lathe and it produced fantastic smooth threads which is pretty important for accurate shooting :-) Had to be pretty fast at engaging the split nut though. Not really relevant to CNC but an interesting story.

[The_kid]

absolutely there is an application... and your right bob right cutting speed is important for smooth threads. plus the chips fall away and have no chance at jamming into the cut. there are definitely some advantages.

[cherokeechief79]

i teach machine trades for voc school. someone in class asked if a "knurl" could be cut with a threading tool so we took it as a challange and tried it. it simulated ok in mc but the tool didnt have enough clearance to cut the threads smoothly in the haas tl1 we were using.also we had to keep cutting back on the thread pitch because it would exceed the max feedrate for the machine.to get the knurl to look truely like a diamond it would take about 3 inches per rev which was too much for the machine. we settled at 1.5 inch per rev which allowed us to go about 100 rpm.this gave the diamonds a very pointy look instead of square but all in all it did make something that resembled a knurl when it was done.i only needed to simulate the left hand thread in mc properly to see how it would come out. i used the same prog for the right and left by just turning the tool over and runing an m04. we used 38 starts and a pitch of 1.5 per revolution. although the "knurl" was not true squares (more like diamonds) we did prove that it could be done.

thanks for the help!

[cherokeechief79]

heres the file if anyone is interested. remember to check true threads in the simulation.

THREAD KNURL.MCX-5

[tozmaster]

Another interesting Manual Lathe thread cutting story:

I set up a tracer with a template to kick the tool away from the part at the shoulder when threading.

This allowed us to cut threads at extremely high RPM's for a manual lathe without fear of crashing into the shoulder.

Again not related to CNC but an idea for anyone out there that may still do things the old fashioned way.

[crazy^millman]

Crazy, that was implied... you can use right hand tool upside down and spindle opp way. but is it a good idea?

 

The Kid was not trying to put your level of knowledge down, was just trying to educate if that was not know. I have done many different things and used what I have had when I needed to get the job done. I have no problem with tools upside down in a CNC Lathe since that keep the chips going to the floor and not the door. People will disagree, but since I am left handed I always look at the world a lot different than right handed people. Look at all CNC machines where is the control? What hand are they expecting someone to run and operate the machine with? What people consider the main spindle I see as the sub spindle. If it were up to me the control would be on the left side on CNC Lathes and the spindle on the right side, but I am crazy like that. Years of cutting threads on a CNC Lathe and you will try just about any tool or any method as long as it gets the job done. I can remember cutting 3/4-20 0 deg x 45 deg buttress threads. We had a piece of wood we would use as a follow rest for the tool. The threads were 12" long and if you tired cutting them with the tool facing up got chips in your face. With the tool facing down the chips fell into the chip pan. We had a M00(GRAB SURF BOARD) we would call it riding the threads. Again just sharing what I know and hope it can be of assistance.

 

I can remember using 3 jaw chucks to cut 3 lead threads and 4 jaws chucks for cutting 2 or 4 lead threads and scribing out lines with xxxxm to 5 lead threads. We likes it when they were 6 or 8 lead threads because then it was back to the 3 or 4 jaw chuck for cutting them conventionally. We use to cut a taper threads and would take the tail stock and kick it off center about .1 to .2 and cut the thread about 12" away from the chuck. Was a lot easier than used the taper attachment.