Lathe help helical groove or thread?

[Incogneeto]

Hello Gentleman,

Could use a little guidance on this it is a dwg file that i stripped most of the drafting off they have not sent me a real file to work with

yet but i'm trying to jump ahead. I'm sending just the helical section.(policy) Would you define this as a thread or groove. Tooling may be an issue also I'm

using a .25 straight groove tool any help is of course appreciated. dimensions for cut detail are .875 across the top .750 bottom .436 depth with a 106 degree lead

Dave

[crazy^millman]

Dave, I assume you guys are not aware of having the thread cut on a thread cutting machine? I use to have a 4" dia x 144long 3TPI Acme lead shaft cut years ago by a company in Georgia. We sent them the TGP and they sent us back shafts cut with the ACME thread on them and we would then prep the ends like you need here even with timing to a certain posting thread to timing keys we machined on them. 297" length screams having the shaft done a thread cutting machine then coming back with a thread over sleeve timing the end to the key way if it is important. Normally just not something you attempt to cut on a CNC lathe unless you have some serious follow rests and steady rest to help keep the part from whipping. Then you have to worry about them digging into the threaded area once the thread is cut into it.

[Incogneeto]

Hahaa!! You are amazing!!

Because of the mix of MM and Standard I of course took that as a Metric dim. It wasn't. Too Funny. Do you still have the name of the place?? And I would still like to see if there is a way to cut a true helical thread . Really Thanks so much for looking at that for me and responding.

Dave

[Incogneeto]

And Millman I forgot they want a mirror finish total length. And I mean't I want to see if MCX has the capability to cut the helical. I see that there is a place in Homerville Ga.

Could that be Them??

Dave

[crazy^millman]

And Millman I forgot they want a mirror finish total length. And I mean't I want to see if MCX has the capability to cut the helical. I see that there is a place in Homerville Ga.

Could that be Them??

Dave

 

Yes that sounds like them. Good luck mirror finish is not really a finish you need a RA, Surface Finish or something else along those lines. You tell someone mirror then you get into all types of questions. It can be 2 light band flat which is almost perfect and not be a mirror finish. Mirror finish is more of a plished finish and again has nothing really to do with a requirements of size. are they calling a RA or a 2 or 4 finish?

[Incogneeto]

Funny, But that is why i said it. There is no callout the print literally says in type mirror finish! Too funny. This whole print has been a fiasco. And when I finally got the real print it turns out it was a product we turned down 8 months ago. But thanks to you I turned them on to Derek at Southern Machine works. So hopefully someone else has an opportunity for work. And they can get their

Machine built.

Thanks Dave

[Incogneeto]

Soooooo Do you have an idea if it is possible for MCX to program that thread I still want to learn from this. I have tried it as a thread and a groove and I'm trying it again in dynamic rough.Am shutting down all the retracts and just trying to get it to follow the partial chain. Any suggestions? Besides give up?

[crazy^millman]

Yes, draw that shape as a custom tool then ues the lathe threading cycle with the custom tool and you should get what you are looking for. No way I would every try to cut that with the full profile tool. I would probably do that with 3 inserts. One to do the root then one to do one side and one to the other side. Tool Pressure is going to be the fight trying to machine. If anything I would machine it as best I could and then send it out and have the thread ground where tool pressure is not an issue and then the unknown finish requirements for mirror might get met. There have been plenty of jobs and would bid $1 million on to make them and never got and not sure if that would have been enough. This is one such part without all the right equipment in place not an easy one to take on in my humble opinion.