Swiss Screw Machining needed - what kind of equipment am I looking for?

PBSteve · May 21, 2020

Hello,

Machining n00b here (another damned engineer). I am looking to have a part machined on a swiss screw machine. It has a complex helical profile requiring the tight tolerances of a swiss screw machine, a .75" OD, and eventually I'm looking to have a 600-1200 mm long part made.

I know next to nothing about swiss screw machines. I'd like to avoid refixturing if I can, is there some kind of continuous feeder that I should be looking for which is capable of precisely feeding the part into the machine? Am I just looking to use the wrong kind of machine? If I include features for re-indicating the part, can a swiss machine pick that up?

I'm looking to hit a .001" profile tolerance over the 800-1200mm, for what it's worth. I'm aware of many of the challenges here, and am just trying to get a start on it.

Any help or guidance on equipment I should be looking for in a vendor is greatly appreciated!!!

AJ H · May 21, 2020

I think you're dreaming

TeachMePlease · May 21, 2020

You want a CNC Swiss Lathe. This part can run on pretty much any 20mm Swiss Lathe. Depending on the programmer, you can pick up on an existing part... But most people won't want to, and it adds to cost. Easier just to machine the damn thing properly the first time, and be done with it. The .001" profile tolerance is possibly doable, though tight, and will add to cost..... Most people are happy to hold .005" over a couple inches repeatably.

If you're unfamiliar, here is a video of a Citizen L20X running a sample part.

YouTube

mneuro · May 21, 2020

I cant think of a swiss machine that can make a 47" long part.

Without seeing what the actual part is, I would rough machine in a standard lathe, then grind between centers for the profile.

AJ H · May 21, 2020

TeachMePlease said:
You want a CNC Swiss Lathe. This part can run on pretty much any 20mm Swiss Lathe. Depending on the programmer, you can pick up on an existing part... But most people won't want to, and it adds to cost. Easier just to machine the damn thing properly the first time, and be done with it. The .001" profile tolerance is possibly doable, though tight, and will add to cost..... Most people are happy to hold .005" over a couple inches repeatably.

If you're unfamiliar, here is a video of a Citizen L20X running a sample part.

YouTube

Used to run A20 with the long part catcher on it. I don't remember what the max length on the box was but I don't think it was no 47"? At that length if you let a breeze from the shop door hit it the thermal growth is going to change it by more than .001

TeachMePlease · May 21, 2020

Eesh.. I was reading too fast. Read it as 60-120mm which is CAKE...

600-1200...

Someone smarter than I am will have to do that job

ChipSplitter · May 21, 2020

What is it, a dowsing rod?

PBSteve · May 21, 2020

Part catchers etc. can be modified, just looking for a machine that can accurately feed stock. I don't have the expertise to build a custom solution for this.

AJ H said:
Used to run A20 with the long part catcher on it. I don't remember what the max length on the box was but I don't think it was no 47"? At that length if you let a breeze from the shop door hit it the thermal growth is going to change it by more than .001

Yes, the shop will need temperature controls. Print indicates a temperature range which is acceptable for inspection. We can help them if they need assistance with this.

ChipSplitter said:
What is it, a dowsing rod?

A device for a free electron laser (FEL).

PBSteve · May 21, 2020

mneuro said:
I cant think of a swiss machine that can make a 47" long part.

Without seeing what the actual part is, I would rough machine in a standard lathe, then grind between centers for the profile.

I can't provide details, but it's basically a big "dovetail-like" profile thread. Grinding ain't gonna do the trick.

pcasanova · May 21, 2020

YouTube

this shows a lathe using the sub to pull the material past, the longest config on that machine I believe
is 1300mm minus the chucks. The machine can be ordered with a hollow sub and can be loaded with a liner.
The machine is a nothing special, it's a standard emco lathe, again I posted this before and people swore this machine had to be some specially set up machine, and again the only thing special is the chuck.
the 840d Siemens is really what makes this thing happen with the trailon command. and it's standard
in the control.

Haimbuch made the chuck that went from clamp to guide bushing, and the story I got was, a guy in their shipping department came up with the idea and only that one chuck was ever made.

So I would say this can be done, but not knowing the material or the shape might throw this process out the window. but you have do multiple re-chuckings to pull it through, again not seeing the profile that would have to be re-chuck on wouldn't know for sure if it that would even be possible.
And down to .001 tolerance, hhmmmmm

And here's a test video I did to see if the trailon would do g2,g3 tapers ect. and it syched
move to move.

YouTube

PBSteve · May 21, 2020

pcasanova said:
YouTube

this shows a lathe using the sub to pull the material past, the longest config on that machine I believe
is 1300mm minus the chucks. The machine can be ordered with a hollow sub and can be loaded with a liner.
The machine is a nothing special, it's a standard emco lathe, again I posted this before and people swore this machine had to be some specially set up machine, and again the only thing special is the chuck.
the 840d Siemens is really what makes this thing happen with the trailon command. and it's standard
in the control.

Haimbuch made the chuck that went from clamp to guide bushing, and the story I got was, a guy in their shipping department came up with the idea and only that one chuck was ever made.

So I would say this can be done, but not knowing the material or the shape might throw this process out the window. but you have do multiple re-chuckings to pull it through, again not seeing the profile that would have to be re-chuck on wouldn't know for sure if it that would even be possible.
And down to .001 tolerance, hhmmmmm

And here's a test video I did to see if the trailon would do g2,g3 tapers ect. and it syched
move to move.

YouTube

Interesting! The OD is a high-precision ground cylinder, 6000 series T5 Aluminum.

mneuro · May 21, 2020

PBSteve said:
I can't provide details, but it's basically a big "dovetail-like" profile thread. Grinding ain't gonna do the trick.

As a self identified noob, I wouldn't discount things you don't understand. I am currently working on a project where we are holding a .0005" profile across a 46" span. Certainly are not going to accomplish that in a turning center.

It is quite common to form grind, especially when you are talking tight tolerance, over long distances, using a less than ideal material.

Could you provide a sketch of what the profile looks like?

PBSteve · May 21, 2020

mneuro said:
As a self identified noob, I wouldn't discount things you don't understand. I am currently working on a project where we are holding a .0005" profile across a 46" span. Certainly are not going to accomplish that in a turning center.

It is quite common to form grind, especially when you are talking tight tolerance, over long distances, using a less than ideal material.

Could you provide a sketch of what the profile looks like?

Sorry, you're correct, I shouldn't disqualify anything at this point.

Unfortunately I can't provide any images, what I can say is the helical groove is roughly trapezoidal, the groove width is ~7mm wide on average, but narrower towards the OD by about 0.2mm.

Guest · May 21, 2020

TeachMePlease said:
You want a CNC Swiss Lathe. This part can run on pretty much any 20mm Swiss Lathe. Depending on the programmer, you can pick up on an existing part... But most people won't want to, and it adds to cost. Easier just to machine the damn thing properly the first time, and be done with it. The .001" profile tolerance is possibly doable, though tight, and will add to cost..... Most people are happy to hold .005" over a couple inches repeatably.

If you're unfamiliar, here is a video of a Citizen L20X running a sample part.

YouTube

With my data capped internet of 15 GB a month and the fact I became a self employed army of one since a half dozen years ago I am probably a new technology dinosaur. Considering that I could not imagine a Swiss machine with a 4 foot Z stroke or how much it would cost. What is the longest stroke on a Swiss machine these days? I know you can do re chucking as I have a 4" stroke one I have made 12" long parts on, without a sub spindle.

GENERALDISARRAY · May 21, 2020

Is this going in a Space Laser?

Is a space laser an ITAR thing?

TeachMePlease · May 21, 2020

Dualkit said:
With my data capped internet of 15 GB a month and the fact I became a self employed army of one since a half dozen years ago I am probably a new technology dinosaur. Considering that I could not imagine a Swiss machine with a 4 foot Z stroke or how much it would cost. What is the longest stroke on a Swiss machine these days? I know you can do re chucking as I have a 4" stroke one I have made 12" long parts on, without a sub spindle.

I dunno averages, but my "little" 16mm machines are just shy of 8 inches. I know the 32mm machines depending on type can be significantly greater than that.

PBSteve · May 21, 2020

GENERALDISARRAY said:
Is this going in a Space Laser?

Is a space laser an ITAR thing?

No, and:

*This item is neither ITAR nor NADCAP controlled.

lol

mneuro · May 21, 2020

Could you make this modular. Instead of one single piece, you have maybe 6 pcs that get attached then lapped in together?

PBSteve · May 21, 2020

mneuro said:
Could you make this modular. Instead of one single piece, you have maybe 6 pcs that get attached then lapped in together?

No, we took a look at that, unfortunately other performance considerations make it a non-starter.

Rick Finsta · May 21, 2020

You can rechuck and infinite number of times in a swiss and you could do phased turning with the part running through (and clamped in) the subspindle, with a collection tube sticking out of the cabinet.

I would not want to program or set it up, but I think it is doable. Uuuugh picking up a thread over and over? I can't imagine what I'd scrap to get a good part. But I'm a novice.

That said, holding those tolerances over that length is probably a grinding thing.

Swiss Screw Machining needed - what kind of equipment am I looking for?

Plastic

Hot Rolled

Diamond

Cast Iron

Hot Rolled

Diamond

Titanium

Plastic

Plastic

Hot Rolled

Plastic

Cast Iron

Plastic

Guest

Guest

Hot Rolled

Diamond

Plastic

Cast Iron

Plastic

Stainless

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