Gang Tool Blocks

[Black Forest]

Doc, check your private messages.

[BCRider]

This style of machine is widely known as a GT-27. GT, of course, for "gang tool", and 27 for the capacity. They're generally 5C machines, which have a max capacity of about 1-1/6", or about 27mm.

OK, so I wasn't realizing that the overall size of the machine was quite small.....

I was thinking that it could accept different chucks and work around larger parts when I wrote my reply to old mart. Apparently not the case.

Still..... the idea of a larger scale of machine, which I suspect Onmi also has, could use the idea of a rather long'ish cross table with blocks positioned that it can reach wherever they need to reach. Even out to the OD of some maximum size parts. It's a rather neat concept.

[old mart]

Lets have some pics of your lathe, Doc, I for one love to learn new things, and had never heard of gang lathes, all the lathes at my old firm were either manual, or cnc with the extra axis.

[Doc Nickel]

Doc, check your private messages.

-What? There's no check in my private messages. And anyway, how would you know who to make it out to?

OK, so I wasn't realizing that the overall size of the machine was quite small.

-It's not the "overall size", it's the capacity. Hardinge, for example, has a GT-27 machine that has a 10HP spindle and weighs some 6,000 pounds.

The idea here is that this is a general size that takes dirt-common 5C collets, and can make thousands of different parts in 5C holding range.

My Omniturn is about 1,600 lb, over 6' tall, about 7' wide and roughly 3' deep. It's no toy.

the idea of a larger scale of machine, which I suspect Onmi also has[...]

-Actually, Omniturn makes the GT-75, and a slightly smaller version called the GT-75 Jr. Which has the same capacities and travels, just a reduced enclosure for shops with limited space.

Lets have some pics of your lathe, Doc, I for one love to learn new things[.]

-I've been posting a write-up over on my own board, if you fellows would like, I can repost the blow-by-blow over here. It's not a "rebuild", the machine was running when I got it, but it DID need some attention.

Doc.

[reggie_obe]

Is your machine broadly classified as a "Chucker"?

[DR]

Is your machine broadly classified as a "Chucker"?

I have the same machine as Doc. IME "chucker" usually refers to machines that don't have tailstocks. So, yes.

Also called "gang tooled" which implies no tailstock because a workpiece usually can't pass over the tools (except Swiss type lathes can be gang tooled and still have a tailstock or sub spindle, but that's a fairly specialized situation) .

[Doc Nickel]

Believe it or not, Omniturn has a tailstock-like device, for longer, thinner parts. But when using it, you can only use two tools- one mounted above, and one mounted below the workpiece.

But that's an accessory part for odd setups, not a standard piece.

I've never heard of a gang-tooled CNC lathe referred to as a 'chucker', but as DR notes, the description fits. In my understanding, in the industry, the term "gang tooled" is the ubiquitous one- everyone knows what that means.

Doc.

[tomato coupe]

Also called "gang tooled" which implies no tailstock because a workpiece usually can't pass over the tools (except Swiss type lathes can be gang tooled and still have a tailstock or sub spindle, but that's a fairly specialized situation) .

Yes, gang-tooled implies a tailstock isn't used, but it doesn't imply the lathe can't have a tailstock. Gang tooling can be used on all sorts and sizes of lathes. I have a 16" lathe with tailstock that is set up for gang tooling about 25% of the time, and a Dorian QCTP about 75% of the time.

[Bented]

I've never heard of a gang-tooled CNC lathe referred to as a 'chucker', but as DR notes, the description fits. In my understanding, in the industry, the term "gang tooled" is the ubiquitous one- everyone knows what that means.

Doc.

The name Chucker Lathe has a wide range of meaning in the business, some consider any CNC lathe without a tailstock a chucker, tooling may be gang or turret tool changer, chuck work only.

Haas calls this a chucker lathe.
https://www.youtube.com/watch?v=QwhK7SY4bPM

[DR]

Haas calls this a chucker lathe.
https://www.youtube.com/watch?v=QwhK7SY4bPM

The Haas lathe is interesting, they put a turret on it presumably because that provides more tooling space than having tooling on a slide like the Omniturn. I would think that turret adds quite a bit to the cost of the machine. Hardinge built a similar capacity machine with only a long slide for tooling.

The Haas machine has a lever type collet closer operated by an air cylinder. That's a big draw back IMO. It doesn't allow for slight variations in bar stock diameter. I saw the machine back when first introduced at a tool show and mentioned that to the product manager for the machine who happened to be at the show. He didn't understand what I was talking about. I would never have a bar fed automatic without a variable grip collet closer.

[Doc Nickel]

A couple days ago, I had a small project where I needed sixteen of some small part. I got the job done manually, but it's the kind of thing that I should be doing on the CNC, if only just for the practice.

Really, just sixteen fairly simple parts, and considering I'm still so slow at programming this thing, it was a case of doing it manually was faster.

BUT.... like anything else, you never get good at it if you don't practice, and there's a couple other parts on this batch-build where I'll need eight to sixteen parts at a time.

The current one is, it's time to start installing the feed necks, which will be very close to finishing the Vee-Twin bodies. (At least, those without additional mods and customization.) The feed necks need to be fairly precise and consistent since they're press-fit to the body. I can do that manually, of course, but it would be ideal if we could hold fractional-thou tolerances, easily and repeatably.... the kind of thing a CNC is good at.

Now, this is a simple OD turn and maybe a little chamfering at the end. But what I'd like to do is also have the machine part the finished tube off to length- again, to make them as consistent as possible. That means a parting tool, which I don't have- at least, not one that fits the Omniturn.

Factory tool blocks for a parting tool, for the set needed, border on $400, and that's just a little steep for my blood right now. I have some small indexible parting tools I'd picked up for the Logan CNC, so I just needed a toolholder to hold it.

I scrounged around in my McGee's Closet and found a big hunk of thick steel, that looked like it wanted to join the fun.



A quick ride through the bandsaw got me four pieces (one mostly scrap because of the torch cut) about 4" long, each.



And, at the mill, since one face had been flame-cut, and was nasty with hard spots, slag and junk, I got out the big cobby indexible shell mill, and proceeded to do the usual "squaring up the stock" protocol. (Note the bit of round aluminum at the front jaw.)



Once it was squared up and smooth, I milled a 1/2" slot, centered, at the clean end...



And lightly chamfered the corners.



Located and spaced four 5/16-18 setscrew holes, and drilled and tapped 'em....



Which holds the parting tool like so.



This particular holder has a nice, thin blade, but they're kind of fragile. There's just enough slop in my Sheldon lathe's cross slide that I've caught and crashed a couple of them. Hopefully they'll hold up a bit better in the more rigid and flood-lubed CNC.

If not, I can bump up a size on the holder, if I can find one that keeps the same center height.

Once I had the tool mounted, I could take some measurements, and determine exactly how much to mill off to get the tool point exactly on center.



And with that done, I could locate, drill and counterbore the mounting bolt holes.



A quick test fit to make sure everything's kopacetic, then a good scrubbing and degreasing, and a slobber of Cold Blue.



The blue came out really splotchy for some reason- I had it pretty thoroughly degreased. Maybe it's a weird alloy? It cut like mild...



Anyway, didn't have time to program anything or take a test cut, I'll do that Friday, but I don't see why it wouldn't work.

And at some point I might re-degrease it (maybe get some TSP) steel-wool the bejeebers out of it, and try hitting it with the blue again, but for the time being, it should work fine!

Doc.

[Dan Dubeau]

Nice work Doc. If you find out what you did on the blueing I'd love to know. I like it, reminds me of the old Starret tools. I'd love to be able to reproduce that finish on putters. I've read about various ways to do it over the years by case hardening with various sources of carbon from ground up bone to leather inside a sealed bag, but have never tried it. One day when I get a heat treat furnace I will.

[hornluv]

Those look really great, as do your latest additions. Do you have a video of this thing in action? I'd love to see it doing its thing.

[Doc Nickel]

Those look really great, as do your latest additions. Do you have a video of this thing in action? I'd love to see it doing its thing.

-Here's the best one so far:

Doc.

[BCRider]

Nice work Doc. If you find out what you did on the blueing I'd love to know. I like it, reminds me of the old Starret tools. I'd love to be able to reproduce that finish on putters. I've read about various ways to do it over the years by case hardening with various sources of carbon from ground up bone to leather inside a sealed bag, but have never tried it. One day when I get a heat treat furnace I will.

Dan, a local gunsmith buddy managed to re-finish a small part with cold blue products using a mix of water and oil. I've yet to find out anymore about this idea but apparently while not perfect he said it came out well enough to mask the repair the firearm needed. So perhaps there's a clue to work with if you just want the look without the hardness.

The comments on parts sizes over the past dozen or so posts is worth discussion. When I consider how I use my own lathe and mill I'd say that at least 70% of the things I make or modify easily fit in the palm of my hand without sticking out of my fist. So that means that 80% of what I do could be done in a machine that is the size and ability of Doc's Omniturn setup.