Holding Parts That are Machined in Strips on a 4th Axis

Pete Deal · Jun 22, 2021

I make a lot of low value small parts out of 6061 and 1018. To try to make it worth the effort I machine them in strips. All of these parts need to be machined on at least 3 sides and many of them 5 sides. Currently I have a few Orange double vises setup and each set of jaws is an operation.

I have 4th axis for both of my machines but currently don't use them. I've been thinking for a long time how it would be a great improvement in efficiency and accuracy if I could hit 3 sides of the parts in one operation using my 4th axis. There are all kinds of interesting holding gadgets around but I've never seen anything to hold parts this way. What I would really like to do is to have some sort of compact talon grip type setup to hold the bar but that would take a super short compact but wide vise.

My latest idea is to make some sort of square tomb stone say like 4" square then make little pallets that could be bolted onto the faces. I would need to get an end support (tailstock) to go with the 4th.

Anybody got any very clever ideas for holding parts this way?

Larry Dickman · Jun 22, 2021

we had a similar situation and had good luck using Stevens Bricks

Stevens Vises

and also Mitee Bite fixtures work well

Booze Daily · Jun 22, 2021

I do this.

AARONT · Jun 22, 2021

I think your idea is the right track. Not sure how small you're talking about or the quantities, but you could do a hexagon style tombstone on the rotary. One strip per side held in with Talon Grips and Pit Bull clamps. It would be about as fast to load and unload new bars as it would be to load and unload pallets.

Pete Deal · Jun 22, 2021

Larry Dickman said:
we had a similar situation and had good luck using Stevens Bricks

Stevens Vises

and also Mitee Bite fixtures work well

I've seen those Stevens Vises and thought about them or maybe a shop made one more that is more in proportion with what I need.

Booze Daily: This turns the parts along the wrong axis for what I need. I need to hold and turn them along the long axis of the bar. It seems to be the more typical configuration though.

AARONT said:
I think your idea is the right track. Not sure how small you're talking about or the quantities, but you could do a hexagon style tombstone on the rotary. One strip per side held in with Talon Grips and Pit Bull clamps. It would be about as fast to load and unload new bars as it would be to load and unload pallets.

My main reason for thinking little pallets was not so much for changing out pallets of parts but because there are many different flavors of parts. This way I could make a pallet with the fixturing, maybe Pit Bull or whatever, per flavor. And the tomb stone could pretty much stay put. Maybe have some locating pins on it.

DavidScott · Jun 22, 2021

Yeah, lots of ideas, I have a few jobs like this. The specific solutions depend on the parts and features you need to cut and the quantities needed, both per run and over the lifetime of the part. Once you get it set up on your 4th you will be kicking yourself for not doing it sooner. I say this from experience.

You have to be careful with pitbull or uniforce type clamps as they can bow fixture plates that are not stout enough. Stout enough is probably thicker than you are thinking of, it certainly was in my case.

mhajicek · Jun 22, 2021

I made a tombstone / pyramid fixture with four dovetail vices, which I use for four or five axis parts.

Pete Deal · Jun 23, 2021

DavidScott said:
Yeah, lots of ideas, I have a few jobs like this. The specific solutions depend on the parts and features you need to cut and the quantities needed, both per run and over the lifetime of the part. Once you get it set up on your 4th you will be kicking yourself for not doing it sooner. I say this from experience.

You have to be careful with pitbull or uniforce type clamps as they can bow fixture plates that are not stout enough. Stout enough is probably thicker than you are thinking of, it certainly was in my case.

I was wondering about those clamps bowing the fixture. I see these fixtures with bunches of them lined up and figured that had to be an issue.

mhajicek said:
I made a tombstone / pyramid fixture with four dovetail vices, which I use for four or five axis parts.

The thing here is that adding a dovetail is another operation I can't afford on these parts. I can see on higher value parts, which the ones in the photos appear to be, makes complete sense.

Shawnrs · Jun 23, 2021

can you send a picture of the parts you want to machine on the 4th axis. I am sure a few of up can give you some good ideas on what to use for fixturing.

Pete Deal · Jun 23, 2021

Unfortunately no I can’t post pictures.

mhajicek · Jun 23, 2021

Adding a dovetail takes about 30 seconds, and then it lets you setup easier and cut faster. Maybe you can't afford not to.

Pete Deal · Jun 23, 2021

mhajicek said:
Adding a dovetail takes about 30 seconds, and then it lets you setup easier and cut faster. Maybe you can't afford not to.

Maybe you're right but I can tell you it will be a last resort. The parts are .75" thick, stock is 1" thick. I got .2" on the bottom to hold onto so I hope to be able to do it that way. Currently using Talon grips for first op. Something This is where I gravitate to first.

Edit: And thinking more, how is a dovetail better than a talon grip type grabber for a short wide part grabbed on the long side? By talon grip I just mean that type grabber, maybe another brand.

One thing that David Scott said applies. These are parts for my products that I have a machine dedicated to so I think it's worth building some dedicated fixturing to optimize.

Probably the way to go is to just build the tomb stone and start experimenting.

DavidScott · Jun 23, 2021

I tend to design and build my own fixtures and clamps so I have total freedom with the design. I will take and post a photo of the solution I am thinking of later. What is the cube size of your parts? What material?

While I love dovetails I almost never use them. Serrated clamps and stops work almost as well and don't add an op or two and more wasted material like dovetails. They are a good tool in your toolbox when nothing else works though.

mhajicek · Jun 23, 2021

Talon grips and the like are pretty good, and you could do the same sort of fixture with them instead of a dovetail. A dovetail will grip stronger than a talon grip, because it's holding more material with a larger contact surface. For the bone plates in the first picture and many more similar, I was holding 3mm deep and about 3" long across 1/2" wide of material in those dovetails, dynamic roughing 1.25" deep with a Helical brand 1/2" 5 flute at recommended parameters for "rigid" fixturing. Five hours tool life. Ran those 24/7 for three months, fixture shows zero wear.

Garwood · Jun 23, 2021

I make a bunch of 1018 parts that are 10" long, 1.4" wide and .700" thick. I mill one face and a bunch of through bores in the part in a vise first. 2nd op goes on a 4th tombstone where expanding mandrels grip inside the bores. They're just bosses with a slit and pipe plugs inside. The 4th finishes the rest.

Mtndew · Jun 24, 2021

Larry Dickman said:
we had a similar situation and had good luck using Stevens Bricks

Stevens Vises

and also Mitee Bite fixtures work well

I've never seen those soft bricks before, any idea on price?

Pete Deal · Jun 24, 2021

DavidScott said:
I tend to design and build my own fixtures and clamps so I have total freedom with the design. I will take and post a photo of the solution I am thinking of later. What is the cube size of your parts? What material?

While I love dovetails I almost never use them. Serrated clamps and stops work almost as well and don't add an op or two and more wasted material like dovetails. They are a good tool in your toolbox when nothing else works though.

Start with a bar of 6061 1"x2"x8" down to 1"x1.25"x8" (family of parts starting with different bar sizes). End up with 4 parts that are 1.5" wide, 1.45" tall, .75" thick. Machined on 5 sides. The 5th op is just to drill and tap some holes in the side and do some engraving while I'm there.

Rick Finsta · Jun 24, 2021

At the old shop we did this on several machines. We'd mount a Lang zero point plate to the 4th and then you could just build fixtures with the studs installed on them. The plates are expensive but a set of the studs is only like $80. That's chump change when you're buying a bunch of stuff from Mitee Bite / Carr Lane / etc.

We had an eight station Kurt rotary vise we modified, and then dozens of job-specific fixtures. I had a few fixtures that were just chunks of aluminum we stuck in a Lang Makro-Grip on the 4th and cut for clamps, which was cheaper and faster (other than buying that vise LOL) than setting up a direct-mount fixture.

DavidScott · Jun 24, 2021

Here is a photo of one of my 4th axis fixtures. Right now it's all aluminum but if I end up making enough of the parts it holds I will replace the center stops with the one in the picture and make new clamps out of heat-treated A2 with the same serrations as the loose stop. This fixture holds steel parts, a real rarity for my shop, and has worked much better than I expected. So far I have yet to lose a part from it slipping, but I've only made a couple hundred so far. The fixture is held to my 4th with a pneumatic tailstock and I drive the clamp screws with pneumatic torque-controlled drivers. I have about 20 seconds of spindle downtime to swap fixtures and swap parts while the spindle is running. This fixture can hold 24 1" long parts at a time.

mhajicek · Jun 24, 2021

DavidScott said:
Here is a photo of one of my 4th axis fixtures.View attachment 323473

I'm thinking of making something similar, but I want it to have an adjustable span to be more general purpose.

Holding Parts That are Machined in Strips on a 4th Axis

Titanium

Titanium

Titanium

Stainless

Titanium

Diamond

Diamond

Titanium

Stainless

Titanium

Diamond

Titanium

Diamond

Diamond

Diamond

Diamond

Titanium

Stainless

Diamond

Diamond

Similar threads