Home brew quick change fixtures/Midaco micro pallet

thunderskunk · Dec 21, 2018

Mornin guys,

I saw Midaco's micro quick change pallet system (see link below) and was just thinking... how hard could it be to take some old pull studs and either buy or turn some cones and make the fixtures yourself? Maybe weld armature onto a set of Jergens's ball locks? Point being to both save setup time and allow fixture loading while the spindle is turning.

In the grand scheme, the $4000 price tag for the Midaco isn't that bad since it claims <.0001" repeat-ability, but if you want to implement it, every new job would automatically have an extra $1000 or so tooling charge tacked on.

I've used automatic pallet changers on old Matsuura RA3's, and I know they're indispensable for production work. My current job has an old Haas VF3 with four pallets, but the tables sometimes fall off so they just use it so they don't need to pull fixtures off. I've also gotten quotes for installing Midaco's dual changer; at that price point I can get their micro pallets and a used robot.

I've seen the Rovi/Pierson Workholding fixtures too, but they only claim .0002", and for another 2k I think the Midaco would be far superior. On the opposite end, if I can make pallets for less than $100, it'd be as easy as making vise jaws.

Thanks guys,

Midaco system:
https://www.amazon.com/Midaco-Corporation-Pallet-Changer-System/dp/B06X1B2JW2/ref=sr_1_2?ie=UTF8&qid=1545399319&sr=8-2&keywords=midaco

Cones from McMaster:
McMaster-Carr

Volitan · Dec 21, 2018

Can you fix that McMaster link? I want to see what you're talking about because I'm really interested in this subject. Just this morning I was looking at Jergens Ball lock stuff and getting some sticker shock too.

wheelieking71 · Dec 21, 2018

Its pretty much impossible to link to a specific McMaster page. Easier to just tell people the item# to search themselves.

wheelieking71 · Dec 21, 2018

thunderskunk said:
My current job has an old Haas VF3 with four pallets, but the tables sometimes fall off

HUH?! Please elaborate. I cant imagine how, if the pallet table is aligned properly, this could happen.

Hazzert · Dec 21, 2018

For $4k I'd sacrifice a few seconds and just build something based on these. They claim .0028" total locational accuracy with all tolerance stack ups but you could build it better yourself probably.

Carr Lock(R) Fixture Plates (12 x 14) | Carr Lane $227 ea for a 12x14 plate
CL-2-CLC-.75 Carr Lock(R) Clamps | Carr Lane $78 ea 4 rqd

Edit: just saw you mentioned a robot.

dandrummerman21 · Dec 21, 2018

We have one of those Midaco pallets. We almost never use it. But we do use it for about 3 jobs.

The pallet base is probably more complicated than you are suggesting, but not terribly so. Have you seen the guts of it?

It doesn't locate with "cones", it has a couple dowel pins, one round and one diamond. the 4 corners are just pull studs

I am not saying the Midaco is the best, simplest, cheapest solution. But you could buy the base, and copy the pallets. Besides, I hate the aluminum pallets anyway, make em steel. Running thousands of parts, the 8-32 tapped holes for mitee bite fixtures die and I end up putting helicoils in it.

Get some plates cut up and blanchard ground, throw corner holes and ream holes in it.

I have nothing against ball locks or any other pallet system. I only use the midaco because someone bought it for a job 20 years ago, it got stuffed on a shelf and forgotten for the next 10 years (job didn't repeat) until I found it. We only had few extra pallets for it. I have not had many jobs I felt it would be useful for. Too small for most of our work.

DDoug · Dec 21, 2018

What would be wrong with a dowel and diamond pin each engaging
a drill bushing ?

Hazzert · Dec 21, 2018

digger doug said:
What would be wrong with a dowel and diamond pin each engaging
a drill bushing ?

The robot has a hard time working an allen key.

DDoug · Dec 21, 2018

Hazzert said:
The robot has a hard time working an allen key.

Vektek: Products: Hydraulic: VersaCam™ Swing Clamps (Standard)

Hazzert · Dec 21, 2018

digger doug said:
Vektek: Products: Hydraulic: VersaCam™ Swing Clamps (Standard)

I know solutions exist but I am still not sure how the OP was planning on actuating the handle on the fixture he pictured with the robot.

Personally if I had to come up with a solution I would just use a vacuum subplate and dowel pins as you suggested.

thunderskunk · Dec 21, 2018

Volitan said:
Can you fix that McMaster link? I want to see what you're talking about because I'm really interested in this subject. Just this morning I was looking at Jergens Ball lock stuff and getting some sticker shock too.

These are the ball locks at the bottom of the page. I'm assuming they're either Jergens or the exact same.

McMaster-Carr

And these are the pins for locating. I would use the cone-heads as it's pretty close to what they use on the other machines.

McMaster-Carr

To anyone posting McMaster Carr links, I guess if you hit the "catalogue" button at the top it gives you a nice permanent link.

DavidScott · Dec 21, 2018

I have been using aluminum pallets located with 2 dowel pins and held with vacuum for many years now. Cheap, simple, compact, fast clamp/unclamp and no reason to do anything different. IF the pallets get used a lot, over 5000 cycles?, then I may need to insert the locating holes to tighten them up, but that has only happened once. Usually the design changes before the pallet wears out.

thunderskunk · Dec 21, 2018

DavidScott said:
I have been using aluminum pallets located with 2 dowel pins and held with vacuum for many years now. Cheap, simple, compact, fast clamp/unclamp and no reason to do anything different. IF the pallets get used a lot, over 5000 cycles?, then I may need to insert the locating holes to tighten them up, but that has only happened once. Usually the design changes before the pallet wears out.

I'm glad you mentioned it. Kind of funny, I went and asked the lead engineer here what he thought of it, and he mentioned we've got one collecting dust somewhere. Seems like it's much more versatile. Do you have a particular model vacuum plate you use?

Hazzert · Dec 21, 2018

thunderskunk said:
Do you have a particular model vacuum plate you use?

Just make one. It's just a block of aluminum with a bore and cross-drilled hole tapped NPT a couple dowel pin holes, an outer o-ring profile on the the face for the pallets, a few o-ringed c-bored holes to fit your subplate or table and some grooves or channels for the vacuum to get across the entire plate.

Orange Vise · Dec 21, 2018

thunderskunk said:
On the opposite end, if I can make pallets for less than $100, it'd be as easy as making vise jaws.

You can buy our new pallets for less than $100. Make them for $50.

DavidScott · Dec 21, 2018

thunderskunk said:
I'm glad you mentioned it. Kind of funny, I went and asked the lead engineer here what he thought of it, and he mentioned we've got one collecting dust somewhere. Seems like it's much more versatile. Do you have a particular model vacuum plate you use?

I make my own, here are some photos of the vacuum generator I use. The second photo shows the entire unit bolted to the side of the receiver. The red line is air in, the clear line is exhaust and the brass knob on the left is the "switch". Photo on the left shows the body and vacuum generator. It uses .4 cfm and pulls 27 inches mercury. The vacuum unit is from Vaccon.

thunderskunk · Dec 21, 2018

DavidScott said:
I make my own, here are some photos of the vacuum generator I use. The second photo shows the entire unit bolted to the side of the receiver. The red line is air in, the clear line is exhaust and the brass knob on the left is the "switch". Photo on the left shows the body and vacuum generator. It uses .4 cfm and pulls 27 inches mercury. The vacuum unit is from Vaccon.

How tough is the holding force? I'd imagine if you have the right sized pump and air lines, it's 95% how well the fixture seals.

I'm planning on beating the crap out of this fixture: High speed contour milling of steel parts for long periods of time. No special alloys, but not aluminum. I figure most of the force is going on the cones/pins, so maybe that's negligible.

Winterfalke · Dec 21, 2018

I did a lot of work with vacuum pallets, and they all used the pin/diamond setup. We had several of Mitee-Bites Vac-Magic setups, and I have to say I was less than impressed with them. The one I used for most of my short run work was out about .0025" across 12" or so, I had to dissassemble the entire thing and recut each surface to get it actually flat and repeatable. The others were just left as is and we marked each fixture for use on only one vacuum unit. I even bolted a 6" Kurt to one vac plate so I could use it without pulling the vac fixture from the table, it was repeatable beyond what I could measure with our equipment. I made a lot of parts with stacking +-.001 tolerances, but I wouldn't want to try to do any work better than that. All of our fixturing was made from Mic 6 jig plate, with Mitee-Bite pin/bushing setups and Pitbull clamps.

DavidScott · Dec 21, 2018

My experience from doing plate work profiling around the outside corners is the most dangerous spot as that is where it is most likely to lift, mostly soft plastic plates. For pallets you want to size the dowel pins to the load and have a good receiving hole with minimal play, say .0005" over the pin size. All my pallets use 1/4" pins and I routinely pull 100-120% spindle load facing aluminum with a 10hp spindle on my Kitamura, specifically with a 6"x12" pallet. Funny but I have only machined aluminum and plastic on my vacuum pallets and haven't ever done any heavy side milling.

The setup I show is not perfect. These venturi vacuum generators can lose a lot of vacuum if your seals leak coolant into it. I have another setup where I use a fluid trap to make sure coolant does not get to the pump with a vac gage to watch to make sure I have 100% vacuum all the time. The gage always gets to at least 25 inches so that is what I use to calculate hold-down force. For O-ring seals I get the foamed rubber cord stock and use about 15% diameter compression, LINK. The foamed cord stock is real nice for soft plastic and works just fine for everything else, just don't store it in a compressed position for best performance.

How big are the pallets you expect to need? How heavy of milling do you expect to do? Can you calculate end mill lift for your heaviest cuts? Will you be using wedge clamps? I ask because they can/do bow the fixture. I have only had problems with parts lifting out of the clamps, I have never had a pallet lift.

thesidetalker · Dec 21, 2018

Orange Vise said:
View attachment 245013

You can buy our new pallets for less than $100. Make them for $50.

That looks real nice... a helluva lot faster than fudging around with the dowel pins I'd imagine.

Home brew quick change fixtures/Midaco micro pallet

Cast Iron

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Cast Iron

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Titanium

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