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Thread: Vacuum Fixture for Small Sign Production

  1. #1
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    Vacuum Fixture for Small Sign Production

    This week I started to move forward on setting up for a small sign thing for equestrians after making some prototypes that I like. Because these will be personalized, I needed a work holding setup that was accurate, quick and secure. Vacuum is excellent for this and that's the route I chose. I happen to have a nice Gast vacuum pump that I've owned for many years for lathe work. It's not appropriate for larger CNC tasks, but perfect for fixtures that hold smaller workpieces. So I relocated it from the lathe stand to under the CNC machine and then proceeded to create my fixture for these small signs.

    I chose to use some Corian scraps for the fixture...no leakage, easy to cut and very durable. I created the design in VCarvePro, starting with the existing prototype sign profile to provide a recess that increases lateral hold and then milled an air chamber and gasket groove. The end result...

    IMG_1059.jpg


    Since I need provide for an air path from a connection to the vacuum pump, I setup for a double sided job using indexing pins so I could flip the workpiece and route a groove in the underside of the top layer to provide for that path. Note I stopped this groove shy of the edge so its essentially asymmetric nature wouldn't interfere with drilling a 1/2" hole in from the edge for the air connection.

    IMG_1058.jpg

    I then used Gorilla glue to laminate the machined piece to a second piece of Corian, using cauls to insure things stayed absolutely flat. Once that cured overnight, I cleaned up the edges and then drilled my 1/2" hole for the threaded air connection. Theoretically, I should have used a slightly smaller drill bit and then tapped the hole, but I'm not setup with tooling for that, so I decided that I'd get just enough bite from the threads cutting their own and then the epoxy would insure everything stayed tight and sealed. And that turned out to be accurate, especially since the nature of vacuum pulls the connector tighter, rather than the opposite as it would with compressed air.

    IMG_1064.jpg IMG_1065.jpg

    Interestingly, when I tested the holding power, even without a gasket installed (material arrives tomorrow), I could not pry the sign blank off the fixture even with a flat screwdriver.

    IMG_1067.jpg

    So this is setup job one ready to go. I have a few more things to work on before I start offering actual product, but I'm happy to be making progress. I'm setup with the local Corian distributor, too. I seem to be getting pretty comfortable with the toolpathing aspect of these simpler projects and get get through a design and set of cutting files pretty quickly at this point. Still "walking" before "running", but going in the right direction.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  2. #2
    That looks really good and efficient, Jim. Hope it works well for you and it looks like it will.

    David
    David
    CurlyWoodShop on Etsy, David Falkner on YouTube, difalkner on Instagram

  3. #3
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    Jim, What are you using for vacuum to hold your small parts? are you using the vac pump for the cnc or another type?

  4. #4
    His first post up at the top says he's using a Gast pump.

  5. #5
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    Quote Originally Posted by Adam Bullington View Post
    Jim, What are you using for vacuum to hold your small parts? are you using the vac pump for the cnc or another type?
    Quote Originally Posted by Mark Bolton View Post
    His first post up at the top says he's using a Gast pump.
    Yes, it's the Gast pump I originally bought for Vacuum Chuck work at the lathe and later adding vacuum veneering. It's got a third purpose now...fixtures on the CNC. I chose not to buy a vacuum table setup for the CNC...I don't expect to do much cutting of sheet goods, particularly on a 4x4 format machine and couldn't justify the expense on that basis. I could easily add it in the future if that were to change.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  6. #6
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    I had the opportunity to test this fixture today while fleshing out the personalization tool path setup for the signs that will come off of it. It held really well while doing the v-carving, even considering that the material I was working with was "more porous" than the Corian will be. Setup is simple with a couple of steel rods to register square with the bed and then a quick x-y zero via the laser to set the center point. The test cut was "very crispy" using an Amana insert 60º V-bit and didn't move an iota. The tiny lip in the fixture combined with the vacuum works great to hold the blank in place.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  7. #7
    So why/how do you zero off the center of the part when you are using rods/pins to register to the machine? That would seem a wasted step? Would seem wiser to register off the pins with a part perhaps 1/16 oversize, register off lower left, or right, run the sign, then pull the pins and a skim profile pass?

    Other than for layout purposes I have never been able to get my head around a center zero.

  8. #8
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    I would not expect movement to be a problem. That gast pump likely achieves somewhere between 20" to 25" Hg. If you start using thick or softer gaskets because of stock variances you can find you can get movement in the gasket material.

    Your jig is very nice, but I think in this case you could have saved yourself some time and used an on board gasket without any grooving of the surface. This is my favorite (http://allstaradhesives.com/cart/pro...il/cr_06_25/51) for that application. Your stock needs to be nice and flat to use the very thin gaskets. If not, achieving a seal can be impossible or a nuisance. I was going to suggest you could add a final tool path to size the part, but without a tool changer that will take more time than your method. I cut a few 4"x6" signs a night or two ago using two of my 3"x4" pods and a pump similar to yours. The stock sits on top of the gasket in the link, and nothing else other than friction holds them from moving.

    If you keep your port close to one edge of the jig you can also save yourself some time so long as you use 3/4" thick material and a 1/8" NPT x 1/4" tube fitting. You can drill and tap that thickness quite easily.

  9. #9
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    Mark, for small signs like this, zeroing center is pretty common. To your point, it's not really important "where" one zeros as long as it's consistent with how the design was built. The pins I mention are merely to insure that the fixture is square to x and y as that would affect the quality of the personalization and it puts the fixture in a convenient place for me on the bed. There's no need for skimming or profiling on the fixture...as mentioned in the next paragraphs.

    Brad, this fixture hold pre-cut sign blanks that have already had the edges chamfered, screw holes drilled and a graphic applied. They are cut from 1/4" thick Corian in a quantity of 36 at a time (out of a 30" x 48" piece which is the maximum length my machine supports) and are 221mm x 70mm. The Corian is very flat and the gasket is barely protruding...in fact, I really don't need it for this material, but may for others, so I incorporated it anyway.

    When a customer orders the product, they provide me with the personalized text for the sign (horse name and a second line of text for this particular product) and I then apply that to the pre-created sign blanks that are held by this fixture by quickly modifying the V-carve tool path. There's no sizing of the sign on the fixture...just V-carving the text. I can easily use the same process even for a variation of the product that has a custom graphic in addition to the text, such as for an equestrian operation that wants to standardize branding within their barn, or for a fund-raiser for a 4-H group, etc.

    Example of how this works...

    IMG_1377.jpg
    --

    The most expensive tool is the one you buy "cheaply" and often...

  10. #10
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    I figured you were pre-sizing blanks after I recalled your machine setup. I gather you do these as/when you are approached. How much time does it take to turn around a sign not including the time to make the blanks? Graphic, toolpath, cut, finish to cash in hand?

  11. #11
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    Quote Originally Posted by Brad Shipton View Post
    I figured you were pre-sizing blanks after I recalled your machine setup. I gather you do these as/when you are approached. How much time does it take to turn around a sign not including the time to make the blanks? Graphic, toolpath, cut, finish to cash in hand?
    Well, I'm about to go into marketing and production, so hopefully, I'll have a handle on most of that real soon now. For the physical production of personalization of the sign blank...about 10-12 minutes or so to adjust the tool path in the design file for the custom text, output the file and cut the thing. They will be priced accordingly. "Cash in hand" happens at order, not production/shipment--paid in full. Larger jobs, such as furniture and tack trunks, I get 50% up front and the balance on completion prior to delivery.

    I just got my color samples yesterday from the Corian distributor and will be ordering the first material in a few days for delivery next Thursday. (Delivery if free for orders above $300 which is really easy with this stuff. LOL I'm being optimistic on this based on conversations I've had socializing the idea with folks, but if it doesn't work out...such is life. And it's just one small piece of the ideas I have to monetize my shop.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  12. #12
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    Be sure to let us how it goes. I see lots of people doing this type of thing, but I can never tell if it does much other than help pay for the machine. I was at a wedding recently that my brother made the gift card box for and my sister-in law had dressed it up. My sister in law has gotten very good at her card making and making sign stamps. The box he made was pretty basic, but she had applied some very nice lettering. It looked very good. I pondered looking at it for a few minutes in the mindset of a consumer trying to decide if I would pay anymore for a box like this to be vee-carved, and I concluded I likely wouldn't. Thinking about it now, I have never asked how long it takes her for something like that. I will have to ask her how much time it took her. I have seen her craft room, but never really looked at the steps involved.
    Last edited by Brad Shipton; 06-29-2018 at 12:22 PM.

  13. #13
    I think the masses are pretty much a wasted effort unless you land on some novel idea and can capitalize on the profit before the pinteresters take you down. Jim's on the right track establishing in a market with people with a known passion, and one that is likely fairly expensive to be involved with in the first place. At least then you've somewhat setup your customer base with people who potentially have money and will spend in that market.

  14. #14
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    I totally agree Mark. The true equestrian that owns horses from $100k to $1mil plus are much easier to deal with. I do not have those nearby. I asked some friends with expensive horse collections, but not to the equestrian levels and I got mixed feedback. I am interested how it goes for Jim as I trust what he will say. The pinteresters would have us all believe epoxy tables are the way to go.

  15. #15
    Quote Originally Posted by Brad Shipton View Post
    The pinteresters would have us all believe epoxy tables are the way to go.
    HAHA. That gave me a chuckle. I cant tell you how many times people, and designers, have sent me a photo of one of those tables wanting a price and I ask them if they looked at the prices when they got the photo, and if not, why? When they see that a couple of figured live edge slabs are worth a chunk, and then there is 3-5 gallons of epoxy and dye in one of the large versions to the tune of $100+ a gallon, then a set of custom fab'd welded legs, and you still havent factored in labor and the cost of finish, the phone goes silent.

    Now I just send them the pages tied to the images they send me and when they see the "river coffee table" they drooled over with a 2200-2700 dollar price tag... the conversation comes to a hault.

    Those tables will go the way of pallet wood and all the other flash in the pan fad's and will wind up in estate and yard sales for 50 bucks one day lol. Gotta give credit to those who find the people willing to pay that money.

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