Low cost DIY vacuum jigs

[Skip Weiser]

Greetings,

I just joined SMC a few days ago and I love this place !!! There is so much knowledge assembled here and everyone is so willing to help one another and share information, it's great.

I have a Shopsabre 4896 model that I've had for about 5 years now. I cut small parts out of Dymondwood material for a couple of different customers and I was looking for a good way to hold small pieces without using tabs (bridges).

I stumbled across Bill Polumbo's site at Baycraft Designs. I'm sure he's familiar to many of you Shopbot folks. The vacuum pump setup he shows on his Shopbot page intrigued me, so I built one and it works great. The Gast vacuum pumps are available at The Surplus Center online for $89.95.

The vacuum jigs are made out of two pieces of plastic. The bottom piece is grooved for airflow and the grooves connect to a 1/4" quick disconnect air fitting. The top piece gets shallow pockets a little smaller than the parts you want to cut, and holes are drilled through the pockets into the grooves below. I used 1/32" spoilboard gasket between the plastic pieces, and on top.

I've made small jigs as pictured, and I have one that is 3 ft. x 2 ft. The small jig with the lighter shaped lines is used for cutting .040 thick trim pieces that get glued onto Zippo lighters. I don't know how I'd cut those without vacuum.

I didn't mean to ramble on so, and I hope this isn't old news to the forum here. Just trying to share some ideas that others might find useful.

Thanks,
Skip

[Mike Null]

Great idea! Thanks and welcome to SMC.

[Michael Kowalczyk]

Hey Skip,
Welcome to the Creek. Thanks for posting your DIY vac jigs. I have a question for you. Well probably several. first are you using Allstar gaskets for your top material? Can you take another picture and zoom in on the area that I cropped below. I am curious to see how you are actually holding those parts down. Your tool path punctures the membrane in several areas, such as perimeter and your drill points. With that many areas exposed for vac loss and running a small vac pump how do you maintain enough vac to hold the parts down? Are you drilling tiny holes, inside the perimeter tool path, to allow the vac enough volume to hold it securely? How fast or slow are you running when you are cutting something like what appears to be knife handles?

[Keith Outten]

Skip,

Very timely post,

I am getting ready to order parts to build my first vacumm hold down for my ShopBot. I have been cruising Joe Woodworker's web site and I think I will purchase his plumbing package that comes with the vacumm guage and all sorts of other items necessary to plumb up the rig. I already have a Gast Pump and and plenty of Corian for vacuum pucks.

Thanks for the pictures, there is always a good idea that comes to the forefront of my mind when I see pictures of other peoples stuff.

.

[Skip Weiser]

Hi Michael,

I've made an approx. outline of where the pocket is for these pieces. The holes I drill into the handles doesn't break the seal because they are outside of the vacuum pocket area. I've tried to show the grooves that are in the bottom piece of plastic, and the holes that are drilled through the top pocket, into the grooves. Of course the grooves run the entire width of the bottom piece and aren't short like I show them in the pic.

The gasket material on top, and between the two pieces of plastic, is from Allstar Adhesives. It's great stuff. It's their adhesive backed 1/32" material.

I found that it wasn't necessary to take the time to trim the gasket from around each pocket on top, I just poked holes in it with a scribe, or slit it a little with a razor blade.

I can easily pull 20Hg of vacuum with this setup, which is plenty. I only cut them at around 25 IPM because (a. I use 1/8" end mills so I can squeeze out more pieces per sheet (b. A Porter Cable router for a spindle and (c. This material is 1/4" thick Dymondwood and it's pretty hard stuff.

I used an adjustable vacuum switch from McMaster Carr on the pump so it doesn't have to run constantly also.

For me, this is a great setup and it's adaptable for just about any type of non-porous material that I'd have to cut.

I'm also attaching a small picture of the lighter trim pieces that I use one of these jigs (posted above) to cut . I have to use a 3/32R corner rounding end mill with a narrow plunge point on these to give them a rounded over edge.

Just got your reply email, Keith. Glad you liked the post.

Thanks,
Skip

[Steve knight]

here is one jig I use. I like to make jigs this this as all of the parts are at the same level so it makes it easier to setup the z. the vacuum just holds the parts down. this one is really precise so the pieces can't move back and forth ans there is not enough vacuum surface to keep that from happening.
the other one is a 24"x24" vacuum table for thinner sheetstock. I wanted something super flat and Moen that was strong enough for smaller parts. it has a 1/2" truepan top and uses a fien vac.
http://www.knight-toolworks.com/cnc/vac%20jig%20alo.JPG
http://www.knight-toolworks.com/cnc/small%20vac%20table1.JPG

http://www.knight-toolworks.com/cnc/small%20vac%20table3.JPG
http://www.knight-toolworks.com/cnc/small%20vac%20table4.JPG

[Skip Weiser]

This is the largest jig I use my vac pump setup on. This is the 3 ft. x 2 ft. one. I wanted to show how I grooved the bottom piece. The connecting groove for the air fitting is under the gasket though and can't be seen.

The top sheet has shallow pockets inside the cut perimeters like the picture I posted earlier, with holes drilled through the pocket into the grooves of the bottom sheet. Again, small holes are poked through the gasket over the pockets. I know it probably looks like one of those "how does that work?" pictures, but if I took a closeup photo you'd be able to see the holes in the gasket material over the pockets.

I use this jig to cut 3' x 2' sheets of 1/4" thick G10 epoxy/fiberglass composite. Any of you ever cut that stuff? Talk about material being tough on tooling, this is the worst material I've ever cut on my router. It eats up at least three 1/8" TICN coated carbide end mills per sheet. I've tried diamond coated tools, and depending on the brand I can sometimes get 2 full sheets from one tool, but for what they cost it's cheaper to use the $10.00 coated carbide ones. For a comparison, an uncoated tool will do one row and it's junk. A coated tool will do 2 rows, sometimes 2 1/2 rows.

I hate cutting G10, but sometimes you have to take the bad work to get the good stuff.

Skip

[Michael Kowalczyk]

Hey Skip,
Thanks for the reply. It looks like there is a little concave section in the middle of each of the handles and with your pin holes so I can see how yours works now. I make a 2" x2" grid (1/4" deep) on a sheet of HDPE. It is gasketed off on the perimeter. This is my universal grid system. For my dedicated ones I use the same HDPE but just do a 3/4" offset (inwards) of the toolpath and then apply the grid pattern inside the offset and clean it up as needed. I will line up the grids and drill through to allow for air flow. My parts aren't as small as yours so it is good to see how spoilboards for smaller parts are made. I wanted to make a pod system (like the Carter flip pod or the one pictured below) but just haven't taken the time to get the material I want to do it with or decided which way I want to pursue. Having a 5 x 8 table makes it a little harder to find what need at a price you want. For small parts I usually just put a 3/4" piece of LDF that has been flycut and then a piece of 1/4" mdf as my actual spoilboard also known as a carry board when doing high production runs. In my book it is cheaper to replace the 1/4" board than to have to fly cut the universal main board each time you switch a program.
Now this may not work for most DIY because of the Vacuum (CFM's)needed to keep up with the leakage. I have a Busch 5hp and a Travaini 20hp so I can switch between them when I need a dedicated or a universal spoilboard. The 5hp definately saves $$ on the electricty bill and with my dedicated spoilboards I can usually maintain 25 to 27 hg.

[Skip Weiser]

That's a nice setup Michael, I'd love to be able to pull the vacuum that you do with those big blowers that you use. I'm just a one man shop though, with a laser and a cnc router, so just about everything I do puts me over budget... ha

Steve, I went to your website and looked at those BEAUTIFUL hand planes that you make. The purple heart, well all of them really, are awesome !!! You are a true craftsman. I like your vacuum setups also. I tried a Fein powered vacuum jig similar to yours but it just wouldn't hold the small parts well enough. Works great on sheet goods though.

Thanks guys, I appreciate your input.

Skip