A cheap way to make custom vacuum templates.

[knight_toolworks]

I found problems holding some solid woods with my vacuum pucks. Like beech really wants to leak. I found a simple solution and that’s to coat the side you’re holding down with a thin layer of woodworking glue I use yellow glue. I use a putty knife and scrape off all the excess. This then gives me a very good seal over bare wood.
Well this got me thinking. I had planned on making some templates like Brady shows to seal small parts when using a vacuum. So you don’t have leakage. Well it just popped into my head why not just make your spoilboard into one? Just coat the area you plan on using with yellow glue let it dry and then zero on the table and make a real shallow pass cutting out the template shape into the spoilboard. There you go almost instant template anywhere you need it. I will be trying this out in the next few days but it should work well. The best part it is dirt cheap to do and easy to remove after your done. This would be more practical for the one off’s and such then ones you need to sue all the time and change.

[davidp]

Steve

Our next door neighbour produces glues and paints so he supplies me with latex paint, so I use that to make a vacuum mask following s imilar proceedure to that which you mentioned. I works very well especially as you say for small runs. It is quick cheap and very effective.

Regards

David

[knight_toolworks]

I like the glue because it dries in minutes and only needs a single coat. does the latex seal in one coat?
I have 50 beech boards to seal on this project. they are horrible under vacuum.

[john_l]

Joe is experimenting with rubber cement for Vcarving masks...

http://www.talkshopbot.com/forum/messages/315/23923.html?1196617015

Considering how quickly the rubber cement dries, how easily it removed in my own little tests, it may be a candidate for vac masking as well. Note; I do not speak from experience cause I havent set up my vac yet. Just a thought.

[Brady Watson]

I've tried several 'liquid' gaskets and masks for vacuum, and they all performed poorly. Depending on the size of the parts, and how powerful your vacuum is, you can get away without any gasketing much of the time.

When I speak of a vacuum 'mask', I am referring to a thin piece of material that blocks off vacuum everywhere but under the areas of your parts. You can use the BradyVac II to do this, with a build in grid, or create your own generic grid that you lay a piece of 1/8" or 1/4" masonite onto that has holes in it only where your parts will be cut. It doesn't get any cheaper than $10/sheet for masonite.

If you have very small or textured parts, you can use AllStar spoilborad cover to maintain a good seal with your parts. 99% of the time, it is not necessary, nor economical if you are not going to reuse the mask again.

It sounds to me like your Beech is porous, and the only 'non-pain in the butt' method is to throw more CFM at it to make up for the leakage OR do what I do - grab a handful of sawdust and work it into the areas that are leaking. It should self-seal. Another idea would be to buy some .040" styrene plastic sheet (comes in 4X8 for under $10) and lay it on top of the porous material. Tack it with tape or something. Then use a downcut to cut thru the styrene and into material, then change to your normal tools. Without seeing what's going on, it's hard to make a suggestion....

This is what I call a 'VerandaVac' - not after some hot blonde...but the material - ONLY Veranda is useable for a vacuum grid - Trex is inconsistent and has holes in it that make it hard to use. This is Veranda composite decking only sold at Home Depot.

In the next few pics you'll see 1.5" PVC tubing feeding 2 large 'pucks' that I use in conjunction with masonite masks that fit onto the grid area, that direct air ONLY under the parts I want to cut. It's cheap & effective and best of all, completely non-porous. The PVC fittings you see just slip-fit into the Veranda. No gaskets, no sealants, no leakage. This should give you some ideas on how to make your own.

On a side note, the Fein does not do well with small pucks made out of this stuff. I would go no smaller than 12" long X width of Veranda (about 5") - Plane the Veranda to take off any texture, rip on table saw if you need square edges or want to run several in parallel as I have done here. Fein plugs right into rubber reducer.


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-B

[knight_toolworks]

I was hoping to use the liquid gasket over having to use AllStar spoilborad cover for the job on these 3x4" plastic parts.
I have a vacuum puck I use for all kinds of things it is 6" wide 36" long with 4 zones it uses a small gast vac pump. I use allstar gasket material. I think I am using the 1/16" I find some woods don't seal well and some do. beech is really bad and I am lucky to get 10" so coating the back gives me 20" or better sometimes.
I have a larger pump and it would do a bit better but not a lot. it is the jig on the right that is my general use.
but is all of the beech all 130' of it


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[richards]

I use self-adhesive shelving paper to seal the underside of 'leaky' lumber. It seals the surface so that the vacuum works. It is inexpensive, and it easily peels off.

[knight_toolworks]

th problem with the paper is that the holddown is only as strong as the connection of the paper to the wood. with what I am doing it would not be strong enough.

[Brady Watson]

If you don't have a pump with enough reserve CFM to overcome the leakage, then there's not a whole lot you can do about that, other than what has been suggested using only vacuum. You may have to resort to some kind of clamp, a sub-board with paper glued in between your part, or some other type of fixture. As nice as vacuum is to work with, it's tough to employ when you have thick hardwoods with high cutting forces combined with low surface area. An immediate solution may be to reduce the cutting force by drastically reducing stepdown and chiploads. The downside being longer cutting time, the upside being able to cut out the parts.

-B

[knight_toolworks]

I wonder how big a pump I would need? right now the glue takes care of it. but this job with 50 boards is a bit of a pain. most of the tropicals I cut on it hold really well. I usually only cut them at 1ips. the beech I am doing it at 2ips I have so many that I need the speed.
I find American woods leak the worst.

[beacon14]

I'm getting good results using the FEIN vacs on hardwoods as long as the surface is smoothly planed. The Gast pumps rely on a nearly complete seal and the wood is just too porous for that. I use the entire spoilboard and lay flat scraps of 1/4" cabinet back material (1/4" MDF with vinyl on one side) to cover the unused area of whichever zones are being used. For aggressive cuts I place blue tape around the wood and over seams in the scrap material and any uncovered areas due to the shape of the workpiece. Just turn on the FEINS and cover anything that leaks. You can get the blue tape on Ebay fairly reasonable. The scrap material seals the vacuum and also keeps the workpiece from sliding.

Here's a piece of ash cut all the way through with tabs using just the two FEIN vacs, as Brady suggests I tossed sawdust into each opening on the last pass as the through cuts were being made. With the two FEINS the wood was held down solid as a brick, I was using 1/2" and 1/4" diameter bits and 1/4" deep passes, total depth of cut 1.875".


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[knight_toolworks]

I have not tried my spoilboard for must solid wood. I will have to play with it. the cuts I am doing now I htink would be too aggressive. I am hollowing out these boxes and the first pass at .37 is 3ips and the second taking about 1/2" is 2ips. thats a good chipload and I have 13 hours at that speed to cut it all.
most of my solid wood has been tropicals and even at 1ips I think there is a lot of pressure since the wood is so hard.
even with a good seal I have had wood come loose on my vac setup. the boards may be a bit warped and I have to kneel on them to get them to grab. so then the spoilboard would be useless.

[knight_toolworks]

I tried using the spoilboard vacuum to hold down a piece of 24"x9" beech. even with all the rest of that zone closed off the beech wanted to slide around. the plywood and such I covered the rest of the spoilboard with was holding better then the beech.

[beacon14]

Was the beech surfaced smooth and flat on the bottom face? If not it probably won't work. Was the plywood butted tight up against the beech on all sides? If the plywood won't slide then either will the beech if the two are in contact with each other. Did you try taping the joints between the plywood and the beech? That usually makes the difference for me for tricky hold-down situations. Also, plywood is porous, so if you can use something non-porous like melamine, or lay some plastic over the plywood that might help as well.

My last resort in a situation like this is to screw the wood to a piece of melamine (from the back if necessary) and hold the melamine down with the vacuum table.

[handh]

I don't know if this helps but I sometime rout out a place in a sheet of plywood to hold the smaller part with very good results. I made the rout a little larger and use wedges and have had no problems.

[knight_toolworks]

I know I could have worked harder to hold it in place. but it was interesting how it moved more then the other things did.
I have nailed and glued something non porous to smaller pieces of wood so I can use my vac jig.
I may have a big job that I have to cut a lot of small parts from full boards of 8/4 beech. they will be too large to flatten (I hope) I am trying to figure out the best/fastest way to hold them down. I figure I will be going through 15 or 20 boards I want a faster way then drilling each one and using screws. my brad nailer does not have long enough nails to really hold well. these are cut at 2ips with a 1/2" bit so they need a good hold down. I want to remove one board while others are cutting so I cna keep thins going. I may put a sheet of melemime down to attach the wood to to save my spoilboard and use the vacuum to hold it down. the boards will vary in width so thats an issue with hold down too.

[Gary Campbell]

Steve..
We have been able to cut on solids with little or no problem. We plane the piece first, and in a few cases we had to spray a thin coat of lacquer to seal it. We just cut out a bunch of Oak pieces for a staircase, some with 1/2 bits @ 1/2 deep @ 1-2 ips. One of the pieces was rocking up off the table by 1/4" and we just put a clamp on both ends. Masking for a stair stringers notches creates some unique problems. Our vac setup is minimal, 4 zones with a direct mount vac motor for each zone. 100cfm/7"Hg. max
Gary

[knight_toolworks]

since I will have the table loaded but it will have gaps between boards I don't think my two fiens would be good enough.
I think nailing them down to a sheet of melemine is about the fastest way. or maybe I will make some brackets that will hold the wood down but let me nail the brackets down. I want to be able to do this fast to save time.