Spoilboard replacement

[Gary Campbell]

My first couple spoilboard versions were loose laid. Although not a bad option in many cases, I have found that for cabinet cutting, especially when using mortise and tenon joinery, a fully adhered spoilboard is much more stable. One of the main reasons that I resisted the change to a fully glued spoilboard was the difficulty in removing it when its useful life was over. The dust alone from surfacing off that last 1/4" is atrocious.

The last couple board replacements have been much easier. I now surface down to about 1/4", and using my original plenum files, machine a shallow v groove on all the original vectors. (Pic 1) This allows me to place a dollup of Titebond on top of every other "block" in my plenum and a double heavy bead on all the zone border areas. Keeping the glue confined to the original glued areas seems to allow great flow. Before placing the glue on the old spoilboard, I run all 4 edges of a sheet of Trupan thru the edgebander and then surface .015" off one side. This side goes down on the glue.

Once the glue has been placed, (sorry no pics I was rushing) I use my sheet lifter (Pic 2) to set the new spoilboard over the old, top it off with a sheet of PF plywood and turn the vac on for an hour. I surface the next day after moisture content has equalized. (pic 3)

You can see in Pic 4 the 2 different colors of edgeband. I now have a brand new 1 1/16 thick spoilboard that is ready for 6-8 months use.

[Brady Watson]

Gary,
Not sure I totally get it...Do you cut right on top of the grid & score it with the cutter - hence the need to surface, or ???

-B

[Gary Campbell]

Brady...
I must have messed that up if I confused you.

I have a fully glued (alternating blocks) spoilboard. Instead of surfacing off the thin used up spoilboard down to the plenum, I glued another over the thin remnants of the old.

[dlcw]

Looks familiar Gary. I'm about two re-surfacings away from doing this same process a second time. The first time I did it (after my phone call with you and your suggestion) I marked where my plenum high points were and put a drop of glue there and stuck the new 1/2" spoilboard on top of the old one.

Has been working great. Thanks for the suggestion a couple months ago.

[Gary Campbell]

Don...
This the second go round on this method. I didnt want to post until I (we) were sure it worked. The thick spoilboards sure have a lot more holding power than the thin.

[Brady Watson]

Needed a re-read...have the flu this week...so I'm running on 11 cyl. I literally look exactly like this right now --> :p

That's a very good idea - thanks for posting it up! I thought that this would work in theory, but never tried it. I still use the 1 sheet 'BradyVac' setup just for versatility. Looking to do a grid setup like yours when I get the Becker fired up in the new shop...which can't come soon enough...



The thick spoilboards sure have a lot more holding power than the thin.


Yeah...I noticed that too. I think the added thickness acts like a surge tank of sorts, which buffers losses better - thicker seems counter-intuitive, but it isn't.

-B

[dlcw]

Once I run out of 1/2" material I will be switching to 3/4" material. I'm looking forward to increased holddown capability with the thicker material.

[knight_toolworks]

Here is a way to make life easier. before you glue the sheet put it on your table cut it into 4 oversized pieces. seal the inside edges and glue one on at a time. this way you isolate the zones and it is easier to deal with the sheet stock since it is 4 pieces. this gives me better vacuum when doing less then full sheets.

[tom]

gary so by using a different edge band eliminates the marking or painting old spoilboard? oh and rub it in on your lift lol ;)

[Gary Campbell]

Steve...
My vacuum sheet lifter lets me place the sheet with ease. I have tried the 4 piece spoilboard, and in my case I didnt gain any hold down. My system has close to 400 cfm, so small losses may not be evident.

[frank134]

Hi Gary.. That look like a great idea. A couple of question those. Did you use your same pattern on your plenum when you glue down your spolilboard to it. did you skim coat it so the glue didn't go into the channels. Also looking at the picture you posted did you used MDF for both the plenum and the spoilboard . As you know I still used the plastic nail. I shoot the spoilboard to the plenum which seem to work good so far. when It get to 1/4 in thick I put on another 3/4 sheet and shoot it down. I may try your system with glue and see if it any better.

[Gary Campbell]

Frank...
Yes, I used the vectors from the plenum, which was cut with a 1/2" ballnose, and did an on vector, .050 deep "drawing". This let me know where NOT to put the glue.

I used a pea sized dollup in the center of every other square. Also put 2 1/8" beads along perimeter and between zones.

My plenum is industrial particle board sealed with about 3 qts of polyurethane. The spoilboard is Trupan or ULDF


Tom...
Something has to help us ol farts get those 85# sheets up on the table. The 2 color edgeband wasnt a plan. It was just a roll that doesnt match anything we stock. But now that you mention it......:rolleyes: I guess it will let me know when its time to add another layer.

[bleeth]

I have glued a second spoil board on top of the remains of an older one often. I have 8 zones and just run glue lines between the zones, around the border, and a ring around the center of each zone where the vacuum is. I'll then throw a sheet of melamine or something on top of it and turn the vacuum on for an hour or so. Works like a charm.

[zeykr]

Gary, Have you got a commercial lift like an Anver or did you make one? If you made it, would love to see some details. A vac lift is high on my list!

[Gary Campbell]

Ken...
I made that one. All air powered. Uses 34' of barn door track from Tractor supply to allow moving sheets from my storage area to the ShopBot.

An air motor powers a winch for lift. Air piloted solenoid for pushbutton control. An air powered vac generator supplies the suction.

[knight_toolworks]

Steve...
My vacuum sheet lifter lets me place the sheet with ease. I have tried the 4 piece spoilboard, and in my case I didnt gain any hold down. My system has close to 400 cfm, so small losses may not be evident.

that could be part of it

[frank134]

Gary is that what that oil filter type looking thing is? Is that the ait vac motor? That really look nice. Did you make the pad or did you buy them?
all I can say that is really nice. I use the same rail from tractor supply but I going to change it to unistrut because I want to make a 90 with it and Master Mc sell a 90.

[Gary Campbell]

Frank...
That "oil filter" is the silencer for the vac generator. (it is an oil filter, but dont know if its modded or not) I made the vac pads from Starboard and adhesive backed gasket material.

[frank134]

Gary…
I have another question for you. When I first build my table. I started with a sheet ¾ “birch plywood. Then I glue down a sheet of ¾” MDF. Then On top of that I glue another sheet of ¾” MDF which I cut for my plenum. I seal all sheet with polyurethane. Do you think I have one too many sheet?

[Gary Campbell]

Frank...
I cant say that you have too many, but you do have one more than I do. I used two 4 by 10 sheets of MDO splined together into a 5-3 by 8-2 piece. After the glue in the joint was dry I sealed the bottom side with 2 coats of poly. Next day I bolted it down and glued a 49 by 97 Ind. particle board to it, using screws to make sure it was down tight. Next day I cut the plenum and put 3 coats on everything. When that was dry, I surfaced a little off the top to give me a good surface to glue my spoilboard to.

MDO is a very stable material due to the layers of phenolic paper on both sides. I cant say how stable your products are. Go with what you think is good.

[frank134]

gary I think I will try your way. All my sheet are a full 5 x 10. That will give me another 3/4" to play with if I every need it. Like you I bolt down the plywood but I shoot the mdf down with plastic nails.

[frank134]

gary I forgot to ask on your vacuum lift. do you think two 12 x 20 pads would be the right size to pickup 3/4" x 4' x 8' plywood?

[Gary Campbell]

Frank...
Depends on the vac source. I went a little overkill on mine. I have 22 inHg to the pucks. Rule of thumb is 2 inHg = -1psi +/-.

Formula would then be: Puck area (L x W) * inHg/2 = Weight you can lift. Should add (or actually subtract) in a safety factor.

In my case: 2 pucks 7.5 by 11.5 = 172.5 sq in

172.5 * 11 = 797.5 pounds. This assumes no leaks, that nothing will fail, and that my support structure could take the weight, which it cant.

I was very surprised to see how well it held the Trupan. Not so well after one side was surfaced. Melamine and PF plywood are no problem. I have yet to try it on a sheet of 3/4 unfinished plywood. I am sure I wont have a problem based on the Trupan results.

EDIT: Area of the puck is the area INSIDE the perimeter gasket!

Most 4 by 8 sheets of plywood weigh about 50#. Lets figure the minimums. With a measely 5inHg and a 6" square puck you could lift: 36 * 2.5 = 90#. I obviously would never go that small, but in theory it will lift a 90 sheet with no leaks. I oversized mine so that I can lift sheets from the vertical and carry them horizontal.

In theory there is no difference between theory and the real world. In the real world, there is no evidence to support the theory. Thats the main reason I cant see eye to eye with programmers and developers. ;)

[frank134]

Thank Gary. with that info I could be al right. I be happy if it lift 100 lb. I am getting older and the pywood is killing be. This will help oh so much.

[bleeth]

Gary: I believe you are familiar with the design that Frank Leinbach did years ago for a lift. He actually used a large pot lid he raided from his wife with some gasket. He used his 7.5 hp vac pump. Frank did a lot of work with 5 x 10 3/4" MDF and had no trouble doing it. My point is, as you discovered with your formulae, is that it doesn't really take that much to lift a sheet of normal substrate or cabinet material. Here is the link to Frank's original:
http://www.talkshopbot.com/forum/showthread.php?t=5387&highlight=frank+lift&page=3

[Gary Campbell]

Dave...
I think about Franks (and others) posts every time I grunt a sheet of 2 side melamine up on the table. Something you office guys know little about!!!! :D