Spoil board thickness with Fein vacuum

[richards]

I read an interesting thread on the WoodWeb forum about using thicker spoil boards with low powered vacuums. One of the suggestions was to use a MDF spoil board that was AT LEAST 3/4-inch thick and then to add a 1/4-inch spoil-board/pallet-board, making the spoil board package about 1-inch thick (total thickness minus the material removed when surfacing both sheets). The claim was that the thicker package worked better than the thin (1/4-inch to 1/2-inch) spoil boards that are more commonly used.

Have any of you tried using full thickness spoil boards with a 1/4-inch carrier/pallet/spoil board with a Fein vacuum?

[Brady Watson]

Mike,
MDF is a gamble when it comes to using it as a bleeder. Some work really well and others have so much resin in them that there is NO flow thru whatsoever. I was at a shop where they just hooked up a 25hp Cascade pump (14hg, 650 cfm) and they surfaced both sides down to 3/8" final thickness with NO suck thru...I was totally amazed that there was THAT much resin in the sheet!

I REALLY like Trupan as a bleeder board. I am not sure why a thicker board would give you any better performance than a thinner one? Could it be that it slows the vac flow down enough to impair leakage & directs it to the places where there are parts sitting? I don't know...

-Brady

[evan]

I have a Fein III set up and start with a 3/4-inch edgebanded ulra-light MDF spoil board.I do have a problum with my spoil board after I've resurfaced it a few times (once it gets down to about 1/2-inch) it will warp, and the vacuum isn't strong enough to pull the spoil board flat down to the table. Once I put the sheet to be cut on it and turn the vacuum on it'll suck both pieces down, but at this point if I have too many through cuts it'll loose vacuum and parts will move. At this point I'll either have to change spoil boards or screw the spoil board down. Putting a 1/4-inch carrier/pallet/spoil board sounds counter intuitive to me. As soon as you cut into it and relieve stresses in the 1/4-inch board it'll be likely to warp...

[btk]

I use 3/4 inch Trupan and replace often.
I have tried a 1.25" piece of Trupan to try to avoid changing so often, however 3/4 works much better.

Brian

[pfulghum]

I use a 3/4 100# MDF... just skinned on both sides...When I cut MDF on top of the MDF spoilboard I bet I could hold some melamine. No problems here....

You just has to have the surface area of the part to be cut to be about 30-40 sq.in. and don't push the cut too deep or too fast.
-- pat

[richards]

I just tried a 3/4-inch MDF spoil board on my new vacuum platen and immediately took it off. As Brady wrote above, some brands of MDF must have more resin than others. The Plum Creek brand that I've used in the past is no longer carried by my regular supplier. The no-name brand that they sell now cuts beautifully and literally "snapped" onto the platten when the little Fein was turned on (which should have been my first clue that the sheet wasn't letting much air suck through). I surfaced the MDF on both sides, used a little silicone to seal the edges and then laid a sheet of 1/4-inch MDF (which had been mostly sealed with a coat of shellac) on top. With my old platten and spoil boards that sheet of 1/4-inch MDF has been held tightly to the spoil board. With my new spoil board, I could easily lift the 1/4-inch MDF and even slide it without exerting too much effort.

Unfortunatly, Trupan is not available in Utah, so I'm stuck with trying to find some porous MDF.

[davidp]

Mike,

We use 18mm (3/4) MDF as a spoil board on our system. It is a 7,5kw Side Channel blower pulling approx 12"HG at 144cfm. We surface both sides of the board, removing approximately 2mm each side. We cut parts a small as 150mm from 3mm mdf with no tabs. We also cut parts for a shop fitout company from 16mm melamine faced MDF in a single pass with a 3/8 two flute compression cutter.

The thicker MDF spoilboard holds much better than thinner board.

One day when I have time I will jot down the readings from our pressure guage and let you know the results.

[kerrazy]

JJ murphy from Allstar adhesives told me Thermwood did a test and they found a thicker.3/4 inch spoilboard worked the best, they were able to get a greater pull on it. My guess is it allows more vaccuum to create in the chamber of the plenum..But this is just a guess.
Dale

[syrcast]

I need to find trupan in Utah or somewhere close.
Any help will be greatly appreciated.

we are just getting our router up and running. This is all new to me. So any hints would be great.
Thanks

[gpari]

NOTE: I've got a roots pump, so YMMV.

I was consistently getting 12-13" when my trupan spoiler was new (18mm to start, then skim both sides). But as it got thinner over the months, I noticed a decrease in holding power and reading at the gauge. Now the board is ~1/4" and the max I can get is 6" of vacuum. The pump is not bad, as I can shut off all the valves and still reach the 14" magic number, and the filters are clean, gauge upstream of the bypass reads the same as the gauge at the table. So I'm figuring the spoilerboard is too porous now that it is thin. Over the weekend I will be changing it out, and will report the results.

One of the shops that used to cut parts for us used a 3/4" spoiler with 1/8" top sheets that they would just toss when they got chewed up. That way they never bit into the 3/4". Might try that too. Need to see how much a stack of 1/8" mdf runs.

My $0.02

Gabe

[jhicks]

We use 3/4" Trupan for bleeder board(sealed edges), topped with 3/4" trupan for spoil board, then surface spoil board based on usage until its as thin as practical, usually 1/8" or so. This leaves our bleeder in perfect shape and easy to drop on new spoil boards as needed. With 2 Rigid 6HP vacs it works great over our 5x10 PRT

[gabepari]

Well, put on the new 18mm Trupan ultralite spoiler. Sealed the edges with silly-cone, and now we are getting 10" when cutting 3/4" mdf with white melamine down. A little higher when cutting prefinished baltic birch, maybe 11".

To me, it seems as though the Trupan is TOO porous, small areas that are not covered create a significant leak in the system. Next time I'm gonna try a slab of 1" 5x10 regular MDF and see how it works.

Happy cutting,

Gabe