Problems with plywood

[Andrea Weissenseel]

I'm using plywood sheets and something (too often ;)) they are not completely flat and which runs me into the problem that the wood is not cut all the way through :( I was thinking to use clambs and fix the sheet to the honeycomb, but that only solves the problem at the edges and not in the middle or as soon as I make a cut.

How do you solve this problem ?

Cheers, Andrea

[Norberto Coutinho]

I think that if you use a spray adhesive like Spray Mount ( 3M ) or similar, you solve the problem.
Norberto

[Norberto Coutinho]

Also do a search for
Double-Sided Acid Free Scrapbooking Tape Removable

[Andrea Weissenseel]

thank you for your answer, Noberto.

I should have been more specific with my question :o, the wood I'm using is not the veneer type, it is 3mm, 4mm and 6mm thick therefore I don't think that a spray adhesive would hold it down, plus I need a clean backside

[George M. Perzel]

Hi Andrea;
I cut a lot of plywood and am very familiar with the problem. I found that the problem can be minimized by clamping the edges at various spots, depending on where the warp is.
To do this, I use a sectional honeycomb table consisting of a corner piece and two outrigger pieces which can be positioned depending on the size of the plywood. See the cdr for detail of construction. It helps to add some additional weight to the outrigger pieces to insure that they stay on the table if the ply tries to lift. I use very inexpensive spring clamps with the rubber tips removed and the tips bent inward for a better grip (see diagram).
This allows me to accomodate any size workpiece.
This may not be very effective for ply thicker than 6 mm which is badly warped.
Hope this helps
Best regards;
George
LaserArts

[Dan Hintz]

It's not an ideal solution due to the time involved, but if a piece is really warped in the middle, this should resolve the issue. Drill a small hole in a scrap area as close to the warped portion as possible. Run a screw through the hole with a fender washer on the top of the board and the bottom of the vector table. You may have to reposition your cutout slightly, but it will hold the piece completely flat.

[Andrea Weissenseel]

thank you, both suggestions sound great. I was thinking about the "hole thing" also - cutting two holes in the middle and use a piece of wire to fix it to the honeycomb.

I like the idea of an sectional table George, unfortunately I can't open you CDR - only have V11 of Corel

Andrea

[Mike Null]

Here it is in v9.

If you don't want to make any cuts in the honeycomb grid consider using screws washers and wing nuts to hold areas flat to the grid.

Also, be sure to store your material flat rather than standing.

[David Fairfield]

Sometimes its possible to cut cleanly through ply by running the job twice. Refocus a little deeper between jobs. You can adjust the speed a little faster than for a single cut. Not very sophisticated, but it can work.

[Tim Eddings]

I use a simple toggle bolt. When doing the set up I first see how the plywood will lay, then put a toggle bolt where needed to hold it flat.
131913

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Hope this will help.

[Lee DeRaud]

How do you solve this problem ?Buy better plywood. Seriously.

If a piece of ply thicker than 3mm isn't flat, it's probably because it's cheap, um, stuff, full of knots, interior voids, and blobs of glue that wouldn't cut through cleanly even if it was flat.

(And no, 'stuff' isn't the word I wanted to use.)

[Dan Hintz]

Tim,

It took me a few seconds to figure out what your second picture was.. I thought you found some cool new metallic material and those were cutouts of it. the more than two braincells kicked in and I realized it was a view of the vector table through the wood cutouts.

[onur cakir]

Tim,

It took me a few seconds to figure out what your second picture was.. I thought you found some cool new metallic material and those were cutouts of it. the more than two braincells kicked in and I realized it was a view of the vector table through the wood cutouts.


+me !

First i thought somehow honeycomb grid is cut !

[Mike Null]

Ohhhhh! :rolleyes:

[Belinda Barfield]

Tim,

It took me a few seconds to figure out what your second picture was.. I thought you found some cool new metallic material and those were cutouts of it. the more than two braincells kicked in and I realized it was a view of the vector table through the wood cutouts.

+1:o

That vector table is way too clean! My first thought was "wow, way cool material, wonder what he's making with it" . . . LOL

[Lee DeRaud]

+1:o

That vector table is way too clean! My first thought was "wow, way cool material, wonder what he's making with it" . . . LOL+2. Mine wasn't that shiny when it was new.:eek:

The fact that the first picture (showing the bottom side of the grid) looks like the top side of mine didn't help any either.

[Frank Corker]

Got me too! Never seen a vector table that new since.......since I bought my laser! I think you would have to have big signs to remind you to remove that device, it would bend your cutting bed extremely easily but I do get the idea.

[Tim Eddings]

Sorry for the confusion. I just assumed that it would be self explanatory.
Doesn't any one clean there vector grids. :D
That one is two years old and it looks better in the picture then it is.
Thanks
Tim

[Scott Erwin]

Sorry for the confusion. I just assumed that it would be self explanatory.
Doesn't any one clean there vector grids. :D
That one is two years old and it looks better in the picture then it is.
Thanks
Tim


Clean their vector grids? How do you do that? I could use that good of a cleaning on my stove....

[Tim Bateson]

Will this method work if the plywood is flat and the grid sags? :eek: Actually using good flat wood, this is an advantage as those pieces fall right out.

[Andrea Weissenseel]

lol I thought the same "what is he cutting there?"

thanks a lot for the great tips and the V9 file :)

Mike, I have a sheet of 6mm here and it isn't completely flat, bought at a Holzfachhandel (I trust in the google translator:rolleyes:) though - but maybe your right and I have to look for another source. Ought to think about storage too, at the moment I have to store them standing. The other issue is, that you barely can use those bend parts of the sheet - cause nobody wants a wooden christmas tree that's bend to half past seven, even if it's nicely cut

Cheers, Andrea

[Mike Christen]

Tim,

It took me a few seconds to figure out what your second picture was.. I thought you found some cool new metallic material and those were cutouts of it. the more than two braincells kicked in and I realized it was a view of the vector table through the wood cutouts.

Hi Dan

Thanks for helping my only braincell wake up too:D
I thought the same thing, its one of those optical illusions

[Dan Hintz]

bought at a Holzfachhandel
My German is rusty... would this be like a wood specialty store, or more of a general purpose home-improvement store (i.e., a Borg)?

[Jim Beachler]

Andrea, I work will a lot of plywood. It must be stored flat. If you are still having a problem with it bending, a potential problem could be the humidity of where it is stored.

This may sound dumb but during the winter, when it is dry, I run a humidifier inside a makeshift tent over my pallet rack of wood. Keeps the wood very flat.

Another suggestion is to keep the wood clamped flat or have a weight on it to keep it flat.

Just a few ideas.

[Andrea Weissenseel]

Dan, more of a wood specialty store :D

Humidity was a good hint, Jim I maybe I store it at the attic that should be perfect than plus I can store it flat there

[Lee DeRaud]

FWIW, I get my plywood from Aircraft Spruce and Specialty. It's from Finland IIRC, slightly more expensive than the borg stuff, certainly not enough price difference to cover any time spent mucking around with elaborate hold-downs. They're local to me, so I have no idea how their shipping runs...then again, Andrea is about 6000 miles closer to the source than I am.:D

Another factor may be that I chunk it up into laser-sized (12x16 for me) pieces as soon as I get it home and store it on-edge in Rubbermaid bins. But flat or on-edge, I've never had a piece warp.

[Larry Browning]

I read your post and was thoroughly confused. I thought to myself, well, duh!, just raise the blade on the table saw a bit higher, then it would cut all the way through.
Then I realized this was a post in the engravers forum.:confused: