plywood breakout

[Robert R]

So, I've been attempting some eagle cut-outs. I'm using a #2 blade, ply is Baltic Birch and in the intricate points between spaced feathers that are more pointed on the end the top layer of ply will break away. I have not tried to push the blade through but let it do the cutting and still I get this.  So, I switched to ¼" MDF and it works fine, no chip outs or breaks, is this pretty much the norm?  I use the ply because I can pick what way I want the grain to move through the project and I didn't want to paint it.

 

Edited May 26, 2023 by Robert R

[CharleyL]

Reduce the size of the blade hole in your scroll saw table.

I have a thin 3/32" piece of Baltic Birch plywood that I have drilled a small hole into that I place the scroll saw blade through as if going to begin cutting. Using the tensioned blade helps me get this piece of Baltic Birch positioned perfectly. I then apply a couple of pieces of double sided tape to the under side of this plywood and stick it down to the table. The close edges of this hole to the blade will help prevent the blade from splintering the edges of your project. Using smaller blades, and the "reverse tooth" blades with the lower inch or so of the blade toothed in the upward direction also helps. Keeping your blade waxed also helps some too, by reducing the friction on the sides of the cut. Cabinet makers use a "zero clearance blade insert" in their table and miter saws to minimize the gap between the table and blade for this same reason.

Masking tape applied to the bottom of your project can hold the wood fibers as the blade cuts them and this can help too. 

 

Charley

 

Edited May 26, 2023 by CharleyL

[Robert R]

Thank your Charley, I do use a reverse cut blade (bottom portion) but it's not on the bottom this is happening.  It is the top. I do hold it down tight against the table top.  I also should say their were no voids in the ply that I could make out either.

[Scrappile]

buying you plywood from Windsor plywood?  I  shouldn't say them, but that is where I have purchased my last few pieces and they have been, crap.  Hard to find the good grade BB plywood anymore.  There has been talk on here about sheet goods you can get at places like Home Depot.  Hope someone will speak up about it because I cannot remember what it is called.  It gets good reviews.

[Robert R]

21 minutes ago, Scrappile said:

I used scrap I had from previous projects.  I've cut up the piece I used and find no voids and looks great, but looks are deceiving.  I used my cutoff saw and cuts clean, the table saw again, clean.

 

[OCtoolguy]

Regarding what Charley said about using a zero clearance type of insert, I use a playing card that I saw to the center and then use packing tape to close the slit and to hold the card to the table. 

As for what Paul was talking about, I think he is referring to project panels that can be bought at Home Depot. They are are 11 by 17 inches and come in different species of wood on top and bottom with a solid core in between. I've not tried them yet but from what I have read here on the Village, they work well. Just a bit more expensive.

 

[Dak0ta52]

I'm not certain but are you having break out or is the plywood outer layer tearing away from the inner layers. If so, that is referred to as delamination. The most common cause is cheap plywood. The better grades of plywood you get from the big box stores are very poor quality and will delaminate as well as have voids between layers. I'm limited as far as a wood source in my area and usually have to resort to the box store quality. One way I've attempted to overcome the delamination is by double stacking with the two pieces I'm cutting facing each other. That will help but not eliminate the issue. Also, some patterns require you always place the pattern on the front of the piece of wood. Examples of this would be words in the pattern or certain things that require left and right orientation. If you double stack face to face, one of the pieces would be mirror imaged.

As Paul (Scrappile) said, quality wood is hard to find, especially Baltic Birch. If you do find it, the cost usually precludes the purchase. Another alternative would be milling down solid material but that can be very time consuming, and if you don't have the proper equipment, very expensive.

I also try to keep sharp blades in the saw. Again, it doesn't eliminate the problem but reduces the chance of serious delamination.

[Millwab]

1 hour ago, OCtoolguy said:

As for what Paul was talking about, I think he is referring to project panels that can be bought at Home Depot. They are are 11 by 17 inches and come in different species of wood on top and bottom with a solid core in between. I've not tried them yet but from what I have read here on the Village, they work well. Just a bit more expensive.

 

I bought a box of these panels to try and have been thoroughly disgusted with them.  Nothing like being a few hours into cutting a project and hitting a void in the core or having the veneer chip off in large pieces. They may be useful to me if using the panel whole, but I won’t make the mistake of using them for fretwork again. 

[OCtoolguy]

1 hour ago, Millwab said:

I bought a box of these panels to try and have been thoroughly disgusted with them.  Nothing like being a few hours into cutting a project and hitting a void in the core or having the veneer chip off in large pieces. They may be useful to me if using the panel whole, but I won’t make the mistake of using them for fretwork again. 

That's the first negative response I've heard. 

[Robert R]

2 hours ago, Dak0ta52 said:

I'm not certain but are you having break out or is the plywood outer layer tearing away from the inner layers. If so, that is referred to as delamination. The most common cause is cheap plywood.

I have been having break out, as a chunk of the core material will just fly out. I have talked to a millwright and he thinks, it's poor gluing of the layers, or just a bad spot within one of the layers. It's just frustrating when it happens half way through your project.

[MarieC]

Robert,  I am sorry you are having this trouble.   I also have had that issue so now I just use hardwood but typically 3/8 - 3/4 inch.  I do have a wonderful bandsaw for resawing to the thickness I want, then use my Jointer (sometimes drum sander) and planer to finish it....pretty happy with the results.

[Roberta Moreton]

I am NOT trying to say anything about the poor quality of plywood now, (I know it’s bad). I have learned that when cutting feather tips that are very pointy,  never finish the point coming out of the cut, it will break 99% of the time.  I spin the blade and go down the side. 

[Millwab]

22 hours ago, OCtoolguy said:

That's the first negative response I've heard. 

That may be, but out of the first 6 projects I’ve had 3 failures of one kind or another. I’ve spent way too much time repairing these faults to risk buying it again. 

[crupiea]

What happens many times is the little part you are trying to cut will be unsupported by the whole in the table.  Then it breaks out because its not supported. 

Couple simple ways to address this.

1- a playing card with a hole in the middle of it like the kind you can buy at casinos.  Put the blade up through the hole and tape the card to the table.

and/ or

2- Put another piece of scrap under the piece you are cutting and cut both at the same time.  This will give you more support to stop the breaking out stuff. 

[CharleyL]

Blue tape (under the pattern) or packing tape above or below the pattern (clear) will work on the top of the project for reducing splintering too, but nothing will stop splintering of sub standard plywood - plywood with voids, or plywood with missing glue areas.

Charley

[Norm Fengstad]

On 5/26/2023 at 2:08 PM, CharleyL said:

Reduce the size of the blade hole in your scroll saw table.

I have a thin 3/32" piece of Baltic Birch plywood that I have drilled a small hole into that I place the scroll saw blade through as if going to begin cutting. Using the tensioned blade helps me get this piece of Baltic Birch positioned perfectly. I then apply a couple of pieces of double sided tape to the under side of this plywood and stick it down to the table. The close edges of this hole to the blade will help prevent the blade from splintering the edges of your project. Using smaller blades, and the "reverse tooth" blades with the lower inch or so of the blade toothed in the upward direction also helps. Keeping your blade waxed also helps some too, by reducing the friction on the sides of the cut. Cabinet makers use a "zero clearance blade insert" in their table and miter saws to minimize the gap between the table and blade for this same reason.

Masking tape applied to the bottom of your project can hold the wood fibers as the blade cuts them and this can help too. 

 

Charley

 

I wonder if a a thin kitchen silicone cutting sheet would work , secured with two sided tape?

[CharleyL]

Between the table and project, most anything with a small hole in it will work, but it needs to be attached to the table so it doesn't move with the project while cutting. Thin and sturdy with a small hole is what you need. My original was very thin plywood large enough to let me attach strips of wood under the edges and against the edges of the saw table to keep it from moving. Now, many pieces of thin plywood later, I don't use scraps of plywood that large and use double sided tape to hold it to the table now. All you need is something to hold the wood fibers up close to the cut so the blade can't deflect them as it's cutting. The down stroke is usually the problem, but if you are having it on the up stroke, something like clear packing tape against the top surface of the wood with the pattern attached to the top of it can work, but nothing will work top or bottom if the plywood isn't made well.

Charley

Edited May 30, 2023 by CharleyL

[clocks and more]

I have had problems with tear out on top, and fond out I had the blade in upside down. I hope this wasn''t your case'

[CharleyL]

" I have had problems with tear out on top, and fond out I had the blade in upside down. I hope this wasn''t your case' "

That will certainly cause problems. The workpiece will be very hard to hold down against the table too. I'm certain that everyone who has been a scroller has done this a time or two (maybe more). Yes, I have done it too. I now rub my finger over the teeth to be sure that I have it right, since I need optics to see the teeth now.

Have you ever put the blade in with the teeth on the back side? (I've done this too, but less often). Old age and eyesight causes things like this. It's just something for private laughter inside you when it happens. Fix it and move on, after enjoying this little bit of personal old-age humor. 

Charley

[OCtoolguy]

1 hour ago, CharleyL said:

" I have had problems with tear out on top, and fond out I had the blade in upside down. I hope this wasn''t your case' "

That will certainly cause problems. The workpiece will be very hard to hold down against the table too. I'm certain that everyone who has been a scroller has done this a time or two (maybe more). Yes, I have done it too. I now rub my finger over the teeth to be sure that I have it right, since I need optics to see the teeth now.

Have you ever put the blade in with the teeth on the back side? (I've done this too, but less often). Old age and eyesight causes things like this. It's just something for private laughter inside you when it happens. Fix it and move on, after enjoying this little bit of personal old-age humor. 

Charley

Been there & done that! 2/0 is very small.

[Wichman]

Going back to the original question; have you tried cutting without reverse teeth?  The reverse teeth may be bending the plywood up and then the regular teeth bend it back down and the grade of plywood you're using just can't take the strain?

Another thought would be to use a light coat of shellac on both sides of the project, before, you apply the pattern. This would stiffen the material to keep it from moving as much while you cut, and perhaps penetrating the fibers and reinforcing them.

[Robert R]

1 hour ago, Wichman said:

Going back to the original question; have you tried cutting without reverse teeth?  The reverse teeth may be bending the plywood up and then the regular teeth bend it back down and the grade of plywood you're using just can't take the strain?

Another thought would be to use a light coat of shellac on both sides of the project, before, you apply the pattern. This would stiffen the material to keep it from moving as much while you cut, and perhaps penetrating the fibers and reinforcing them.

No I have not, I'll try it the next time I get into the same situation.  I can see where a sealer of probably anytype would help the situation.

Thanks

Edited May 31, 2023 by Robert R