Help needed with 1/8th BB ply.

[Foxfold]

As you all know, I bought some 1/8th (3mm) BB ply last week.  I've noticed that the back layer breaks.  Is this normal ?

I've done a few things - tightened my blade, slowed the blade down, speeded the blade up quite high, slowed my rate of feed, worked quicker with my rate of feed. Not much seems to make  a deal of difference, although slowing the rate of feed seems to work best.

Never having cut anything other than ¼" ply before I'm wondering if it's something I'm doing or is it the nature of the wood.

I wouldn't say I'm a raw beginner at scrolling any more but this is totally flummoxing me.  Any help appreciated.

This is the backside of a piece I'm working on so that you can see what I mean. Oh, and there are a LOT of fuzzies too, it's just that I took them off for the sake of the photo.  I'm using a No 3 reverse blade (Niqua/FD)

Edited August 10, 2020 by Foxfold

[Jim McDonald]

I have never seen tear out like that Baltic Birch. I assume you are cutting single layer (not stacked).

It looks like the teeth are are being super aggressive on the down stroke. Plus, IMHO, a #3 on single 1/8" is too big.

Are blade reverse or ultra reverse?

Edited August 10, 2020 by Jim McDonald

[WayneMahler]

Hi Brenda

Every once in a while I experience this same thing. I sort of attribute it to the lack of clue between the layers of veneer. Slowing you blade down is not the answer, I increase me blade speed. Theory being the slower the blade the longer the contact with the veneer giving it time to pull if it is loose. Using a zero clearance insert or covering helps as it supports the material over the hole. I use cheap playing cards with a little tape to hold them in place. Watch your feed rate too, give the blade a chance to do it work. I am a huge fan of Flying Dutchmen blades. I use a #3 UR which has every third tooth reversed. Hope some of this helps.

[Foxfold]

Just now, Jim McDonald said:

I have never seen tear out like that Baltic Birch. I assume you are cutting single layer (not stacked).

It looks like the teeth are are being super aggressive on the down stroke. Plus, IMHO, a #3 on single 1/8" is too big.

Yes, it is a single layer, I've yet to try stack cutting. 

[Foxfold]

1 minute ago, WayneMahler said:

Hope some of this helps.

It does Wayne, thank you. I'll try the zero clearance tomorrow. I think the blades are Ultra reverse, but I'll check in the morning.  I think I may try stack cutting too and see if that makes a difference. 

[Jim McDonald]

Let's just figure that piece of wood is ruined and we will use it for experimentation. 

Turn the wood over and make a few cuts. If the tear out continues, it might be a blade/speed/feed issue.

If the problem goes away, it is as @WayneMahler said, and there is a glue problem in the ply. 

[kmmcrafts]

Exactly why I run my saw full speed when cutting BBply... I typically stack cut 4-6 pieces and this sometimes happens.. I find it ( for me ) seems to happen in thin spots where two cuts are real close to one another with just a thin like separating and sometimes I've attributed it to pushing a dull drill bit though the wood rather than letting the bit do the drilling, LOL Usually a new bit helps with some of it for me.. though on rare occasion it just happens..no matter what I do..     

[Rockytime]

If the front is OK I would not worry about the back. No one will see it.

[Foxfold]

8 hours ago, Rockytime said:

If the front is OK I would not worry about the back. No one will see it.

The front looks great Les so perhaps I worry too much, but it concerned me as I've never seen it before.

[Foxfold]

8 hours ago, kmmcrafts said:

I find it ( for me ) seems to happen in thin spots where two cuts are real close to one another with just a thin like separating and sometimes I've attributed it to pushing a dull drill bit though the wood rather than letting the bit do the drilling, LOL

I think you may be right Kevin, when I look at it,  it is where there is a 'thin' line separating and also I know that the drill bit I used wasn't the sharpest and I did 'push' a bit    I would never have thought of that. 

[Tomanydogs]

Not sure if this would make a difference, but I tape both sides of my board. But I also don’t use a straight blade. 

[don in brooklin on]

I usually stack cut if doing 1/8 but some times you must do as single sheet if something like a personalized ornament.

Couple of things I have done is given the sheet a coat of sanding sealer. (shellac/alcohol 50/50) and lightly sand.

I also try and use a dull blade.  Some one here suggested using your blade first on a few cuts of hard maple.

Steve Good keeps a dull blade around just for this.  See his blog http://scrollsawworkshop.blogspot.com/2020_07_21_archive.html

 

 

[JimErn]

Set the machine to high speed, and feed the wood slowly.  I regularly cut 1/8 BB ply with pegas MG #3 and only occasionally see that happening.

But like Les said, who looks at the back of the piece when you are done.

[NC Scroller]

I seldom cut only a single piece of 1/8" (3mm) Baltic Birch but when I do I use a #1 or even a 2/0 reverse tooth blade. Unlike many others I slow the saw speed down again only when cutting a single piece.

Don't fret (pun intended) about the back.

 

[Foxfold]

3 hours ago, don in brooklin on said:

I also try and use a dull blade. 

That answers a lot.... I kept changing my blade thinking it wasn't sharp enough     Well, you learn something every day. !!!!

[Rolf]

Like the others I never cut a single layer of 1/8. And certainly not with a #3 blade. You want as many TPI  on the wood, no less than 3. Even if you use an Olson 2/0 R  28TPI there is a problem. The gap where the teeth change direction is almost 1/8. It will definitely tear out the wood. 

I have also gone to a 28 tpi blade with no reverse teeth, and deal with the fuzzies after with a Mac mop.

If you want to cut only one at least put a backer of some crap plywood under it. 

[Rockytime]

The Pike #1 has 42 TPI!

[don watson]

I would use a sacrificial piece underneath and take my blade down to a #1 (even lower if needed).

If you use the smallest drill that will do the job it will have to run as fast as you can get it and use a LITTLE pressure otherwise it will burn.

Don W

[Fish]

I use a #1 or less. Not a skip tooth for sure.  I also found where I get mine must have gone with a cheaper supplier and have a thinner layer of Birch. I never had a problem before. It might just be cheap quality wood.

[crupiea]

#3 is a pretty big blade for that thickness so you might try a smaller one. I use a 2/0 for 1/8" bb on the very slowest speed the saw will go. 

Notice how the blow outs are all on the cross grain edges.  The lines that are going with the grain seem fine.  Just something to keep in mind when laying out the pattern on the wood. 

Dont know what type saw you are using but if you have a larger size hole where the blade goes into the table, that is where the wood is unsupported during the cutting so those tiny extra vibrations can cause this too.  A zero tolerance thing might help fill that hole a bit. 

I live by the beach and keep my wood near an open window and think that some pieces seem to be more affected buy that then others. Like the glue reacts differently somehow.  Of course I cant tell until I start cutting but sometimes have to just start over with a different piece and its fine. Just something to think about. 

 

[Mikeewms]

one other thing to try is stack cutting. I stack cut at least three pieces of 1/8 birch. you get three projects for one.

[nrscroller]

HI

When I do my stuff and I use just 1/8 BB I use the the Pegas puzzle blades only. I would not use a reverse tooth blade with that thin wood. I have been scrolling for years and get very little break out on back side. 

Good luck

Nrscroller in Wisconsin

[loftyhermes]

Brenda, the large blade size does have something to do with the breakout as does the drill bit. When drilling holes, especially when they are close together, I always use a 1mm bit and make sure it's sharp, light pressure when drilling and that the ply is hard down on a piece of sacrificial piece of wood, also when I cut a single piece of 1/8th BB ply I usually use a 2/0 or a No.1 blade, nothing larger. 

[Foxfold]

2 minutes ago, loftyhermes said:

Brenda, the large blade size does have something to do with the breakout as does the drill bit. When drilling holes, especially when they are close together, I always use a 1mm bit and make sure it's sharp, light pressure when drilling and that the ply is hard down on a piece of sacrificial piece of wood, also when I cut a single piece of 1/8th BB ply I usually use a 2/0 or a No.1 blade, nothing larger. 

Thanks Steve, however, I've looked everywhere for  a 2/0 blade and can't find any. I usually use Niqua.

[don watson]

Hi Brenda,

I use the Hobbies.uk site and find that their 'Yellow Pack' is Niqua They have all sizes (I think these are also the cheapest I have ever found).

Don W

https://www.hobbies.co.uk/tools/power-tools/yellow-label-fretsaw-blades-various-grades