Forrest WWII tearout on plywood

[david kramer]

I'm pretty much an every-other-weekend warrior so I'd rather not be bothered with changing blades on the table saw. I recently bought a Forrest WWII 10" 1/8" kerf blade for my saw (SS 3 hp with ZCI). I made some test cuts on good quality 1/2" plywood. The bottom face of the plywood showed between 1/16 and 1/8" of tearout. The top face was immaculate. Melamine particle board is kinda ugly too, but I guess that's expected.

I was hoping to use this blade for pretty much everything. This tearout is bad enough that it is quite noticeable. I'm wondering if I can expect any better than this from this blade? Am I being unreasonable? Should I just bite the bullet and get a plywood blade for working with ply?

David

[Dave Falkenstein]

Are you using a zero clearance insert?

[david kramer]

Yup, that's the "ZCI" codeword that I used above. Not only am I too lazy to change blades, I'm too lazy to type in whole words :)!

David

[Prashun Patel]

I think asking a gen'l purpose blade to crosscut plywood flawlessly is asking a little much. Have you tried taping the underside of the cut line?

[glenn bradley]

ZCI will help but the WWII is a 40T blade . . . I run an 80T for ply. You can change a blade in less time than it takes to fill your coffee cup. I don't know why people make such a big deal out it. I have ZCI's for all blades and my WWII and Lietz 40T blades are my most seldom used. They are strictly for bulk-run rough sizing.

[Dave Falkenstein]

Yup, that's the "ZCI" codeword that I used above. Not only am I too lazy to change blades, I'm too lazy to type in whole words :)!

David

Oops - sorry, I missed the ZCI note. I use a 40 tooth Forrest WWII on a Jet cabinet saw with a ZCI, and I get really good cuts in plywood and in melamine. I wonder if you have a bad blade? How many teeth on your WWII? Is is new? Do you get good cuts with any other blade?

[scott spencer]

Try scoring the underside of the ply first. You could still get a special Hi-ATB blade for ply if you cut alot of it, but scoring first should give you immaculate cuts. You could also try one of the Hi-ATB general purpose blades like the Infinity Super General 010-044 (http://www.epinions.com/review/Infinity_Super_General_10_40_Tooth_General_Purpose _Blade_epi/content_420337454724) or Freud Fusion...both of those blades should cut better in ply than a standard ATB grind.

[david kramer]

I'll give scoring a try. Thanks for the suggestion.

Glenn, You may be right about changing blades, and if I find myself with a ton of plywood to cut I'll buy a specialty blade. But now that I've bought this blade I'd like to at least understand what it can and can't do.

David

[James Williams 007]

I use the Freud fusion 40 blade and have had great results but I do have a 60 tooth blade on hand that I use for ply if I know it has to be perfect.

[Mike Spanbauer]

It's a great blade for not changing it out, but bear in mind that it won't be the best at anything.

You've the 40T or 30T version? (I believe it comes in both).

Pre-score the plywood as suggested about 1/8" of an inch, and then come back with the blade raised high enough to clear the carbide above the sheet. As long as everything is tuned, you should get satisfying results. Not the same as a 100T ATB sheet good blade, but good.

mike

[glenn bradley]

I'll give scoring a try. Thanks for the suggestion.

Glenn, You may be right about changing blades, and if I find myself with a ton of plywood to cut I'll buy a specialty blade. But now that I've bought this blade I'd like to at least understand what it can and can't do.

David

Sounds like a plan. I do get pretty good rips with it in tight grain woods like Beech. Oak not quite as good and of course, cherry loves to burn given half a chance so just speed up your feed rate.

The tip on scoring ply is right on. I should have mentioned that one ;-) You don't have to really cut deep. I just run an X-Acto knife down the line. I'll do this in splinter-prone hardwoods when cross cutting as well; ash, oak and the like. It really leaves a clean entrance.

A backer board will help with exit blowout on ply but when doing larger panels this isn't real doable. With big panels I'll just cut a bit oversize and come back and cut off the poor edge to get my final size.

P.s. I don't have one but that is one beautiful saw, safety feature or not ;-)

[Chris Padilla]

I've had good results with a CMT General (50 tooth) in cutting hardwood, plywood, MDF, etc. (rip and x-cut). As a blade to toss in the TS and forget about, this one does me all right as long as it is clean and sharp.

As I get on in my years as a weekend ww'er, I tend to change out blades for their intended purpose.

[Gary Elore]

You can also try bringing the blade up just high enough on the first pass to make a scoring cut and then crank it up for the second pass to complete the cut.

When using this method, the veneer is cut almost in line with the surface of the sheet, which serves to support the veneer and minimize splintering.

BTW I'm almost hesitant to bring this up but, veneer ply is especially sensitive to saw tuning. I'd double check that if you haven't already.

Gary

[Joe Vincent]

Since I bought a Freud plywood cutting blade and have gotten such great cuts from it, I don't mind at all changing the blade anymore. To me, it takes less time to change the blade than to score lines, apply tape, etc. Just my experience.

[Matthew Hills]

David, I use the thin-kerf 30T WWII and can get pretty good results in red oak plywood.

Things I've found important:
- use a ZCI (was your ZCI cut with this blade, or a previous blade?)
- set blade height: I go about 1/2 tooth above the plywood. Higher gives a cleaner top cut but worse bottom cut, and vice-versa.
- if still having problems, set up your cut and then use painter's masking tape (wrap tight and press in place -- seems to help support the fibers)

I use the pre-scoring method with router, but haven't been as successful with the table saw (I've tried cutting a knife line first and also tried a shallow saw cut. but definitely worth a shot; you may get them to work better than I have).

Matt

[Scott Whiting]

Two sided melamine just isn't going to work. Plywood will have differing results depending on the species, the moisture content and the quality of the veneer. I don't use zero clearance inserts because I think they make the blade run hotter.

General rule of thumb: if the cut chips on the bottom lower the blade, if it chips on the top raise the blade.

General purpose means average. 40 tooth blades are best suited for solid wood. I use specialty plywood and melamine blades when called for.

[Curt Harms]

I don't know about plywood, I've had no problems with a clean sharp Freud F40. I was cutting quite a bit of borg Melamine for a some cabinets and did the two-pass procedure. First cut about 1/16-1/8" deep then thru cut on the second pass. Poor man's scoring blade:). I was worried about the cuts not being in line and leaving a "step" but no problems.

[Peter Quinn]

I've had mixed results with my WWII in laminate material, excellent results in hardwood. As others have suggested, if you cut plywood that requires a clean edge on a TS, get a plywood blade. You won't regret it. Always use a fresh ZCI, cut with the blade you are using raised to the height you will be cutting.

A WWII may be among the best general purpose blades, and the first to both rip and cross cut reasonably well, but it is not the best weapon for plywood and is nearly useless in melamine. Of course I also feel melamine itself is nearly useless, so perhaps it is the best blade?

[Brian Kincaid]

I too was getting poor results with my WWII in plywood, but after lowering the blade for 1-2 teeth visible the cut is much improved. The top looks good, the bottom has tiny splinters, and the edge is fairly smooth.

BTW a throwaway plywood blade is $10 at the borg.

Best regards,
Brian Kincaid

[Robert Chapman]

I don't have problems with my 40 tooth WWII. I do keep the blade low. Check www.woodbin.com/ref/tips/cutting_plywood.htm (http://www.woodbin.com/ref/tips/cutting_plywood.htm) has a few ideas that might help.

[fRED mCnEILL]

I have a couple of WWII blades that I use exclusively.

In crosscutting plywood I first score the plywood by raising the blade about 1/32 of an inch and then run the plywood over the saw BACKWARDS. Then raise the blade and finish the cut.

I have examined the cut under a magnifying glass and there is no splintering AT ALL.

This mimics a scoring blade. And because the blade only protrudes 1/32 there is no danger that the saw will grab the plywood.

Fred Mc.

[Joe Jensen]

The original poster said he used a SS, which I think means a sawstop. I have one and I'm not sure there is a ZCI for SawStop saws. Their insert is quite nice, but not a ZCI..joe

[glenn bradley]

I assume most folks make a half a dozen right off the bat using their factory insert as a guide regardless of saw brand.

99207

I use them in the CMS (http://www.sawmillcreek.org/showthread.php?t=54160) as well.

http://www.sawmillcreek.org/attachment.php?attachmentid=60353&thumb=1&d=1174011120

[Matt Meiser]

I have one of Forrest's plywood blades and it works well. I don't recall ever using my WWII for that purpose. My Festool saw gives me the best cuts in Melamine. Taping the cut line with blue tape does work too.

Maybe I missed it but I haven't seen anyone ask about the quality of the plywood itself. If you are cutting up that Chinese birch from Home Depot with the paper-thin veneer it is going to tear out much worse than a good quality ply with much thicker veneer.

[Chris Padilla]

I use them in the CMS (http://www.sawmillcreek.org/showthread.php?t=54160) as well.

http://www.sawmillcreek.org/attachment.php?attachmentid=60353&thumb=1&d=1174011120

Bad assumption! :D :o I've been staring at my CMS for 6 years and saying to myslef, "Gosh, I really should make a ZCI for that!"

:rolleyes:

[glenn bradley]

Bad assumption! :D :o I've been staring at my CMS for 6 years and saying to myslef, "Gosh, I really should make a ZCI for that!"

:rolleyes:


Booowah-ha-ha-ha. I just sprayed my monitor with coffee. Despite my many gadgets and widgets, I have sooo many of those " I'm gonna get to that real soon" things its ridiculous ;-)