choosing blades

[soccerdude]

i was wondering if someone could give me a bit of guidance on how to pick what kind of blade for cutting wood? Example: my circular saw came with a 150 tooth and a 40 tooth (or something like that). Today I was cutting 4x4s and chose the 40 tooth, it just looked more heavy duty. Then later, I was cutting some 1/4" hardboard and picked the more toothy blade...

no rhyme or reason to my decisions, so I was hoping someone could shed a bit of light on how to pick the best blade for the job?

[jussi]

In general the more teeth equals a smoother but doesn't cut as easily. But you also have the take into account other aspects like the rake. Guys like KnottScott will have much better info on this.

[LCHIEN]

As a very general rule the blade with more teeth cut smoother and in general are suited for cross-(grain) cuts. The blades with fewer teeth (and bigger spaces-gullets- between teeth) generally perform rip (down the grain) cuts better - faster.

These are not totally hard and fast rules but given other similarities will generally hold.

There are a whole bunch of criteria about what makes blades of a given diameter perform and affects them:
Kerf width
Hook angle
Tooth configuration (ATB, FG, TCG, etc)
carbide hardness and thickness, body thickness, laser cuts
as well as construction quality tolerances held (uniformity, concentricity, flatness, etc.) and quality of its initial sharpening.

There's all kinds of tradeoffs, for example some tooth configurations cut better but the teeth dull faster so have to be sharpened more frequently to provide the same performance. Softer carbides may be easier to sharpen well but will dull faster. Thinner carbides will be cheaper but you can't resharpen them as many times.

10" blades for saws generally cost anywhere from a few dollars to well over $100.

Using specialty blades can give you very good cuts, for example an 80 tooth finishing blade will give you very smooth crosscuts and clean cuts in plywood and thin veneers.
A 24-tooth ripping blade will perform the best when making long, rips of an 3/4" of an inch or more of depth.

But its always a pain to keep changing blades so there is a class of blades called general purpose or combination blades often with 10" tooth counts around 40 to 50 that perform all-round duty quite well and do both ripping and crosscutting.

Table saw Blade selection with specific model recommendations is discussed at some length in my BT3 FAQ which several people recommended you request.

For 7.25" circular saws, I assume maybe that's what you were referring to in the original post,
150 tooth is generally a HSS (not carbide tipped, so it won't last as long), good for hardboard, plywood, and other thin sheet goods.
your 40-tooth is probably good for crosscutting 2x and 1x dimensional lumber. You have to make two passes from opposite sides to crosscut a 4x4. Many original and aftermarket blades for 7.25" saws are just HSS and not carbide tipped- and cost just a few bucks. I've heard it claimed that carbide tipped blades will outlast a HSS blade 50 times.
Probably a 18-20-tooth would be good for ripping.

[dbhost]

Not that what I am going to contribute here is all that important, but I wanted to mention that this is an EXCELLENT question, that I bet a LOT of folks have wondered, but never bothered to ask... (I actually did a LOT of digging around researching this on my own before diving into blades...).

So great question, and another great answer on Loring's part...

[herb fellows]

Bottom line, you happened to use the right blades for each cut.

If you have some spare material, go ahead and make cuts with the opposite blades and compare them.
While Lorings post is quite correct, I can imagine it's way too much information for your current tools and expertise.
There's nothing quite like seeing the results in person to either validate someone else's take on something or to establish your own decision regarding the exact tool you own.

[cabinetman]

This may be of some help.
http://www.woodcraft.com/Articles/Ar...?articleid=691
.

[Knottscott]

I have a blog about saw blades on Lumberjocks.com that might have some info you can use.

[soccerdude]

Thanks for the replies - really good info. People on this forum are a cut above the rest (), so all replies are really appreciated.

[wd4lc]

Will someone please point me in the direction of Loring's bt3 FAQ that he mentioned (I saw his acronym guide but not the setup faq).

I need to get a rip blade this weekend (for 2 x 4 cedar). I've been using a Dewalt blade (24 tooth, states it is good for fast cutting and various woods) that I felt was much improved for ripping compared to the BT3 stock blade. Since then I'm not sure if the blade has dulled, if I'm ripping incorrectly or if I've just become a bit more cautious with saw....but I'm feeling as though I'm having to force the stock through the blade and perhaps placing too much load onto it. The saw seems to slow as you hear the pitch dramatically drop.

Thanks.

[pelligrini]

Will someone please point me in the direction of Loring's bt3 FAQ that he mentioned (I saw his acronym guide but not the setup faq).

Check his signature in any of his (LCHIEN) posts: http://www.bt3central.com/showpost.p...95&postcount=2

The blade might be dull, but there might be other things slowing you down too.

When's the last time you cleaned the blade? I've found that I wasn't really cleaning mine enough. Cutting pine or other sticky woods will gum up a blade in no time.

Check your alignments. Make sure your riving knife is centered on the blade. Check the alignment of your rip fence too. Are you getting teeth marks and or burning on your rips?

Another contributor to slow speeds is the quality of power. If you're using an extension cord make sure it's at least 12 gauge, and as short as possible. Long cords and/or insufficient wire size can lead to voltage drops which eventually can lead to a burnt out motor.

[wd4lc]

The blade might be dull, but there might be other things slowing you down too.

When's the last time you cleaned the blade? I've found that I wasn't really cleaning mine enough. Cutting pine or other sticky woods will gum up a blade in no time.

In all honesty, I had no idea blades needed to be cleaned. I'll take a look.

Check your alignments. Make sure your riving knife is centered on the blade. Check the alignment of your rip fence too. Are you getting teeth marks and or burning on your rips?

At one time the riving knife was way off the mark. After inspection, one of the arms that gets bolted down was actually bent. I gently bent it back in place. Now, the alignment is not perfect but only ever so slightly off. I'll reinspect to see if moving over one shim will do the trick.

The fence is also so very slightly off. Really this has always been the case. I think the end pulls slightly to the left if I remember correctly.

I do not believe in my last batch that I've obtained any burn marks (though I have in the past ripping pine using the stock blade). I do see (and feel) marks on the wood as if there was a slight shift which was probably my fault.

Another contributor to slow speeds is the quality of power. If you're using an extension cord make sure it's at least 12 gauge, and as short as possible. Long cords and/or insufficient wire size can lead to voltage drops which eventually can lead to a burnt out motor.

Ugh, that would not be good. I really enjoy this table saw.

Well, I'm now using a power switch from Rockler. The cord is fairly short (7'). 15 amp switch, not sure of the wire gauge. I believe the pitch lowered (bogged down) even before using this but then again I used an extension cord before using this switch.

Thanks for the tips. Not too long ago I saw a thread elsewhere with a massive troubelshooting guide on things to look for and how to fix them (could have been Loring's perhaps). I'll hunt for that again. I had actually had trouble with my blade slowing to a noticeable wobble. One of the things to check for was the spacers. I took the spacers off and blew off a collection of saw dust. I really didn't think anything of it but I think it was that and tightening it further helped clear up the wobble. One thing that has just started up is a clicking when the blade slows towards the stop. Time for more troubleshooting thread searching!

[pelligrini]

Yea, pitch buildup on blades needs to be cleaned off from time to time. A clean blade will produce less tearout and burning. Same goes for router bits too. Clean bits and blades produce cleaner cuts.

I picked up a cleaning kit from Rockler not too long ago. It's pretty handy to have. It's a lot easier to use than the 5 gallon bucket I was using before. Some guys use simple green for cleaning. Rockler will have that Kit on sale from time to time, I think I got mine when it was 50% off.

On that ticking part, check down inside the saw for any thin offcuts that might have fallen down there too.

[Ed62]

You should keep an eye on the blade getting dirty. If it has a build up on it, it will become hot a lot quicker, and have to work harder to make the cut. That's not good.

It sounds like you'll really benefit from reading Ray's write up, which you'll find by following my signature. It could very easily keep you from getting badly hurt. I'd suggest you read it before you do much more with the saw.

Ed