Did I obsolete half my saw blades?

tvrgeek

Scott
User
Getting used to my new table saw. Riving knife and blade guard splitter are both for full kerf. Had not thought about it as with 3 HP, I can cut anything full kerf. I already had CMT rip blade, a couple 40 tooth and just got a new Amana 80 in full. I can get a thin kerf splitter ( $70, they really stick it to you for accessories) but no option on the blade guard. I was kind of thinking, maybe I should just dispense with thin blades. Not ready yet, but might look into Shark guards for their dust collection. I could get a thin one in that.

A 3 HP is a new luxuery, so just looking for wisdom. Full kerf should in theory give a smother cut. Plus I can add and subtract 1/8 inch, where every one of my thin blades are different.
 

FredP

Fred
Corporate Member
I only use full kerf blades. I have a couple thin ones and I use those for the occasional pieces of MDF or particle board. No need for a splitter for this garbage. I've also used 7 1/4" circular saw blades for trash wood. They are a lot cheaper if you catch a nail, screw or staple.
 

JimD

Jim
Senior User
I prefer a full kerf blade but my 1.75hp PCS really doesn't like them much. So I am stuck with thin kerf unless I want to risk tripping the saw's thermal overload. I don't know about your saw but I use the normal sawstop riving knife with thin kerf blades but I had to adjust it's position to get it well centered on the blade. It is 2.3mm thick which is .0905 in real measurements and 3/32 is .09375. So for the most common thin kerf thickness the riving knife is thinner but not by very much. They offer a 2mm but it is pricey. You might want to measure your riving knife and if it is thin enough, consider just centering it and using up your thin kerf blades for non critical cuts. One reason I say non critical cuts is it messes with the rip scale for your rip fence. I would set it for your primary blade type and then just remember it is a bit off for the thinner blade (it would be on the safe side, the rip would be a little wider than the setting.
 

tvrgeek

Scott
User
Knife and guard are both way too fat for my thin kerf. Personally, I want the knife or guard in place for every cut. Kickback does not care if hardwood, plywood or MDF.

Different blade thickness is one reason I have been looking for right-to-left reading rulers with 1/32 graduations.
 

David Turner

David
Corporate Member
My 3 H.P. SawStop unit came with 3/32" blade and splitter ( I believe) and so therefore there is no problem when I run a 1/8" blade.
 

Oka

Casey
Corporate Member
Just make a thin kerf riving knife. 1018 steel would be good enough I would think. If you want to go harder 4140 or 4340. After all, you already have a template. Should be easy enough to fab. Just make sure not to over heat when making.
 

tvrgeek

Scott
User
Casey, Thought about that. I can probably get square foot from McMaster. Profile is not bad, but the taper on the fork might be a pain as I only have "hand" milling machines. .075 is available. A little thin but probably wide enough to work. Clamp is really stiff, so it might be worth getting a harder steel so it won't get bent.

David, of course it works for a 1/8 inch full kerf. Too wide for most of my thin kerf blades. A thin knife is more like .085 or so. Not .093.
 

Oka

Casey
Corporate Member
Call a local machine shop. I bet you can get the correct thickness with not too much problem.
Be nice if you have a plasma cutter. See? I just gave you a reason to buy a Plasma cutter............ it's justifiable
 

junquecol

Bruce
User
I don't understand why saws can't run full kerf blades. My Delta contractor's run full kerfs all the time. One saw has 1.5HP motor and other has 2.0HP motor.
 

RJweb

RJ
Senior User
I have a 3hp Sawstop, and I believe that the manual says you can not use a thin Kref blade, RJ
 

Oka

Casey
Corporate Member
That makes no sense, what you are not supposed to use on a saw stop is an anti-kickback designed blade. Otherwise the stop function on the saw-stop may not work.
 

tvrgeek

Scott
User
That makes no sense, what you are not supposed to use on a saw stop is an anti-kickback designed blade. Otherwise the stop function on the saw-stop may not work.
"Blades with depth-limiting shoulders may take longer to stop in the event of an accident than standard blades, and you could receive a more serious injury. Therefore, SawStop recommends using blades without depth-limiting shoulders. viii. The SawStop safety system is designed for use with standard 10 inch blades with kerfs from 3⁄ 32 inch to 3⁄ 16 inch. Blades with kerfs much thinner than 3⁄ 32 inch should not be used because those blades might not be strong enough to withstand the force applied by the brake when it activates. As a result, those blades might deform and stop more slowly in the event of an accident, resulting in a more serious injury. Blades with kerfs much thicker than 3⁄ 16 inch are heavier than standard 1⁄ 8 inch kerf blades, and should not be used because they may stop more slowly than standard blades in the event of an accident, resulting in a more serious injury. Similarly, stacks of two or more 10 inch blades should never be used on your SawStop saw as the combined weight of the blades may be too heavy to stop quickly. If you need to use a blade with a kerf thicker than 3⁄ 16 inch, use an 8 inch dado set with the optional Sawstop 8 inch dado brake cartridge."

So some anti-kick back blades like one might use on a RAS might not stop as quickly, or some ultra thin blades ( I have an 8 1/2 that is really thin) might warrant extra care.

But that has no bearing on my Harvey riving knife and blade guard.
 

tvrgeek

Scott
User
I don't understand why saws can't run full kerf blades. My Delta contractor's run full kerfs all the time. One saw has 1.5HP motor and other has 2.0HP motor.
Depends on the blade, wood, and what you are doing. When I was foolish enough to use combo blades, ripping 3 inch oak was almost impossible. Cross-cutting 2 inch purpleheart was really tough. Even ripping framing lumber might stall before I got wedges in the cut. Switching to proper 24 and 60 tooth blades, 1 3/4 was adequate. Going thin kerf, was fine. With 3 HP, it will just glide through anything. Also note, the HP rating of the motor does not tell the full story. Some are more optimistic than others in how they calculate efficiency, power factor and derive the actual shaft power.
 

tvrgeek

Scott
User
Call a local machine shop. I bet you can get the correct thickness with not too much problem.
Be nice if you have a plasma cutter. See? I just gave you a reason to buy a Plasma cutter............ it's justifiable
No, but a member of the local MG club is a salesman for WaterJet. .075 might be just fine. It does not take much to keep it strait enough for the rear tooth to just cut rather than catch.
 

cfield60

jeff
User
My old Powermatic model 66 does not have a riving knife and I have not ever noticed a need for one. In my line of work, which is building cabinets for new home construction, I rarely cut any material thicker than 1 1/2". I have discovered that I can get excellent finish and longevity using 7 1/4" thin kerf diablo blades from HD. I can get 2 40t blades usually for $14 and they work as well as my expensive blades. I have freud fusion, Forrest wwII and other similar and I can tell you the cheap diablo blades perform. My saw has a 5hp motor but I believe using the smaller diameter blades one could get by easily with a 1 hp saw. This is my experience and I use these for 1 1/2" and less thickness material, usually 3/4" and 1/4".
 

JimD

Jim
Senior User
I do not like riving knifes that are a lot, like .020, thinner than the blade because they will not stop the kerf from closing on the blade. When that happens, it is possible to put a wedge in the kerf but I prefer the riving knife give me a chance to complete the cut without that aggravation. They still will give reasonable protection against kick back, I think. But with a riving knife closer to the blade thickness you get both things - but you have to be really careful to get it centered on the blade.

I made a thicker riving knife for my old BT3100 and it worked great. I used 7075 T6 aluminum plate from McMaster Carr. This grade of aluminum is relatively hard and does not bend. It will fracture if you try to bend it without heating it. It is easier to cut than steel. But I find my Bosch jig saw works well to cut mild steel or aluminum. If I needed to put a bend in the material, as I believe my SS requires, I would use mild steel.

My PCS is at least my fourth 120V table saw and the first to give me a very hard time with full kerf blades. Part of the trouble was the fact I was using Infinity blades. First a 50 tooth with 40 ATB teeth and 10 rakers. Once the trouble started I switch to an Infinity 24 tooth ripping blade. Neither would rip the glued up 2x4 material I used for legs on my grandkids bunk bed without the saw hitting the thermal overload. Then I tried a 24 tooth Freud blade which was not new but was relatively clean. It worked OK but required a slower feed rate. Then I dug out a 24 tooth thin kerf blade (Freud) and could go back to normal feed rate. Since then I have ripped similar glueups with a thin kerf Fusion all around blade (40 teeth). It worked well. But the wood was not warping into the blade like the bunk bed legs seemed to. My conclusion is to retire the nearly new Infinity blades and to use Freud thin kerf blades in this saw. With them, I have had no issues. Including in 3 inch thick cherry glueups. I am using the 2.3mm riving knife the saw came with, however, which is only very slightly thinner than the 3/32 blades I am using. That helps to avoid one of the power robbing issues of the kerf closing on the blade.

I think the thermal overload on my PCS may be set somewhat conservatively. But I am not going to mess with it if I can solve the issue with a thin kerf blade. It is, for me, an expensive tool and I would rather it be well protected.
 

tvrgeek

Scott
User
.085 does not seem to be a common thickness of anything. I did find some .080, but in 2 ton rolls.

Jeff, maybe you never saw the need. I have. Some people jump out of perfectly good airplanes and do fine. I know two who did not. FWIW, I am fond of "Stickley" style furniture so tapering 3 inch oak is a must. I also like 18 and 19th century provincial Chinese style, so again, sometimes larger stock.
 

Rwe2156

DrBob
Senior User
It's totally up to you, but I think you're better off keeping everything standard.

Personally, I would never use a table saw without a splitter or riving knife. I never had a saw with one or used one for 25 years. So for Jeff, his experience doesn't mean anything, tho I've had a few kickbacks and I'll tell you they are not fun.

Its not the thick stuff, its the 1/4" plywood that'll get you.
 

JimD

Jim
Senior User
Forget what I said about using the regular riving knife with thin kerf blades. I have made it work but went out to the shop to start a dresser in cherry and my saw is fighting me. SawStop only wants $15 for the 2mm (~.080) so I ordered one. With cherry any hessitation in feed is a burn mark. I cleaned the blade and the riving knife, which they needed. I adjusted the riving knife a little to the offcut side. I am still getting burns. So I will try the thinner knife. While I'd like to have this dresser done it is also cold today so it gave me an excuse to come back inside. I guess I will need to use a wedge when the wood closes in on the kerf - which isn't often.

Maybe after I warm up I will swap back to a full kerf blade (but not an infinity) and try to get some work done while I am waiting on the riving knife. I think it will be good to have both type knives. This dresser is all out of 13/16 material so my saw should handle a full kerf blade for this project. I don't like to have to change the pointer on the rip fence or set it with a steel ruler but that is just whining.
 

Phil S

Board of Directors, President
Phil Soper
Staff member
Corporate Member
I almost never use a thin kerf blade. The thin blades tend to flutter/wobble when they hit a knot, especially if you are cutting thru the edge of a knot. A standard kerf (.125) stays straight. I said almost never because sometimes I rip soft straight grain, knot free material like cyprus when milling canoe strips and I will use a thin kerf then to save wood.
 
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