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Negative Hook Angle

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Forum topic by myxology posted 09-07-2019 04:59 PM 550 views 0 times favorited 13 replies Add to Favorites Watch
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myxology

92 posts in 1724 days


09-07-2019 04:59 PM

At the risk of sounding like a complete novice… Does this really matter? I’m a hobbyist. I use a table saw and a sliding miter saw mainly. My understanding is that I need both a good rip blade and a good cross cut blade for the table saw and a good cross cut blade for the miter saw. So far I’ve been using blades from the big box stores or Harbor Freight. Here is my silly assumption…. Aren’t those manufacturers making them with the right hook angle for your average user? I realize I may be opening a proverbial can of worms here, but somebody just mentioned it to me the other day and I had never heard of such a thing. Thoughts?

-- Is this thing plugged in?


13 replies so far

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bilyo

828 posts in 1587 days


#1 posted 09-07-2019 05:24 PM

My understanding is that the negative hook blades are designed primarily for radial arm saws and maybe sliding miter saws. These blades are a bit less “grabby” to reduce the machines tendency to grab the wood and pull itself through the cut too rapidly.
Otherwise, manufacturers make many configurations to cover a wide variety of machines and situations. It is up to the user to find the correct blade for his particular purpose. There are blades that work well for most typical applications. A 40 tooth combination blade is an example. A step up would be blades with teeth shaped to work best for ripping or cross cutting. Beyond that, there are specialty blades designed for particular uses or materials.

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Rich

4848 posts in 1073 days


#2 posted 09-07-2019 06:11 PM

I use a negative hook angle blade on my table saw for some sheet goods that are prone to chipping, like melamine. What it provides is a downward shear on the walls of the cut, much like a down-spiral router bit.

The downside is that it’s such a clean, sharp edge that it’s easy to cut your hands when you pick up the board. I’ve had a couple of experiences where everything seems fine, but I suddenly start to see red streaks on the board.

Another time I might use it is for plywood where I’m going to use edge banding. I almost never do that though, and any other edges are hidden inside dadoes or behind face frames, so I rarely bother switching from my regular blade.

-- There's no such thing as a careless electrician

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Aj2

2432 posts in 2282 days


#3 posted 09-08-2019 12:01 AM

The negative hook angle is also a close example of how the Bryd inserts cut wood. Although I do think they still have a small amount of forward rake 10 degrees at the most.
I’ve also done the same as Rich mentioned used my Forrest chop master on my tablesaw to cut across plywood.
It’s a very slow chipfree cut with crisp edges.

-- Aj

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CaptainKlutz

1785 posts in 1978 days


#4 posted 09-08-2019 01:11 AM

This blog post has complete dissertation on saw blades that might help?
https://www.lumberjocks.com/knotscott/blog/12395

Hats off to Knotscott for posting it.

-- I'm an engineer not a woodworker, but I can randomly find useful tools and furniture inside a pile of lumber!

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Fred Hargis

5700 posts in 2977 days


#5 posted 09-08-2019 10:50 AM

Negative hook teeth give you a much smoother cut and have several uses. A nearby plastic supplier uses them to cut any sheet goods that need to be trimmed down to avoid the chipping caused by aggressive hook angles. On an RAS they reduce (greatly) the amount of self feeding these saws can have. They absolutely suck at ripping cuts, but if you want glass smooth, chip free….then a negative hook s the blade of choice. Along with that is the slower feed rate you must use.

-- Our village hasn't lost it's idiot, he was elected to congress.

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JayT

6279 posts in 2695 days


#6 posted 09-08-2019 11:34 AM


Aren t those manufacturers making them with the right hook angle for your average user?

- myxology

Yes, the manufacturers make them. That doesn’t mean most stores stock them. Retail stores are going to keep in stock the items that sell the best and make the most money. If the consumer doesn’t know what to ask for and buy, then the retailer isn’t going to do it for them.

What has happened is that most of the saw blades you see in big box and hardware stores are compromises. The blade geometries are middle of the road, so they aren’t the best for any one purpose, but will do most things decently. That means stores can stock fewer different items and still get good sales numbers. For the majority of the buying public, it’s not a problem, as the most of the blades sold are for construction and mixed usage. When the saw is going to be used for a variety of tasks, from framing to trim work, the user isn’t going to take time to constantly change blades, so the compromise blade is used.

You can make those blades work just fine, but if you want superior performance for specific tasks, then it’s time to look to a specialty retailer. The cabinet shops I know aren’t going to the BORG to pick up blades, their saws are set up for one task over and over, so they put the blade best designed for that work on them. Those generally come from either a specialty retailer or, many times, are purchased from whoever does their sharpening.

-- https://www.jtplaneworks.com - In theory, there is no difference between theory and practice. In practice, there is.

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knotscott

8329 posts in 3860 days


#7 posted 09-08-2019 12:15 PM

Just about any blade made to cut wood will make cuts on your saws, but that doesn’t make them ideal. A RAS or SCMS should have a blade with a low or negative hook angle…..somewhere in the negative range up to maybe a few degrees positive. Blades with a steep positive hook can cause “climb” or self feeding when you don’t want it.

Since the blade is a critical component in your sawing system, it’s worthwhile to buy a good blade that’s suitable for the saw and the task. If your crosscut blade will fit both saws, and is suitable for the task on both saws, there’s no reason you can’t keep just one good crosscut blade and switch them as needed.

You don’t have to spend a fortune on good blades, but you should at least take the step towards an upgrade from stock caliber blades and most cheap entry level blades. Some brands offer different quality levels, but if you stick with something like a Freud, Infinity, Forrest, CMT, Ridge Carbide, Irwin Marples series, Amana, Tenryu, etc., you should have good basic quality, so you only need to focus on choosing the correct blade for the task.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

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MrRon

5666 posts in 3728 days


#8 posted 09-08-2019 03:14 PM


- knotscott

Mr. Knotscott, I cut a lot of aluminum and plastics with my table saw. What would be the best blade to use that will leave a clean burr free cut? I have drilled a number of small holes (1/8”) equally spaced @ 1/4” and then ripped down the row of holes at the center to form a scalloped edge. The scalloped edge doesn’t allow for deburring the edges, so I need a blade that will leave a smooth burr free edge.

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knotscott

8329 posts in 3860 days


#9 posted 09-08-2019 03:50 PM


- knotscott

Mr. Knotscott, I cut a lot of aluminum and plastics with my table saw. What would be the best blade to use that will leave a clean burr free cut? I have drilled a number of small holes (1/8”) equally spaced @ 1/4” and then ripped down the row of holes at the center to form a scalloped edge. The scalloped edge doesn t allow for deburring the edges, so I need a blade that will leave a smooth burr free edge.

- MrRon

That’s a tough one…I don’t cut much of either of those materials. You might be best off with two different blades. I’d likely lean toward a high tooth count Triple Chip Grind (TPG) for the aluminum, and a low melt style blade for the plastics. The side geometry of the low melt blade will allow you to keep a higher tooth count blade with less heat. Sorry I don’t have a specific brand/model recommendation.

-- Happiness is like wetting your pants...everyone can see it, but only you can feel the warmth....

View therealSteveN's profile

therealSteveN

3656 posts in 1058 days


#10 posted 09-08-2019 05:32 PM

Typically for thin non ferrous they suggest 80 tooth count, and for plastics a 60 tooth count.

I have had pretty good success with this blade on both

I cut the aluminum just bit slower than I would push through for wood, and the plastic goes through a little faster than wood. I find the metal gets jumpy if you go faster, and of course that effects the edge. The plastics if you go too slow will tend to burn/melt a little.

Actually if I only have one cut to make I’ll use a 3/8” HSS blade that I usually keep on my 14” BS. I’ve never used either when they were used as an edge, so minor variation in cut quality never was much, so a BS cut works fine.

On the other side of the coin, both Forrest, and Amana sell a blade specifically marked as a no melt blade. I’ve never followed them to see exactly what type of blade they are, tooth geometry etc. I imagine they also both have specialty blades for Aluminum. Might actually be some science to them, but my gut tells me it’s more marketing.

-- Think safe, be safe

View Eric's profile

Eric

83 posts in 722 days


#11 posted 09-08-2019 09:39 PM

I can cut wood and non-ferrous metal with a negative rake tooth blade so that’s what I use on my mitre saw and SCMS. Choosing the right design blade isn’t marketing rather it’s knowledge. I use my gut for beer and my brain to learn why reputable companies offer choices…

-- Eric

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runswithscissors

3060 posts in 2509 days


#12 posted 09-11-2019 04:08 AM

If you are getting a climbing effect on a SCMS, you are doing it wrong. You push the blade through with a miter saw, you don’t pull it. Unlike a RAS, where there really is a tendency to climb, even, to a lesser extent, with a negative hook blade. Somebody, I think B & D, made a RAS that had some kind of brake to mitigate the tendency for the blade to climb. Don’t know how well that worked.

As for cutting aluminum, I do just fine with a combination wood cutting blade.

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened

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farmfromkansas

125 posts in 98 days


#13 posted 09-11-2019 11:48 AM

Menards had a pair of blades on sale last year, painted orange. I bought a pair, one was a rip blade, the other a crosscut, took them home and tried them and they were so good, went back and bought 2 more sets. Tried the fine blade on my miter saw, was great, and the rip blade is great on my unisaw. They are both thin kerf, and are a little tight on the splitter, but really cut well, CMT brand. My miter saw is a Makita, scms 10”, and table saw is a uni.

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