Riving Knife and sheet goods

[Kent Adams]

Ok....so I managed to do something I never thought I would do, stop the blade on my 5hp PM2000. I was cutting 5ft long 1/2" BB with a Forrest Duraline HI-A/T Thin Kerf (bought when I had a contractor TS with only 1.75hp). What caused the binding was a full kerf riving knife. I removed the riving knife and the sheet good went through like butter. Lesson learned.

Now, I have just two questions:

1. Did I just damage something with my TS by making the blade bind and stop?
2. Is it safe to run full length sheet goods through the TS without a riving knife? I don't think it is, because kickback could still occur. However, to mitigate kickback without a riving knife, I'm also using Jessem's TS stock guides which have an anti-kickback feature to them, which I'm thinking mitigates the lack of a riving knife for something like sheet goods cut lengthwise through an entire panel.

[Jamie Buxton]

You didn't likely damage your saw.

Get a full-kerf blade.

[Prashun Patel]

1. No. Binding a blade may at most cause the saw to trip off, but it wont (or at least hasn't for me) caused any kind of damage after you reset.

2. My RK was also too thick for think kerf blades. IMHO, the right solution is to grind down your RK or to use a full kerf blade. I think plywood has a reasonable risk of kickback because the rip cuts can be wide and prone to twisting. Second, thinner plywood (1/4") can be prone to lifting.

[Kent Adams]

1. No. Binding a blade may at most cause the saw to trip off, but it wont (or at least hasn't for me) caused any kind of damage after you reset.

2. My RK was also too thick for think kerf blades. IMHO, the right solution is to grind down your RK or to use a full kerf blade. I think plywood has a reasonable risk of kickback because the rip cuts can be wide and prone to twisting. Second, thinner plywood (1/4") can be prone to lifting.

Thanks Pashun. I don't, at the moment, intend to buy another blade like this with full kerf. I did buy a stabilizer to use with it for the more powerful TS. The Jessem TS guides prevent the plywood from lifting up from blade to fence and at a 5 degree angle toward the fence, I think should eliminate the stock from getting twisted back into the blade. I'm thinking the Jessem TS guides eliminate the need for the RK.

[Peter Quinn]

I don't see the relationship between right knife, tk blade and stopped saw. If the blade is thin, the plywood hits the thicker knife behind the blade and pretty quick it stops the plywood, blade continues to spin in the kerf it's made while you try to find a way to stop the saw roughly 8' away from the switch with most of a sheet of plywood in your hands. My guess is the binding happens when you start reacting to the situation and shift the plywood. I doubt any harm has come to your saw, these things are made tough. Sheet goods can definetly come back at you. I'd check to see if Sawstop can provide a thin kerf riving knife for use with your thin kerf blades, probably cheaper than a new blade. It's unlikely that a full sheet would kick back, but the knife is still nice to keep things from drifting away from the fence.

[John TenEyck]

You should always use a RK or splitter; bad things can and do happen w/o them. If you can't get a thinner RK and aren't up for making one, then make a ZCI out of BB plywood and install a wood splitter behind the blade.

John

[Erik Loza]

No firsthand experience with your particular machine but IMO, go back to full-kerf blades on a 5HP saw. Save the thin-kerfs for jobsite tools. Can't tell you how many customers I have had who put the thin-kerf on their sliding table saw and it vibrated, made noise, sub-par cut, etc. Freud and other good blades, not contractor junk. I personally think you need a blade with more mass once you get into the heavier machines, 5HP, etc. Hope this helps,

Erik

[Von Bickley]

I don't buy thin-kerf blades anymore.

[Rod Sheridan]

Hi Kent, I would purchase a full kerf blade for your saw, they work much better than the thin kerf models.

You can also buy a different thickness riving knife for your saw if you want to run thin kerf blades.

No, it isn't safe to make any non through cut without a riving knife of splitter..............Regards, Rod.

[Mike Heidrick]

I'm thinking the Jessem TS guides eliminate the need for the RK.

Your off cut can go into the blade very easily.

[Andrew Pitonyak]

You should always use a RK or splitter; bad things can and do happen w/o them. If you can't get a thinner RK and aren't up for making one, then make a ZCI out of BB plywood and install a wood splitter behind the blade.

John

Yes yes yes. I had a nice kick back many years ago. It was probably the first piece of wood I ever ran through a table saw. I turned off the saw and did not use it for a week while I was reading up on how to safely use a table saw. That table saw did not have a riven knife. At this point, I am not likely to use a saw without one. I did exactly what John recommends and I used an aftermarket splitter that went into the ZCI.

[Jason Beam]

I'm thinking the Jessem TS guides eliminate the need for the RK.

What good do they do for the other piece that's cut off?

[Rich Engelhardt]

Run to Woodcraft and pick up this - MJ Splitter.
They work great with a ZCI.

[Jim Dwight]

This won't help the OP but for anybody considering a thin kerf blade I would skip it regardless of your saw. I think it is a bit of a myth that they help underpowered saws. I use a Ryobi BT3100 which has a 15A universal motor. So it is less power full than a saw with a 15A synchronous motor (due to the lower effiency of the universal motor (has brushes)). I have both thin and regular kerf blades. For full depth (3.5 inch) rips, I like my full kerf 24 tooth Freud ripping blade. I can cut hardwood with it full depth but I have to use a fairly slow feed. I have a thin kerf one too and it doesn't allow a significantly higher feed rate. I have all around blades of both types too and again I see little to no difference.

So I think full kerf blades are the way to go regardless of your saw. They have more carbide and are stiffer so they have other advantages. Any gains in cut speed are minimal and not worth the disadvantages of greater flexibility and smaller teeth inherent in the thin kerf blades.

If you have a problem with feed rate, I think you need to be sure that you are using the right type blade for your cut and that the blade is clean and sharp. Those are the important variables in my experience.

Now a minor bit for the OP, I use a riving knife I made that is slightly thinner than a thin kerf blade and I arrange it so that it for sure doesn't protrude towards the rip fence. I use this for all blade types. I have no problems with this setup. I think you should look for a thinner riving knife until you use up your thin kerf blade(s).

[Justin Ludwig]

1. Is it safe to run full length sheet goods through the TS without a riving knife? I don't think it is, because kickback could still occur. However, to mitigate kickback without a riving knife, I'm also using Jessem's TS stock guides which have an anti-kickback feature to them, which I'm thinking mitigates the lack of a riving knife for something like sheet goods cut lengthwise through an entire panel.

Yes.

I don't use a RK, splitter or anything on my PM2000 (3hp). I do use full kerf blades. I rip and crosscut full sheets of 3/4 ply by the bundle on that puppy, no problems. I did throw away the UHMW fence and replaced it with MDF and formica. SO much better IMO. I had one kick back 8 years ago on a Delta Unisaw crosscutting a 1/4 sheet of hickory bead board, it hit me in the butt. It happened because my head was up my butt (luckily the sheet missed my head while it was up there )

If my worker uses the saw, I put the riving knife in.