Needed a Riving Knife

dusty · Post by **dusty** » Sun Apr 20, 2008 9:27 am

Earlier this week, I started a project that required a lot of bevel cuts. I hadn't cut but two or three pieces when I decided that I needed a riving knife.

With the table at 45 degrees, the SS riving knife created some problems. The plastic blade guard did not operate properly. So that I could complete the project without delay, I removed the plastic guard from the riving knife. We finished the project when promised and the neighbors went home happy.

Now what to do? Put the saw guard all back to together and forget it or prepare for some future project requiring bevel cuts.

chrispitude · Post by **chrispitude** » Sun Apr 20, 2008 11:54 am

Very nicely done dusty!

- Chris

paulmcohen · Post by **paulmcohen** » Sun Apr 20, 2008 6:23 pm

dusty wrote:Earlier this week, I started a project that required a lot of bevel cuts. I hadn't cut but two or three pieces when I decided that I needed a riving knife.

With the table at 45 degrees, the SS riving knife created some problems. The plastic blade guard did not operate properly. So that I could complete the project without delay, I removed the plastic guard from the riving knife. We finished the project when promised and the neighbors went home happy.

Now what to do? Put the saw guard all back to together and forget it or prepare for some future project requiring bevel cuts.

If you are not planning to put the guard back I would cut the knife to be the same height as the top of the blade so you would never have to remove it.

What is the advantage of the extra height?

dusty · Post by **dusty** » Sun Apr 20, 2008 7:02 pm

The regular saw guard will be used on a regular basis. It has already be reinstalled.

The alternate riving knife will only be used for those situations when the Shopsmith riving knife won't work. The only situation like this that I have ever experienced was when cutting this big batch of bevels.

Even then, it may have been a setup problem. I won't be at all surprised to hear from Nick that the SS riving knife is totally compatible to my problem configuration and I didn't need to do this.

As for there being a requirement for height above the blade - probably none except that it gives me something to take ahold of when I want to remove it. I used the real riving knife for a pattern.

Lesson Learned: Don't cut bevels, of any description, on a tilted table unless you have reason to believe that you have control over the cutoff that rides above the blade. Kick backs don't occur often, except in this situation. In this situation, a kick back of some sort is almost guaranteed unless you guard against it.

One must deal with the cutoff that is below the blade as well but that need be nothing more than a fence. I was savvy enough to recognize that right from the beginning. Someone recently referred to an anti-gravity devise. That's sort of what the fence is.

I have a thing about using a helper to pull cut-offs away from the outfeed side so I try to avoid that whenever possible. The fence on my tilting outfeed table takes care of that except for really long pieces.

fjimp · Post by **fjimp** » Sun Apr 20, 2008 7:30 pm

Okay Dusty, as much as I hate making a public display of my stupidity it's fact.

To date I haven't needed a seperate riving knife. In that I try to meet these needs in advance. I hope you will educate me. From your description I am unsure if you manufactured the knife you diplayed or created it by disassempling a shopsmith guard. I want to get a seperate knife and would love to hear an economical yet workable method to get one. Jim

Thanks in advance for the education.

dusty · Post by **dusty** » Sun Apr 20, 2008 8:32 pm

Jim,

Since going on a fixed income, I have had to change my spending habits. In the past I would not have fooled around with this stuff. I would have just gone out and bought it.

My wife will quickly add - "And that is just why we have to be more careful with our spending today"!!! She is probably right.

To answer your question. I did both. I disassembled the SS upper saw guard to get the riving knife. Using it, I completed my cutting tasks. Before I reassembled the upper saw guard, I used the riving knife to create a pattern and from that pattern I made a riving knife. The riving knife in the photo I posted is the one I made.

I will not use the riving knife that I made when it is possible to use the upper saw guard. I believe in capitalizing on the protection that the plastic guard and the kickback pawls provide. Why set it aside when it is available to use?

You can buy what I made from Shopsmith. Part number 514367 sells for about $35.00 and comes complete with kick back pawls.

Incidently, while cutting bevels, the kick back pawls were sort of in the way. Because of the tilt, the left and right pawls don't get activated simultaneously.

brown_hawk · Post by **brown_hawk** » Mon Apr 21, 2008 12:07 pm

Dusty,

Been a while since I did the bevels like that. But if I recall, the upper guard needed to be lifted up and set down on the wood at aboutthe time the front of the wood got over the arbor. Otherwise it pushed the riving knife to the right and into the wood.

The other thing that occured to me was the anti-kickback pawls were getting in the way, but your second post seems to disqualify that for a reason.

And if you are doing a lot of cutting at a bevel, duct tape and a piece of plastic on the right side will give some protection.

Just make sure that the upper pawls engage. Since the lower is below the blde and not liable to fall into the blade, it doesn't have the kickback potential of the upper piece.

Good work on the replacement knife.

Hawk

dusty · Post by **dusty** » Mon Apr 21, 2008 5:16 pm

brown_hawk wrote: Been a while since I did the bevels like that.

But if I recall, the upper guard needed to be lifted up and set down on the wood at aboutthe time the front of the wood got over the arbor. Otherwise it pushed the riving knife to the right and into the wood.
Hawk

OK Hawk, I'll bite. If you don't cut bevels on the tilted table anymore - how do you cut them?

Pictures would be nice.

Nick · Post by **Nick** » Mon Apr 21, 2008 5:35 pm

Dusty, Drew and I tried to recreate a situation in which is was impossible to cut a bevel with Upper Saw Guard as it comes and we could not. When the plastic cover was in the way, we simply swung it up and back. The anti-kickback pawls seemed operate reasonably well at steep table angles as long as the slot was clean and the riving knife was waxed.

Until I better understand why you could not use the saw guard for your operation, I have to say that the shopmade riving knife you show is potentially dangerous because it does not have anti-kickback pawls. This ommission almost guarantees the "uphill" piece will kick back at the end of the cut.

Could you please send me a two-view or three-view of the piece you were cutting via fax or e-mail? Drew and I will experiment with it and show a way to make it safely in this week's Sawdust Session.

With all good wishes,

brown_hawk · Post by **brown_hawk** » Mon Apr 21, 2008 8:43 pm

dusty wrote:OK Hawk, I'll bite. If you don't cut bevels on the tilted table anymore - how do you cut them?

Pictures would be nice.

Dusty,

I just haven't had any projects that needed bevels in a long time.

And I agree with Nick on the anti-kickback pawls. Absolutely necessary for that upper piece.

Hawk

ETA: You could use a router with a 45 degree bevel, or a Skil saw with an edge guide. For production, I'd want a router table if I didn't use the SS. I would probably use the Skil for large pieces only.

I just don't feel comfortable not having the pawls for that upper piece. Getting hit once with a small piece made a believer out of me.