Home made European Riving knife

I've am determined to replace the blade guard-splitter on my Jet Supersaw. None of the aftermarket splitters does the job of a European Riving knife, so I am designing my own. Jet did a beefy job in designing the mount system for their guard/splitter. I wish they had finished it and put in a Riving knife instead. Anyway, I have figured out how to build a knife that will hug the blade and tilt with the blade. Height adjustment will be a manual affair with two handscrews.
I am contemplating an automatic height adjustment design that would require the blade be mounted in a sliding metal channel. This would be tied mechanically to the motor mount which adjusts with blade height. The very nature of placing the blade in a sliding channel would mean it would have some slop in it, probably about 5-10 thousandths. My sense is that this would be acceptable for a Riving knife application, provided it is a strong mount.
By the way, an overhead, basket style blade guard will replace the existing blade guard. I am considering a design pictured in The Workshop Book published by Scott Landis.
All opinions are solicited and appreciated.
Bob
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: I've am determined to replace the blade guard-splitter on my Jet Supersaw. : None of the aftermarket splitters does the job of a European Riving knife, : so I am designing my own. Jet did a beefy job in designing the mount system : for their guard/splitter. I wish they had finished it and put in a Riving : knife instead. Anyway, I have figured out how to build a knife that will : hug the blade and tilt with the blade. Height adjustment will be a manual : affair with two handscrews. : : I am contemplating an automatic height adjustment design that would require : the blade be mounted in a sliding metal channel. This would be tied : mechanically to the motor mount which adjusts with blade height. The very : nature of placing the blade in a sliding channel would mean it would have : some slop in it, probably about 5-10 thousandths. My sense is that this : would be acceptable for a Riving knife application, provided it is a strong : mount. : : By the way, an overhead, basket style blade guard will replace the existing : blade guard. I am considering a design pictured in The Workshop Book : published by Scott Landis. : : All opinions are solicited and appreciated. : : Bob :
Go to Home Depot and spend some time studying the Ryobi BT3100.
Yeah, that's the $299 "toy" saw that includes all those advanced features such as the riving knife you describe along with built-in dust collection and a sliding miter table in the base purchase price.
--
Steve
www.ApacheTrail.com/ww/
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"Bob Davis" <wrote

On the basis of having owned (a) a contractor saw with the stock guard/splitter (more accurately, without); (b) a contractor saw with a Delta aftermarket splitter and Beis overarm guard; and (c) a small sliding table saw what you are calling a riving knife arrangement, I honestly think there's no point trying to remanufacture your saw. The benefits are not there to justify that kind of effort, IMO, versus going with the aftermarket splitter and guard set-up. Plus, it strikes me you're going to exchange a small hassle, pulling and replacing the aftermarket splitter every so often, with what sounds like a much bigger one: manually adjusting the splitter height for each change in blade setting.
...By riving knife, i assume you mean the arrangement where the splitter is made to track up and down with the blade height, as well as the tilt. I can see two__potential__differences versus the aftermarket splitter. Depending on how it's been engineered, it __may__hug the blade closer than the aftermarket version, and (b) it__may__be possible to set it such that it stays a touch below the top of the blade. I am skeptical that (a) makes a decisive difference, even where true. (b) is a useful attribute, since it means it can stay on for non-thru cuts. But (unlike riving knives), the aftermarket splitters are designed to come in and out easily, somewhat offsetting this...Anyway, as long as the splitter, a splitter, is in place when it's supposed to be, I would suggest other issues, like having a safe way to crosscut, and a good guard, warrant more concern safety-wise.

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Thanks for your comments Woodstock. I'm not opposed to spending the money on aftermarket if I find something that does what I want. Easy removal of the splitter is not a meaningful option for me because it means the splitter is not designed to work with some cuts. A Riving knife can stay attached all the time. Also I have no use for the kickback pawls used in American Designs. I found these actually caused more hangups and potential for problems than they saved.
I looked and looked and looked for an aftermarket that I liked. The Beis guard is nice and I really considered buying it, but it was not available for my saw when I checked (jet Supersaw).
Your comment about exchanging hassle of changing heights vs. removal of the splitter is not correct. Any splitter that does not have the height adjustment hassle is one that is designed for a fixed (maximum) distance from the blade. I can accomplish the same thing with my design - just set it for maximum blade height and forget it. It will do the same job as the aftermarket splitter. By the way, my current splitter design took 2 hours of cutting and trying and $3 worth of parts to make it work. It was worth it to me. It seems that its the same hassle as one of the delta splitters that also uses a thumbwheel to mount/dismount the splitter. If I get this automatic height adjustment thing working, it will be superior to anything on the aftermarket by a long shot.
Now back to the guard - you are absolutely dead on. You really have to work to save any money over the aftermarket items, assuming your time is worth something. I guess I get absorbed by the challenge. I also think I can make better dust collection than some of the aftermarket items I've seen.
Best regards, Bob

Supersaw.
knife,
system
Riving
will
manual
require
very
have
strong
existing
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"Bob Davis" < wrote

Also I have no use for the kickback pawls used in American

Basically agree on the pawls, though I found them generally unobjectionable on the aftermarket splitter I had (which was the Delta one). At one point I contemplated adding a sliding table accessory to my old saw and/or making a crosscut sled that could be used with the aftermarket splitter in place. It seemed that both should be workable, provided the pawls were removed. I did not test this approach out in the real world before getting a different saw...but assuming it would work, it'd cover all situations except non-thru cuts, which would be pretty high percentage of all cuts.

I'm thinking maybe you're referring to the Beis splitter, and not the guard. I have seen the claim that the Supersaw's internal mechanism is the same as the Jet contractor's saw. The Beis web page shows a splitter for the latter model. Maybe that would work, if the mechanisms are indeed the same? If you do mean the guard, I have the Beis one and believe it should present no problem with the SuperSaw. It has a pretty big range of adjustment for saws with different front to back and right side table formats.

One of Tage Frid's books features a shopmade splitter/guard, fitted to a Rockwell saw. It was fixed to the standard attachment point under the blade insert, but was curved in shape to complement the blade, rather than upright like the aftermarket kind, and had a wooden crown guard on top...interesting design that somewhat mitigates this...admittedly, poses some guard issues, however.
I can accomplish the same thing with my design - just set

If I get this

Sounds like it would be.
...You've probably thought of this already, but engineering in some easy means of micro-fine adjustment would be a big plus. On my saw, the splitter is mounted to a heavy piece of folded steel that ties back to, and travels up and down with, the arbor. There's no provision for adjusting the alignment and out of the box it was not acceptable. Scotch tape shims and trial and error eventually did the trick but it would have been nice if some adjustment were built in at the factory...The alignment of the splitter is critical, obviously, and small misaligments in the bar that carries the splitter are much exaggerated by the time they reach the business end of the splitter because of the distances involved and the inevitable vibration.

I feel the Beis guard is a very high quality piece of equipment that one would be hard pressed to better as a guard. I've don't have my guard hooked up to dust collection; based on what I've seen, I'm sure you're right about being able to surpass that aspect of it.
Anyway, I hope you'll post a description/pix of your design once you've built it. It sounds like a pretty interesting project.
--W.

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