Shopsmith Forums

billmayo wrote:...g, I somehow forced the 2X4 into the 3 HP 220 VAC radial arm saw blade. Instantly the saw blade shot the 2X4 across the room just missing me and through a 8" concrete block wall. It actually bent the saw blade. ....

The suspense is killing me!

Did the workpiece get messed up?

;-)

dusty wrote:
If anyone reading this has the new riving knife, please measure it's thickness and post that here. ...e

just under 5/64, or .075"

Hi Gang;
I meant to reply to this thread sometime ago but am just getting around to it. I have used a ZCI for some time but never decided to modify it to use the upper guard until after a near serious problem.
While making doll cradles for the Toys for Tots program this season I did get a kickback that left a nice bruise on my ribcage for two weeks, me dazed for several minutes and then realizing that things could have been much worse.
I modified the ZCI by putting a 1/4" wide slot at the top of the insert using the router table. A very simple procedure that should not get put off.
Maiking the slot long enough permits using the upper saw guard as well as the riving knife and the anti kick back pawls in the conventional position with no modification.
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By the way, I mark each one of the ZCI's for the specific blade that it was made for to account for the differences in blade thicknesses. These things don't have to be fancy or high tech to do the proper job but the guards DO have to be in placein order for them to do THEIR job!!
Bill V

I don't worry about the kerf, in my ZCI, getting a bit wide. It still does the work of a ZCI except for the very smallest of pieces and I don't worry about those either. The dust collector will take care of them.

However, with this sort of an attitude, I do go through ZCIs at a fairly rapid pace. That is why I built my ZCI sled.

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CAUTION: Don't run with the blade exposed so much. An 1/8" exposure is good enough.


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CAUTION: Don't run with the blade exposed so much. An 1/8" exposure is good enough.

I use this same sled, on the drill press, to drill and counter sink the screw holes. I have, before this sled, drilled a lot of screw holes that were off just a little bit. Now I use a template and the holes are always just right.

When I extend the slot to facilitate the saw guard, I am careful not to extend it too far. This provides a secure fit for the riving knife and eliminates any unwanted movement of the knife.

The one thing I do not like about the ZCI that I make this way is that they tend to sing. I have contemplated cutting the ZCI using a wide kerf blade to eliminate that singing.

The other day I was making a slit (like a dado but only a single kerf width) in a 2 x 4. So the guard is out. But being careful (I hoped) I was used a feather board and a push stick. then BANG. I don't know what happened except not a drop of blood was shed. I cringe to think what would have happened if I have just used my hand. Maybe I will mount this beauty to a plaque and put on the wall in my workshop.