Zero Clearance Insert

beeg · Post by **beeg** » Thu Jul 03, 2014 9:19 pm

benush26 wrote:I understand I may be over zealous about safety, but wouldn't omitting the guard negate some of the benefit of the ZCI?

Be well,
Ben

I don't think that's possible.

JPG · Post by **JPG** » Thu Jul 03, 2014 10:37 pm

beeg wrote:I don't think that's possible.

I don't think there is any 'connection'.

i.e. what is negated by the omission of the upper saw guard?

The 'primary' purpose of the ZCI is eliminating(or at least minimizing) tearout and providing a surface for the work piece to rest upon all the way up to the sides of the blade. Any safety 'improvement' is coincidental.

I agree being overzealous re safety is not possible. I refer to attitude, not hardware.

dusty · Post by **dusty** » Fri Jul 04, 2014 6:09 am

benush26 wrote:Confusion I've only made a couple, but each time, after I lower the table as far as I can, to make as long a slot as possible, I remove the ZCI and extend the cut towards the rear so that the upper guard has a place to slide down before using it. Saber saw works well.

Do most of you not use the upper saw guard (or riving knife) when using a ZCI? I understand I may be over zealous about safety, but wouldn't omitting the guard negate some of the benefit of the ZCI?

Be well,
Ben

I do extend the saw kerf to facilitate the the riving knife. That is what I use the ZCI Sled for. I cut the kerf in the normal manner by lower the table down onto the blade. Once the kerf is cut, I can slide the slide to extend the kerf as far forward and rearward as I want. My actual sled has some guide marks showing how long I want the kerf. The sled is also used to accurately drill the holes for the two Table Insert Screws.

On the drill press, I locate the sled by positioning it so that the drill bit (1/4") aligns to the holes in the sled. With the sled secured in that position, I insert the ZCI and drill....etc, etc. When I make ZCI, I usually make several at the same time. Using the sled allows me to make these somewhat identical with very little measuring and quickly. I use 1/2" stock to make ZCI.

Caution: Use hold downs to keep the table insert properly positioned in the cutout. Without the hold downs, the ZCI may be lifted out of the cutout while cutting the kerf. Hold downs not shown.

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keakap · Post by **keakap** » Fri Jul 04, 2014 3:24 pm

benush26 wrote:Confusion I've only made a couple, but each time, after I lower the table as far as I can, to make as long a slot as possible, I remove the ZCI and extend the cut towards the rear so that the upper guard has a place to slide down before using it. Saber saw works well.

Do most of you not use the upper saw guard (or riving knife) when using a ZCI? I understand I may be over zealous about safety, but wouldn't omitting the guard negate some of the benefit of the ZCI?

Be well,
Ben

Definitely use the guard when ever possible.
As for making ZCI, cut whatever rearward slot needed for guard of course, but on the front end, I make the slot MNIMUM needed. The "zero clearance" part of the ZCI is only where the teeth first meet the workpiece-, so you don't need a longer slot than what you get at the depth of cut you work.

Then, as the ZCI slot widens with use and becomes less helpful, you need only expose a wee bit more blade to get a brand new zero clearance insert. Who cares what the slot looks like behind the cut? (of course some blades with fatter teeth require a bigger "wee").

[some assumptions are made, naturally, such as parallelism] **-- and not super-thin cuts

keakap · Post by **keakap** » Fri Jul 04, 2014 3:57 pm

dusty wrote:I do extend the saw kerf to facilitate the the riving knife. That is what I use the ZCI Sled for. I cut the kerf in the normal manner by lower the table down onto the blade. Once the kerf is cut, I can slide the slide to extend the kerf as far forward and rearward as I want. ...[ATTACH]25531[/ATTACH]

Now there's another great sled idea. I'm gonna print this out so I can stea-- uh, that is, borrow it later.

Query: have you considered making the slot forward only as long as is needed for your shallowest cut? Making the rear slot as usual. Then you would have at hand x number of ZCI's ready to be quickly fine tuned for Any depth cut.

dusty · Post by **dusty** » Sat Jul 05, 2014 9:11 am

keakap wrote:Now there's another great sled idea. I'm gonna print this out so I can stea-- uh, that is, borrow it later.

Query: have you considered making the slot forward only as long as is needed for your shallowest cut? Making the rear slot as usual. Then you would have at hand x number of ZCI's ready to be quickly fine tuned for Any depth cut.

Yes, I have given that some thought - ever since you proposed it here. I am sorry but I do not see any real utility in doing that. When I make ZCIs for use in the saw mode, I cut for a 3" depth of cut and then (still using my sled) I extend the cut rearward to facilitate the riving knife. This gives me a kerf for the riving knife that is right in line with the blade.

Doing this does not insure that the riving knife is in line with the blade but it does insure that I am aware when it is not in line.

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