Zero Clearance Insert

db5 · Post by **db5** » Sun Jun 29, 2014 11:13 am

Why is the cut on a ZCI offset from center?

rcplaneguy · Post by **rcplaneguy** » Sun Jun 29, 2014 11:45 am

The ones I made for my table saw are off center to allow access for blade changing wrenches. And to have space for a finger hole for grasping.

http://youtu.be/Jgh1Hqg1LY8

Be sure to look at the following video at the 1:55 mark. ;-)

http://youtu.be/U66tr4r0Pyc

dusty · Post by **dusty** » Sun Jun 29, 2014 12:21 pm

I don't know why and for that reason when I make ZCI I do not offset the cutout but for the thickness of the blade.

I am speaking of a 510/520 configuration now. When the carriage is slid up against the rubber bumper on one side and the headstock on the other side, if the quill is unlocked (no quill extension), the left side of the blade will be right on the center line of the table insert.

A related thread.

JPG · Post by **JPG** » Sun Jun 29, 2014 2:28 pm

db5 wrote:Why is the cut on a ZCI offset from center?

Because God made it that way!

If it were closer, Some folks would try to get it centered to within 0.005!:D

Really! The centering relies upon a rubber sleeve bumper!

dusty · Post by **dusty** » Sun Jun 29, 2014 2:52 pm

Actually, it is because that is where the user put it, if it is in fact offset.

I just looked at the catalog and discovered that Shopsmith does not offer a ZCI. They do sell a blank table insert so that you can put the cutout wherever you want it.

I put mine where I do because I use that as an aid to verifying table alignment.

As a side comment, ZCIs don't remain ZCI very long unless you are very careful. This is particularly true of the Shopsmith because of the unpredictable relationship between the headstock, the carriage and the quill.

I don't discard my ZCI just because the cutout has gotten wider. I just don't rely on them as zero clearance. As the cutout gets wider, a ZCI simply becomes a table insert.

.

keakap · Post by **keakap** » Thu Jul 03, 2014 2:05 pm

[quote="dusty"]...As a side comment, ZCIs don't remain ZCI very long unless you are very careful. This is particularly true of the Shopsmith because of the unpredictable relationship between the headstock, the carriage and the quill.

I don't discard my ZCI just because the cutout has gotten wider. I just .../QUOTE]

raise the blade 1/4". Bingo- new ZCI.

dusty · Post by **dusty** » Thu Jul 03, 2014 2:11 pm

keakap wrote:
dusty wrote:...As a side comment, ZCIs don't remain ZCI very long unless you are very careful. This is particularly true of the Shopsmith because of the unpredictable relationship between the headstock, the carriage and the quill.

I don't discard my ZCI just because the cutout has gotten wider. I just .../QUOTE]

raise the blade 1/4". Bingo- new ZCI.

My ZCI cutouts tend to get wider not longer. Raising the blade...hmmm

JPG · Post by **JPG** » Thu Jul 03, 2014 3:31 pm

dusty wrote:
keakap wrote:
My ZCI cutouts tend to get wider not longer. Raising the blade...hmmm

Hmmmmm! A reason to not lower more than necessary the first time.

benush26 · Post by **benush26** » Thu Jul 03, 2014 8:53 pm

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

wa2crk · Post by **wa2crk** » Thu Jul 03, 2014 9:17 pm

Benush
Good point on the upper saw guard. I extend the slot using a 1/4 inch straight router bit on the router table. I had one near miss by not having the guard in place. I use it now. No exception!!!
Bill V