Zero Clearance Insert

dusty · Post by **dusty** » Tue Nov 25, 2008 4:44 pm

When using a Zero Clearance Insert, is it normal for the saw blade to sing or is that a sign the zci was cut incorrectly.

[ATTACH]2429[/ATTACH]

[ATTACH]2430[/ATTACH]

wa2crk · Post by **wa2crk** » Tue Nov 25, 2008 4:58 pm

Dusty;
It appears that your ZCI is has a different clearance at the rear of the blade than it does at the front of the insert. This may be an optical illusion though.
When I first cut my ZCI's they do sing a little bit because the teeth of the blade will make a slight contact with the insert. The body of the blade, however, will clear the insert.
When I cut plywood for a project and I am really fussy about the cut I generally make a new ZCI and then the zero part really means what it says "zero" hence the slight singing of the blade.
Bill

dusty · Post by **dusty** » Tue Nov 25, 2008 5:07 pm

[quote="wa2crk"]Dusty]

Yes, Bill. There is a slight difference in the kerf between front and back. I have done a little mill work for the riving knife and a couple secondary cuts to widen the kerf just a little to reduce the singing.

If the general consensus is that I should just sing along for the benefit of a "zero clearance" I will.

I suppose that a heavier material used for the insert may effect that also. This one is made of a plastic material and is quite flexible. I know some of you use hardboard and some use baltic birch plywood.

shydragon · Post by **shydragon** » Tue Nov 25, 2008 6:33 pm

I just ordered a zci from SS. I never even thought about the riving knife.

ldh · Post by **ldh** » Tue Nov 25, 2008 6:54 pm

Dusty,
I make mine on the cheap using scrap ¼" baltic birch with scrap formica laminate. I use a 3/4" baltic birch template that I made for the 520 and double stick tape to route to it. Crown down so that I can sand to fit. Couple of pics for what it's worth. I make several at a time and use them for most all of the cuts I make on the SS.

ldh

dusty · Post by **dusty** » Wed Nov 26, 2008 9:08 am

ldh wrote:Dusty,
I make mine on the cheap using scrap ¼" baltic birch with scrap formica laminate. I use a 3/4" baltic birch template that I made for the 520 and double stick tape to route to it. Crown down so that I can sand to fit. Couple of pics for what it's worth. I make several at a time and use them for most all of the cuts I make on the SS.

ldh

Thank you for the input, IDH.

Looking at your photos I note a comment written about hole sizes. I assume there is some history for why the mounting holes have to be different sizes, am I correct.

ldh · Post by **ldh** » Wed Nov 26, 2008 10:47 am

dusty wrote:Thank you for the input, IDH.

Looking at your photos I note a comment written about hole sizes. I assume there is some history for why the mounting holes have to be different sizes, am I correct.

Dusty,
Yes, the hole in the in-feed end is 5/16" and the out-feed 27/64". I am not sure what the reason is for the difference, but I think that is the size you will find on the factory inserts. I use a couple of cone setscrews inserted upside down in the saw table to mark (register) the exact center on the template for the holes. I have found that it is best to use the template for the table that it was cut for (so I put the SS serial number on the template) as there are some slight differences from table to table.

ldh

Ed in Tampa · Post by **Ed in Tampa** » Wed Nov 26, 2008 11:16 am

ldh wrote:Dusty,
Yes, the hole in the in-feed end is 5/16" and the out-feed 27/64". I am not sure what the reason is for the difference, but I think that is the size you will find on the factory inserts. I use a couple of cone setscrews inserted upside down in the saw table to mark (register) the exact center on the template for the holes. I have found that it is best to use the template for the table that it was cut for (so I put the SS serial number on the template) as there are some slight differences from table to table.

ldh

IDH
I just went and measured my inserts from SS and in every one the hole is identical front and back, they are all 5/16 actually the holes are 41/128" which is 1/128" bigger than 5/16 but close enough. Also all my inserts have holes placed in the identical location. So I'm confused?????
Can you explain why you say each table is different so each insert has to be drilled in a different location?

ldh · Post by **ldh** » Wed Nov 26, 2008 12:41 pm

Ed in Tampa wrote:IDH
I just went and measured my inserts from SS and in every one the hole is identical front and back, they are all 5/16 actually the holes are 41/128" which is 1/128" bigger than 5/16 but close enough. Also all my inserts have holes placed in the identical location. So I'm confused?????
Can you explain why you say each table is different so each insert has to be drilled in a different location?

Hi Ed,
Try measuring the holes using drill bits. I have found the factory inserts to be very close to the 5/16 and 27/64 measurement. I pulled a couple of my factory inserts from the wall and inserted a 5/16 bit in the in-feed side and a 27/64 in the out-feed side and shot a couple of pics for you. I sure hope it is not our dry weather here in AZ causing the holes to expand or your humidity in FL to cause them to close. Just kidding, let me know what you find.
ldh

Ed in Tampa · Post by **Ed in Tampa** » Wed Nov 26, 2008 4:10 pm

ldh wrote:Hi Ed,
Try measuring the holes using drill bits. I have found the factory inserts to be very close to the 5/16 and 27/64 measurement. I pulled a couple of my factory inserts from the wall and inserted a 5/16 bit in the in-feed side and a 27/64 in the out-feed side and shot a couple of pics for you. I sure hope it is not our dry weather here in AZ causing the holes to expand or your humidity in FL to cause them to close. Just kidding, let me know what you find.
ldh

IDH
Okay here is what I found. All my SS factory inserts that are made from plastic have 5/16 holes at both ends and work just fine on my Shopsmith. These include the blank, those pre cut for the riving knife.

All the metal SS factory inserts like the one that comes with the 510/520, router, molding head cutter, drum sander have the larger hole at one end. I have no idea why. It isn't needed. Sorry for my previous post but all my metal inserts were buried and I only checked the ones I use all the time.

I have made ZCI for my SS out of wood and I have always only drilled my holes to be 5/16 and they have worked fine.

A 13/64 tapered hex slot screw is used to secure them to the table so 5/16 hole allows for plenty of adjustment

I have no idea why the holes are different, this is where we need Nick to run out into the factory and to bring back the official word.