ZCI, Saving Yours from Mutilation

dusty · Post by **dusty** » Fri Oct 16, 2009 4:51 pm

I regularly chew up up my ZCI because I can't seem to get the table returned to the same location on the tubes every time. I typically make ZCIs about a dozen at a time.

I'm trying to change that. I put together a little jig that will allow me to return the quill to the same location (with respect to the left miter track) every time.

[ATTACH]6198[/ATTACH]

[ATTACH]6199[/ATTACH]

[ATTACH]6200[/ATTACH]

In the last picture you can see what happens to a perfectly good ZCI. The one on the right with the kerf opened up like the Grand Canyon.

Opps. I also see that I didn't cut the kerf long enough for a riving knife.

mickyd · Post by **mickyd** » Fri Oct 16, 2009 6:36 pm

dusty wrote:I regularly chew up up my ZCI because I can't seem to get the table returned to the same location on the tubes every time. .......

I thought contact between the carriage stop set screw and headstock was supposed to ensure exact repositioning of carriage stop to blade (assuming the quill is fully retracted)?? Or, if that's not the case, when repositioning the table, wouldn't the table get lowered down over the blade first to ensure that the blade is aligned with the slot?? Remember, question is coming from a greenhorn so don't laugh too hard if I'm missing something real obvious.

dusty · Post by **dusty** » Fri Oct 16, 2009 7:32 pm

mickyd wrote:I thought contact between the carriage stop set screw and headstock was supposed to ensure exact repositioning of carriage stop to blade (assuming the quill is fully retracted)?? Or, if that's not the case, when repositioning the table, wouldn't the table get lowered down over the blade first to ensure that the blade is aligned with the slot?? Remember, question is coming from a greenhorn so don't laugh too hard if I'm missing something real obvious.

Nope, there is nothing to laugh at. What you describe is exactly what is suppose to happen. You can see from the third photo that it doesn't work, at least not for me.

Also, I don't have a carriage lock set screw. That is a feature of the earlier models. In lieu of the set screw, I have a rubber collar on one of the way tubes. It acts as a bumper that supposedly spaces the headstock and the carriage a fixed distance apart.

mikelst · Post by **mikelst** » Fri Oct 16, 2009 8:16 pm

But... knot all arbors are made alike....

Some of us are just to cheap.. I mean frugal to get rid of our old arbors after we upgrade.

dusty · Post by **dusty** » Fri Oct 16, 2009 8:34 pm

mikelst wrote:But... knot all arbors are made alike....

Some of us are just to cheap.. I mean frugal to get rid of our old arbors after we upgrade.

I understand your statement but I think I have missed the point. Why would you have to change arbors? Your arbors locate the blade in the approximate center of the table insert, don't they?

Incidentally, there is only one person that participates on this forum that is more frugal than I.

foxtrapper · Post by **foxtrapper** » Sat Oct 17, 2009 4:55 pm

Your problem may be blade flex. It wasn't a problem when everyone ran thick blades. But as thin kerf blades became popular, it became more and more of a problem. Thin kerf blades are weaker and more easily deflected. And on start-up, they often times slightly wrinkle, like a drag racers tire. This will cause them to dig into a zero clearance insert.

dusty · Post by **dusty** » Sat Oct 17, 2009 5:53 pm

foxtrapper wrote:Your problem may be blade flex. It wasn't a problem when everyone ran thick blades. But as thin kerf blades became popular, it became more and more of a problem. Thin kerf blades are weaker and more easily deflected. And on start-up, they often times slightly wrinkle, like a drag racers tire. This will cause them to dig into a zero clearance insert.

I just cut a new ZCI. I'll watch it for awhile to see if that might be a problem.

Thanks for the tip.