enlarging a zci pattern slightly

[Chris Curry]

With a slight grin I will tell you I scored a stash of coian from a resturant reno. I was only consulting on the comm/data and came away with the whole counter. Since I did not need the entire 36"x290" for the wash area cupboards for loml, I thought about zero clearance inserts for the contractors saw. I trimmed a broken chunk of corian and double sided taped the original. I sunk a flush trim bit in the router table and it worked perfectly. But... without the small push-pin button thingies to hold tight, the new insert is too loose in my opinion. I have heard of sinking a screw in the side/thickness of the new insert, leaving the head slightly exposed and adjustable for a friction fit. Since it is sooo sloppy, I was wanting to make the next ones slightly larger than the original. I dont like how spongey the bit's guide bearing gets when wrapped in a half dozen wraps of Red Green's handyman's secret weapon. Can someone recommend another way to get my next attempt slightly larger than the pattern?
Many thanks for any/anticipated input.

[Tony Bilello]

Maybe you could get a slightly larger ball bearing for the router bit. That way the cutter edge will be set back from the bearing and give a slightly larger piece from the smaller pattern.

[Bruce Wrenn]

First, it's standard practice to add a couple of set screws to the side of ZCI's to take up the free play. If they were made to exact size, they would be a bear to remove from saw. Commercial versions have to be adjustable, as not all saws are the exact same size.

[Mark Godlesky]

If there is only a little slop I would run a little masking tape around the original insert. If the masking tape is too spongey use aluminum tape instead.

If there is a lot of slop maybe use a straight bit with a router bushing. That will increase the size of you new insert by the offset x2.

[Chip Lindley]

Another approach: drill and countersink a couple of brass flat-head screws into one side of the ZCI. Adjust the friction for best fit. As the brass wears, the screw can be backed out a "tad".

Following my OCD tendencies, I would persue making my own spring/button thingies. I would go to my invaluable junk box for some little ball bearings, brass hobby tubing, and a ballpoint pen spring for starters. That would be really cool.

[Barry Richardson]

put a wrap of tape around the bearing on your flush trim bit to increase its diameter slightly, I've done it many times for various reasons...works fine.

[Dan Friedrichs]

+1 Barry

I think the set screws sound like a pain. Wrapping a few carefully-trimmed layers of electrical tape around the bearing of your flush trim bit works great.

[Andrew Pitonyak]

put a wrap of tape around the bearing on your flush trim bit to increase its diameter slightly, I've done it many times for various reasons...works fine.

Duh!!! Brilliant.

[Chris Curry]

Again, thanks for your suggestions and help.
I am having to work with the tape solution. As I indicated, with the original plate being too uncomprtably sloppy and having tried the duct tape because of its thickness I was looking in other directions. I have settled on the electrical and foil tape combo on the pattern and bearing. Chip's comments have stimulated other experiments though. I will have to cave to the more conventional for now.
Cheers

[Matt Day]

I recently did the same thing - put a couple layers of masking tape around my old ZCI that had slop which helped, then drilled and tapped for set screws on the sides. They work some much better now, I don't know why it took me so long!

[Alan Schwabacher]

Put the set screws in the saw rather than the ZCI so you only need to do it once. Tapping cast iron for machine screws works well.

But a pin at the back of the ZCI will avoid any possibility of it being lifted and thrown at you.

[Lee Schierer]

Instead of adding screws to the side of your insert drill and tap it, but put in ball plungers. If you mark the locations on your saw you can add dimples in the recess for the balls to drop into and they will lock your insert in place.

[Erik France]

I dont like how spongey the bit's guide bearing gets when wrapped in a half dozen wraps of Red Green's handyman's secret weapon. Can someone recommend another way to get my next attempt slightly larger than the pattern?

You can get a pattern/overhang router bit. A 3/32 bearing overhang might be a little bit too much.

Instead of wrapping the beaing I'd wrap the original in a layer or two of tape.

[Chris Curry]

Oh yes... I forgot about using a pin at the back, behind the blade.
Thanks Alan!

[Chip Lindley]

Eureka, I found It! (but Lee found it first) No need to conjur up ho-made bullet catches. Somebody already thought of them! 1/4" diameter--just right! Also in 3/8" and 1/2" diameters.

http://mortiselatchesetop.co.cc/bull...4-brass-plated

Bullet Catch 1-4.jpg