enlarging a zci pattern slightly

[Chris Curry]

With a slight grin I will tell you I scored a stash of coian :D 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. http://lh4.googleusercontent.com/public/N5AeRUTTNlUzFyVtZZtg6LVcuQyXJT4CWp8sG05wQFyULzvAR2 nnVxuG8OIcKSzq0_dk3eTE9NCsue7ERKVcWkZUs65dfCztZ0Um R81xOv52nOtFTIVByl_slQYQpVzr3ofvZnbcIFI4H2ZzJROVjN HtuvWO56hRZ390isfLRg=s90 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/bullet-catch-1-4-brass-plated

188951

[Chris Curry]

This is a great idea too, added to Alan's suggestion to do it once and for all in the saw table. I know Lee Valley has a similar type of catch available now that I get the prompting. I was experimenting with a pen spring inside a spent .22 cal. short casing on the side of the insert. A little epoxy and these bullet catches in the table and I am home free. I smell victory.
Thanks