ZCIs... 1/2" or 3/4" material?

[Scott Hildenbrand]

So, I'm going to make some ZCI's out of UHMW plastic. I can get it at 1/2" or 3/4" thickness..

Now... My issue is that the plate is a hair under 5/8th... Around 15.3mm to be flush with the table.

So... Should I go with the 1/2" material, drill and tap it and add in some set screws to level...

Or.... Should I go with 3/4" material and have to hog out the back to allow it to set flush...

Was hoping to just use some 5/8th material, but can't get any at that thickness.

What are your opinions?

This will be for a Ridgid R4511 btw.. I plan on making at least one insert with a replaceable center section, too..

[Walter Plummer]

Go with the 1/2" and set screws to flush it up to the table. The replaceable strip is a great improvement, make plenty of the blanks so you don`t have to stop and make one in the middle of a project.

[John Ricci]

The 1/2" with the set screws sounds to be the best of your options. I make the inserts for my General 650R from 1/4" phenolic panel and I use set screws with locknuts on the bottom side. Give yourself the tweaking room...

http://img.photobucket.com/albums/v102/LPBlue/Workshop/03-11-08_1546.jpg

http://img.photobucket.com/albums/v102/LPBlue/Workshop/03-11-08_1545.jpg

http://img.photobucket.com/albums/v102/LPBlue/Workshop/03-11-08_1540.jpg

J.R.

[Scott Hildenbrand]

What's the best way to go about cutting the riving knife grove.. Just flip it end for end and run the blade through on one side then the next?

[Bruce Page]

What's the best way to go about cutting the riving knife grove.. Just flip it end for end and run the blade through on one side then the next?
I use my band saw for the short slot for my splitter. I think you could do a riving slot like you suggest.

[John Ricci]

What's the best way to go about cutting the riving knife grove.. Just flip it end for end and run the blade through on one side then the next?

I used my stock insert as the template for the router table to cut the blank and then left the whole thing taped together to go back into the saw top. The first cut was with the stock insert in the table and I brought the blade up through it. I flipped it end-over -end and made the same cut as the first one which extended the slot perfectly for the riving knife.

J.R.

[Chip Lindley]

I've never used UHMW plastic, but many here complain about it not being perfectly flat AND expensive. If it's flatness can not be depended on, why bother?

Lotsa flat ZCI's can be made from 3/4" MDF. (high pressure lam glued to the surface is optional) Every different blade and dado width can have it's very own ZCI! And on the Cheap Too!

As suggested before, use the stock insert as a pattern for routing the outside profile. A template can easily be made of 1/4" tempered hardboard to route recesses to clear the "ears" inside the table opening where the insert rests. Set screws can be added to level the *cheapie* inserts perfectly.

[Pat Stewart]

To add to Chip's comments, I used some used 3/4" t&g ash. Resawed and planed down to thickness. The insert "ears" and saw top were level/square/uniform enough that I didn't need set screws to level the insert. I paid $20 for 100+ bd. ft. of the used ash t&g.
http://www.sawmillcreek.org/attachment.php?attachmentid=130622&d=1256079249I