Simple, Cheap ZCI's

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Project by Dchip posted 01-13-2011 09:38 PM 2405 views 8 times favorited 7 comments Add to Favorites Watch

There are many different methods for making zero clearance inserts and a lot of saws require very specific dimensions, but I would like to share a very simple method that has worked wonders for me. This will probably only be valuable for those with a need for a 3/8’’ thick insert (My saw is a new portable ridgid).

Essentially, I had a recent epiphany that 1/4’’ +1/8’’ = 3/8’’.

To elaborate, I realized that I could glue some 1/4’’ mdf to 1/8’’ hardboard (both true thicknesses, unlike plywood) and eliminate what’s to me the most difficult step of achieving proper thickness for the insert (I’ve seen people plane down wood to accomplish this, though I imagine it could be subject to movement). After that, all that was left was roughing out the shape on my bandsaw and then a flush trim with the original insert, a finger hole on the drill press, and some finish and a waxing.

*A note on the first picture – In using scraps I didn’t realize until it was too late that one piece of hardboard was actually 3/16’’, and thus I had to knock of 1/16’’ from the bottom border.

This insert should be stable as well as sturdy and I could batch out a number of them in short period of work. I experimented with 3 to start, but will be making enough to cover common blade kerfs, blade angles and dado sizes in the near future.

I hope this proves helpful to some, I welcome any questions/comments you may have.

-- Dan Chiappetta, NYC,

7 comments so far

View NBeener's profile


4816 posts in 3171 days

#1 posted 01-13-2011 09:42 PM

Good idea. Thanks for sharing !

My only issue with my DIY ZCIs has been … that the sharp “claws” of my anti-kickback pawls … like to dig into the (usually Baltic Birch ply) that I use to make them.

In theory, I could inset a scrap of UHMW where the pawls hit, and probably stop that, but … if you have similar pawls, how do THEY treat the hardboard ?

-- -- Neil

View Randy Sharp's profile

Randy Sharp

363 posts in 3669 days

#2 posted 01-13-2011 10:15 PM

Nice job, Dan. Thanks for sharing.

-- Randy, Tupelo, MS ~ A man who honors his wife will have children who honor their father.

View mvk5150's profile


3 posts in 2687 days

#3 posted 01-13-2011 10:41 PM

I have the same saw(R4510?) and was just going to make some inserts for it. Thanks for the post, I’ll be making them your way (simple and easy!)

View Dchip's profile


271 posts in 3249 days

#4 posted 01-13-2011 10:47 PM

Beener – I have to admit that I only use the riving knife and a good push stick (more like push boot). I can see how this would be a problem, and you’re right, the UHMW or phenolic inserts would probably be best.

mvk – Yup it’s for the 4510. Works out real well. The original insert is a little thin, so the flush trim bit can be a bit tricky on the first one, but after that you can just use the old insert as a pattern.

I’m sure the higher end inserts are still best, but from what I’ve read about inserts in the $10-20 range, this is probably better and gives you the opportunity to batch out as many as you may need (I recommend making more than you think you’ll immediately need).

-- Dan Chiappetta, NYC,

View RDR's profile


38 posts in 2669 days

#5 posted 02-01-2011 02:05 AM

I have the same saw and have been meaning to make some ZCIs. I was wondering if you included any sort of tab on the front, or anything to hold the insert in the saw like the factory insert has?

-- The Dude abides...

View Dchip's profile


271 posts in 3249 days

#6 posted 02-01-2011 03:29 PM

Hi RDR – without much thought I started to nail in a brad, but quickly realized this would split the mdf. You could pre-drill a snug hole for one. A better option would probably be a small kerf cut of the bandsaw or table saw if you have a tenoning jig, then glue in a thin scrap. I admit I have not yet done this, but I think the only real risk of the insert coming dislodged is if there is too much play on the edges or if you raise the blade in the middle of a cut. I may have to go back and revisit this, though.

-- Dan Chiappetta, NYC,

View RDR's profile


38 posts in 2669 days

#7 posted 02-01-2011 07:11 PM

I’m not sure what I’ll do yet, but I’m going to be sure to add something. I was reminded of this in a recent blog posting in which a workpiece moved a ZCI just enough to contact the blade and it kicked back right into the user’s stomach because it didn’t have any sort of mechanism securing it to the table. The pictures looked mighty uncomfortable, to say the least.

Like you said, though, there must have been too much slop built into the ZCI for this to have happened. But, it’s something to consider.

-- The Dude abides...

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