Archive for the ‘Power Tools’ Category

Making a .001 clearance insert

June 28th, 2009 13 comments
Padouk Insert

Padouk Insert

Tired of closing my eyes as I trim boards, fearful of the offcut falling between the blade and the stock insert and being launch back at me,  I decided to make one of these high-falootin gizmos called a zero clearance insert. These inserts are a panacea… they protect you from the aforementioned offcut falling between insert and blade and also improve cut quality by backing the material, reducing tear-out. Beyond that, they are known to get rid of warts and make you more virile. Ehhh maybe not all of that, but we live in age of over-hype and unsubstantiation so I’ll ask you kindly to not question my claims.

I have a bit of a history with zero-clearance inserts or ZCI’s as we call them in the biz ( the “as we call them in the biz” is there simply to annoy). You see,  I’ve previously mauled an HDPE,  which is High Density Polyethylene aka “space plastic”, version. Ideally you’re able to just stick a blank insert in throat, clamp a sacrificial board over it, and raise the blade to cut the kerf. No such luck with my Craftsman 22124 (Steel City clone) as the blade sits to high and prevents the insert from sitting flush for the operation. So I aligned my fence with the throat and pushed the blank insert over the blade to create the kerf in the right spot. It seemed to work but when I installed the new ZCI it just bound up my blade and made the belt whine like a Guantanamo detainee (What?? Too soon? I don’t condone torture, I just make fun of it so we can all heal… and by “all” I mean those of us that weren’t tortured of course… I’m guessing those guys are scarred for life). I tried to make the insert work but I ended up just making a mess of things… so I just declared “mission accomplished” and walked away.

Recently I got the nerve to try it again. Pretty much forgetting my first experience, I went ahead and repeated most of my mistakes… and yes, I interrogated the hell out of that blade and belt again. This time I made the insert out of some padouk, a rather dense and stable hardwood. The stable part is the important word there… a zero clearance insert needs to not move… especially if it wants to expand and become a negative clearance insert, or NCI as we call it here in the biz. Actually, I would think “zero” clearance insert is a bit of a misnomer as well, as it would imply that that the entire insert is always in contact with the blade.

We should probably be calling these things .001 clearance inserts or something, as presumably one tooth is going to be set fractionally further out than all other teeth and/or slight variations in blade path as the arbor is raised enlarge the kerf, etc. This strikes me as potentially being on the anal side of things so I will not mount a substantial campaign to do so. Anyways, back to my incompetence. First off I half-assed the making of the insert after bandsawing it to shape… no, wait… I half-assed it well before that by jointing only the top surface since set screws are the mating surface on the bottom to the machine (since it’s hardwood, everything should probably be uniform to ensure that there’s no impetus for that sucker to move).

After bandsawing I doubled-down on my half-assedness (achieving overall full-assedness) and brought it to finally shape with a spindle sander instead of using a router with a bearing to follow the exact shape of the stock insert. I guess I just wanted to see how well I could do it freehand and frankly I just like playing with the spindle sander as it’s just one of those tools you can get into a zone on…. especially with that woooo-waaaa, woooo-waaa sound that I find so soothing (yes, I just dropped some onomatopoeia on ya… and how come that sounds dirty?). I’m half tempted to replace my white noise machine in my bedroom with this sander.

This is where I cut the kerf in exactly the same way as I did previously. They say it’s a sign of intelligence to repeat things that don’t work with the expectation of a different outcome (still waiting for my invite Mensa… hint, hint). My table saw was kind of enough to make sure I got the message this time by tossing the insert back at me… I think I even heard it say “No soup for you!” at the same moment. I didn’t get the reference but was still offended. I finally grew a brain cell and carpet taped the new insert to the top of stock insert, clamped a board on top and proceeded to raise and lower the blade 418 times. The insert no longer grabs the blade.

Lastly I replaced the stock safety guard/splitter with a slightly more compact home made version.


For the short-term I’m going to use it. Shortly after making that decision, however, I found myself engaged in further debate of the idea. The conversation (with myself) went something like this: You know that you are still a relative newbie to this woodworking thing don’t you? Well, duh, your point being? Do you really want to always have the question in the back of your mind “is this insert going to blow up because I didn’t know what the hell I was doing” every time you use this inherently dangerous tool? No, no… you make a good point… and um… nice pants, by the way. Thanks! I didn’t think you noticed any more. [end scene] So with that I ordered a phenolic insert.

When I started writing this I was concerned that there wasn’t much to say about it and thus removed my tangent muzzle…. begs the question, overcompensate much??? Wait, are you talking to me again? Seriously?? You’re going to take a shot at me after I complimented you on your pants, wtf? [And with that I’ll take this conversation offline as it’s about to get heated up in here]

On a separate note, I think it’s time that I start educating my viewers with short educational videos covering the more complex and nuanced aspects of woodworking.  First up, how to properly chuck a bit:

How to chuck a drill bit. on Vimeo – Watch more Videos at Vodpod.

I will certainly endeavor to continue sharing my woodworking knowledge. Please be patient as I’m sure you can understand that these videos take considerable time to storyboard, shoot and produce. I mean getting the gaffer(me), key grip(me) and best boy(me) on the same page is a nightmare.

Categories: Power Tools Tags: