Weekend Woodworker

In the very first podcast of Woodwoorking ONLINE’s podcast series, the presenter demonstrates a simple technique for making grooves and dados without measuring them out. I suck at rudimentary math and my measuring skills are fairly basic as a result… as I’m also without a dado blade, I thought the it would be interesting to have a try myself. 

The basic premise is fairly simple: establish the blade height, account for the width of the blade to establish the left outer cut, factor out the width of whatever materials will ride in the dado to establish the right outer cut, and then clear out the waste. Clearing the waste involves taking advantage of the width of the blade kerf; the teeth on my CMT fine cutoff blade are supposedly 2.5mm so I simply move the work piece over about 2.5mm with every successive cut. For the rest of the article I’ll discuss the other steps involved.

Establish the blade height

If you’re lapping two pieces of wood, you’ll generally want to set the blade height to half the height of the work piece. This can of course be measured but I’ve found the technique described here to be very accurate.

Start with a piece of scrap wood the same width as the wood you’ll be using. Use your eye to set the blade height to slightly less than half the width of the stock. Cut the first slot and then flip the work piece over and make a second cut from the opposite site as though you were making a tenon. The two cuts probably won’t meet up so sneak up on the centre point by raising the blade height progressively—bear in mind you only want to raise the blade by half of the width of the remaining waste as you’ll continue cutting from both sides.

When the final sliver is nipped away, you’re at the halfway mark for the stock in question. Lock down the blade height so things don’t move.

Establish the left outer cut

You’ll need to determine the width of the slot left by your saw blade for this task. Although the teeth on my saw blade are marked as 2.5mm, in practice I’ve found a piece of scrap 3mm MDF fits perfectly into the slot left behind. The work piece will initially be positioned in relation to the rip fence and the blade; the 3mm spacer provides the offset necessary for the first cut.

Roll the fence into position, drop in the spacer, and then position the work piece against the mitre gauge. Adjust the fence to line up the first cut and then lock the fence in position. If the work piece it too short, use an additional block to pad out the gap between the fence/spacer and the work piece. Make the first cut to establish the left shoulder.

Note the fence is only being used as a stop block; as usual, you shouldn’t use the mitre gauge and fence at the same time, although in this case there is less opportunity for the work piece to bind if the fence is out of alignment.

Establish the right outer cut

Look ma, no measuring! No math! Leave the fence where it is and remove the spacer. Keep the extra “pad” block in place if necessary. Position an offcut of the same width as the material that will sit in the final dado between the fence and the work piece (or pad block). This offsets the work piece the width of that material. Make the second cut to establish the right shoulder.

Clean out the waste

At this point go ahead and clear out the waste material. When you’re done, the material intended to fit into the dado should fit fairly perfectly! The one issue I ran into was a result of the  teeth on my blade being angled in opposite directions; this resulted in a series of v grooves that would necessitate some additional cleanup with a shoulder plane or router. To correct this situation, the Woodworking ONLINE presenter suggested shifting the work pieced left and right over the blade; this does an okay job but I’m not sure what would happen if the work piece came in contact with the shoulder of the dado!

I’ve read about table saw kick-back, I’ve seen the kick-back demonstrations on YouTube and other woodworking video sites, and I’ve even read the kick-back warning sticker on my own table saw. In short, I understand why kick-back happens and the precautions to stop it happening.

Yet today I experienced my very first kickback and the power with which the exposed blade threw the wood over my should was awesome. So what happened?

Firstly, I was experimenting with dado-making using a regular cross-cut blade so I had the splitter and blade guard off the saw. I’ll point out had the blade guard been in place the kick-back would not have happened but of course it needs to be off since I wasn’t cutting all the way through the piece.

Secondly, I wasn’t cutting a board. Most of the internet videos demonstrating kick-back using a square piece of foam or plywood. While I was using a scrap 2x4 I wasn’t expecting to be any safer but in theory there may be less opportunity for kickback with a smaller piece of wood.

Thirdly, while the blade guard was removed, I was being extra careful having never used the table saw without this critical piece of equipment. In short, I was not standing directly behind the blade but off to the side and I was being careful not to twist the work piece while applying sufficient pressure to stop the blade lifting lifting it off the table.

Finally, as mentioned, I was using a regular cross-cut blade to kerf out the dado; this meant taking pass after pass to arrive at the correct width. To keep moving, I would take one pass and leave the blade spinning while sliding the work piece back to the front of the table for the next pass.

The dado making went quite well, apart from the v-grooves from the blade. As I stood back for a final check of the union between my scrap “shelf” piece (another 2x4) and my new dado, I fumbled and dropped the shelf piece. It landed on end in front of the blade and before falling forward onto the still-spinning blade.

Although it crossed my mind to lunge forward and knock the piece out of the way before it hit the blade, I thought better of that idea and stood back while the drama unfolded. As you’d expect, when the wood made contact with the blade it was gone before I could blink. Just for “kicks” (sorry!), the impact dislodged the metal throat plate and it got mixed up with the blade.

I was standing to the right of the blade and the piece of 2x4 (which was about fifteen centimetres long) ended up in the back corner of the garage with a thump. When I later went to find it, the gash from the saw was deep and rough. Again, very impressive.

In one sense, I hoped to never experience kick-back but at the same time I did want to know what it’s like to really experience this mythical event. Having been there now, I can honestly say I hope it never occurs again and I’ve learned to shut down the saw unless I’m working with it directly. I’ve also been meaning to get a decent leather shop apron to shield my torso if I were to even get hit directly.

In normal operation, the saw’s safety items would be in place and I’d probably be using feather boards and push sticks as well, if not clamping the work piece to the mitre gauge.

Hi, welcome to the new blog! As the title of the blog suggests, I’m a weekend warrior when it comes making things with wood; while  I’ve fallen in love the material, the tools and the craft, I’m a young buck and still have a lot of learning to do. The plan is to use this blog to document my experience setting up shop in my new house, applying the techniques I learn and the information I glean from various sources, and of course relate my screw-ups in gory detail!

Hope you enjoy reading,

--Michael