Monday, January 19, 2015

Learning to hand-cut dovetails

I started wood-working a year and a half ago.  I learned whatever little I have learned so far by watching many many hours of youtube videos from folks like Matthias Wandel, Frank Howarth, and about another dozen channels I follow now.  I really like Matthias' videos because of the engineer-like approach he takes on problems, and being an engineer myself, that really got me interested.  Frank's channel is another one of my favorite because not only his videos are gorgeous, the stuff he makes is really beautiful and simple, just the style I like myself.  Those two channels among many really were a big influence and source of inspiration for me.

A couple of months ago I came across Matt Cremona's channel and a third big wave of inspiration hit me.  Matt does a lot of amazing intricate hand-tool work, as well as using modern power tools.  I was started to get a tiny bit bored of doing the same old rabbets, dados and miter joins, so finding Matt's channel has really gotten me interested in learning to do more hand work to incorporate into my pieces.

I decided to start by learning how to hand-cut dovetails.

Before I started cutting anything, I learned how to sharpen my chisels.  I already had a few sharpening stones but hadn't really gotten my technique really down, so I spent a lot of time researching on the internet for what folks are doing.  Not surprisingly somehow, I discovered there's about a different sharpening method per fellow sharpening chisels out there, so I ended up with my own method with ideas from here and there, and then my own.  I describe it in this post.

Once I got my chisels ready to go I then spent a lot of time doing research on hand-cut dovetail techniques.  After several hours of watching videos for days, I think I figured out how I'd do it, so I made a list of tools I'd need:

At the top is a dozuki Japanese pull saw, which I bought months ago as an impulse buy at Rockler.  From right to left is my cheap coping saw (which I bought a decade ago for something random and never used until pretty much now), a square, a marking knife , my marples chisels, a rubber mallet which I have also owned forever, a marking gauge and a veritas dovetail marking guide.  I bought the last two today (and they made a big difference!).

My favorite videos so far to learn how to cut these are this one from Matt Cremona (start around minute 5), this video with Frank Klausz from Wood and Shop, this super detailed series also from Wood and Shop and this one from David Barron.  There's a bunch of others but those are my favorites.

So with all that, I finally sat down at my shop (actually stood up, although one thing I learned is I need to build me a stool for this or my back will pay), and made my first dovetails:


You see you watch all these guys in youtube and they make it look so easy.  But as my motto goes, the best way to learn is to screw up as much as possible.

For that first try I eyeballed all the positions and angles for the tails and pins.  I didn't own the dovetail guide yet (although that's not really needed, it's just a convenience), pretty much just cut without even marking the line.

I also didn't own the marking gauge so I scribed the depth lines using the marking knife, which I don't think was such a hot idea because the v-groove it leaves is a bit too big.

Some of the things I learned from this one:
  • When chopping the waste, I went directly against the line, but this pushes the wood back so you end up past the line.  I realized that first chopping most of the wood and then going a second time against the line would work a lot better.  This was also a detail mentioned in some of the videos I watched which somehow flew right over my head.
  • The poplar I used probably not the best choice of wood.  Really unpleasant and fibrous to cut through.
So I gave it a second try:

Which came out even worse!

The things I learned from this one:
  • The fit was really really tight (you can even see how I cracked the wood).  So probably a bit of fine tuning after the initial cuts are done would be a good idea.
  • There were still lots of gaps in most places.  This was mostly because of my sloppy technique for chopping off the waste and my also slopping technique for cutting with the saw.

    For chopping the waste, I would do it in two steps and then try to pair it flat with the chisel. which made a bit of a mess.  I started to intuitively realize that if I tilted the chisel a bit in the last chop it'd leave a cleaner cut, and more importantly, no need to pair the surface flat since it'd be a bit concave (I later saw this trick in a video as well).

    For the saw, I figured that what I was doing wrong is basically causing the saw blade to get caught too much and almost wobble.  I later learned that first making a dent, then cutting straight on top, then going down lightly and accelerating would yield a much better cut.  In essence, use a lot more confidence in the cut :)
  • Also at this point I was still tracing the lines by hand and I think making the angle a bit too steep.

I made a couple more tries which were just a bit better.  This happened at least twice too:

Where I cut the tails off and only realized it in the end.  So the advice you see everywhere about marking your waste with an X, is really, great advice.

I was at this point two days into cutting 4 sets of dovetails and not looking very promising.  This is when I went back for some more youtube'ing and found and watched all the videos in this series as well as a few others.  It's amazing how much more it sinks in when you have actually tried to do it first.

I also went to the store this morning and picked up a marking gauge and the veritas guide thing.  Then I gave it another try:

A huge difference!

I consider these my first set of 'decent' dovetails.  Still far from great but compared with the previous attempts they look so much better.   A few things I learned this time:
  • Going over the gauge lines with a pen really helps see it.
  • It's probably best to leave the tails a bit proud so they can be sanded later (you can see the pin on the right has the opposite problem).
I made a few mistakes with my cuts too but that's a matter of more practice, but overall it was pretty exciting to get something decent after the first crappy attempts.

I am going to practice a bit more and try to make a box, and will post later or shoot a video with the method I came up with in the end, once I have it a bit more polished.

Tuesday, January 13, 2015

Restoring and sharpening a chisel

I got an 80 year old chisel handed down from my grand father, which is made out of really hard good steel.  It hadn't been used for decades so it wasn't in a great condition.  This is how I restored it.

The metal had come off of the handle so I used a good dose of epoxy to glue it up in place.  I cleaned the blade with a series of dry wet super high grit sand paper and then buffed it with my dremel.  I didn't take pictures of that.

One that was done, I set out to flatten the back, reset the bevel and sharpen it.

This method also works for setting up any brand new chisels you'd get from the store.

To flatten the back I use wet dry sand paper at 350, 800 and 1500 grit.  These are fixed to a piece of scrap glass using double sided tape tape.  I spray those with window cleaner.

This particular chisel's back was pretty uneven so I actually spent some time on the coarse diamond stone before this.

In this picture you can see it half way through:

And this is once it's completely flattened:

To reset the bevel I use the veritas mkii jig, which is a bit pricey but awesome.  I had tried doing this by hand and ended up with a convex bevel.  Then I tried a cheaper jig, which didn't work very well for me, so I finally went for the veritas.  It was worth the money.

Here I am setting the bevel to 25 degrees:

I use coarse fine and extra-fine DMT diamond stones, also with window cleaner:

This is how the bevel looks almost finished:

The veritas jig has a neat feature to add a bit of a micro bevel by just turning this knob:

After that I do a couple of passes on the back to remove the burr:

I made a quick stropping board with  piece of plywood and a piece of leather glued to it.  I rub chromium oxide on it and then give it a few passes to finish it off.

My favorite way to test and make sure it's as sharp as I need it is by cutting a piece of paper.  It should leave a super clean cut with very little effort:

You can also try and get some shavings off of a piece of hardwood end grain.  This method definitely makes the chisels as sharp as I need them for what I ask them to do.

Here's a great video from Paul Sellers on how he does it, most of my technique is inspired by him, except I am not good enough to do it completely free handed.

And here's another video from one of my favorite recently new youtube woodworking channels by Matthew Cremona.