Beginner - making accurate 90 degree cuts by hand

[downlode]

Hi, I'm making a housing for an electronic musical instrument - basically a box, sloping down from back to front, with a metal faceplate on top instead of a lid. I'm using black walnut. I want to use what I think are called box joints or finger joints to join the four side pieces. I've marked up my pieces, and I did the same on some scraps and tried cutting joints as a test. Now I'm doing this by hand with a basic dovetail saw, as I don't have a table saw, and I don't see how to make sure that I'm cutting straight, and perpendicular to the top edge.

In my test, I tried clamping two pieces together, offsetting them by the width of the saw blade, and cutting into the waste sections, so doing both pieces at the same time. The cuts were often not straight enough.

Two problems:

1. Marking up. The vertical edge of my piece of wood is cut by hand, so it won't always be exactly square to the bottom horizontal edge. So if I use a 90 degree square from the vertical edge to mark up the horizontal join cuts, they won't always be exactly parallel with bottom edge.
2. It's difficult to cut in a straight line!

Any tips? Should I be using a saw guide of some kind? I have a feeling I will get better results just cutting one piece of wood at a time, instead of trying the two clamped together trick.

[Upscale]

A saw guide would make it quite a bit easier. Here's a few workable but cheaper ones. The price goes up from there.

?c=1&p=51155&cat=1,42884?c=1&p=51869&cat=1,42884

[Maxwell Lol]

You have two choices - by machine or by hand.

The cheapest "machine" jig for making box joints I know is a router and a set of templates. It's about $25 by Woodhaven:

also need a router bit and guide bushings.

If you do it by hand, then you will need to practice. You need to learn how to draw a thin line, and saw so you just follow that line exactly.

Also make sure all ends are square and parallel.

[lmlitwin]

Polish the saw blade to a shiny (mirror) finish. Mark a line square across the edge and along the face as deep as the box joint goes. When cutting follow either line but make sure that the reflected image on the saw blade is dead straight. The cut will be 90 in both directions. A trick taught me by an old framing carpenter more than 35 years ago. It works.

[beatbox]

I have a handheld router, but I thought I would need to invest in a router table to do this. I'll look into the options.

Squaring off is pretty difficult when you're using a handsaw. I think this was one of the main problems with my test run.

[beatbox]

Nice tip, thanks.

[dadiOH]

That's what saw guides are for. Not to mention low angle block planes.

You might want to give up on the box joint idea until you are able to get an end that is square in all directions. First things first IOW...

[Michael Faurot]

You might want to look into the Veritas Right-Angle Saw Guide[1]. I have one of these and the Veritas Dovetail Saw as well. Like you, I'm not very good at cutting straight with a hand saw, so this little tool works very well for me. I've also got the 1:8 dovetail guide[2] as well.

That's how I've done box joints, cut by hand. I do mine in a similar fashion to the way I do dovetails. I'll start by cutting all the pins/fingers on say the front and back sides of the box. Now that I've got the front and back sides cut, I'll use those to lay out my lines on the left and right sides of the box.

When you're marking things, it also helps to have some type of numbering/label system so that you can keep track of the front side of a piece, its orientation and which is the left and which is the right side. If you don't all ready have a system worked out, here's what I do:

For the front piece I number the left side 14 and the right side 12. The first digit 1 represents the first piece. The second digit represents which piece it connects to.

The right side gets labeled 21 on its left side and 23 on its right side.

The back side gets labeled 32 on its left side and 34 on its right side.

The left sides labeled 43 on its left side and 41 on its right side.

Thus you would use the pins/fingers of 12 to mark out the 21 side and the pins/fingers of 14 to mark out the 41 side. Then the pins/fingers of 32 are used to lay out 23. Then 34 is used to lay out 43.

For the orientation part, I just draw an arrow on the piece to represent which direction is "up". The sides that have marking on them are the outside of the box. I mark the outside because it will be easier to scrap/sand those markings off later after they've been glued up.

When you're doing your mark ups. It also helps to put an 'X' or other mark in the waste section. I forgot to do that on a couple of pieces, got distracted and wound up cutting into the wrong areas and ruining one of my box sides.

[1]:

[Dave Gordon]

Cutting both pieces together will be, ah, interesting, as the cut needs to be on one side of the line for one piece and the other side of the line for the other piece. Best to mark them out together, but cut them separately. If you make a balls, its then only one piece messed up, not both.

[Lew Hodgett]

basically

Take a look at Fred Bingham's book, Practical Yacht Joinery.

Has sketches showing how it's done.

Lew

[SonomaProducts.com]

[beatbox]

Thanks all, useful ideas in there...

[Father Haskell]

Heavy saw set if it wanders. Asymmetrical set if it always pulls to the same side.

What brand saw? How thick is the lumber you're cutting?

Stand back and shift left and right until the two lines on the adjoining surfaces look like a single line. Put the saw on the line and cut, eyeballing the saw and the line(s) together.

[Patriarch]

beatbox wrote in news:1187356905.250738.95140@

22g2000hsm.googlegroups.com:

A decent router table can be made, for at least many uses, from a piece of good, flat plywood. Drill a hole large enough for the bit, and screw the router to the ply, with the bit extended through. Set it on sawhorses, a Workmate, or screw it to a workbench...

Lots of the kitchen cabinet folks use such tables in the field all the time. Upside: cheap, portable, quick to make. Downside: chip collection.

A fence can be as simple as a straight piece of stock clamped where it needs to be.

I've done this with a Porter Cable 69x series router, and it works well.

Patriarch

[Maxwell Lol]

The way this box jig works, you need some spaced blocks, and clamp and route both ends at the same time. There is a offset you need for one of the boards, to make sure the joint lines up.

I think I used a backing board out of pieces of plywood, some spacer blocks, and four clamps.

I seem to recall that when I bought this, there was a complete set including router bit, guide bushing, etc. for something like $50.

But I don't see this option any more om the web page. The picture shows the setup

it's a thumbnail. :-(

Perhaps you can call them for more info.

But I think this is one of the cheapest machined box jig you can get. (You CAN make your own.....)

[Oughtsix]

For a nice straight edge on a hand cut board cut the board by hand about 1/8" long. Use a framing square to clamp a straight edge perpendicular to the long edge of the lumber. Use your router with a straight bit to trim the cut edge to a perfectly straight end.

For box joints get an adjustable dovetail jig.

[Lowell Holmes]

Or take a couple of classes and learn to cut them square by hand. Three days at Homestead Heritage or a similar school will leave you with the knowledge and skill to do it.

'm sure Woodcraft will have weekend classes.

If you take this approach, you will save a lot of money on tools.

[Michael Faurot]

If you're going to "hand cut" boards with a hand saw, then you may as well clean up the edge with hand tools as well. In which case the way to do that is with a shooting board and plane.

[Michael Faurot]

About a year ago I took the one day course Woodworking With Hand Tools at Homestead Heritage. That's a really fantastic course, and if someone is truly interested in learning to do things with hand tools, you just can't beat this course for the amount you'll learn for the price[2] at $100. While this course doesn't specifically teach someone how to make box joints, it does teach one how to do dovetails. I've adapted what I learned in making hand cut dovetails to doing hand cut box joints.

Not necessarily. :) I think my collection of *quality* hand tools has doubled since I took the Woodworking With Hand Tools course. I believe this is what many refer to as "the slippery slope".

At some point I would like to take the whole Foundation Course as well as a number of the other courses they offer. For anyone that's living in or near to Waco, TX--you owe it to yourself to check this place out.

[1]:

[Lowell Holmes]

snip

Now that is the slippery slope. I've taken both of their rocking chair classes and I'm going to the Windsor chair class in October.