Full Chisel Blog

October 9, 2008

Squaring up

Filed under: Proper Tools,Techniques,Uncategorized — Stephen Shepherd @ 6:46 am

While moving and setting up my new shop, still in progress, I needed to use my large wooden square with a mahogany leg and maple tongue.  I grabbed another of my squares a smaller one of the same composition and checked the larger square.  One of them was out of square.

So I got another square and checked those, soon all my squares were out on the bench and the task began.  I found a straight piece of wood and scored a mark with the square against the straight wood, reversed the leg and checked the reading.  As you know this is the standard way to check a square.  I also got out a ruler and my slate board and did some calculations (thanks Pythagoras) to double check.

I determined that it was the large square that was out of square, but the others needed a bit of attention as well.  These squares are all about 10 years old and have seen plenty of use,  I don’t use the large square that much so I hadn’t noticed it was out of square.  The others had just adjusted with time and needed some attention at the corners where the wood had adjusted, so the wood was at slightly different levels.

The first thing I did was take a card scraper and gently go over all surfaces to remove any surface accumulations.  I used alcohol to wipe off pencil marks. 

Squares, etc.

(Left to right; Ebony and Holly, Rosewood and Brass, Teak and Beech, Mahogany and Maple, Teak and Beech and the two on the right are Mahogany and Maple.  The triangles are maple, the finished one has beech edges).

I also had a triangle made of mahogany with beech edges that needed to be squared and the miters trued.  The other two raw mahogany triangles had never been trued up, but had adjusted for a number of years, so it was time to bring them into good order.

The inside end of the tongue of the large square needed to be trimmed more than with just a card scraper.  I use the scraper to adjust the proud end grain on the squares, but the large square needed more work, it was out over 1/16″.  The corner joint was tight so the adjustment had to be made in the tongue.  I used a shooting board to hold the square while I planed off the necessary wood.  I also had to address the error on the outside which was not quite as bad as the inside, this I am not sure I understand why?  It required planing the leg, end-grain at the joint to true up the square.  This I did on the shooting board.  I relieved the edges with a slight chamfer to prevent the end grain from snapping off, as they were unsupported by any kind of back up, like the stop on the shooting board.

Square and tools

I then noticed that my shooting board was perfectly square on the ends, so I could use that to do preliminary testing, it was handy to have a ready reference to square.  I also used the protractor (which I made) to check angles as well as the miter gauge (which I first had to test for accuracy) to correct the triangles.  I also used the small miter shooting board for the small triangle.

I even check the ends of the tongues and legs to insure they are square as well.  I sometimes use the ends to transfer square marks, so I make sure all of the ends are square.  I also make sure all surfaces are square with one another.  This is more important when making squares, but it is a good idea to check older wooden squares as they can change shapes.

The mahogany/beech edged triangle proved to be a challenge.  I had to get the hypotenuse straight before getting the miters right then to the square corner.  The two ‘new’ triangle/squares were also not right, so following the same procedure, getting the long one straight first, then the miters then the square.

Not only do the squares need to be square, the tongues and legs need to be parallel and square in section, the parts need to be straight as well.  As the pieces were being brought up to square I check them with a straight edge.  I first had to determine the edge of the straight edge was straight, as I make my own straight edges (and rulers). 

I make most of my layout tools, so they need to be accurate, especially when using them to make other tools.  The first thing is a straight edge and the easiest way to get a straight edge is with a string line held taught, it is straight every time.  From there with a little mathematics or by just practical methods, a 90 degree line can be established, from that the miter angles determined.

I like the thicker legs on squares as this allows them to be set on end on a board with the tongue determining vertical.  The larger squares are thick enough, but when i make any new ones I will make them with fat legs.  I now use multiple mortise and tenons to secure the tongue to the leg and it is glued with hide glue.  The joints are tight enough that there isn’t any play, if however the joint is a bit sloppy yet held tight with hide glue, it is possible to warm the joint up to 145 degrees (F) then the square can be adjusted.

I will still periodically test each square to determine it is still ‘in square’.  I also use a pencil for layout or an awl, but I never use a sharp knife or sharp striking knife when using wooden squares.  I don’t think I need to explain why.

Stephen

 

5 Comments »

  1. Stephen,

    Fascinating post. I have been wanting a large square since my carpenter’s square seems to have disappeared some time ago.

    I may just try my hand at making one.

    The hide glue joint makes perfect sense.

    BTW, I have been using hide glue on some things lately, and I am really enjoying it. Also I have been using garlic which seems to work well although I haven’t stress tested it.

    With my naturally warm shop, I get open times of 40 days and 40 nights. I am still looking for a better way to heat the glue though. I have been doing it on our gas stove, but I have to watch it closely and keep tracking back and forth to the kitchen.

    Luke

    Comment by Luke Townsley — October 9, 2008 @ 9:57 am

  2. Luke,

    Also metal squares can go out of square, but are fairly easy to square up, but they are heavy and will dent fine furniture, so I don’t use one.

    Wooden squares are fun to make and even more fun to use doing actual woodwork.

    You might want to try an alcohol torch (lamp) to keep your glue hot, being as you don’t have to heat it up that much. A thermos full of boiling water can also be used to refresh the cooling water in the water jacket. I will sometimes sit my glue pot in a pile of sawdust and bank it around the sides to insulate the pot. I have also heated up a large flat piece of iron on the wood stove and then put the iron nearby and place the pot on the iron to keep it hot.

    Stephen

    Comment by Stephen Shepherd — October 9, 2008 @ 1:12 pm

  3. Thanks for the suggestion. I have been thinking about it today, and have been experimenting with a vegetable oil lamp. I think it will give me plenty of heat. I got it burning well with a homemade copy-paper salted wick.

    I still have to figure out how to hold a glue pot above the flame and put it in something to hold the heat in. I have an idea, I just have to put it together somehow.

    It won’t be thermostatically controlled, but I think it can work well enough. Also, it will be portable with no cords to trip over. I am not overly concerned about fire since our house is made out of cement with a tile floor. Also, the oil seems a lot safer and cheaper to me than alcohol.

    Comment by Luke Townsley — October 9, 2008 @ 7:27 pm

  4. Luke,

    You might try a large metal can like a coffee can and cut an opening in the bottom of the can to receive the glue pot, then cut an opening on the top to access the heat source. With the can inverted it will hold your glue pot at a good height, depending on the can.

    The reason I suggested alcohol is that it is soot-less. The vegetable lamp should work fine. A suggestion for a wick is natural cloth, cotton or linen soaked in borax (and water) and allowed to dry. This makes the wick fireproof, so it won’t burn, the oil will instead.

    Stephen

    Comment by Stephen Shepherd — October 10, 2008 @ 8:44 am

  5. Hi Stephen & Luke,

    I posted a photo of my glue-pot at

    http://www.flickr.com/photos/23218266@N06/2930452074/

    Strictly non-period, but it’s simple and it does work.

    I have seen some pretty high-level violinmakers being rather cavalier about their hide glue. One fellow would put the hide glue in a baby-food jar, then that in a teapot with about a half-inch of water. Bring it to a boil, stir up the glue, and apply. When he needed it again, he’d just put the teapot back on the heat. He would determine the ‘goodness’ of the glue by watching it run off a brush dipped into the glue.

    In violinmaking or repair, you don’t need huge quantities of glue at any one time. Given that, I imagine the old makers didn’t keep the glue pot constantly heated.

    Ken

    Comment by Ken Pollard — October 10, 2008 @ 5:12 pm

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