Wednesday 10 February 2016

About Donkeys And Horses

What's the difference between a sawhorse and a saw donkey?

Good question.

Whatever will be the answer they are great helper in the shop.





The Challenge


While gluing up the bench top for my new work bench I recognized that I will have a problem in the near future.
The new emerging bench top is too big to handle it on my actual bench. The new bench base isn't installed yet.
But I have to prepare the bench top surfaces.
So, what to do?
With all this in mind I read a post on Ralph's blog. He had the idea to build some saw donkeys how Richard Maguire calls them.

The Idea


Hm, the reading is interesting. Richard designed some sawhorses for the special purpose of bench building.
It is a simple but very sturdy design. I think they have some characteristics of a donkey.  A bit stubborn, a bit tenacious and somehow trusty. A donkey is stronger than a horse of the same size. Keep in mind, donkeys are herd animals. So build two.

And Ralph's report about building them encouraged me to think about those saw donkeys too.

I had a lot of off cuts from my bench top lumber. Just enough to build two of this model.
So I could kill two birds with one stone. Getting rid of the off cuts and having two helpers for further bench top preparation.

The construction is dead simple. Have a look at Richard's post about it for some details.

The Implementation


I've layout all of the joinery first. It is simple mortise and tenon joinery. The only challenge is that it will be through tenons. Keep in mind, this will be work shop devices and not fine furniture.
I took the opportunity to train the making of some big joinery. And once again I followed Richard's approach of using less and simple tools.

I started with the mortices in the top cross beam. Mine are 20 mm wide. about 70 mm long and about 50 mm deep.
I have sharpened a 20 mm chisel, grabbed my chisel hammer and started chopping.


Chopping mortices

Three passes from the underside and approx. three passes from the top and I was through. Truing up the inside walls a bit and I was done.
As I had to make the other mortices the next day and that was a Sunday, I had to switch the methods.
Instead of chopping I had drilled out most of the waste. The rest of the waste I've pared out.

Drilling out the bulk of the waste
 
In comparison both methods went well. Drilling out the waste is more or less noiseless and I chose this method in order to spare the nerves of my neighbors.

In direct comparison the mortise which was drilled and pared has got the crisper joint lines. I'm still struggling to achieve crisp joint lines with chopping.
So far, so good. In the next step I had to make the tenons.
I have sawed down the shoulder line first and then down the tenon cheeks. Although I wanted to train the splitting method a bit more it was impossible in this case due to the grain.
Nevertheless I have cleaned the cheeks only with a chisel. And that went pretty well.
I think it is the over all approach. You are building a workshop device. Nobody will care about how it will look. And you can concentrate on a specific task you would like to improve.
For me it is paring to the line.


The cheeks done I have inserted the tenon into the mortice and what can I say. It fits in the first try. I'm surprised about myself. The joint is really tight and will hold without any additional help like clamps or glue.


The first joint done

Nevertheless the joints have some minor issues. Even at the top. I've got some slight gaps. But nearly too thin to fix it somehow. 
And at the end - workshop devices! I don't sweat it.


The 1st saw donkey

The Additions


That's pretty much the construction. You just have keep one important thing in mind. Don't make the mistake to layout the tenons in the same direction. You have to change it.
Let's say you are looking at the face of your leg, then the lower tenon has got to be in the line of sight. But the upper tenon has to be crosswise.


Tenons in opposite directions

Richard's and Ralph's version are draw bored. I ever wanted to try this. As mentioned above. A workshop device is ideal for trying new things or techniques.
And even if I should have done it until yesterday, a small problem prevented me.
All fitting drill bits I have got are too short to drill through. And for the bits which are long enough I haven't got fitting dowel material.
That recognized I have postponed this step


One question Ralph brought up is, how to prevent the slippage of the parts that are rested on the cross beams.
Typically you will put some leather on the slippy surface to avoid that. I'm doing that in my shop too. But I'm not willing to pay much for some leather nor won't I spent much time to get some. So I'm using chamois leather. It's real leather (mostly sheep or goat). You can get it easily in every homework department of a supermarket. And it's cheap.
I made my strope out of it and it's working fine. If it will be worn-out I just glue a new piece on.


Chamois leather


I'm using spray adhesive to mount it. The nice thing about spray adhesive is that you can use it for permanent and reversible bond. There are different manufactures out there. Just have a look.


The Conclusion


These saw donkeys are a bit different from the more conventional, triangular design. But I like the idea pretty much. Mine are not as high as Richard has made them. So I still can use them for stock preparation. 
They will provide me an alternative, temporary working place if I need one.
And for me they are better to store and will use less space as the triangular design.


Their first job will be to hold the new bench top, so that I will be able to flatten and prepare it for the final assembly onto the bench base.


And if I finally don't know what to do with them, I can do some gymnastics on them.


Stay tuned!
Stefan

5 comments:

  1. Hallo Stefan,

    sehr schön geworden, aber rein optisch fehlt mir eine weiter Querverbindung zwischen den Beinen, gerade wenn Du darauf hobeln willst.

    Liebe Grüße
    Pedder

    ReplyDelete
    Replies
    1. Hallo Pedder,
      danke. Ja rein optisch fehlt(e) mir die auch. Zur Zeit bin ich ohne weitere Reste. Ich muss ja auch nur einmal darauf hobeln. Wenn ich merke, dass das nicht funktioniert, dann mache ich eine Querstrebe rein. Dann kann ich Überlattung noch ein bisschen üben :-)
      Viele Grüße
      Stefan

      Delete
  2. Hi guys,
    Pedder's proposal was to have a lower rail between the legs.
    I know that Ralph from the Accidental Woodworker Blog had this plans but he refrained.
    What do you think?

    Talk soon,
    Stefan

    ReplyDelete
  3. That would have been my first inclination too, but as Ralph mentioned, it would interfere with them nesting easily for storage. I look like it could use a lower rail for solidity, but if your mortise are tight should be OK??

    I guess the final answer lies after a few months of uses.
    Are they still tight?
    Do you have the room to store them not nesting ?

    The answers should reveals themselves with uses

    Cheers
    Bob

    ReplyDelete
    Replies
    1. Hi Bob,
      hmm. We will see. At the moment I only need them to complete the workbench top.
      As my room is limited, that was my second intention to build these.
      Currently they are making the impression to be pretty sturdy.
      I think too that the time will show how racking resistant they are.
      Cheers,
      Stefan

      Delete