Saturday, July 12, 2014

A Miter Jack Of Excellence



Last month we received an email from a tool collector who sent us some pictures of a beautiful miter jack manufactured by the La Forge Royale company. The collector asked if we'd like to see the tool. We said, "absolutely". The gentleman replied, "I'm just up the street from you, I can come over at your convenience."

I wasn't sure if he was pulling our leg. Turns out he wasn't actually just up the street. It was more like just across the creek.

Earlier this week we got together to pore over this gem of a vise.

First off, a little history. La Forge Royale was under the direction of at least two men that we're aware of. A Mr. Lemainque, and later, Mr. Feron. It was the latter's catalog that the Midwest Tool Collector's Association reprinted in the 1980's, and from which we derive all of our images of this firm's wares.

This vise comes from the earlier period under Lemainque. The vise itself is stamped at least 5 times with A. DENIS, likely a previous owner of the vise.

I've used miter jacks for many years, and have built several versions to handle everything from full size case mouldings to diminutive parquetry for musical instruments. They are powerful fixtures that are more versatile than shooting boards (although more complex to construct.) They also require a more advanced technique to master. Get ham-handed with them and it isn't long before you've planed away all your accuracy. One big plus of the miter jack is that it places the workpiece in such a position that you can use a typical bench plane in a normal fashion, not on its side as in a shooting board. I prefer a low cutting angle, since most of the work is on end grain or some angled variant of such. I'm usually not a fan of bevel up planes, but for miter jacks I love them. They have a low center of gravity which feels grounded on the angled ramp of the jack. I usually use my Lie-Nielsen 164. You can also plane a miter from virtually any direction, which is especially helpful when planing moulded pieces to avoid blowing out the moulded elements. Tweaking the angle is also easily accomplished by subtly shifting the workpiece off-angle in the jaws. It doesn't have to sit dead flat on the ramps.

But enough about how miter jacks work. They work. If you don't have one, build one.


The first mystery we tried to unravel was the configuration of the clamping block, with its bold cyma reversa profile. With the jack in position for planing 45 deg. miters the inside of the block is parallel to the planing surface, and the bench it rests on.



With a holdfast position close to the front of the bench*, the jack can be held somewhat securely. However, I don't think this method would withstand the rotational forces encountered in use. 

*For illustration only. I don't have a hole in this bench close enough to the front, so the jack is positioned too far away from the front edge of the bench to be functional.



As I looked close at the sides of the block, I found some V-shaped notches in both sides. With the jack position for 45 degree planing, these notches matched up perfectly with the square dogs in my wagon vise.



The jack sits firmly on the bench held between dogs. A holdfast in the pocket would improve the stability even further.


While turning the vise around countless times I noticed the bottom of the mounting block was left with a toothed surface.


Underneath the fixed jaw I discovered a metallic hook and screw to engage the hook.


I pivoted the hook into position, then operated the vise.


A secondary, but much smaller jaw was now traveling along with the main jaw. What was this for? I didn't have a clue.


I looked closer at the screw itself. It's beech (as is the entire vise), precisely made, with a straight section to which is pinned a brass sleeve that engages a garter screwed to the moving jaw.



The end of the screw is made of steel, and I surmise that this bit of hardware also engages the pin through the brass sleeve. I couldn't investigate this further without doing harm to the vise.


The handle of the screw is fitted with a detachable lever, presumably to increase torque or speed when adjusting the vise. The lever would not engage the octagonal handle past this point. It may have been intended to slide off entirely. Note that this feature is not pictured in the catalog image.








I soon returned to the clamping block. The opposite side (above) has its face at 45 degrees to the opposing face, and parallel to the face of the opposing pocket. That places the pocket above at 45 degrees to the opposing pocket.



In other words, when the vise is placed along the front edge of the bench, the pocket is now parallel with the top of the bench, and the entire vise can now be held very securely to the bench (since the clamping block and body of the vise form a massive rabbet) with a single holdfast. The vise is now positioned for 90 degree (square) planing.

But it wasn't until I started operating the vise in this position that the smaller moving block started making sense.


As I opened the jaws, I had forgotten that I left the metal hook engaged. The small block moved with the larger and I immediately recognized its purpose.


I grabbed a bevel square to check.


The angle was 22.5 degrees. Beautiful.


Actually it was more like 23. And here's the eerie thing. The number "23" is written on the small block's ramp. Perhaps the maker or owner wrote that on there as a reminder of the actual degree of the ramp? But why not correct it?


One last detail I couldn't figure out. This little dowel sticking out the end of the fixed jaw. It's not pinning anything. The top half of the jaw is just finger jointed to the bottom half. No other joinery here.



So if this post hasn't motivated you to build one of these, what's your excuse? I'm going to build a reproduction at some point, even though I have perfectly serviceable jacks in the shop.

Special thanks to the owner, who is letting me examine the vise for a few more days. Without a doubt, a very sweet miter jack.



10 comments:

  1. You're going to laugh at this, but I think I know what the dowel/button is: It allows you to store the miter jack resting on that surface. Without the button, the lip of the jack would cause it to lean over slightly.

    I wonder if it was original to its manufacture?

    -jamie

    ReplyDelete
    Replies
    1. Actually, I thought the very same thing. It does protrude the right amount to allow that.

      Delete
  2. Any chance you might post some rough dimensions. OA length, width, thickness of stock for frame, Height, thickness of jaws and a photo of the underside of the moveable jaw. One shot appears to show a key in a rabbit but is there a simple cross member on the bottom of the moveable jaw that keeps it in place

    ReplyDelete
    Replies
    1. I plan to draw this in Sketchup in the near future.

      Delete
  3. I have an old miter jack I'd love to learn to use. There's very little info out there on it though. Could you do a blog on the proper technique? I'm afraid of dinging it up with a plane.

    ReplyDelete
  4. It seems the grain direction on the various parts was not chosen randomly. In particular for the two triangular parts assembled by finger joint. Could you give us more details, please.
    Sylvain

    ReplyDelete
    Replies
    1. The nut block orientation such that a piece 2-1/4" thick can be used. However, the actual jaws are much larger, and if solid wood were used the pieces would need to be over 5" thick. I don't think we can say why the original was built this way. The grain direction on the blocks is not consistent, there was no effort to make certain faces in the radial or tangential plane, even within each jaw.

      Delete
    2. Thank you for your answer.
      I could not check earlier.
      I was asking because the finger joint seems to be an important feature as it is shown in the old catalog.
      Sylvain

      Delete
  5. I think the grain is oriented as to have end-grain only showing in the blocks (maybe to make it a bit harder to plane away the accuracy, but of course, one is not supposed to plane into the jaws ;) )

    ReplyDelete