OK – now the plane shell is starting to move along. It’s time to prep the sole assembly and cut the tongue and groove for the mouth. This part of the plane construction is only applicable for bevel-up planes, and doesn’t generally apply for bevel-down planes — which are the vast majority of infill planes.
For a bevel-up plane, however, we’re looking for an extremely fine, tight mouth – and the only reasonable way to do this with ‘conventional’ tools is by splitting the sole in two, then rejoining it once the ramps have been fit. The first step, then, is to split the sole in two right where the mouth would be, and shape the ramp and rear of the mouth.
Filing the Ramp
There is really no secret to filing this ramp other than to be very very patient and painstaking. Once it’s close to the final level, draw-filing gives very clear indication of where the high spots in the ramp are, and where it is out of flat. This process is not nearly as difficult as it might appear at first glance, but it definitely requires patience… this ramp is the most critical single point of support for the blade in the final plane, and should to approached accordingly. Did I mention patience?
I’m using a 22.5-degree bedding angle, with a sole thickness that is 5/16″ (.3125″) thick. Some quick trigonometry calculation give me the following:
TAN(22.5) = .3125 / x [where 'x' is the run of the ramp]
x =.3125″ / TAN(22.5)
x = .754″
so I mark out the rear of the ramp at 3/4″ from the mouth. In order to make it simpler to cut and file at the angle I need, I position the sole piece laterally in my vise at exactly 22.5-degrees — this way if I saw perfectly horizontally, I know I’m hitting the proper ramp angle. This makes it simpler to hacksaw the series of comb-cuts to remove the bulk of the material for the ramp.
Here are some closeups of the cuts from front to back – ideally they should get as close to the ‘lines’ as possible, but they mustn’t go over or I’ll be left with a nasty mark in my bed. And nobody likes that.
At this point, I would now whack out the ‘tines’ and then file to the final ramp surface as precisely as possible. I wanted to show the method here for the benefit of anyone who wants to try this for themselves — but as I am a weak man who is currently suffering a nasty bout of tendonitis, this is where the siren-song of the new mill became too much to resist. I milled out the bulk of the waste (though the surface still needed some final filing to get it just-so)
The final results are hopefully the same, whether using a mill or a pillar file – a nice, clean, and very flat bed. Here’s what I have after some very careful finish filing:
Tongue and Groove
Next, I open the groove for the tongue and groove joint that will register the two halves of the sole together. First I mark out the groove – roughly 1/3 the thickness of the sole, and about 3/16″ deep. I put the sole piece back in my vise, this time perfectly vertical, and with the depth of the groove right at the top of the jaws to give me a guide to saw to:
Then carefully, I saw for the front side of the groove:
Once I’ve gotten to depth, I flip the piece in the vise and saw for the other side, taking my final cuts across both sides of the groove. Then I refine both sides with files.
Here’s the final groove:
Now it’s on to the front half of the sole. The front piece is filed similarly, but I use a 45-degree angle for the throat piece. Additionally, I leave 1/4″ of extra material for the tongues that will register the front and back portions of the sole together. I’m cautious to do a lot of test-fitting to ensure the joint fits properly, and that there is as little ‘step’ in the sole from front to back as possible – I’ll have to lap out whatever differential there is at the end.
ere’s both halves of the sole, ready for dovetailing:
Dovetailing the sole
Finally it’s time to cut the dovetails to join the sidewalls to the sole. In the interest of brevity, I’m not going to detail all the cutting and filing operations here – it’s been well-covered in earlier entries. One important item to keep in mind, though, is that when joined together, it’s important that the dovetail joints force the tongue-and-groove joint closed, rather than open – so when marking out, I want to ensure the joint is very tight. I put the sole assembly in a parallel clamp to force it tight, and carefully mark out all the dovetails directly from the sidewalls:
From here, it’s back to – you guessed it: more hacksawing, and much more filing. Finally, though, after a lot of filing, checking fit, filing some more, and checking fit again…
I get to another milestone… the sole and sidewalls are now fitted, and all of the metal joinery for the plane is now complete.
The mouth is consistent across the plane, and just a sliver of light – this is good, as it means I’ll be able to lap it open to the size I want once the plane is finished.
Now it’s time for a break – I’ll put the front and rear profiles on the sole next, and then (at last) I get a chance to actually work with some wood. Definitely starting to look more and more plane-like now.