When last we left our humble plane-to-be, it was in heaving anticipation of finally being bent into shape, finalizing the shape of the sidewalls and bridge assembly that is so critical to the design. This is, quite frankly, one of the most nerve-wracking parts of planemaking… the bend needs to be carried off with a high degree of precision in order to end up with a proper fit to the bridge, and a square, properly formed shell.
Getting Bent
Until recently, I did bending operations using a simple wooden or steel form and a vise, in the way Bill Carter demonstrates on his site ( if you’re not familiar with his work, you should take the time to GET familiar with it — he is as close to a ‘hero’ as I have). This works quite well, with a couple of limitations; first of all, you are basically limited in the length of the plane, which generally needs to be less than the capacity of the vise you’re using. My modern taiwanese vise has an opening capacity of just under 5″, and my old Columbian 504 opens to a bit over 6″ — neither is nearly enough for this plane. Also, when you get to stock over 1/8″ thick, the vise method becomes much more physically difficult, requiring a fairly sizable lever to get anywhere. The biggest problem with a plane the size of the Towell, though, is in tweaking to get the final degree of precision.
So earlier in the fall, I made a modest investment in a ‘compact bender’, which avoids some of those limitations. To be honest, I wouldn’t really recommend it to most people – it’s far from ‘necessary’ – but if you intend to do a lot of this sort of work, it’s worth the $80 or so I plopped down for it.
As a general ‘rule’, I find that it’s relatively straightforward to get within 1/16 of an inch of the desired symmetry. Unfortunately, however, 1/16″ is nowhere near close enough for proper fit – so I need to be able to correct the bend somewhat to get it ‘just so’. With smaller stock of 1/8″, this is fairly easy to do gently hammering in a vise as Carter shows at the link above. With a 3/16″ sidewall of tool steel, however… not so much. In order to tweak the bend in the location I needed to, a little creative fixturing was in order, as shown below:
It was very fortunate for me that I had come into the t-slotted table pictured here just prior to this point. It came attached to a number of other bits of metal, but for the purposes of this operation, the table and the clamping setup shown were all I needed. More on the ‘rest’ of the table a bit later…
If you look closely, though, you’ll see how this works, letting me very precisely adjust the bend at the lower part of the rear curve without risk of losing the straightness of the plane sides — in this case, pushing the ‘top’ side of the plane a smidgen further forward to bring it into exact symmetry with the other side. The Bessey clamp worked just fine, though it was probably operating at the limits of torque it’s capable of. At any rate, this got the plane body to just the shape I needed, ready for the bridge and front plate to be inserted, and the whole assembly peined. First, though, the bridge needs to be shaped and finished.
Shaping the Cupid’s Bow bridge.
Shaping the bridge for a wedged plane is one of my favorite tasks; in general, the ‘sculptural’ elements of the plane are the most fulfilling to me, and I look forward to them. Forming a Cupid’s bow is not difficult, but it helps significantly if you ‘slave’ its dimensions to fit the tools you have — specifically, I try to make sure the concave curvature matches one of my round files, preferably a size I have both roughing and finishing cuts of file in.
I’m not covering the procedure in detail, but the setup I use to make these should give anyone interested all the information they need to make a very solid attempt at one of these.
Notice the angle of the bridge in the vise, which means basically all file work is done with the file perfectly horizontal. Once I’ve roughed out the entire shape, I refine it with contoured sanding blocks (available from any number of sources).
I generally like to finish the cupid’s bow itself to a pretty high polish – leaving the rest of the bridge with a coarser finish of about 320 grit or so. I like the counterplay between the textures, and find it really draws the eye into the decorative feature.
A few minutes with abrasives on granite surface plate to finish the flat surfaces, and the bridge is done. I finish the underside as well – if for no other reason than to be SURE I have removed all the burrs from the underside of the bow, which can wreak havoc on the finish of the wedge otherwise… or so I’ve been told.
Assembly and peining:
In order to slip the bridge in place, I need to open the body slightly. I use the jaws on my machinist’s vise as a spreader to do this.
Then, using the vise to close the plane up, I can insert the front plate into its dovetailed ‘home’ and the sidewall assembly is ready to be peined together.
The first section I pein is the bridge tenons – this brings the back half of the plane into alignment, and closes up the sides tight to the bridge. You can see the ‘gap’ at the lower side of the bridge here; if I’ve tapered the mortises properly, the peining process will automatically close this up and leave me with a very tight fit.
Once the bridge is peined, I can turn my attention to the front plate. The front side of these dovetails is a bit of a pain to pein closed, as there is no way to ‘back up’ the hammer blows on an anvil. The best I’ve managed to come up with is to pein it with the sidewalls pinched in my bench vise, readjusting the plane every minute or so as it slides down the jaws a bit. This is the reason I spend so much time making sure this particular fit is extremely tight when cutting the front plate joints — if I have to close up even a small gap, it can take literally hours to get enough movement to do so. The goal is to have a joint that is tight enough already that I only need a few minutes to close up the small seams from the front:
Once the front of the plate is piened, it is extremely secure in its ‘seat’, and I can safely pein the sides of the dovetails without concern for pushing the plate outward.
At this point everything looks good, so I grind off the rest of the excess material. This is one of the nicer points in making a plane like this, giving me my first glimpse of the overall ‘form’ of the final plane.
So far, so good – next it’s time to start work on the sole.
Aldo says
Hi Raney,
Thank you for this wonderful blog. I have a couple of questions regarding attempting this mitre plane with brass sidewalls. What brass alloy would you recommend (i.e., a 200 series forming brass or something like a 464 navel brass)? Additionally, do you operate the compact bender differently when using brass?
Kindest regards
Aldo