Help identifying a dado plane

[Zach Dillinger]

All,

My father purchased a 3/4" dado plane for me a few months ago. The skewed iron is, as far as I can tell, original. The nicker iron is there, but with uneven and possible re-done nickers. I replaced the original main iron wedge (which was missing) with a nice piece of straight grained mahogany. The original front wedge looks like mahogany as well. It has a brass depth stop that retracts into the body. The plane is marked "A Smith Lowell" with some other letters underneath that I can't quite make out. It appears to be say "G P ???" It also has "3/4" stamped into the front. I haven't taken pictures of the plane yet, but I'm curious if anyone has any insights as to the age of the plane. I would like to use it but I don't want to if it is really old or valuable.

I will try to get some pics tonight. Anyone have any ideas?

Thanks!

Zach Dillinger
Charlotte, MI

[Wiley Horne]

Hello Zach,

From "American Wooden Planes", Emil & Martyl Pollak, 4th Ed.........The "A. Smith/Lowell" mark is found on planes of Alpheus Smith of Lowell, MA, who was a drygoods and hardware merchant from 1832-37.

Quite an old plane! Nevertheless, you should use it. The missing wedge takes away whatever collector value it might have. I really get a kick out of how well our ancestors could craft these planes. Pick em up 150-200 years later, and they work very well! Built to last.

Wiley

[Zach Dillinger]

Thank you so much for your help. I really appreciate it. I just need to sharpen up the iron and maybe redo the nickers. Any tips on how to do that?

[Wiley Horne]

Zach,

I've put a few of these old dado planes back in service. They're really fun, and the amazing thing is how well they work.

I have two questions of you, both regarding the current state of the blades. First thing you want to know is whether the main blade skew is right. Put the blade in the plane until you have a little blade showing below the sole. Sight down the sole and determine whether the blade is projecting evenly--will it take an even shaving? Can you adjust to where it will take an even shaving. What you do next depends on whether you need to grind a new skew on the blade, or whether it is about right as it stands.

Second thing is that you want the two cutters on the nicker to be at about the same depth, so they're cutting together. Question: Are the two nicker cutters at the same level? Or is one longer than the other?
What you do next depends on the answer to this.

Wiley

[Zach Dillinger]

Wiley,

I can adjust the skew iron so that it will take an even shaving, but the shavings clog in the mouth even when the iron is set for a fine cut. The nickers are uneven (one may have broken off at some point). Can these be filed, like sharpening a saw?

Thanks,

Zach

[Wiley Horne]

Zach,

On the main blade, sounds like the next thing to do is just get it critically sharp. Bevel angle of 25-30 degrees will leave plenty of clearance--exact angle is not important, clearance is.

On the clogging issue....First, find out why the clog is occurring. There should be plenty of gap ahead of the blade back, when the blade is in cutting position. There's a good 1/32" of gap (at the narrowest point just ahead of the cutting edge) on a couple dados I just checked. You mentioned you replaced the wedge. Check the lower terminus of the wedge and how it is detailed: On the examples I checked, the wedge terminates at the bottom of the 'escapement chamber' (made up term), and does not extend down into the channel in the 'skate section' (another made up term). Secondly, the wedge terminates in a thin and smooth edge, so that the shaving will easily ride up over it, and not have a tendency to hang and create a pile-up. The minute the first shaving hangs is where the trouble starts. Also, is the escapement well-opened on both sides to allow chips to escape? If not, take care to put a lateral taper on the bottom of the wedge to direct chips toward the more open side. I'm saying all this without looking at your plane--it's a common sense thing and will become clear to you when you analyze where the shavings are piling up, and why.

On regrinding the nicker.....I have never had to do this before, so maybe others will chime in--they should anyway! But here's how I would go about it. First I would verify the width of the nicker to be 3/4", so you won't be doing a bunch of work for nothing. OK, now that test is passed. You say one nicker is longer than the other. I'm not looking at a picture of this nicker, but my thought is to grind the long nicker off blunt, back to the same level as the short nicker. In other words, all the metal below the short nicker should be wasted. Just walk over to a grinder, and grind the long nicker back, until the long nicker is blunted back to the level of the short one. Don't fool around trying to sharpen it back with a stone and maintain its shape--just waste the extra metal off.

At this point, you're starting over with whatever you have left. If you have a Dremel (I don't), that could be very helpful right here; otherwise, start filing. You want to put two fairly thin nickers on each side. Length of the 'horns' are not critical--you might figure on about 3/16" to 1/4". You want the nickers to terminate in more or less a semicircular shape so they'll cut coming and going. And you want them sharp. And you want the bevel on the INSIDE (that's important), and the outside of the nicker pretty much flush with the plane body. Just keep in mind that the nickers are leading the blade, and you want a good match between them, so that the nickers are defining a channel the width of the blade. Nickers need to have enough spread so that the blade is not ragging the sidewalls of the channel.

Final thought....If you think you need to do some surgery on the main blade (like to adjust its width for example), come back and let's talk first. Real easy to ruin the plane messing with the blade width and geometry.

Hope others will join in. If this talk is not clear, I'll try to post a drawing later to show the nicker geometry, and the wedge termination.

Wiley