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In:In the Shop, Vintage Tool Talk

Comments Off on Restoring a Miller’s Patent Plow Plane

A little while back I acquired a Miller’s Patent plow plane, near as I can tell, it’s a model No. 43 Type 5.  It came with 3 cutters and was in good shape overall, but I felt like it could use a little attention before I put it to work. Here’s a quick summary for those who may be looking to restore a similar tool.

The tool as I received it

As shown, the tool is in decent shape, but the body is grimy, the handle is dirty, and the brass components are dull and worn.

One more picture of the tool before I began cleaning it up.

Before the restoration can begin, one of the most useful things to do is disassemble the entire tool.  This reveals several details that may have otherwise gone unnoticed: a cracked part, a missing screw, a mechanism that’s corroded and no longer functioning properly, etc.  If you do nothing else with a new-to-you vintage tool, take it apart, verify everything is there and working properly, and put it back together.

A plow plane in pieces.

One area to pay special attention to with a plow plane is the chip deflector.  This part not only provides the downward clamping pressure on the cutter to hold it in place, but also sends the shaving being cut out of the tool and away from the user.  If the face of the deflector is dented, rough, or has any kind of tacky residue on it, the shavings may not flow out as they should and could get jammed up in the tool which can be annoying.  I used a smooth, half-round file to remove some of the dents and burrs, then smoothed the face with fine sandpaper.

Before…

…After (apologies on the out-of-focus photo)

Next, I had to address the depth stop.  This was pretty badly worn.  There are two critical surfaces: the face that touches the body and the bottom face that ultimately touches the work when the final depth has been reached.  These two surfaces need to be flat and perpendicular to one another.  As you can see in the pictures, they were not.  I lapped them on with sandpaper on a granite surface plate, checking for flatness and perpendicularity as I went.

This face gets clamped against the body. It should be flat, but clearly has a deep hollow in the middle.

The bottom surface also needed to be re-flattened. Additionally, I eased the edges when I was done to ensure no sharp corners would scratch up my work when the depth stop makes contact.

After addressing the few functional issues above, I took all the small brass and steel bits and threw them in my tumbler for a few hours to clean them up.  This gave everything a nice, uniform finish and removed any remaining grime from the parts.  Steel parts were oiled to prevent rust.

I didn’t do much with the body, just a quick cleaning and scrubbing to brighten it up.  This, along with a bath in Evaporust went a long way to making it look new(ish) again.  Finally, I lightly sanded the handle and hit it with some Watco Danish Oil to freshen it up.

The result of my modest efforts were well worth it. I debated re-painting the body since most of the original japanning had worn off, but decided to leave it alone.

…and a shot of the other side.

Detailed shot of some of the brass bits. Nice.

With the tool brought back to glory, I sharpened up the cutters and took it for a spin.  The results are excellent.  These tools can take very aggressive shavings compared to most because the grooves are typically narrow (1/4″ – 1/2″ wide).  A narrow shaving means low material removal and low push-force, so the cut can be a lot deeper to compensate.  These are also not cutting a show-surface, so some tear-out on the inside of the groove isn’t a concern.  This style plow doesn’t even have a depth adjustment for the cutter. Why not?  Because it doesn’t matter and it’s not critical.  Just sight the distance the cutter is projecting by eye and lock it down.  If you really set it too heavy or too light, one quick re-adjustment is usually all it will take to dial it in.  The point being, it’s a PLOW plane, plow through the work with the heaviest shaving possible.  If you do, a typical groove can be completed in under a minute, maybe 2-3 if it’s a longer board and/or harder material requiring a lighter shaving.

Testing the plow for a 1/4″ groove.

And the results.

Overall, this was a pretty minimal restoration, more of a basic tune-up and cleaning, but it pays dividends in the long run.  Next up, a few posts on making a work bench for my kids.  Cheers.

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