Hollow grinding plow plane irons?

[Tim Best]

I recently picked up a good user grade Record 050 combination plane. While the plane body is good shape and complete, the straight plow cutters need some serious attention. All seem to have been freehand sharpened by previous users/owners. Most are skewed with a wide variety of bevel angles. This is particularly true of the smaller irons. I have recently begun hollow grinding chisels and plane irons and was wondering if plow plane cutters can be hollow ground and then honed on water stones. Would it better (less risky?) to regrind the bevels with sandpaper using an Eclipse style jig and then hone on the stones? My first thought was that plow plane irons would be very similar to chisels, but I thought I would appeal to the collective for thoughts/advice before I jump in.

The best I can tell the 050 is circa 1950s with the original tungsten steel cutters.

Thanks,

Tim

[lowell holmes]

There is a lot of metal in plow plane iron. If it were me, I would try it on one iron. If you do not like the results, you can take back to flat grind. I do think hollow grind is good on chisels, but I do not see the need to do it on a plow plane.

[Jim Koepke]

That is an interesting question Tim. All of my plow plane blades have a flat grind but that is because my powered sharpening system is a disk instead of a wheel.

A hollow grind on plane blades doesn't seem to be a problem for other bevel down plane users. A hollow grind does make it easier to free hand sharpen a blade.

jtk

[Derek Cohen]

All my plough plane blades are hollow ground at 35 degrees. These are free hand honed directly on the hollow grind.

Hollow grinding does not weaken the edge. I use an 8” CBN wheel.

Regards from Perth

Derek

[justin sherriff]

What I like to do to reset a edge is use a cheap eclipse gude but I use it on my belt sander. Then I put a small 2nd bevel on with my water stones. I do not have a grinder.
The wood does not care what is going on much past the edge. Flat grind 1 hollow 1, I bet you will not see any difrence.

[Jim Matthews]

Remember to relieve the sides so they are also sharp.

Plow blades cut three faces.

[Tim Best]

Lowell, Jim K., Derek, Justin, and Jim M.,

Thanks for the advice.

Derek: You mention hollow grinding to 35 degrees. Why do you go to 35? Just curious about your thought process regarding that angle.

Jim M.: I understand that plow blades cut on three sides. How do you normally relieve the sides?

Thanks again for the tips.

Tim

[Tom M King]

I like the Record multi-plane blades, and use them, as first choice, in my Stanley 55's. For the sides, I just hold the iron on edge, on the edges of the stones. I hone all small cutters with the stone sitting on edge, just because it seems like it would be unnecessarily small wear area on a stone face. Mine are flat ground, and honed, as are all my other types of irons. The shape of the bevel shouldn't matter.

[Jim Koepke]

How do you normally relieve the sides?

Hold the full blade on its edge an hone it by moving it back and forth lengthwise on your favorite sharpening medium. It doesn't have to be an edge fit for paring. It also should be free of nicks or rounded over areas.

The side bevels on plow plane blades and other combination plane blades can be honed to the point of cutting. This can be the cause of a rabbet/rebate plane 'walking' if the blade is too proud of the side.

One reason (main reason?) for a side bevel is for clearance (relief angle). A square side to the blade would cause the blade to chew up the sides of the cut or to jam. The side bevels alleviate this problem.

jtk

[Jim Koepke]

In an old thread > https://sawmillcreek.org/showthread.php?242156 < the 10th post has an image of one of my molding plane blades having the edge bevel being honed:

Edge Beveling.jpg

The side bevel doesn't need to be worked to as fine of grits as the cutting edge.

jtk

[steven c newman]

The ones I have with the Stanley 45....simple 30 degree bevel for the cutting edges....they do have a slight bevel on the sides. Without that side bevels....cutter WILL bind in the cut, just the same way as putting the sliding skate even with the outside edge of the cutter's front edge. Sliding skate needs to be like the main stock...even with the back of the cutter, so the outside corner has a bit of room to work in.

Later today, I need to plow a few 5/16" wide grooves, to house a plywood panel.....will post a few photos of mine after that.....including setting the plane up.....

[Tim Best]

Steven,

Thanks. Looking forward to the post.

[steven c newman]

Kind of hard to hold a cutter, and take a photo at the same time....plywood panel matched a #14 cutter..
Saw Til Project, 45 cutter #14.JPG
Then set up the stanley 45...
Saw Til Project, Stanley 45 set up.JPG
Cutter has a single flat bevel, at 30 degrees...corners of the iron go past the out side of the skates.
Saw Til Project, ready to plow.JPG
I get the fence close...then micro-adjust to locate where the groove will be..
Saw Til Project, groove done.JPG
Start at the far end, and work your way back....then a test fit..
SawTil Project, test fit.JPG
On to the next groove...

[Derek Cohen]

...

Derek: You mention hollow grinding to 35 degrees. Why do you go to 35? Just curious about your thought process regarding that angle.
.....Tim

Tim, 35 degrees is the widely recommended bevel angle. Stanley, Record, etc ... even Paul Sellers ... recommend 35 degrees for the extra edge retention. You could get away with 30 degrees.

One addition is a 10-15 degree back bevel for beading blades, when used in a combination plane in interlocked wood.

Regards from Perth

Derek

[James Pallas]

I flat grind on all small sizes, below 1/2” on chisels and irons. I try to keep them at 30 to 35 degrees. I will hollow grind the others and then hand sharpen. I don’t know if it makes much difference but on those small tools they are subject to a lot of pressure when put to work. A 35 degree hollow grind sounds reasonable to leave some back up for a narrow edge tool.