block plane mod

[bridger berdel]

I have a block plane I am considering hacking at a bit. its no big deal as planes go, a no name, no depth adjuster, no lateral adjuster, blade rests on a couple of raised bosses in the casting kind of block plane. it has the big wheel under the cap for tension, and both the wheel and the cap are cast iron, and the body casting while crudely finished is sound.

my thought is to set it up in the mill and drop the bed angle down as low as I can. so what I'm wondering is how low can I go. as it sits the mouth is gaping, but between dropping the bedding angle, going bevel down and perhaps going to a thicker blade the mouth should close right up. what I need is a blade that can perform with an extremely low angle of attack and the associated grind.

any thoughts?

[David Weaver]

I don't think it'll get you where you want to go. A block plane should support the iron as far out to the end as possible, and when you lower the bed, the proper way to do the job (in terms of bedding) would be to mill it down and mill the bed near the mouth so that the iron is supported on it as much as possible.

You can try just supporting the angle so the iron projects further, but I don't think you'll get far. If anything, you may want to leave the bed as is and dovetail in a brass filler or something for the mouth. I don't know what your milling options are, but with soft brass, that's probably something you could do by hand if you widened the mouth to start with so that the brass piece was fairly large (instead of just a very thin strip).

I think the plane isn't going to reward your efforts either way, though.

[Derek Cohen]

Hi Bridger

I'm assuming that this is a BU plane.

You need about 7 degrees clearance, so do not go lower than that.

Then, because this is a BU plane and it takes its cutting angle from the bed plus bevel angles, try honing the bevel at 20 degrees. Now you have a block plane with a 27 degree cutting angle. Use it only on soft wood end grain. See how it goes compared with a typical LA block plane with a 12 degree bed and a 25 degree blade.

Regards from Perth

Derek

[george wilson]

Don't forget,you will be increasing the distance between the cap and the iron. You might have to do something to make the wheel under the cap still reach the blade.

[Jeff Heath]

Some tools, unfortunately, were made to be paper weights. Sounds like you have one of those. You don't have much to lose by trying it, other than your time and an endmill. A 20° bevel on the iron isn't going to perform very well in most woods. If you are working in white pine, redwood, or cedar, then you might have a chance. Without the ability to tighten up the mouth, you're going to be dealing with a lot of tearout.

You're probably better off spending the time fettling a decent older Stanley block plane......but that doesn't answer your question.

Good luck.

[bridger berdel]

I probably have 10 or 15 block planes, of which there are 4 or 5 at any one time in grab and go rotation. I even have a nice low angle one, which comes out for end grain work, or sometimes as a pocket plane as it's small. I'd like a wider, lower one, just because, and this one is the best candidate out of my junkyard. while simple in features it is solid and thick. the cap is held down by a threaded screw down through a slot in the blade into the body casting, so lowering that will be a matter of shortening the screw. I'll get a picture of it up today. bevel up would definitely make fettling easier and shorten the blade overhang. lowering the bed may close the mouth enough- I'll check that out. either way I'll need steel that can perform at the edge of too thin.

[bridger berdel]

pics:

http://31.media.tumblr.com/ac8aea8a0...m32o1_1280.jpg

http://24.media.tumblr.com/b35305cbc...m32o1_1280.jpg

http://25.media.tumblr.com/331f22ab4...m32o1_1280.jpg

http://31.media.tumblr.com/e9ac38b1b...m32o1_1280.jpg

http://24.media.tumblr.com/9f1d2a19c...m32o1_1280.jpg

http://31.media.tumblr.com/1827c2100...m32o1_1280.jpg


so. the wheel is pressed steel, not cast. they say the memory is the second thing to go....

the underside of the head of the screw that the cap engages is beveled, to mate with the countersunk divot in the cap. i think that that setup could handle a few degrees of shift, but the cap would now be pulling that screw slightly off- line. might make keeping a setting a pain.

most of my block planes bed in right about at 20 degrees. my lowest right now is at about 13 degrees.

this one is at 18 degrees at the moment. the mouth is at about 3/32, with another 3/32 of overhang. if i flip the blade it crashes the mouth. the sole could use a little flattening, but not too much. the current blade in it is obviously from a different plane. there is a decent amount of metal at the mouth to support the blade where it exits the body of the plane. the hole for the cap retaining screw is plenty deep and well threaded to the bottom- i can lose a bit off of the top without worrying about it, and there will be plenty of metal left at the bottom after flattening the sole. I suppose it's possible that I have a rare early block plane with vast collector value, but I doubt it. I have very little to lose. the plane was free, and otherwise will be sitting in a junk drawer. I do have some doubts as to how well a block plane will work at say 10 degrees with no positive blade retention other than a screw cap. will it take more tension on that cap screw to keep the blade at setting than the screw can take? only one way to find out, I guess.

[David Weaver]

I'm lost a little bit - isn't part of the process here intended to reduce the size of the mouth?

[bridger berdel]

I'm lost a little bit - isn't part of the process here intended to reduce the size of the mouth?

yes. the other part is to push the envelope a bit on low angle block planing.

lowering the bed angle will close the mouth some. going bevel down will do a lot more. a thicker blade will do even more.

I may find that lowering the bed angle to about 7 - 10 degrees will be enough, in which case I'm done.

[James Taglienti]

Im afraid that if you lower the angle that much the bed will turn into a thin feather of iron that will likely tear. Also if the cutter is ground at any reasonable bevel angle, and used bevel down, the heel of the bevel will hit the work, not the edge. To get the edge to contact the work, the bevel angle on your cutter will have to be so acute it wont hold up.

Sometimes i think of adding a little bed (maybe to a total of 30*) to a standard angle block plane and converting it to bevel down. This would give you a very low cutting angle and an edge that would hold up better.

[bridger berdel]

Im afraid that if you lower the angle that much the bed will turn into a thin feather of iron that will likely tear. Also if the cutter is ground at any reasonable bevel angle, and used bevel down, the heel of the bevel will hit the work, not the edge. To get the edge to contact the work, the bevel angle on your cutter will have to be so acute it wont hold up.

Sometimes i think of adding a little bed (maybe to a total of 30*) to a standard angle block plane and converting it to bevel down. This would give you a very low cutting angle and an edge that would hold up better.

bedding at 7 to 10 would definitely have to be bevel up.

any input about what steels will perform best at more acute angles?

[James Taglienti]

I think the best manufactured cutters for acute bevels are the PMV11 from lee valley. My experience is limited to just a few varieties but i have planed edges of birch plywood with a pmv11 cutter at about 22* with no chipping.

[Matthew N. Masail]

you can also make a 30degree bevel down infill plane using the casting.... you can use a wedge or screw cap to secure the blade. put a PMV-11 blade in with a 25 degree bevel on it. it could end up being something to be proud of.

[george wilson]

Be careful how low you try making the blade angle. I,being an extremist at the time,made a miter plane whose angle was so low,it would NOT CUT!!. There are limits.

[Derek Cohen]

As George notes, there is a limit to how low you can go with BD. As I mentioned earlier, there needs to be about 7 degrees clearance. Assuming a bevel angle of 25 degrees, you could build a plane with a 38 degree bed. That would essentially give you the same cutting angle as a low angle BU block plane. If you go below 7 degrees, the plane is in danger of not cutting.

Here is such a block plane (in front - one I built about 6 months ago). Very sweet user ...



So you see, if you want the lowest cutting angle, you need to use a BU configuration, as discussed early on.

Regards from Perth

Derek