Which Pitch?

[Berlin]

Hello all,

Just a quick question for the brains trust:

I am planning to make a dovetail plane with the blade from a spare rabbet plane and was wondering if there is an optimal bed angle for end grain work (bevel down)?

This will be my first plane so if any of you have encountered any other pitfalls in designing a dovetail plane that I should be aware of, I'd very much appreciate the advice.

[IanW]

Hi Berlin,
I used 60 degrees for mine.

http://www.woodworkforums.com/f44/small-dovetail-plane-80709/

The reason for choosing that blade angle was very simple - I had a HNT Gordon rebate plane blade, which I wanted to use. These have quite a short stem, because that's the pitch he uses. It would not have stuck out far enough if I'd used a lower pitch. It works very well for what I use it for, which is trimming router-cut sliding dovetails to a clean fit. I can cut a full dovetail from scratch (using a fence clamped to the board), but the absence of a nicker means I get a bit of a rough shoulder on some woods, unless I am very careful. It seems to me that any pitch will work fine, having a sharp & well-seated blade is the most important ingredient.

A skewed blade may be better. I thought about it at the time, but decided that getting one angle right would be enough of a challenge on my first try! But here is a link to another forumite's solution - converting an old skewed rebate plane:

Evolving a Dovetail Plane by Derek Cohen (http://www.inthewoodshop.com/ShopMadeTools/Evolving%20a%20Dovetail%20Plane.html)

My (non-skewed) plane was a pretty straightforward build, with a few stuffups along the way, as recounted in my post. Some day, I'm going to make an improved version, with skewed blade, a fence, & a nicker, but the current one does what I need surprisingly well, so I may never get the necssary round tuit.... :U

Cheers,

[Berlin]

Hi Ian,

Thanks for that. I'd seen Derek Cohen's tutorial but hadn't seen yours. That's a good looking little plane.

It's good to know 60 degrees works well because I was planning to go with a York pitch or a bit more. A bit off topic, but I could never understand why one would make bevel up plane on a 20 degree bed. With the angle of the micro bevel at 35 ish, that's york pitch isn't it? What's the benefit to the set up?

Back on the dovetail plane, I will keep the blade itself square, ie I won't be grinding the blade to shape. This means I get a skew when the blade is tilted off axis to make the 1:6 sole angle... Well that's the plan.

Thanks again, plenty of food for thought in both your and Derek's posts

Cheers

[Berlin]

Ok I found some answers to my own questions in this nicely written summary of plane geometry: John Whelan: The Cutting Action of Planes (http://homepages.sover.net/~nichael/nlc-wood/chapters/caop.html)

The low angle bevel up gives the same overall pitch but the sole supports the blade closer to the tip.

A higher angle is generally employed for hardwood and moulding planes.

And 55 degrees is Middle Pitch (not York as I implied)

[IanW]

...... I will keep the blade itself square, ie I won't be grinding the blade to shape. This means I get a skew when the blade is tilted off axis to make the 1:6 sole angle... Well that's the plan.

Berlin - not sure why you don't want to grind your blade to the tail angle? It isn't a terribly difficult exercise, and makes the the construction simpler, to my way of thinking.

But the more important consideration is that without an angled cutting ege, I cannot see how you can cut the corner of the dovetail. When the blade is skewed over to cut the tail, the edge of the blade is going to foul on the shoulder.

Cheers,

[Berlin]

Berlin - not sure why you don't want to grind your blade to the tail angle? It isn't a terribly difficult exercise, and makes the the construction simpler, to my way of thinking.

But the more important consideration is that without an angled cutting ege, I cannot see how you can cut the corner of the dovetail. When the blade is skewed over to cut the tail, the edge of the blade is going to foul on the shoulder.

Cheers,

Hi Ian,

Actually it is possible to make the dovetail without grinding the blade, which is good because it means I don't have to ditch my shoulder plane. I can just swap the blade into the dovetailer.

I have a full set Ulmia planes (barring the dovetail) and it's how they set their version up. I could just buy that and round out my kit but I want to have a go making it... and I have to lug them back to Brissie soon, so the fewer new additions the better.:rolleyes:

I don't know if my diagram is clear or not but that's the principle.

Cheers

[IanW]

Well I guess I need to see it in the flesh, but I can sort of see how it might be done (I'll try it later when I go to the shed...). I will have a go at a skewed blade version one of these days, just for the challenge, but for my first try, I thought dealing with one angle was challenging enough!

Anyway, you should certainly give it a go. Making a plane or two is a very valuable exercise, IMO. You have nothing to lose except a small piece of wood, and even if the first one or two don't function as well as you hope for, you learn some valuable lessons on what makes planes tick, I reckon.

Cheers,

[Berlin]

Well I guess I need to see it in the flesh, but I can sort of see how it might be done (I'll try it later when I go to the shed...). I will have a go at a skewed blade version one of these days, just for the challenge, but for my first try, I thought dealing with one angle was challenging enough!


Yes the compound angle is confusing in a diagram and I'm sure I will have a nice little stack of fire wood before I have something worth showing. I would be chuffed to end up with anything as nice as your plane... but I have a bit of practice to get under my belt first.:)