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Plane bit angles

 
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whatwasithinking
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Joined: 26 Jan 2013
Posts: 230
Location: Washington State

PostPosted: Mon Apr 01, 2013 3:17 pm    Post subject: Plane bit angles Reply with quote

Could someone suggest a combination of preferred bit angles for roughing out, and then finishing, sticks, please?

Henderson says: "The bits, as we see them, or as they come from the maker, ground at an angle of 25 degrees, should not be used unless the grain of the wood is very straight and smooth; the harder, rougher, and more curly the grain, the more vertical this angle should be."

Bolander: "The plane iron or cutter cannot be used as it comes when you buy it, because it has too sharp an angle (twenty-five degrees). It would chip and cut out chunks of wood, especially if there were small knots, curly places and some cross grain. For the planing and roughing-out the octagons use about a fifty to sixty degree angle on the plane iron, and on the graduating and finishing use a seventy to eighty degree angle, which acts like a scraper. I have about three dozen plane irons of different angles ready and sharpened so there will not be any delays in my work."

Well, I've been getting by mostly with stock bits, at about 25 degrees. I can already see that's certainly not going to work well for finishing. Are there planes made with these kinds of angles, or did you refinish them to increase the angles? How did you grind them? How many of each angle and type do you have around?

Ed? You must have conquered this issue.
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wm_crash
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Joined: 24 Feb 2013
Posts: 140
Location: Wilmington, DE - USA

PostPosted: Mon Apr 01, 2013 9:08 pm    Post subject: Reply with quote

I haven't make sticks but I do a fair amount of woodworking. Here's my take on blade angles for planes. Whatever I say applies to bevel up planes only.

Blades come in at a 25 degree from the manufacturer simply because you are expected to set your own personal angle on the blades. When you want to have a lower angle, then you have to regrind the entire bevel. So you have the blade at the lowest angle anyone would ever want. A 30 degree angle (or 35 in the case of very difficult wood with crazy grain - which you wouldn't use for sticks anyways) can be obtained by simply sharpening a sliver of the cutting edge of the blade. There is no need to set the entire bevel to the desired angle. As you sharpen at your 30 degrees for example, the secondary bevel grows in size, and by the time you're through 1000 sticks, the amount of sharpening would have completely converted your blade to a 30 degree bevel.

Most woodworkers find that you really want to work with a rather small secondary bevel. It makes touchups easy every now and then. So after a while, you may find yourself at the grinder (preferably wet grinder so you don't mess the temper) re-establishing that factory 25 bevel just so you have an easy life sharpening a narrow 30 degree secondary bevel.

General purpose block planes come in two flavors: regular and low angle. Regulars have bed angles of 20 degrees, while low angle have a bed of 12. This will add to your sharpening angle to give you your final pitch. Keep that in mind when you decide what angle you sharpen to. Low angle are really meant for end grain only, but sometimes you just work with what you got.

To make a long story short, placing a 30 degree blade in a 20 degree bed gives you a 50 degree angle which is suitable in most situations I have encountered.

cheers,
wm_crash, the friendly hooligan
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whatwasithinking
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Joined: 26 Jan 2013
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Location: Washington State

PostPosted: Mon Apr 01, 2013 10:47 pm    Post subject: Reply with quote

Maybe I misunderstood Mr. Bolander's book. I'd thought he was changing the angle of the face from 20 to 60 degrees. Is that incorrect? And I guess it's only necessary to re-bevel the leading edge of the bit, is that right? All I know right now is that I was having better luck before I changed the bevel...
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wm_crash
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Location: Wilmington, DE - USA

PostPosted: Mon Apr 01, 2013 11:44 pm    Post subject: Reply with quote

I am sure Bolander was referring to total pitch angle, not blade bevel angles. I can see how his writing can be confusing first talking about blade factory angle, then about pitch angle. So if you want to use his angles, subtract the the plane bedding angles.

I am not sure what tools are available to you at this point, but if you are using an old Stanley blade, consider upgrading to a Hock blade (Lie Nielsen and Lee Valley blades are fine too, just that I have experience with Hock). I personally prefer carbon steel blades (or O1) over A2 steel. That's not to say A2 doesn't have its place. But sharpening carbon steel is a pleasure, while sharpening A2 takes some patience and possibly diamond stones (or hard stones like Chosera if you like waterstones).

Didn't want to sound like I was dissing Stanley blades. Many of them are serviceable. But most that I have encountered have a pitted back, bad enough to give you a wavy cutting edge. Those little dents are hard to work out by flattening the back of the blade.

cheers,
wm_crash, the friendly hooligan
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wm_crash
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Location: Wilmington, DE - USA

PostPosted: Tue Apr 02, 2013 12:01 am    Post subject: Reply with quote

Forgot to mention . . . .

Yes you only care about sharpening the cutting edge. You also want to polish about 1/4" of the back to the highest grit so that your edge is where two polished surfaces cross.

There are a lot of YouTube vids on planes. I like the ones put together by Lie Nielsen.

cheers,
wm_crash, the friendly hooligan
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whatwasithinking
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Location: Washington State

PostPosted: Tue Apr 02, 2013 12:15 am    Post subject: Reply with quote

Using a Millers Falls No. 16, which is a clone of the Stanley 9 1/2. I'll check the videos. Thanks.
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Ed Shillitoe
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PostPosted: Tue Apr 02, 2013 5:12 pm    Post subject: Reply with quote

Conquered the issue? Well, I wish I had! I can't add much to what Mr Crash has said, but I can show what I do know. For some time I used the Stanley 9 1/2 with the blade sharpened at 60 degrees or so, using this highly sophisticated jig:



I hold the blade still against the fence with one hand while pushing the sharpening stone back and forth with the other hand. It works really well - by making different jigs you could have several blades sharpened at different angles. However I have now settled on the following set of planes which I like better:



I start with the lowest one, which is a low angle block plane which cuts fast but can leave a rough surface. Then I go to the garage-sale plane which has the blade upside down - its not quite so fast but leaves a fairly good surface. Then I go the scraper plane which is pretty quick and easy and leaves a very nice finish. I use this plane the most. Close to the inside curves of a cambered bow I use the top one. The larger scraper plane came from Metropolitan Music many years ago and is really indispensible. If the house was on fire, that is the tool I would take out with me.

Then again, some days one plane seems best and some days another one seems to work better. I don't know why. I use bloodwood rather than pernambuco, but they are quite similar to work.

You do need to put a little Vaseline on the bottom of the plane every few minutes to let it slide over the surface of the wood, and keep the blades sharp. I put the stick in a vice when I can because that lets the plane cut better. While planing I mark arrows on the stick to show which direction the plane should go - it's hard to remember the correct direction for each of the 8 facets.

I hope this is of some help. I am about to start on a new bow and I was thinking of documenting the whole process, since there seems to be a little bit of interest in it these days. Michael D. did a thread on making a viola a while ago which was excellent, and Roger Hargrave is in the middle of one on making a bass right now which is also amazing (although on a 'different forum'). I don't compare my expertise with these gentlemen, but if I get the time I might try to take pictures as I go.
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ctviolin
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Joined: 07 May 2009
Posts: 961
Location: Roswell

PostPosted: Tue Apr 02, 2013 5:36 pm    Post subject: Reply with quote

Ed Shillitoe wrote:

I hope this is of some help. I am about to start on a new bow and I was thinking of documenting the whole process, since there seems to be a little bit of interest in it these days. Michael D. did a thread on making a viola a while ago which was excellent, and Roger Hargrave is in the middle of one on making a bass right now which is also amazing (although on a 'different forum'). I don't compare my expertise with these gentlemen, but if I get the time I might try to take pictures as I go.


Please do Ed.

I'll be there if you do, asking questions like the bow idiot I am...

I got about half way through the last one (bow), before totally screwing it up.

But I still have a couple decent pernambuco blanks that I bought twenty or so years ago (when I could afford it) that I am slowly going to try after practicing on some rosewood practice pieces.
I thought that perhaps this (making bows) would be a good thing to try after my stroke (now about 9 months ago...) but I must say it is a whole new (perhaps it would be more correct to say "a whole nother") thing - in fact, I broke down and just finished a scroll and neck for the next violin because the bow making was such a screw (trial) up for me.
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whatwasithinking
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Joined: 26 Jan 2013
Posts: 230
Location: Washington State

PostPosted: Tue Apr 02, 2013 6:29 pm    Post subject: Reply with quote

That's terrific, Ed! And very interesting.

How did you grind the bit in the low angle plane? It must be somewhat more obtuse than stock, right?

Somehow I missed the concept of using different directions on different facets. Thanks for mentioning that. I'm looking forward to your detailed record of construction.
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