Planing a straight edge

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Muina

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Ok, I'm new to this forum so I figured now would be the perfect chance to introduce myself since I have quite a difficult problem.

My name is Anthony, I'm at Hull College studying Carpentry/Joinery. I like to think I'm progressing well due to the fact that I've been practising woodwork without tuition for quite a number of years now.

I started woodwork making laminate longbows and have since progressed on to woodturning and now am delveing deep into the world of cabinet making.

So here's my problem: I've started building a bedside cabinet which will be panelled inside the frame, the frame's made of Iroko (I know it's not the best wood to use but it was a bargain, just over a cubic foot for £13) and the panelling of Tulipwood (I think otherwise known as Yellow Poplar?). I'm trying to do everything by hand, except for the seriously long, laborious tasks such as thicknessing and resawing the boards for the panels.

I've tried match planing the Tulipwood to get a nice neat joint between the boards with a freshly tuned up wooden jointer plane and I've ended up with a concaved surface, which as you can imagine is exaggerated by the two boards being put together.

I've asked one of the tutors at my College who is experienced in Cabinet Making and he suggested it might be due to my planing technique, however (although his advice did greatly improve my planing technique) this hasn't alleviated the problem at all.

So I suppose what I'm asking is this: Is this a common problem or is there something I'm doing wrong?

Thanks for any help
 
Bad technique would normally lead to a convex, rather than concave edge.
A concave edge, in moderation, is actually a good thing, provided it closes completely when the board edges are clamped together. The classic "sprung joint".
 
You need at least a n6 or preferrably a no7 plane
to do this(That is what I was told). Also, you need
to have a very flat sole.

Remove the high spots to get a somewhat straightedge
an then use the jointer plane with fine shavings to
get it flat. Use very little pressure. You need a very sharp
blade.

But I am no expert. Wait for some more replies.

Ali
 
How are you holding the wood? It's possible that, if you have long pieces of skinny sections and just clamp them in a vice, you could be bending it as you plane.

If you are holding it fully supported on a nice flat bench top, nice and firm between a bench dog and an end vice, or else held in handscrews which are in turn clamped down onto the bench, discount this suggestion!
 
Thank you for all the replies so far!

You're right John Cee, it is a convex edge it's producing, not a concave, sorry if that confused anyone.

Incidentally, I did see my first No. 7 today (it's been at college all the time but I've just never realised it was there, I know, hard to miss lol), I don't think I've ever seen such a huge handtool!

I've been on countless webpages trying to figure this problem out but I just can't seem to come to an answer. The only thing that seems to have been any logical solution was a video I found which teaches to hollow the center of the edge creating a concave, then planing down until the first continuous shaving.

Thanks again for any help

Anthony
 
Andy T, the wood I'm trying to practise planing is quite thick, at least 3/4", so I don't think bending would be a problem.

Now you can see why it's been baffling me lol, I am a determined person though, so I WILL find a solution :D

Anthony
 
If you keep planing a piece of wood on its edge, end to end, you will end up with a convex surface, as you have found. The way to deal with this is to take what are known as "stop shavings"

Using as long a plane as possible, make a pencil mark an inch from each end and plane between these. Then make another mark a further inch in from these, and plane between the two. Go on like this until the plane stops cutting, then take one or two full length shavings.

You should find that that the board is straight but with a thou-or-so hollow in the centre.

Hope this is clear. There are some good DVDs by David Charlesworth and David Savage (look on their websites) that show precisely how to do this.

Cheers :wink:

Paul
 
Thankyou Paul, I have tried I suppose a slight variation on this technique which I saw on a video (I can't remember where it was, just type into google "how to make a rub joint" and it's the one that says "episode #something ...) in which you simply plane a random hollow, not measured in any way, then take full length shavings until you have a full continuous shaving.

I'll try following your method and let you know if the results are better.

I'll give those videos a look too, I've heard good things about David Charlesworth.

Thankyou

Anthony
 
And that would be the video I mentioned! What a strange coincidence!

Anthony
 
Little bit more research brought up this:

http://www.leevalley.com/newsletters/Woodworking/1/2/Article1.htm

It says on page 2 "The time-honored way to ensure a flat face is to first remove a few shavings from the middle of the face followed by a few shavings along the entire face."

So I guess that just strengthens Paul Chapman's post further up the thread.

Anyway, I've given the plane I was using to the guy who gave it to me so he can check it with a better straight edge to make sure it's all flat and true, then I'm going to see him on Thursday. Hopefully by then I'll have tested out the method on a smaller scale (I'm guessing by using a shorter piece of wood I can use a smoother or jack plane and get the same relative results?)

I'll keep posted for anyone who's interested

Anthony
 
It's always wonderful to see people going down this bit of the slope, cos it's such a massive one-way, no-going-back, cliff edge.

It starts with a slight discomfort that you always knew there was more to it than just hogging away wood, then you realise that you can plane a board to the mm... then you realise that you can plane a board to the width of the line that divides the mm's on your rule...

Finally you realise that with a 'goodun' and a bit of practice you should be able to make a whole component accurate to a tenth of a mm in every dimension and suddenly power tools are unmasked as brutal implements for doing the bulk of the work, leaving you to get on with the really rewarding accurate stuff.

Clicking the add to cart button on a Charlesworth or Savage DVD is the equivalent of shouting geronimo and accepting your unavoidable fate.

Happy landings!
 
Paul Chapman":1q39jo8c said:
If you keep planing a piece of wood on its edge, end to end, you will end up with a convex surface, as you have found.

Yes but does anyone know the technical reason why?

I do as I was told 25 years ago without thought, stop shavings included, but never had it explained why planing a board with a very flat No.8 will eventually lead to a convex edge rather than an edge as flat as the sole of the plane, if you see what I mean... :duno:
 
Muina":1v1bjmrb said:
...
I've tried match planing the Tulipwood to get a nice neat joint between the boards with a freshly tuned up wooden jointer plane and I've ended up with a concaved surface, which as you can imagine is exaggerated by the two boards being put together......
Technique.
Concave means the edge is higher at the ends. This means that you need to plane more wood from the ends.
Sounds too simple, but that's all there is to it.
Could help if you draw a line with a straightedge, and work down to it - then you can see how you are progressing and where you might need to do it differently.
Take your time in getting it right, don't worry about spoiling wood, concentrate on making the plane do what you want, rather than just wanging it to and fro and wondering why it isn't doing what it is supposed to do. Practice on some scraps if you want to save your tulip wood (cheap anyway, good for practice).

You don't need to buy anything, popular though that solution is on these forums. Though you might need to buy some more tulip wood!

PS just re-read the thread. I see it's convex, not concave. The above still applies, except it's too high in the middle instead!
Though there is a difference in that if your plane sole is very concave it would make a straight edge difficult. Doesn't apply the other way round. But I doubt the plane is the problem - it's your technique!
 
Scouse":6vl5ru4d said:
Paul Chapman":6vl5ru4d said:
If you keep planing a piece of wood on its edge, end to end, you will end up with a convex surface, as you have found.

Yes but does anyone know the technical reason why?
I was puzzled by this as well until Paul C drew me some pics round at Newt's place last weekend and the penny dropped. It's difficult to describe but when you see it drawn as a couple of diagrams it becomes crystal...if Paul's around some pics would be very useful - Rob
 
woodbloke":1btlds0p said:
Scouse":1btlds0p said:
Paul Chapman":1btlds0p said:
If you keep planing a piece of wood on its edge, end to end, you will end up with a convex surface, as you have found.

Yes but does anyone know the technical reason why?
I was puzzled by this as well until Paul C drew me some pics round at Newt's place last weekend and the penny dropped. It's difficult to describe but when you see it drawn as a couple of diagrams it becomes crystal...if Paul's around some pics would be very useful - Rob

I think I've figured out why it does it, just never thought of it possibly being able to. Basically, when the blade takes a shaving, it leaves a lower surface behind it, therefore when the back of the sole comes into play you put the pressure on that part and you inevitably lift the blade upwards slightly.

I think that's right, but obviously this is open to correction, it just came to me when I tried changing where I was putting the pressure during the cut. If I planed normally a couple of times to create the convex, then only put pressure on the rear of the plane through the whole cut (including starting off) I found that the shaving tapered off before it'd got to the other end of the wood.

But if that's wrong I would love to see pictures of it to help explain :)

I just find it incredibly fascinating that I'm probably living out the confusions of an apprentice 400+ years ago, just with added google searches :p

Anthony
 
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