Chasing a flat joint

[Wylie2112]

Hello,

I've tried searching on this subject of plane sole flatness but there seems to be some conflicting advice. I'm struggling to get straight joints with my Bailey No. 5 and was hoping for some advice.

When I true up the edge of a board and check it with various squares and straight edges, they seem to show it being flat and right to the face. I do it twice. Then I put the two new faces together and there're gaps. Now I don't know which one isn't true because my other indicators show they both are. So now I don't quite trust my edges and squares.

The kind of gap I get most commonly is at the ends as the edge of the boards seem to be bowed in the middle. What causes this and why doesn't it show up with my straight edge, but only when I try to join two boards together? What might be wrong with either my place or my technique that might cause this bowing?

Help! I'm getting very frustrated and this is just the start of the project!

 

[Scott]

Hi Wylie

Check your square by putting the stock against en edge that is planed straight. Knife a line up along the blade then flip it over and check the blade against the line. If they don't match EXACTLY your square is not square. If it's a cheapo, of unknown provenance, or a woodworking square with a wooden stock chances are it's not square. A good quality steel engineers square that is kept safely and free from knocks and rough handling is your best bet. Also, if the blade of the square is not parallel you may have problems. Make sure you always use the same edge of the blade.

Similar thing for your straightedge. Strike a line and flip it over to check against the line from the other side. Any discrepancy means it's not straight (and many aren't).

Consider match planing your boards i.e. put them both in the vice at the same time and plane the two as one. The face sides (you are only working from one marked face aren't you?) must be together. When you open them out and put them together for gluing any slight angle on the edge of one board will be cancelled out by the same angle in the opposite sense on the matching edge.

As for the length of the boards you should plane them slightly hollow in their length by a shaving or two. Use your straightedge to check where the high points are along the length, not by looking under it but by very lightly trying to rotate the straightedge while it sits on it's edge. The point of rotation is the high point and you want a high point at each end with that wee hollow in the middle.

Do this by taking "stop shavings" where you start the shaving slightly in from the end and lift off while still pushing the plane forward just before you reach the far end. Once you have your tiny hollow (straightedge rotating on the ends only) take one single full length pass and see how the boards match. The fact that the boards are a bit "fat" (talking a thou or two here) at the ends is good because the ends will dry out a bit more than the rest.

I'm assuming you're taking nice fine shavings here by the way.

That's a brief resume of the theory so try that for the woodwork side of it.

As for the plane sole, the straightedge needs to be right to check that too and if it's significantly unflat you may have problems planing a glue edge flat. Concave is a different kettle of fish to convex so you need to check it

Apologies if teaching granny to suck eggs! :lol:

Hope some of it is of use

Cheers

 

[Philly]

Wylie
One thing to check - is the face of the board flat? If not you can't take accurate readings of the edge.
Hope this helps
Philly

 

[Paul Chapman]

It is a fact that if you keep planing a board along its length, you will eventually plane it into a curve. As Scott says, you need to take a few stop shavings then finish up with a couple of full length shavings.

Cheers :wink:

Paul

 

[Wylie2112]

It is a fact that if you keep planing a board along its length, you will eventually plane it into a curve.

Really? What causes that? I'm trying my best to have flat pressure at the ends of the board, but the arc still develops.

Scott, great tips to prevent the arc. Thanks!

 

[Paul Chapman]

It is a fact that if you keep planing a board along its length, you will eventually plane it into a curve.

Really? What causes that? I'm trying my best to have flat pressure at the ends of the board, but the arc still develops.

Best to think of the sole of the plane in terms of an in-feed and out-feed table either side of the blade. In order to prevent the wood curving, without some corrective action, you would need to have the sole at different heights each side of the blade, but that's not practical (although it's been tried). The only way of preventing the curvature is to take stop shavings. David Charlesworth covers the subject in some of his writings.

Cheers :wink:

Paul

 

[Wylie2112]

Paul,

Thanks for that. I was thinking of the plane in just that way and, in my simplistic mental model, that should produce a flat result. But clearly it doesn't (even with a perfectly flat plane?).

I've also noticed that the way the plane iron takes shavings seems inconsistent. On some passes it'll take wood from different places. I was thinking that as a surface is planed smooth, it'll eventually produce a shaving the across the full surface. But that doesn't seem to be what's happening and sometimes I can't find a relationship between the shaving on one pass the shaving pattern on another.

Do you (or any other posters) know of a reference on how planes work in reality? Not so much how to use one, but how they behave as they're being used. I'm clearly not seeing perfect results but don't know what my results are telling me, therefore, don't know what to do to improve either my technique or my tool setup.

In any case, I'm still enjoying it. There's something very pleasing about planing a piece of wood.

 

[Racers]

Hi, Wylie2112


How long are the boards you are planing? the longer the board the longer plane you will need.


Pete

 

[Paul Chapman]

Do you (or any other posters) know of a reference on how planes work in reality? Not so much how to use one, but how they behave as they're being used. I'm clearly not seeing perfect results but don't know what my results are telling me, therefore, don't know what to do to improve either my technique or my tool setup.

Probably the best thing would be to get together with other woodworkers who could demonstrate planing techniques to you. Forum members sometimes organise get togethers.

Another useful source is some of the DVDs by people like David Charlesworth and Rob Cosman. It really does help to see it done sometimes.

Cheers :wink:

Paul

 

[Wylie2112]

Hi, Wylie2112


How long are the boards you are planing? the longer the board the longer plane you will need.


Pete

Pete,
About 3 feet, give or take. I'd like to be using a No. 7, but don't have one, so I'm using my No. 5. I'm beginning to question the flatness of it's sole, too. I'll have a good look next time I'm back in the shop.

 

[David C]

Wylie,

My second dvd shows how precisely it is possible to plane up a small component board. It explains in detail all the techniques used. Face with lack of twist or wind, edge. thicknessing and endgrain.

As has been mentioned, many workshop straight edges are not very accurate.

If you plane ten shavings off a perfect edge it will not stay straight but develop a slight bump or falling away of the ends. Stop or hollowing shavings are a necessity.

Many Bailey planes are not flat enough to plane a straight edge with a fine shaving. Any hollowness in the overall length of the sole will cause this. If so, some flattening is not that difficult.

David Charlesworth

www.davidcharlesworth.co.uk

 

[Jeff Gorman]

Hello,

The kind of gap I get most commonly is at the ends as the edge of the boards seem to be bowed in the middle. What causes this and why doesn't it show up with my straight edge, but only when I try to join two boards together? What might be wrong with either my place or my technique that might cause this bowing?

It looks like a common fault when the worker does not apply sufficient pressure at the beginning of the stroke so that the heel drops, and allows the toe to drop at the finish.

Aim to work with a scooping action. In fact with all planes it is possible to generate a slightly concave profile - useful for cramped joints.

 

[David C]

I am quite certain that the reason for bumps in the length is more to do with the geometry of a bench plane than faulty technique. Hollow soles excluded!

A perfectly set machine jointer/planer can produce a straight edge because the in table is dropped by the thickness of cut.

Bench planes do not have this facility and will not plane straight on their own. Stop or hollowing shavings are necessary, and this has always been standard technique, though unfortunately not widely recognised, by those who did not have a professional training.

David

 

[Wylie2112]

I am quite certain that the reason for bumps in the length is more to do with the geometry of a bench plane than faulty technique. Hollow soles excluded!

A perfectly set machine jointer/planer can produce a straight edge because the in table is dropped by the thickness of cut.

Bench planes do not have this facility and will not plane straight on their own. Stop or hollowing shavings are necessary, and this has always been standard technique, though unfortunately not widely recognised, by those who did not have a professional training.

David

Eureka! David, you know how every once in a while someone will say something about a subject in such a way that what was once mystifying suddenly makes sense? Well, you just did that for me. I couldn't get my head around how a flat plane with a high point in the middle (ie - a plane and iron), could make a perfectly flat surface, or why they don't. You've allowed me to visualise it with that statement about machine jointers so that now I think I can get my head around how a plane works.

Well done!! You know, you ought to teach this kind of stuff!!

 

[bugbear]

Do you (or any other posters) know of a reference on how planes work in reality?

Heh. I've never seen one that I was convinced by, and I've taken part in many abstruse discussions on the subject with some pretty thoughtful and knowledgeable people.

I'd go with thoughtful pragmatism; geometry and mechanics is interesting, but not the only way.

BugBear

 

[Wylie2112]

Well, I got back to the project again tonight and David's advice of taking out the hump in the middle seemed to do the trick. I thought less of making a full-clean pass and just doing whatever it actually took to get a straight edge. That got much more satisfactory results and the kind of closed joints I'm looking for.

Thanks, guys! I'm making progress again!

Wylie

 

[Anonymous]

Hello,

I've tried searching on this subject of plane sole flatness but there seems to be some conflicting advice.

Wylie

It's simple really. Depends on what you want to use the plane for, and thus what plane it is.

Generally, a Jack (#5) or Fore (#6) plane is used to remove lots of material (maybe 6-8 thou shavings or even chips) and the sole fatness is not important. As Chris Schwarx says, look at the sole, see how rough and uneven it is, turn the plane over and, forget it and use it (paraphrased)
These planes are not used to get a good finish and often one gets a little tearout which is perfectly acceptable as other planes follow it.

A Jointer (#7, #8) is typically used to straighten edges and flatten tops, and should have a reasonably flat sole to allow finer shavings of maybe 4 thou or so (thickness of 'normal' printer paper). This plane takes table tops etc. down to a pretty good finish that is nice and flat before it is finished with the smoother.

A smoother (#3, #4, #4.5 - some people might use a #1 or #2, but a #1 is really block plane sized) should have as flat a sole as you can get to allow you to take wafer thin shavings as you are really working towards the final finish. The mouth should be tight too.
Some people use a Jack (of all trades) (#5) as a smoother, but I don't really get on with them when used this way and much prefer to use a 4 1/2.

 

[David C]

Tony,

That is a splendid summary of traditional methods going way back.

If the modern workshop has good planer thicknesser, the face sides and edges of all components, need a little improvement and checking for accuracy, before making out and joint cutting.

Alan Peters states that he used a no 7 for this work, right down to very small pieces, for most of his career. I have followed his thinking but generally use a 5 1/2, with beginners, who might find the size and weight of the 7 a bit intimidating.

For this work, fine tuning and flattening is essential to minimize tearout, as fine shavings will be used.

I know this is a fairly radical approach, but I have not used a 4 1/2 or shorter bench plane for over 30 years.

best wishes,
David

 

[bugbear]

Hello,

I've tried searching on this subject of plane sole flatness but there seems to be some conflicting advice.

Wylie

It's simple really. Depends on what you want to use the plane for, and thus what plane it is.

Generally, a Jack (#5) or Fore (#6) plane is used to remove lots of material (maybe 6-8 thou shavings or even chips) and the sole fatness is not important. As Chris Schwarx says, look at the sole, see how rough and uneven it is, turn the plane over and, forget it and use it (paraphrased)
These planes are not used to get a good finish and often one gets a little tearout which is perfectly acceptable as other planes follow it.

A Jointer (#7, #8) is typically used to straighten edges and flatten tops, and should have a reasonably flat sole to allow finer shavings of maybe 4 thou or so (thickness of 'normal' printer paper). This plane takes table tops etc. down to a pretty good finish that is nice and flat before it is finished with the smoother.

A smoother (#3, #4, #4.5 - some people might use a #1 or #2, but a #1 is really block plane sized) should have as flat a sole as you can get to allow you to take wafer thin shavings as you are really working towards the final finish. The mouth should be tight too.
Some people use a Jack (of all trades) (#5) as a smoother, but I don't really get on with them when used this way and much prefer to use a 4 1/2.

As an additional qualification (not correction) everything you say is true for cabinetmaking sized work.

If you're making small pieces (e.g. jewellry boxes) the same comments apply. but to proportionally smaller planes.

BugBear