Pros and Cons of Adjustable Mouth vs Fixed Mouth Block Planes

[Bob Deroeck]

I'm developing a need for one or more decent block planes. I've used the search function to try to find out the pros and cons of adjustable vs fixed mouth block planes. There's probably a few good threads on this subject, but I can't seem to find them.

So, I'd appreciate any input on the pros and cons of adjustable vs fixed mouth block planes. For what type of cuts is the adjustable mouth a significant advantage?

Thanks.


Bob

[David Weaver]

If the mouth on a fixed mouth plane is fairly fine, it will work just fine. A lot of the inexpensive older planes that are fixed mouth don't have a mouth that fine, though, and if you find yourself beveling the end of something, you won't like the wide open mouth too much, especially if what you're beveling is narrow. That beveling could, of course, be done with a sharp chisel instead.

An adjustable mouth plane is a better tool because it lets you control all of those things.

[Frederick Skelly]

Im brand new at using planes, but heres what I think I understand from reading Garrett Hacks book and responses to my recent questions here. (Lets see if I got it right.) Being able to adjust the mouth lets you make it smaller, which some people believe reduces tear out. Other people seem to disagree, saying that a wider mouth opening is ok if you have a good chip breaker.

From what I can tell so far, being able to make small adjustments here and there lets me have flexibility to tune the plane to the type of wood, the difficulty of the particular grain Im encountering and the work Im doing (roughing it out, smoothing it, etc).

Of course, the more you can adjust, the more things you HAVE TO adjust, and KEEP adjusted. But from my limited experience, I like being able to adjust stuff.

Before I knew all that, I bought and tuned a Stanley block with an adjustable mouth. It took a fair bit of work but it seems to work fine for light work like camphers, etc.

Fred

[Prashun Patel]

The fixed mouth blocks tend to be smaller than the adjustables. So they can be used in tighter quarters and might feel batter in smaller hands like mine. I also use my ln 102 and veritas apron planes for fairing convex cures on spindles and curved legs.

It is really a matter of what feels best in your hand.

[Chris Fournier]

My LN 102 low and high angles are non adjustable. I also have their adjustable mouth block and block rabbet planes. If I could have only one, I would take the block rabbet because it is versatile defined. My favourite? The standard angle 102. It fits in my hand like it's an extension of my body. ability to cut the toughest woods? The 102 gives up nothing to the adjustable mouthed block, sharp being sharp.

Get the 102 standard and the block rabbet and you are KING!

[Jessica Pierce-LaRose]

Like Dave says - an adjustable mouth is nice to keep a corner or something from diving in the mouth when trimming an edge or something.

An adjustable mouth might be nice on a block plane for fighting tear out because you aren't working with a chipbreaker, but I've found sharp is usually a better cure at tearout than closing the mouth. Honestly, I like the adjustable mouth because it lets me *open* the mouth more.

As I get better and better at handling a chisel or knife, my block plane sees less and less use.

[Sam Takeuchi]

I think there's a difference between general purpose block plane, like fixed mouth No. 102 and adjustable mouth block planes. Adjustable mouth plane will afford you more finesse when you need it while allowing you to leave the setting for general purpose for other occasions. It all depends on what you use it for. Adjustable mouth is especially handy if you have to work on small parts, cut involving corners and especially when you are planing thin piece that flex. Not all woodwork are done with thick pieces and when it comes to versatility of dealing with very thin pieces to thick pieces, adjustable mouth block plane works better hands down.

I say that because I make musical instruments and sometimes I need to make parts for stuff like rosette and purfling. I often have to cut 0.012" thick materials as well as 0.024" thick one. When the plane begin its cut, blade bites into the wood and if the original material is thin and flexible (like shaving the 0.024" piece down to 0.012"), open mouth plane will just chews up the material, and cut is more inconsistent.

While most of people making furnitures are probably not concerned about this type of material, I can say that I haven't felt the need for any other block plane as long as I have a suitably tuned adjustable mouth block plane such as that.


Being able to adjust the mouth lets you make it smaller, which some people believe reduces tear out. Other people seem to disagree, saying that a wider mouth opening is ok if you have a good chip breaker.

the more you can adjust, the more things you HAVE TO adjust, and KEEP adjusted. But from my limited experience, I like being able to adjust stuff.

There is nothing difficult about keeping it adjusted. If mouth opening doesn't matter, you open it wide, and leave it at that. That's it. You don't have to adjust it until only when you need to. Block planes (that is the original question here) generally don't have cap iron so the stuff about cap iron is moot in this regard.

[Chris Fournier]

I think there's a difference between general purpose block plane, like fixed mouth No. 102 and adjustable mouth block planes. Adjustable mouth plane will afford you more finesse when you need it while allowing you to leave the setting for general purpose for other occasions. It all depends on what you use it for. Adjustable mouth is especially handy if you have to work on small parts, cut involving corners and especially when you are planing thin piece that flex. Not all woodwork are done with thick pieces and when it comes to versatility of dealing with very thin pieces to thick pieces, adjustable mouth block plane works better hands down.

I say that because I make musical instruments and sometimes I need to make parts for stuff like rosette and purfling. I often have to cut 0.012" thick materials as well as 0.024" thick one. When the plane begin its cut, blade bites into the wood and if the original material is thin and flexible (like shaving the 0.024" piece down to 0.012"), open mouth plane will just chews up the material, and cut is more inconsistent.

While most of people making furnitures are probably not concerned about this type of material, I can say that I haven't felt the need for any other block plane as long as I have a suitably tuned adjustable mouth block plane such as that.



There is nothing difficult about keeping it adjusted. If mouth opening doesn't matter, you open it wide, and leave it at that. That's it. You don't have to adjust it until only when you need to. Block planes (that is the original question here) generally don't have cap iron so the stuff about cap iron is moot in this regard.

While making guitars, with whatever finesse I have had to muster I can say that the LN 102 was never upstaged by it's adjustable brother. Not once. A sharp 102 is a surgical instrument.

[Sam Takeuchi]

I haven't had your success making veneer strips for rosette and purflings, Chris. While tight mouth block plane makes making 0.012" veneer strips a breeze, using anything but tight mouthed plane would cause veneer strips getting pulled up into the mouth, causing inconsistent cut or gets jammed up into the mouth of a plane, ruining the workpiece. I know what a sharp blade can do and does, but that hasn't stopped veneer strips from getting sucked into the mouth of a fixed mouth block plane. For anything else where workpiece has rigidity, fixed mouth would do fine. I have no problem making 1/8" x 1x8" fan brace pieces using gaping mouth block plane, but when it comes to veneer strips, tight mouth block plane achieves more consistent result, at least for me.

0.024" above, 0.012" below

[Brian Ashton]

The basic premise behind chip breakers and narrow openings is the fibres need to be broken as you plane a piece of wood. Otherwise if they have the strength and rigidity combined with a short grain or weak bonding between fibres they can lift the fibres that precedes the blade causing varying degrees of tear out. Having a very narrow opening will cause the fibres to bend on a very acute angle as they're separated from their sub-straight which is intended to break them preventing them from lifting the fibres... The same thing is what a chip breaker does - hence the name chip breaker. Instead of bending them at acute angles the chip breaker is an immovable object that the fibres crash into and break as they deflect. Having the two features in a single plane is about as good as you're going to get when it comes to being able to accommodate a variety of grain characteristics.. If all you plane is straight grained pine all you need is a cheap no frills plane. If you'd like to get stuck into some harder and or more gnarly wood then you'll need the ability to adjust the planes features.

[george wilson]

Try getting your veneer strips wringing wet while you are planing them,Sam. With an adjustable mouth plane,you can also pull leather strips through the mouth to make thin leather thongs should you need to do that.

[John Sanford]

Try getting your veneer strips wringing wet while you are planing them,Sam. With an adjustable mouth plane,you can also pull leather strips through the mouth to make thin leather thongs should you need to do that.

George, how would you know this? Have you started a side business supplying leather thongs to the dancers around Norfolk?

[don wilwol]

the problem with a fixed mouth, you need it in your hand before you buy it. If its reasonable, then you have a decent plane. An adjustable doesn't matter, you can adjust it. Its hard to buy a fixed closed mouth block unless you can hold it. I agree an open mouth can be made to work very well for most applications. Sometimes its nice to be able to narrow it right down.

[Derek Cohen]

A small fixed mouth versus a large fixed mouth ...

The mouth size becomes more important as the cutting angle gets lower. When planing end grain, the mouth size does not matter at all. However, if planing face grain with a low cutting angle, to minimise tearout, close the mouth down and take very fine shavings. This is also the case when chamfering on some woods. A common angle is better for these tasks.

A small mouth enables one to set the blade more easily for a fine shaving as one may better judge the blade projection by touch.

For general work, a standard block plane (or a low angle with a higher grind) is best. Ultra low cutting angles are really indicated for the smoothest surface on end grain, but a common angle works pretty well here as well, as long as the blade is sharp.

An adjustable mouth offers the best of all worlds, but it is very possible to get away with a fixed.

Regards from Perth

Derek

[george wilson]

I work in many media,John. Dancer's thongs is just one of them.

[Derek Cohen]

I work in many media,John. Dancer's thongs is just one of them.

George, the image of you in thongs in the workshop is... frankly ... disturbing :)

Regards from Perth

Derek

[george wilson]

They're not MINE!! They are for the girls. But,they keep getting chaffed on the brass poles,and I have to renew them.

[Jim Koepke]

This thread came to mind yesterday while working on smoothing the circumference on wooden wheel.

Convex surface smoothing is one of the many jobs where an adjustable mouth is a handy feature.

jtk

[Prashun Patel]

Hi Jim. I am curious why an adjustable mouth helps with fairing convex curves. In fact, I find the smaller footprint of a fixed mouth plane easier to maneuver on curves. When skewed, it's almost as versatile as a spokeshave on things like table legs.

[Jim Koepke]

Hi Jim. I am curious why an adjustable mouth helps with fairing convex curves. In fact, I find the smaller footprint of a fixed mouth plane easier to maneuver on curves. When skewed, it's almost as versatile as a spokeshave on things like table legs.

The size of the mouth controls how much of the curve can enter the mouth or be in the working area of the blade.

The planes used in my case are #60 & 65 series planes.

I do not understand what you mean by the smaller footprint of a fixed mouth plane. Some of my block planes are fixed mouth, but they do not have the blade adjustment like my LA block planes.

My recent experience was with a wheel for my wheel barrow project. (Not Enough Fingers to Count the Mistakes) When the mouth was closed my plane was not taking much more than dust like shavings. Opening the mouth enabled the blade to get a better bite. The shaving thickness was adjustable with just the mouth opening.

jtk

[Prashun Patel]

I see your point about more of the curve being able to get into the mouth. When I say smaller footprint, I'm comparing planes like the LN102 and Veritas Apron plane to the Stanley 60 1/2 type planes. Both of those are adjustable depth. Their size makes them easier for me to use one-handed and gets closer to the transitions from convex to concave easier (for me).

[Jim Koepke]

When I say smaller footprint, I'm comparing planes like the LN102 and Veritas Apron plane to the Stanley 60 1/2 type planes. Both of those are adjustable depth.

My Stanley #102 is great for some things, but it doesn't have a blade adjuster. For going across end grain, my preference is for a low angle plane or a spoke shave.

For my wheel barrow project, the Stanley #65 was nice for fairing the wheel. The wheel was made of 2X12 and the blade on the #65 was wide enough to skew slightly and span the width of the wheel 'tread' with the edges chamfered.

In reality what works best depends on what tools one has in their shop at the time.

jtk

[Mike Cogswell]

George, how would you know this? Have you started a side business supplying leather thongs to the dancers around Norfolk?
ROTFLMAO!!
Funniest line ever in this forum!

[steven c newman]

I didn't like having to chose just one type of block plane, so, I went and bought both kinds. use as needed...