Moved from 55 to 45 Bronze #4

[Brian Holcombe]

Thought I'd post up my results of moving to a 45 degree pitch from a 55 on my #4 smoother.

In American hardwoods working with the standard pitch I was able to reduce tear out over the 55 degree pitch for reasons I did not expect.

In my use of the 55 degree pitch I found that attempting to utilise a very tight setting on the chip breaker was resulting in 'accordian' chips' which indicate an over-tight chip breaker well ahead of the range that was actually considered tight by sources such as David Weaver. The result was that I either needed to take a very light cut or back off the chip breaker, the former was producing a tear-out free cut but was taking forever to actually finish a tabletop.

So I moved to the 45 degree pitch and found that the plane is easier to set and achieve a rolled up chip or one that comes out of the plane mostly curled. No crinkles! I could set the chip breaker to the right number and take a decent cut while maintaining a tear out free finish in American hardwoods. The plane with a tight chip breaker is still easier to push than the high pitch with a looser setting.

[Mike Brady]

That's very interesting, Brian. I can see the logic in your theory. I have only one plane with both frogs...I'll have to give it a try. The one I'm referring to is a 4-1/2 and it is a chore to push it with the 50 degree in place. Kind of takes the smooth out of smoother. As to the different shavings, I'll have to see what happens with mine. I actually have avoided that plane in favor of another smoother that is smaller.

[Matthew N. Masail]

One of the reasons I love no.3's..... My current 'want' plane is a LN No.3 with 45degree frog

Brian, were you using a LN with two different frogs? or a back bevel ?

[Brian Holcombe]

Testing out different frogs. I bought the plane with the 55 and actually found my jointer to put out a more reliable good finish, which prompted my investigation and also asking for advice on woodnet. The general consensus was that for practical use with american hardwoods it would be better to use the 45 than the 55, and so I decided to put it to the test.

The plus of the smoother over the jointer is that I can set the chip breaker tightly since I'm generally taking a lighter cut and also narrower cut.

[Winton Applegate]

Brian,
Hey wild man how's it.
What is it do you think/does David think about the 55° that was CAUSING the tearing out ?
and was that over lots of figure or on milder stuff ?

[Brian Holcombe]

Howdy,

Mind you, I presented this as a surface quality issue and that was the issue originally being solved. I found the minimized tear out to be an added benefit of being able to improve the chipbreaker setting.

We're not talking heavily burled woods, mostly straight grained hardwoods such as walnut/maple/ash/oak, ect.

[Malcolm Schweizer]

It's funny you mention this. As you know I work with a lot of figured woods. I have a bevel up smoother (Veritas) that I love and I have high angle blades for figured woods. I also have a toothed blade. I recently got a LN #4 with standard pitch. It makes easy work of the figured mahogany and maple. I had intended to eventually get a high angle frog, but I am very pleased.

[Jeff Ranck]

Seems to be in line with Derek's investigations when he was review the new LV custom bench planes. When he and I talked, he said that based on his investigations, he'd recommend 42 deg. frog with a tight chip breaker or 50 some degree without a tight chip breaker. I'd have to go back and find the post to see what the final high degree number was.

[bridger berdel]

I'm building a 35 degree, bevel down with chipbreaker smoother. it's a block plane with the guts milled out and replaced with wood infills. it's to the point of usability, though the wedge in it now is poorly fitting making adjustment a pain. I have planned a brass lever cap, which should fix the problem. so far, in the few test cuts I've made in heavily figured walnut it leaves a very nice surface and is easy to push. the narrow blade, 1-5/8 wide may be a factor.

Thought I'd post up my results of moving to a 45 degree pitch from a 55 on my #4 smoother.

In American hardwoods working with the standard pitch I was able to reduce tear out over the 55 degree pitch for reasons I did not expect.

In my use of the 55 degree pitch I found that attempting to utilise a very tight setting on the chip breaker was resulting in 'accordian' chips' which indicate an over-tight chip breaker well ahead of the range that was actually considered tight by sources such as David Weaver. The result was that I either needed to take a very light cut or back off the chip breaker, the former was producing a tear-out free cut but was taking forever to actually finish a tabletop.

So I moved to the 45 degree pitch and found that the plane is easier to set and achieve a rolled up chip or one that comes out of the plane mostly curled. No crinkles! I could set the chip breaker to the right number and take a decent cut while maintaining a tear out free finish in American hardwoods. The plane with a tight chip breaker is still easier to push than the high pitch with a looser setting.

[lowell holmes]

You can have multiple irons and grind them to different angles.

I have four different angle irons for my Lee Valley bevel up planes. My bevel down planes all have the same grind to them. I'm not sure what different angle grinds will do for a bevel down plane though.

[Derek Cohen]

Here are my observations. Hopefully they may de-confuse those that are interested.

Firstly, both high cutting angles on BU and BD planes and a set chipbreaker on a BD plane all are effective in taming tearout. None of these are necessary with straight grained wood.

Secondly, a high cutting angle (55 or 60 degrees) on a BU plane will push with considerably less apparent resistance than the equivalent angle on a BD Bailey patten plane owing to the lower centre of gravity of the former. The handle style can lower or raise the effort as well - that centre of effort thingy I have been banging on about.

I cannot feel a significant difference between pushing 45- or 50 degrees in a Bailey plane. The difference in the surface quality is insignificant. There is also not a lot of difference in feel between 42- and 45 degrees, but just enough to make a difference if you are prepared to use a chipbreaker most if the time. Note that the lower the frog angle, the more exacting it is to set a tight chipbreaker, annd the higher ithe angle needs to be at the leading edge.

I would argue that 45- degrees on a Bailey has a similar effort to a 55-degree included angle on a BU plane. If the latter feels harder, then the blade is not sharp enough.

For hardwoods, it would be difficult to tell the difference between cutting angles once a finish is applied. This may be more apparent on softer woods.

Regards from Perth

Derek

[Brian Holcombe]

Makes perfect sense that the BU would push easier since there isn't a chip breaker to increase resistance.

The surface finish shows up more considerably in softer hardwoods, such as walnut. I can hardly tell the difference in Honduras rosewood or ebony, but I can certainly see the difference in walnut.

[ian maybury]

Could it be there's variables in play we don't think much about - or set out to control?

Mentioned it before, but thinking about the dynamics it seems likely that the degree of tear out prevention/hold down force is probably related to how tight a radius a chip can be curled up and around through while still flowing smoothly, and while not suffering one or other sort of failure/break up.

Overstressing the chip (by turning it through too tight a radius) so that it breaks up (which crinkling is potentially the start of?) seems likely to result in the hold down force sharply reducing - at least intermittently/until a new length of chip is raised that can push against the chip breaker/bevel again.

It wouldn't come as a big surprise to find that the precise profile of the tip of a BD chip breaker didn't make a significant difference too - it's possible to imagine the chip heading up the face of the iron only to collide with the nose of the chip breaker - and breaking up if the angle is too steep. The surface finish probably matters too - in that a polished surface is more likely for a given angle to permit the chip to deflect off it to keep on flowing - but the resulting hold down force may be lower and it might (?) behave more like a chip breaker placed a bit further back and/or with a shallower nose angle.

The other extreme - making the angle at the nose of the chip breaker too shallow - might result in a situation where it simply isn't possible no matter how close the chip breaker is moved to the cutting edge to generate enough hold down force to prevent tear out on some woods.

The pitch of the frog Brian sounds like another variable in all of this. Combine a steep frog with a steep nose on the chip breaker (and maybe a less than finely polished breaker surface too) and it seems quite possible that it could tip matters over into overstressing and fracturing the chip, reducing the hold down force, and permitting more tear out than would a less steep set up.

The characteristics of the wood must count too. If there is weak adhesion between fibres, but the fibres are brittle and fracture easily when bent or when compressed lengthwise then it seems likely that such a wood will be very difficult to plane without tearout. The chip will tear out easily, but the max bend radius that can be applied (by steepening the pitch, moving up the chip breaker etc) may be reached quite early. i.e. before the steepest available set ups. These set ups may be perfectly usable on another wood with strong tear out resistance and tough fibres - one that will accept tight bending of the chip and heavy compressive forces without failure.

My guess (in what is mostly a thought experiment) is that the tear out prevention performance of a given set up depends on at least the above four variables. (the characteristic of the wood, the pitch, the angle of the chip breaker nose, and the surface finish) Three variables in the case of a BU plane - in that the bevel angle covers the effect of both the chipbreaker position and it's nose angle.

If this is actually the case then it could be that the drinks (in terms of results) might get a bit mixed/contradictory if only two variables e.g. the pitch and the chip breaker distance setting are focused on during trials and not the others….

[Brian Holcombe]

Thanks for the thoughts Ian. I did not post up the process, but I did run through a lot of changes on these variables prior to settling on my change in pitch, including chip breaker nose angles, finishes and settings.

My thoughts are that the standard angle allows a wider tolerance for what will produce a good shaving, where the high pitch has a more narrow range and also generally requires a thinner shaving.

I do not have time to constantly manipulate the settings on my planes, I like to have a good setting that works for most situations and put it to use. Save adjusting for a tighter chipbreaker setting in situations where it is needed.

I regularly run multiple projects consecutively and so I need something which can run over walnut, maple, ash, oak, ect without much unique consideration.

[ian maybury]

Sorry Brian if it sounded like i was suggesting you hadn't tried stuff - that wasn't the intention. I was more flying a kite/suggesting a possible mechanism for what you found. Trying to explain why a steeper pitch on a given wood might just disimprove rather than improve the control of tearout.

Guess we're all in the same boat - we end up working by applying practical rules of thumb, and it's only when something acts up that we're forced to dig deeper. You did, and what you found was (as i read it) a little counterintuitive. Guess i was in a long winded way theorising as to why that might have been the case - why maybe more of a good thing (as in this case driving even more forward force into the chip to increase the hold down effect) might not necessarily deliver an improvement in every situation...