Frog adjustment

[newt]

Some of you may have the book by GARRETT HACK the plane handbook. On pages 60 and 61 there is I think an ambiguity. With reference to the Bailey type frog, he suggests both in the drawings and the text that the frog should be adjusted so that the plane iron rests on both the frog and the bevel on the sole. It shows that if it is to far forward it is only supported by the frog and if to far back only by the bevel on the sole. Both of these positions will create chatter. Therefore if the only position for no chatter, eg with the frog and sole bevel aligned ( see top left hand drawing page 60) how can it be used to adjust the mouth opening. I have tried the forward position with only frog support and have never experienced a problem. What do you think.

 

[paulm]

Hi Pete,

Speaking from intuition here rather than experience (!) but I would have thought most support is from bedding onto the frog and that any additional support from the bevel on the mouth is small by comparison and probably insignificant as long as there is a decent well adjusted chipbreaker on the blade and/or the blade is a decent thickness ?

Cheers, Paul.

 

[woodbloke]

Pete - I've often pondered on that one. I suppose the position for maximum support is when the frog and sole bevels line up in one plane but iirc this doesn't occur with the Bedrock design as in you No4 LN as you get very good support for the blade - Rob

 

[Paul Chapman]

Pete, my observations suggest that the lack of precision with many Bailey pattern planes is such that you might be fettling and fiddling about for a very long time if you hope to get the blade resting on the frog and its bevel on the sole. In many cases I think you will find that the front edge of the frog is not completely parallel with the rear edge of the mouth.

I've not read Garrett Hack's book, but from your description I don't really buy his argument. I often adjust the mouth of my planes and would be reluctant to adopt any method that lost that facility. In my view the best way to avoid chatter is to go for a Bedrock-style frog, a thick blade and a good cap iron.

Cheers :wink:

Paul

 

[newt]

I agree the bedrock solves the problem, but why does he suggest that its adjustable and then says it must remain flush with the sole bevel. Beats me as he is an expert.

 

[Paul Chapman]

but why does he suggest that its adjustable and then says it must remain flush with the sole bevel.

He probably hoped you'd read that bit quickly and not notice the contradiction :lol:

Cheers :wink:

Paul

 

[Mike B]

It makes sense from a maximum support point of view, but is a contradiction as this then does not allow any adjustment of the mouth. I guess this is why there has been a move towards thicker irons as this will minimise any chatter introduced by adjusting the mouth.

Haven't Lee Valley addressed this in their bevel down bench plane design with a frog that extends all the way through the sole??

Now, what I don't understand is why bevel down planes have chip breakers where as bevel up designs, even when ground to give the same working blade angle, do not seem to require one...

 

[engineer one]

mike, how about th is for a flyer.

if you chisel a piece of wood with the chisel at the same approx angle as your plane blade with the bevel down, don't you kind of dig down into the wood, whereas when you have the bevel up, you can go along in a more straight line, and i think the same applies with planes/

the chip breaker does just that, on a bd, but the cutting action on bu does not peel in the same way i think.

happy as usual to be told that is b******s, but seems more logical. :roll: :twisted:

paul :wink:

 

[David C]

Newt,

I have set up many many planes in this workshop, and have never been worried about getting the frog surface and back edge of throat in line, as I am more concerned with setting mouth width and parallelism.

I am certain that the heel of the bevel on a thicker (2.4mm and above) blade rests on the frog. (Try a full sized drawing).

Garrett's book is a classic but this point can be ignored in my opinion. Though it may have had some relevance for thinner 1.8mm blades used for very heavy work? I need to draw that one out myself!

David Charlesworth

 

[Anonymous]

Newt

I think it is irrelevant if the blade is of a decent thickness such as those in an LN or LV bench plane

 

[bugbear]

Some of you may have the book by GARRETT HACK the plane handbook. On pages 60 and 61 there is I think an ambiguity. With reference to the Bailey type frog, he suggests both in the drawings and the text that the frog should be adjusted so that the plane iron rests on both the frog and the bevel on the sole.

Indeed he does. Which renders the mouth of a Bailey plane effective non-adjustable, since there's (implicitly|) only one "correct" position.

If you believe Hack, that is.

Personally, I find that the issue Hack raises is not a major factor, and use the adjustable mouth as Leonard Bailey intended


BugBear

 

[bugbear]

I

Haven't Lee Valley addressed this in their bevel down bench plane design with a frog that extends all the way through the sole??

Yes

Oh, and adjustable mouth planes with sliding toe pieces bypass the issue in a different way (e.g. block planes, SMT Loopy infills etc)

BugBear

 

[newt]

I agree with David C, as I said, I have never had a problem with the mouth adjustment, its just the confusion and ambiguity that irritated me. A plane is designed with an adjustable mouth, but it can only be in one position!. By the way I found the book very interesting and informative.

 

[newt]

Ref David C post. I took some measurements of my bailey No4 as follows:
The depth of the bevel on the sole is 2mm at angle of 45 degrees, the plane iron is 2.1mm thick, the 25 degree bevel on the plane iron is 4.9mm deep. Transposing these measurements to a 4* scale drawing with the frog face set flush with bevel on the sole, and the iron set flush with the sole eg no set, the bevel on the iron misses the bevel on the sole by .2mm and therefore at this setting the sole bevel is providing no support to the iron. This indicates that even with a moderate depth of cut the blade iron will only just make contact with the sole bevel. Given a 10% error in measurements and manufacturing this shows that the sole bevel is unlikely to provide any useful support and therefore the frog can certainly be moved forward with no significant change in performance regarding chatter.

Of course if you moved the frog back from the flush setting the plane iron will make contact at some point, but this would get a bit messy as the pressure on the cap iron would start to distort the blade as it is pushed away from the frog. Also be mindful of what David said a thicker blade would produce a greater difference possibly to the point that what ever the depth of cut the sole bevel would not be playing a supporting role.

 

[Paul Chapman]

That's very helpful, Pete. Just goes to show that you can't believe everything you read - even when it's written by experts :wink:

Cheers :wink:

Paul

 

[Skip J.]

Ref David C post.
Of course if you moved the frog back from the flush setting the plane iron will make contact at some point, but this would get a bit messy as the pressure on the cap iron would start to distort the blade as it is pushed away from the frog. Also be mindful of what David said a thicker blade would produce a greater difference possibly to the point that what ever the depth of cut the sole bevel would not be playing a supporting role.

Hello from Texas..

My #4 is fettled according to David C.'s article, including the work to the frog, plus a few extras. With the stock blade in place, it does chatter a small amount until being seated on the sole. Moving it onto the sole causes the blade to be in the wrong position and cuts oddly..

Leaving the adjustment at the correct location, or adjusted nearby somewhat, and use of a Hock blade solves the chattering.

 

[Newbie_Neil]

Hi Skip

Welcome to the forum.

Cheers
Neil

 

[newt]

One further point all bevel down planes irons are unsupported in the area of the bevel some 5 to 6mm on the front face back from the edge, more as the blade gets thicker, bedrock does not overcome this. However a thicker iron and cap iron will of course will significantly reduce backward flexing and hence chatter. Bevel up has different dynamics particularly with the adjustable mouth.

 

[Skip J.]

One further point all bevel down planes irons are unsupported in the area of the bevel some 5 to 6mm on the front face back from the edge, more as the blade gets thicker, bedrock does not overcome this. However a thicker iron and cap iron will of course will significantly reduce backward flexing and hence chatter. Bevel up has different dynamics particularly with the adjustable mouth.

Newt is exactly right about that...

Thanks Neil - hope ya'll don't mind my "Texanisms"...