Shoulder plane technique

[JeremyM]

I think its the terrible chatter you describe which is causing the blade damage and its the cause of the chatter that needs understanding. Finely set and well tuned this plane needs remarkably little force to cut across the grain and HNT irons stand up pretty well to tough woods. I'm sure Terry Gordon wouldnt mind an email from you and would help resolve this quickly.

Jeremy

 

[dunbarhamlin]

the 10 deg back bevel on my No 9 allows honing at 20 deg (so blade is sharp at 10 +20 = 30) The effective bed angle is reduced to 10 deg [and the EP] to 40 deg

I think that's quite ingenious. With an O1 blade you could drop that EP into the realms of an unjigged bench chisel.
Unfortunately not particularly useful on a LA block (could only lower EP by 5° without making the edge more acute) but great for BU planes with higher bed angles.

 

[Philly]

D
No, it doesn't work like that on bevel up planes. As I said, its only the upper surface that the wood sees - in this instance all the back bevel is doing is increasing the amount of relief behind the cutting edge.
Philly

 

[graween]

Hi,
On bevel up planes tuned for end grain. If you grind a bevel at 20° instead of 25 (angle at which the blade often comes from factory) it might help to grind a 5° back bevel. Because this give you as pointed by Philly a lower angle but helps having a stronger edge.
That gives you about 7° of relief, and an overall edge angle of 25°, with on a 12° bed gives a effetive angle of 32°.

Garette Hack even recommend for soft woods to lower to 15° (with 5 back bevel).
I have a plane that I want to set like this, but never had time to.

 

[dunbarhamlin]

a) relief
b) back bevel
c) bevel angle
d) edge - the backbevel thickens (ie strengthens) this.
e) effective pitch
and the one I forgot to label, the bed angle, is that between the red lines

Without the back bevel, to have an edge with the same durability would need a steeper bevel angle (c) - like dropping concord's nose.

 

[Philly]

Yes, thats about it. Been going to do a diagram, but you beat me to it :lol:

The only thing the wood "sees" is the effective pitch. With a paring chisel you can lower the angle for a easier cut (obviously trading off edge durability) You can compare the back of a chisel with the sole of a plane and the bevel of the chisel with the upper surface of the iron in a plane. Putting a back bevel on a bevel up plane doesn't alter the effective pitch, and does not make for an easier cut like a paring chisel.
In the diagram angle "E" is the cutting angle - altering "B" has no effect on the effective pitch.

Philly

 

[dunbarhamlin]

In the diagram angle "E" is the cutting angle - altering "B" has no effect on the effective pitch.

Agree. Cutting bevel angle (and therefore EP) can be reduced if a back bevel is used, but the back bevel does not itself reduce the EP.

My unjigged bench chisel would have a bevel of 30°

Given a BU plane with a 20° bed and decent O1 iron:

• minimum relief angle of 7°
• minimum edge angle of 20°

Maximum backbevel is bed angle - relief angle = 13°
So to keep a 20° edge, the cutting bevel = 7°

So lowest EP achievable with 20° edge = bed angle + cutting bevel = 27°
That's lower than my bench chisel used flat against the surface.

(A 15° edge gives a minimum EP of 22° - which is (near enough) paring territory - this'd really be using it as a BD plane - doubt it's practicable, but might be amusing to try )

 

[woodbloke]

Yes, thats about it. Been going to do a diagram, but you beat me to it :lol:

The only thing the wood "sees" is the effective pitch. With a paring chisel you can lower the angle for a easier cut (obviously trading off edge durability) You can compare the back of a chisel with the sole of a plane and the bevel of the chisel with the upper surface of the iron in a plane. Putting a back bevel on a bevel up plane doesn't alter the effective pitch, and does not make for an easier cut like a paring chisel.
In the diagram angle "E" is the cutting angle - altering "B" has no effect on the effective pitch.

Philly

Philly is quite right. With a BU configuration, honing a so called 'back bevel' on top of the existing one increases the effective pitch, ie the angle that the timber actually sees, putting on the underside (the flat part) don't. Thus if the bed angle is 12deg and the blade is honed at 28deg, the effective pitch is 40deg. To make the EP into say 70deg (which is sometimes the EP on a BD cofiguration, where the back bevel is honed on the reverse side) an additional bevel of 30deg would need to be honed - Rob

 

[Philly]

Was reading through "Classic Hand Tools" by Garrett Hack last night - on page 112 there is a diagram labelled "bevel angles". The fourth diagram (on the bottom) displays a bevel up blade and shows a back bevel. It says "a 5 degree back bevel doesn't change the cutting dynamics but makes the edge more durable".
Hope that clears that up :wink:
Philly

 

[dunbarhamlin]

Now I'm confused. Sounds like we all agree. The back bevel makes the edge more durable by rendering the edge "thicker" or less acute. This could alternatively be used to allow a shallower primary/upper/cutting bevel.
Just like concorde's nose. It's the same pointiness (and so similarly durable) no matter what angle it is at.

 

[frugal]

Now I'm confused. Sounds like we all agree. The back bevel makes the edge more durable by rendering the edge "thicker" or less acute. This could alternatively be used to allow a shallower primary/upper/cutting bevel.
Just like concorde's nose. It's the same pointiness (and so similarly durable) no matter what angle it is at.

But if concorde flies at mach 2 with the nose down it snaps off, thus making the worlds fastest convertable

<wonders>

 

[woodbloke]

Now I'm confused. Sounds like we all agree. The back bevel makes the edge more durable by rendering the edge "thicker" or less acute. This could alternatively be used to allow a shallower primary/upper/cutting bevel.
Just like concorde's nose. It's the same pointiness (and so similarly durable) no matter what angle it is at.

But if concorde flies at mach 2 with the nose down it snaps off, thus making the worlds fastest convertable

<wonders>

... used to fly at Mach 2 - Rob

 

[dunbarhamlin]

Now I'm confused. Sounds like we all agree. The back bevel makes the edge more durable by rendering the edge "thicker" or less acute. This could alternatively be used to allow a shallower primary/upper/cutting bevel.
Just like concorde's nose. It's the same pointiness (and so similarly durable) no matter what angle it is at.

But if concorde flies at mach 2 with the nose down it snaps off, thus making the worlds fastest convertable

<wonders>

... used to fly at Mach 2 - Rob

That's why it had a backbevel and lower EP in supersonic flight
Only had issues in high EP mode :twisted:

 

[Philly]

Apologies, D. Yes, we do agree
Philly

 

[dunbarhamlin]

Maybe my mates are right - my prose really is clearer after translation from English to Russian to Chinese and back to English using Babelfish.
(The devils even tried to prove it once)

 

[Chris_belgium]

I have contacted the people at HNT and Terry promptly send me a new blade, great service, but to my surprise the problem still wasn't solved.

I can get full lenght long grain shavings but not thinner than 0,3mm, I then checked the flatness of the sole with a straight edge and the sole in front of the blade is not level with the sole behind the blade, could this be the source of my problems or is this as it should be?

attempted to make a picture:

 

[Steve Maskery]

Ouch! That doesn't look right to me.
S

 

[Ironballs]

That looks like a good candidate for the problem to me, go back to HNT, I'm sure they'd be happy to have a look

 

[Modernist]

There still seem to be some fundamental misunderstandings here to me.

Whilst the sole is a problem I think the sharpness of the blade is the main issue, especially looking at the shavings in and early pic.

The honing angle of 30 deg is not a "microbevel"! it is the standard honing angle. The blade should be honed to about 5 deg steeper than the grinding angle to give a stronger edge than a single bevel. This may be about 20 thou wide in old money. Before all of that the back of the blade needs to be honed to a fine polish.

This is basic stuff but it doesn't seem to have been bottomed here.

Combine that preparation with a fine cut and see where that takes us.

Brian

 

[Chris_belgium]

There still seem to be some fundamental misunderstandings here to me.

Whilst the sole is a problem I think the sharpness of the blade is the main issue, especially looking at the shavings in and early pic.

The honing angle of 30 deg is not a "microbevel"! it is the standard honing angle. The blade should be honed to about 5 deg steeper than the grinding angle to give a stronger edge than a single bevel. This may be about 20 thou wide in old money. Before all of that the back of the blade needs to be honed to a fine polish.

This is basic stuff but it doesn't seem to have been bottomed here.

Combine that preparation with a fine cut and see where that takes us.

Brian

I have tried both, a fully sharpened 30° bevel without microbevel, but also a 30° bevel with a 5° microbevel. Neither worked, the new blade I have recieved from HNT was sharpened by them and was razor sharp, but still no succes.

I tried to get a fine cut, but cannot get a shaving thinner than 0,3mm, if I retract the blade more (checked with feeler gauge) the blade does not touch the wood anymore.