IanB
Established Member
I've just bought my first one. Should I put a secondary bevel on the blade?
Low angle, bevel up jack plane
- Thread starter IanB
- Start date
Help Support UKworkshop.co.uk:
AESamuel
Established Member
Using secondary bevels definitely makes sharpening faster, but just pick your desired angle and go for it.
Caveat that I only have standard angle bench planes... but a major selling point of a low angle jack is sold as better performance in end grain where the lower angle helps slice the fibres.
If you have the 12 degree bed angle + 25 degree primary bevel, then + 5 degrees for a secondary bevel and maybe even a micro bevel on top your quickly going to end up with something thats essentially the same as a standard angle plane (which still works great).
I would suggest maintaining a 25 degree bevel angle and just polishing the very edge at +2 degrees to give you an overall angle of 39ish degrees. If you find this to be a major hassle you can always introduce a secondary bevel later.
If you have the 12 degree bed angle + 25 degree primary bevel, then + 5 degrees for a secondary bevel and maybe even a micro bevel on top your quickly going to end up with something thats essentially the same as a standard angle plane (which still works great).
I would suggest maintaining a 25 degree bevel angle and just polishing the very edge at +2 degrees to give you an overall angle of 39ish degrees. If you find this to be a major hassle you can always introduce a secondary bevel later.
Another approach would be to try at 25, if the edge doesn’t hold up in use, then add a micro bevel increasing the angle til it holds up in use.
mad has been said once you get too high on the bevel it’ll be presenting at the same angle as a regular plane and so is no longer “low angle”
mad has been said once you get too high on the bevel it’ll be presenting at the same angle as a regular plane and so is no longer “low angle”
Derek Cohen (Perth Oz)
Established Member
A 25 degree bevel will create a 37 degree cutting angle (25 + 12 degree bed). This is fine for end grain and for traversing across the grain, but absolutely hopeless for face grain, unless you are planing a straight-grained Pine with the grain!
For comparison, a Stanley bench plane (regardless of the number) has a 45 degree frog which, used bevel down, creates a 45 degree cutting angle. The Stanley would be passable on face grain, as long as one takes fine shavings. For interlocked timber. you control tearout by closing down the chipbreaker.
A bevel up plane, such as the LA Jack, relies on a high cutting angle to control tearout. This would be a cutting angle of 55-65 degrees. For example, a secondary bevel of 50 degrees creates a 62 degree cutting angle. That is excellent for face grain.
Regards from Perth
Derek
For comparison, a Stanley bench plane (regardless of the number) has a 45 degree frog which, used bevel down, creates a 45 degree cutting angle. The Stanley would be passable on face grain, as long as one takes fine shavings. For interlocked timber. you control tearout by closing down the chipbreaker.
A bevel up plane, such as the LA Jack, relies on a high cutting angle to control tearout. This would be a cutting angle of 55-65 degrees. For example, a secondary bevel of 50 degrees creates a 62 degree cutting angle. That is excellent for face grain.
Regards from Perth
Derek
Derek's advice is good. I'm avoiding duplicating his efforts after spending my personal gas tank trying to help people avoid getting into the scrub rage.
Derek's advice tests out from pine to cocobolo denser than water, though.
Derek's advice tests out from pine to cocobolo denser than water, though.
IanB
Established Member
Thanks for all the advice. Looks like I'm going to need to invest in a second blade to give me different options!
Jacob
What goes around comes around.
Don't they come ready to use out of the box? In which case you don't need to do anything.
But when you get around to having to sharpen it at 30º you may find that rough grinding the back of the bevel (not the edge) at slightly shallower angle will help speed things up, instead of having to fine hone the whole bevel.
This is the only purpose of the "primary" bevel - it is about speeding up sharpening, removing metal faster, and has no bearing on the cutting ability of the edge.
I wouldn't bother with a second blade, if ever, until you are totally on top of planing/sharpening with what you already have.
PS I just edited this - I get confused about modern sharpening terminology "primary/secondary" etc and for some reason they call the face the "back" but they don't call the back the "face". It was all re written in the 80s or 90s.
Last edited:
David C
In Memorium
No planes work out of the box, the blades are ground but not sharpened.
The less this ludicrous idea is mentioned the better.
Happy new year,
David
The less this ludicrous idea is mentioned the better.
Happy new year,
David
Jacob
What goes around comes around.
You are right (ish). They say "Precisely made, fit and finished, all Lie-Nielsen planes are ready for use right out of the box with minimal honing required" which means they are NOT usable out of the box as, guess what, minimal honing is required!
I always thought it was a ludicrous idea myself!
So that's the answer for our OP: honing is required. 30º is the angle generally.
Happy new year to you too David
The last I checked, they hand lap the backs of the irons. I'd imagine there is one of two reasons they don't prepare the irons and charge another $10 for it (as in prepare the bevel side and the chipbreaker).
1) there may be some lame insurance reason
2) if you actually sharpened a plane, people would complain about the way you sharpened it
IanB
Established Member
Interestingly, veritas tell me that the primary bevel is actually ground to 23°, and as supplied it is ground with a 2° micro bevel (which on close inspection is indeed there, though barely visible); so for end grain work, just sharpen at 25° to maintain the 2° secondary bevel angle.
Derek Cohen (Perth Oz)
Established Member
Every BU plane blade I have received over the years gets a 25 degree hollow grind to prepare the way. This is just a first step.
These are my blades, and I (as does everyone) have a preferred sharpening method. Don’t simply treat what a factory does as being cast in concrete.
Regards from Perth
Derek
These are my blades, and I (as does everyone) have a preferred sharpening method. Don’t simply treat what a factory does as being cast in concrete.
Regards from Perth
Derek
