Query - Cambered Blades on BU Irons??

[Woodbloke]

Right chaps, this is a specific query, so please, please don't turn it into an interminable sharpening discussion!

The background is that for many years I've always maintained (wrongly as it happens) that it's virtually impossible to generate a deep enough camber on a BU blade, so I've always used a flat blade with rounded corners...sort of a 'hybrid' blade as explained by Garret Hock in one of his UToob videos.

During the recent very hot spell, the 'shop was too hot to work in so I spent time in the coolest room of the house looking at a few videos from the late David Charlesworth, one of which was this one in which he demonstrates that a camber of .5mm each side can be ground on the Tormek using the SE77 jig.

David maintains that this is enough of ground camber for a BU plane, but you then need to hone a secondary bevel which will follow it and I wondered whether or not the Veritas camber roller would provide enough 'swing' each side to match a 0.5mm bevel? The online bumf suggests that it's a 'limited' camber but gives no indication of how much. I suspect the Veritas camber won't match David's ground BU camber and is intended more for BD plane irons.

I don't want to disappear down a grinding rabbit hole if I can't find a honing jig that'll match the grinding bevel; the other 'el cheapo' option I've got is an original Eclipse jig with a narrow roller which would do the job, but I'd rather use the Veritas camber roller.

Any useful experience; what say ye? - Rob

 

[Dr.Al]

Right chaps, this is a specific query, so please, please don't turn it into an interminable sharpening discussion!

The background is that for many years I've always maintained (wrongly as it happens) that it's virtually impossible to generate a deep enough camber on a BU blade, so I've always used a flat blade with rounded corners...sort of a 'hybrid' blade as explained by Garret Hock in one of his UToob videos.

During the recent very hot spell, the 'shop was too hot to work in so I spent time in the coolest room of the house looking at a few videos from the late David Charlesworth, one of which was this one in which he demonstrates that a camber of .5mm each side can be ground on the Tormek using the SE77 jig.

David maintains that this is enough of ground camber for a BU plane, but you then need to hone a secondary bevel which will follow it and I wondered whether or not the Veritas camber roller would provide enough 'swing' each side to match a 0.5mm bevel? The online bumf suggests that it's a 'limited' camber but gives no indication of how much. I suspect the Veritas camber won't match David's ground BU camber and is intended more for BD plane irons.

I don't want to disappear down a grinding rabbit hole if I can't find a honing jig that'll match the grinding bevel; the other 'el cheapo' option I've got is an original Eclipse jig with a narrow roller which would do the job, but I'd rather use the Veritas camber roller.

Any useful experience; what say ye? - Rob

I have very, very limited experience so take what I say with a pinch of salt. I've done no measurements or calculations or anything like that.

I followed Derek Cohen's suggested approach and started with a 25° bevelled iron for three different irons. The secondary bevel was then ground to a different angle for two of them to get different options. All were cambered with the Veritas roller and I found it quite easy (or at least, as easy as a LA plane ever is) to then adjust the blade such that it cut evenly in the middle but tapered off slightly at the edges, just like my BD plane would.

 

[Woodbloke]

I followed Derek Cohen's suggested approach and started with a 25° bevelled iron for three different irons. The secondary bevel was then ground to a different angle for two of them to get different options. All were cambered with the Veritas roller and I found it quite easy (or at least, as easy as a LA plane ever is) to then adjust the blade such that it cut evenly in the middle but tapered off slightly at the edges, just like my BD plane would.

I've seen the DC video on UKW which is now pretty old (if it's the one I'm thinking of) but Charlesworth's approach to grinding the BU blade bevel is much more sophisticated. It would appear that you had some success Dr. Al using the Veritas Camber Roller with your BU blades...any chance of a pic or three so see if it's the sort of thing I'm after? - Rob

 

[Cabinetman]

Sorry to be contentious, I’ve been making furniture for 40 years -seriously for the last 15 and only ever felt the need to round off the sharp corners a bit. What are you doing that needs that rounded bottom “groove” ?
Hoping not to get my head bitten off.

 

[Dr.Al]

I followed Derek Cohen's suggested approach and started with a 25° bevelled iron for three different irons. The secondary bevel was then ground to a different angle for two of them to get different options. All were cambered with the Veritas roller and I found it quite easy (or at least, as easy as a LA plane ever is) to then adjust the blade such that it cut evenly in the middle but tapered off slightly at the edges, just like my BD plane would.

I've seen the DC video on UKW which is now pretty old (if it's the one I'm thinking of) but Charlesworth's approach to grinding the BU blade bevel is much more sophisticated. It would appear that you had some success Dr. Al using the Veritas Camber Roller with your BU blades...any chance of a pic or three so see if it's the sort of thing I'm after? - Rob

I've not seen any videos (DC or Charlesworth) about cambers: just read the blurb on DC's website, which I think he linked to here.

Happy to take pics later, but I'm not sure what you want them to be of. The camber isn't very obvious to look at (although you might be able to see a difference in width of the shiniest bit I guess - depending on my photography skills). I judge it to be good enough if I can adjust the squareness of an edge, although I rarely use the BU plane for that.

 

[Woodbloke]

Sorry to be contentious, I’ve been making furniture for 40 years -seriously for the last 15 and only ever felt the need to round off the sharp corners a bit. What are you doing that needs that rounded bottom “groove” ?
Hoping not to get my head bitten off.

I'm not sure meself :lol: either but it's just an itch that needs scratching. I've been building furniture for a lot longer than 15 years and have always used a flat plane blade (with corners rounded) but I wondered if there was an advantage to be gained with a cambered BU iron. Many users think there is; the downside is that it's a lot more awkward to maintain a constant curved camber, which is another thing that Garret Hack mentions.

Please don't let this discussion stray into flat vs cambered...we don't want to go there! - Rob

 

[Dr.Al]

I took a photo. I've no idea whether it'll be useful to you :lol:

This is a close-up of one side of my high-angle blade (I chose that one because it was on top of the pile of not-fitted to a plane blades ). I didn't sharpen it for the photo and it's definitely been used since last sharpening.

As with all of them (as per DC's guide), the primary bevel is 25°; the secondary is 40° on this one (I was aiming for 38° for a 50° combined angle, but got lazy and the Veritas honing guide has a 40° setting). The camber (which was created by putting more pressure down on each side for about 20 back-and-forth strokes on a waterstone if memory serves me correctly) is a lot more obvious than I thought it would be. Grid paper is 5 mm squares; I lined the blade up so both front and side edges ran along the grid lines.



I think the brown marks are out-of-focus sawdust.

Does that help at all?

 

[Woodbloke]

Thanks for that Dr.Al, very handy bscene-drinkingcheers: If those are 5mm squares, it looks like you've achieved the requisite 0.5mm camber at the end of the blade, which is the sort of result I was looking for - Rob
Edit - I think what I'll do is to get hold of one of they Veritas cambered rollers and have a test run on one of my BU plane blades after I've followed David Charlesworth's grinding instructions on his video.

 

[Philly]

Rob
Not sure if I'm too late, I have a cambered Veritas roller you can have if you haven't already pulled the trigger?
Drop me a PM
Philly

 

[Woodbloke]

Rob
Not sure if I'm too late, I have a cambered Veritas roller you can have if you haven't already pulled the trigger?
Drop me a PM
Philly

Philly, you're a star! I'll drop you a PM soonest - Rob