Thread: Anyone built a roubo frame saw?

I thought I should give the Blackburn Tools style kerfing blade a trial. Really I only established that it cuts:

P1070687 (Medium).JPGP1070688 (Medium).JPG

It was not much of a test as the wood was short (and I don't know what it is). The bare blade was held in my bare hand so the conditions were less than ideal to put it mildly! However, based on this very poor test I think it will work well when set up properly in a plane body and a fence even on long lengths of timber.

Regards
Paul

I wanted to publicly thank @BushMiller for sending me a chunk of saw plate.

I am stoked.

He was incredibly generous in prepping/cutting it for me, plus posting it in his own time and dime.

+17 karma points, plus a happy chap on this end

Thank you kind sir!

Originally Posted by Bushmiller

I thought I should give the Blackburn Tools style kerfing blade a trial. Really I only established that it cuts:

P1070687 (Medium).JPGP1070688 (Medium).JPG

It was not much of a test as the wood was short (and I don't know what it is). The bare blade was held in my bare hand so the conditions were less than ideal to put it mildly! However, based on this very poor test I think it will work well when set up properly in a plane body and a fence even on long lengths of timber.

Regards
Paul

How long did you make that blade? Looks like you could make 2 kerfing planes from that. The Blackburn one is 10" long.



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Originally Posted by Cklett

How long did you make that blade? Looks like you could make 2 kerfing planes from that. The Blackburn one is 10" long.



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CK

The camera never lies but it does deceive! Actually even that is not true today. It is 250mm, which is of course very similar to Blackburn's 10". The timber is short and not a good test piece.

Regards
Paul

Originally Posted by Bushmiller

CK

The camera never lies but it does deceive! Actually even that is not true today. It is 250mm, which is of course very similar to Blackburn's 10". The timber is short and not a good test piece.

Regards
Paul

What a deceit [emoji6]. Are you planning to build a kerfing plane around it?

I also noticed that Blackburn has like a long tapered leading edge in front and behind the teeth line. Not sure if that has an advantage or not. Maybe to have a smoother entry into the cut?

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Just for anyone placing an order with Blackburn tools, just received a note from Issac on the current state of things.

"Thank you for your order. Yes, I'm still running behind and with little relief in sight. I had no idea that the covid effect would be so strong, and am even more surprised at how long it has lasted.


The estimate of 8-12 weeks is still what I'm expecting, if not a little longer. I'm doing all I can to catch up, but it's been slow going."

I don't have a plan for bandsaw for a while so I'm keeping my order in the queue as being able to resaw by hand with this saw specifically is something I've wanted for a while. Have plenty of energy to burn at times so think it will match me and my hand tool ambitions well. Worth the wait

Cheers
Nathan

Originally Posted by Cklett

What a deceit [emoji6]. Are you planning to build a kerfing plane around it?

I also noticed that Blackburn has like a long tapered leading edge in front and behind the teeth line. Not sure if that has an advantage or not. Maybe to have a smoother entry into the cut?

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CK

Please accept my apologies for not replying before. I saw your post almost immediately and planned to try the blade on a more representative piece of timber and comment at the same time. However I was unable to get around to it until today. I am not planning to make a handle in the short term purely because of other more pressing matters, but may look at it down the track. I found a longer piece of pine timber to test. The blade, still without a handle, grabbed in the pine and was very awkward. I tried a rag around the blade and it worked better: It really does need a handle for a proper evaluation!

P1070690 (Medium).JPG

The fence was just a piece of flat bar, which works ok because of the absence of set. I then found a piece of Forest Red Gum (Blue Gum in QLD) and if anything it worked better in the FRG probably because it was unable to bite as deeply.

P1070689 (Medium).JPG

One interesting observation is that the sawdust is more akin to the shavings from a plane than the chips from a saw. It really is a multitoothed scraper. I would have liked to continue to the full depth of the gullets, but the custom built rag was not conducive to sawing!

P1070692 (Medium).JPG

WP

I had not picked up on that tapered lead into the tooth area. Not sure there is much to commend it, but there again I have not tried it.

I think that for both hardwoods and softwoods I would relax the rake on the first 50mm of teeth to achieve a similar effect: Maybe as much as 10° to ease the start of the cut. If I was being really pedantic, I might do progressive teeth too (6ppi say?) for those first 50mm, but this introduces complication as I would then have to source another smaller diameter round file for the gullets. Without the modified gullets it would be simple. If I was doing a lot of hand sawing with the frame I would consider it, but for only occasional use I would just go with the relaxed rake. I did put the barest amount of negative rake on the teeth, but I think the Blackburn saw uses zero rake (neither positive or negative).

I think with a handle instead of a rag it would go well.



Regards
Paul

Bushmiller, do you think the 5/32" (4mm) chainsaw file did a good job?

Bigger might be better?

Originally Posted by woodPixel

Bushmiller, do you think the 5/32" (4mm) chainsaw file did a good job?

Bigger might be better?

WP

I think it was fine with 5/32". A larger file would of course give more gullet capacity, but at the expense of tooth metal and consequently strength. It might be strong enough but only an experiment would confirm this. probably it is not worth going bigger for the relatively small benefit.

Regards
Paul

More depth or more width will get you a bigger gullet volume. I think there'll be a trade-off where too few tpi will make it uncomfortable to use - a really coarse-toothed saw is likely to be a bear to use across the ends! Looking at Paul's prototype, I reckon he's struck a pretty good balance, but as he says, only putting it to serious work will tell you for sure.
Cheers,

Originally Posted by IanW

More depth or more width will get you a bigger gullet volume. I think there'll be a trade-off where too few tpi will make it uncomfortable to use - a really coarse-toothed saw is likely to be a bear to use across the ends! Looking at Paul's prototype, I reckon he's struck a pretty good balance, but as he says, only putting it to serious work will tell you for sure.
Cheers,

Ian

There is another aspect I have only just realised and it is I have only tried the saw, very clumsily without a handle, on the long face of the board. It may be a little different on the end grain. I would expect it to be more difficult to saw, but probably easier to clear the shavings as the board is unlikely to be more than 300mm wide and the kerfing saw could partialy clear the cut.

Regards
Paul

Paul, the cut across the end need only be very shallow, even 3 or 4mm would do, imo, just enough to start the saw in, so as long as the plane can manage that. It is certainly enough for a bandsaw, which is where I most commonly use pre-kerfing. If you are skilled enough starting your saw, you don't need to put a kerf on the end, but having at least a shallow groove does help with starting the cut.
Cheers,

I was checking out some dovetail saws for Simplicity's new thread and I turned up the Disston Stair Makers saw. It occurred to me that with the additional of a fence the style might suit a kerfing saw.

Disston Stair Builders saw 1921.jpg

Just a thought.

In principle, that's pretty much what the Blackburn stock is, Paul, with an 'open' rather than a closed handle..

You are probably showing it for the shape/design & not suggesting the kerfing saw be an exact copy, but based on my experience with "trenching" saws, I'd suggest 6 inches (150mm) for the blade might be a bit short & harder to control with the large teeth we've been discussing. I did quite a bit of mucking about with those saws & ended up making 3, each of different length & different grip angle, looking for the 'right' combination. One had a grip angle that didn't suit me, one was too long & the last one hit the right note. (It's the bottom one in the pic, blade is 225mm long): Trenching saws.jpg

Now these saws have a very different function from the kerfing saws, they are meant to make clean cuts across the grain, but the principal of getting the various parameters like blade length & tooth size & grip angle adjusted in a package that works well would apply. So what I'm saying is, if you don't want to be mucking about with prototypes getting your saw sorted, it's probably a good idea to start with a 'proven' design. I would imagine Isaac put in a bit of time getting his saw to work well, so I'd start by copying his example fairly closely. Of course some people I know ( ) like fiddling about with prototypes, so if you're one of those, heaven forbid I should discourage you......

Cheers,