Last of the batch - a double-radius compass plane

**IanW** · 25th December 2017, 07:19 PM

Half a lifetime ago (literally) I made myself a small ‘double-radiused’ plane for working on Windsor chair seats. This was early in my plane-making career, & I had only a vague idea of what I was doing, but after a bit of tinkering, it worked well enough to do the job. It was really only meant to be a ‘proof of concept’, and I had always intended making a ‘proper’ one, ‘some day’. But the years rolled by, & lots of chair seats were carved, & this little plane was used on every one. DR 1.jpg

Every time I used it, I cursed its small size & featureless body that made it awkward to hold. I vowed to make a new one, but of course, I quickly forgot about it after each batch of chairs was done.

Another shortcoming was the wood I chose which was Black Bean (Castanospermum australe), simply because I had a small chunk looking for a job to do. I don’t think it’s a great choice; it’s not very wear-resistant, or at least not the piece I used. Sole wear has been quite severe, especially just in front of the mouth. I’ve had to re-form the sole a couple of times (with increasingly less care, as you can see!), to remove the ‘step’ that forms due to sole wear, and it has developed quite a big mouth. DR 2.jpg

Given that this plane has already made more chairs than I’m likely to produce in the rest of my woodworking life, I first thought I’d put up with its size & just ‘fix’ it by fitting a brass insert in front of the mouth, glueing some extra wood at front & rear, & getting a thicker blade for it. But you really can’t make a silk purse out of a sow’s ear – I decided it would’ve been a lot of work for an uncertain outcome. Starting from scratch seemed like a far more sensible option.

I had actually made a start on a replacement a year or two back. I chose Bull-oak (Allocasaurina leuhmanii), thinking that would improve the sole-wear issues, and went for a solid-body design, even though it made construction just a leeetle bit more difficult. Read LOTS more difficult! Digging out the bed & abutments in that stuff proved to be very challenging, and I ended up with chips in the front of the mouth.
The block of wood I chose (the only solid piece I had that was large enough), turned out to have several hidden cracks, one of which caused part of one abutment to split off the first time I snugged the wedge up. I did get the thing working “in the rough” which was enough to show me I’d gone to the other extreme & made the thing too big & bulky. Then a large crack developed along one entire side, at which point I lost heart & consigned it to the firewood pile (Bull-oak makes excellent firewood!). B_O plane.jpg

I got the sulks & decided to shelve the project indefinitely. Then Derek posted his newly-minted travisher, and despite my claiming I’d sated my plane-making appetite for good, that post reminded me that I’d often thought one of these would make a handy contribution to digging-out chair-seats. So I reckoned I may as well stretch to one more while I had the gear out, so to speak. That got the ball rolling, and I also decided to have another crack at a new compass plane while I was at it.

So I scrapped any idea of trying to fix #1, and resigned myself to starting over. Having learned some lessons from #1 & the aborted effort, I reckoned the ideal size should be just a bit larger than the original, but with some sort of front & rear ‘buns’ added, to make it easier to use.
I settled on a ‘hybrid’ construction, with brass sides riveted to a wood infill as the most practical way of forming the body. A large chunk of brass inserted in the front sole-piece should solve the excessive mouth wear problem, & a couple of rivets through it should also add some structural stability in case the wood wants to move a little. I chose Bull-oak again, for the infill wood, for its density & stability. This design requires only a few saw-cuts & a bit of planing & sanding to make the necessary parts, so it’s far easier than chopping out a complete blade bed & escapement. DR 3.jpg

The mouth for a convex sole is a bit more complex than for a square sole, it needs a scoop in the front edge, to maintain a constant mouth opening. I reckoned the safest way for me to get this right would be to shape it in situ, so I began assembly by by glueing the sides to the toe infill: DR 4.jpg

After the epoxy had cured for about 12 hrs (and still a bit plastic), I drilled the rivet holes & set the rivets. Then I proceeded to shape the mouth, sliding the rear infill in to check progress as I went along. After a few sessions of filing and testing, I had a regular gap between the front of the mouth & a mocked-up blade. I carefully marked where the rear infill had to be fixed relative to the sides, & glued it in. Again, before the epoxy had become hard, I drilled& riveted the rear piece in place.

So here we are with the rivets all banged up, & the sole rough-shaped. DR 8.jpg

The front to back curvature is accurate (175mm radius) but the side-to-side radius (75mm) still needs work. It’s just a matter of careful filing with a coarse file & testing the curve against a cardboard template until it matches all the way along the sole. The section that needs to be most accurate is just in front of the blade and the 20mm or so behind it. They have to match the blade curvature very closely, if I want the plane to be capable of taking fine, even savings from the full width of the blade edge. These areas also bear the brunt of sole wear.

It’s always satisfying when I clean up the rivets (first by careful filing to remove the bulk, followed by sanding), and see them start to fade, then completely disappear in another dozen strokes or so, indicating they have been well-set. DR 9.jpg DR 10.jpg

OK, next step is to fashion a lever cap. This involves a bit of educated guesswork, deciding where to position the pivot, and what length to make each part. Obviously, the longer the part with the thumbscrew, the easier it is to apply pressure at the other end, but you also have to consider where the thumbscrew will meet the blade (over the blade-bed, & not on the chip-breaker screw if you are using a chip-breaker) & finally, it all has to look in proportion and made for the plane, not borrowed from a larger or smaller one. I usually make a wooden mock-up to make sure it is going to fit & look the part. The proportions of the LC in this case were pretty straightforward, and the scrap of brass I had was just long enough for the job, so I skipped the mock-up & went straight to the real thing. I get a lot of pleasure out of sculpting something like a LC from a solid chunk of metal. Brass is so nice to cut & shape with hand tools (not a lot harder than Bull-oak, & no grain to chip out!). I drew the outline of the LC on the brass, then drilled & tapped for the thumbscrew (8mm in this case). The basic shape was cut out with a jewellers’ saw for the careful cuts, and a hacksaw where excess metal just needed to be roughed off. The steel washer clamped over the thumbscrew hole is a guide for cutting & filing the top to an accurate circle. DR 5.jpg

After some shaping with files & sandpaper, a nice, shapely lever cap emerges from the lump of brass I began with: DR 7.jpg

The LC was duly fitted in the body, and the woodwork cleaned up & shaped: DR 13.jpg

So here I am, waiting for the blade I ordered to arrive. Thanks to Aus Post having to help Santa with his delivery schedule, it didn’t arrive before Christmas as I’d hoped, so I borrowed the thin blade from the old plane for a test-drive. Even though the edge profile doesn’t quite match, I was able to get it to make both coarse & relatively fine shavings & determine that it is WAY better to hold & drive than the old plane.

Because the plane & travisher have different cutting radii (~75mm for the plane vs. ~120mm for the travisher), they are complementary. DR 15.jpg

You can see the grooves left by the plane in this scoop: DR 16.jpg

Which the travisher eliminated (on this practice piece, at least): DR 17.jpg

So the cunning plan is that the plane tidies up & refines the seat shape after the scorp, & the travisher evens out the plane marks enough for a card scraper to refine the final surface – sandpaper should be all but elimanted. At least that’s my hope – I’ll find out if it works that way when I actually make a real chair seat using my new gear….

Cheers,

**Bushmiller** · 26th December 2017, 09:07 AM

Nice job Ian. Having finished the bulk of your chair making, it looks like you are at last nicely set up

.

Another plane has come into land. many more and you will have to advise Air traffic control!

Regards
Paul

**Mr Brush** · 26th December 2017, 09:39 AM

That's an absolute beauty - excellent work

**labr@** · 26th December 2017, 11:21 AM

Very nice Ian. It's always a pleasure to see your work.

Do the rivets go right through to the other side or do they lock into the timber infill somehow? Any further info on this would be of interest, thanks.

**IanW** · 26th December 2017, 07:10 PM

Originally Posted by labr@

... Do the rivets go right through to the other side or do they lock into the timber infill somehow? Any further info on this would be of interest, thanks.

Rivets go right though, labr@. It's not perfect design, because I have material that can potentially expand or contract, sandwiched between the sides & held by rivets. There's a rivet right through the brass block forming the front of the mouth, so that part of the body is sound. What I would prefer to have done is to use several brass dowels, say about 9mm diameter, turned down to 4 or 5 mm at each end, & place them at strategic points. These would have acted like the sleeves that are used in the best of the best infill planes. Unfortunately, I didn't think far enough ahead, and the way I assembled it ruled that clever plan out. That's the trouble with one-offs, you learn the necessary lessons too late.

The rivets can resist expansion to a very limited extent, but not contraction, so the infill could come loose if it were to shrink a little. I made a plane using the same technique quite a while ago, which has remained rock solid, so I'm hoping this one will do likewise. My theory is if I get it together when the wood is about the median point in the annual moisture cycle, the rivets have enough tension to keep everything tight over a small amount of wood contraction. Time will tell.

Cheers,

**IanW** · 26th December 2017, 07:13 PM

Originally Posted by Bushmiller

...... Having finished the bulk of your chair making, it looks like you are at last nicely set up

. ...

Is it not always so, Paul? As someone else once said, "I finally got my life together, but I forgot where I put it!"

I'm just having fun making all the darn planes I ever thought would be useful to me, plus a couple that just popped up along the way. Given the length of time some of these have been waiting for the round tuit, it's unlikely I'll get around to any more serious plane-making in the shed time I have left.....

Cheers,

**labr@** · 26th December 2017, 07:56 PM

Originally Posted by IanW

That's the trouble with one-offs, you learn the necessary lessons too late.

I can relate to that

Thanks for the info Ian, it's all good stuff.

**IanW** · 27th December 2017, 08:08 PM

The new blade I ordered before Christmas arrived this morning, so I was able to finish the project off.

The blade was clamped in the plane, and the sole curvature marked on it. I first ground the edge to the marked line, then used a crude jig to grind the bevel:
DR 18.jpg
Because the blade is laid over, it's not a true arc, but part of an ellipse, so the compass-drawn arc on the jig doesn't give you quite the right profile if you rely on that alone. You have to use a little extra pressure & a bit of guesswork to grind the edges more than the centre. It took two tries, but I got it pretty close on the second go. I then used diamond files to fair the corners over a bit (so they don't leave score-marks), & honed the bevel.
The mouth is a little wider than I would have liked: DR 19.jpg

I wasn't after a super-fine mouth because I want it to be able to hog out thick shavings when required, but I thought I had it tighter than that. I must have been a bit careless lining up the rear infill when I was glueing it in. It actually looks wider than it is, in the pic, and the plane worked well both with & across the grain, so that's the main thing. DR 20.jpg

It probably won't get as much use as the old one did, but at least I will enjoy this one a lot more when I do use it.....

Cheers,

**Cal** · 27th December 2017, 09:07 PM

Love your work Ian, excellent!

Sent from my iPad using Tapatalk

**Simplicity** · 27th December 2017, 09:08 PM

Thanks Ian another fantastic write up.
Are you personally moving towards a darker side with all this metal work of late.
I mean metal is just like timber only a lot lot harder.[emoji12]

Well done on all the planes.
Cheers Matt

**derekcohen** · 28th December 2017, 03:32 AM

Ian, that is just beautiful work! I shall need to borrow it for carving my seats.

I am in Cape Town at present and do not get back home until the middle of January. I am champing at the bit to get stuck into the planned Windsor seats, but realise that a second travisher (or something) is needed - one with a very gentle curve for final smoothing. I had also been thinking along the lines of a spoon plane (the name for your "double compass plane"). Your comment that your travisher smoothes the carving done by the plane suggests that the curve you put into it is a lot more gentle than mine.

Regards from Perth .. Cape Town

Derek

**IanW** · 28th December 2017, 08:33 AM

Originally Posted by Simplicity

......Are you personally moving towards a darker side with all this metal work of late.
I mean metal is just like timber only a lot lot harder.[emoji12]......

Matt, this is definitely the last of the last for a very long time, if not forever! As I said, I've now made every plane that I've been wanting to make for the last 25 years or more, plus a couple that just happened. Since I put that panel plane together in September, I've done practically nothing else in the shed (other than stupid stuff like repairing the ride-on mower (twice!) & a few other small jobs). All but one of these planes didn't exist before then: Bench planes.jpg

The two little thumb planes in the front of the pack 'happened' because I had scraps with shapes that suggested they ought to become little planes. Even the blades on them are from scraps.

I also made the two smaller shoulder/rebates and refurbished the big one, which was about the first successful metal plane I made (circa 1984): SP 1.jpg

This has been the longest, most enjoyable, most self-indulgent tool-making session I've ever had, and I think I'd better get on with making some 'useful' things (as my better half puts it), now.....

Cheers,

**Simplicity** · 28th December 2017, 08:51 AM

Originally Posted by IanW

Matt, this is definitely the last of the last for a very long time, if not forever! As I said, I've now made every plane that I've been wanting to make for the last 25 years or more, plus a couple that just happened. Since I put that panel plane together in September, I've done practically nothing else in the shed (other than stupid stuff like repairing the ride-on mower (twice!) & a few other small jobs). All but one of these planes didn't exist before then: Bench planes.jpg

The two little thumb planes in the front of the pack 'happened' because I had scraps with shapes that suggested they ought to become little planes. Even the blades on them are from scraps.

I also made the two smaller shoulder/rebates and refurbished the big one, which was about the first successful metal plane I made (circa 1984): SP 1.jpg

This has been the most enjoyable, most self-indulgent tool-making session I've ever had, and I think I'd better get on with making some 'useful' things (as my better half puts it), now.....

Cheers,

Ian,
First I hope I'm not quoting this post in the near distant future [emoji12].
I'm also looking forward to seeing a post possibly on your 'useful' things.
Woman have such a beautiful way of explaining things.

Cheers Matt

**IanW** · 28th December 2017, 09:48 AM

Originally Posted by derekcohen

.... I had also been thinking along the lines of a spoon plane (the name for your "double compass plane"). Your comment that your travisher smoothes the carving done by the plane suggests that the curve you put into it is a lot more gentle than mine....

Derek, the radius of my travisher ended up around 120mm. The fore-aft radius of the plane is 175mm and the beam radius is somewhere between 65 & 70mm. The plane is used more like a scrub plane, initially, & it can get where the travisher can't. For instance, if you put a deep depression at the back of the seat, you'll probably find you need something with a shorter radius than the travisher to be able to cut it cross-grain. This where the plane is particularly useful to me.

Please note, I'm a self-taught chair-seat carver, I have read how others go about it & over the years, adapted/modified various methods 'til I figured out what works for me. I'm certainly not professing any great insights on the process. After roughly scooping out the bulk of the waste with a scorp (I used to use a gouge until my scorp decided to work for me), I switch to the plane. For the deep sweep at the back, I come at it from each side, with the plane laid as far over as I can hold it, & plane around the 'corner' & across to the middle. The curves in the carving toward the front of the seat are typically much gentler, and the travisher could probably accomplish all of that part on its own, but the plane is quick when set up to take heavy shavings. As long as you work predominantly cross-grain, you can safely scoop out huge curled-up chunks (they remind me of giant legless 'pill bugs').

Previously, I would back the plane off after the shape was roughed-out, and clean up enough to use some coarse paper, followed by scraping to get rid of any vestiges of the ridges left by the plane. I'm hoping I can now do most of that part of the cleaning up with the travisher. It went according to plan in my test-run on a bit of scrap, but I will find out if if it really works when I do a seat for real. Up until now I would do somewhere between 20 to 40% of the 'carving' with my little plane, and assume I can do the same with the new one (more comfortably!).

Once you get going on your seats, I think you'll figure out what I'm talking about wrt the deep carving of the back corners, and the 'right' tool for each part will soon assert itself. You'll probably use a different approach from mine, and much will also depend on the wood you choose. I prefer the North American approach of using thick, softer woods for seats, so the carving can be really deep and the weight remains sensible. My favourite seat wood is Jacaranda, which is light and easy to work but is stronger than its density would suggest. It also has a grain structure that is remarkably like Elm (even though the two species are not even remotely related) and if stained well, could fool all but the closest inspection.

Cheers,

**DomAU** · 28th December 2017, 10:26 AM

Really stunning Ian. Great job!

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