Thread: Shaping chair seats

Originally Posted by zelk

I wonder if a Japanese rasp is more effective, http://www.carbatec.com.au/carving-t...ng-tools-rasps, it features a diagonal cutting action, and it's relatively cheap.

Zelk

Dunno - never used one. This - http://www.leevalley.com/wood/page.a...88&cat=1,42524
is my favourite (the #49). If you are realy, really flush go for an Auriou now they are being made again. A good rasp is just sooo much nicer to use than the crap things you get at the local hardware. Blowed if I know why they should be so much better, but they are.
Cheers,

Originally Posted by IanW

Dunno - never used one. This - http://www.leevalley.com/wood/page.a...88&cat=1,42524
is my favourite (the #49). If you are realy, really flush go for an Auriou now they are being made again. A good rasp is just sooo much nicer to use than the crap things you get at the local hardware. Blowed if I know why they should be so much better, but they are.
Cheers,

I have heard of Auriou, but who sells them, anybody here?

Zelk

Originally Posted by zelk

I have heard of Auriou, but who sells them, anybody here?

Zelk

I doubt it - they'd be a pretty low-volume seller. You better have your heart-meds ready when you see the price, too!

The Nicholsons are a pretty good rasp for everyday use, and give pretty good service - I'm on my second in about 15 years, so amortised over that time they aren't rediculously dear. I'm sure the Aurious are truly excellent tools, but the thought of justifying one or two to my better half sends me back to my Nicholson...

Originally Posted by IanW

I doubt it - they'd be a pretty low-volume seller. You better have your heart-meds ready when you see the price, too!

The Nicholsons are a pretty good rasp for everyday use, and give pretty good service - I'm on my second in about 15 years, so amortised over that time they aren't rediculously dear. I'm sure the Aurious are truly excellent tools, but the thought of justifying one or two to my better half sends me back to my Nicholson...

The talk about the Auriou's certainly make them very desirable, a 'must have' item. They're pretty pricey, just as well they're not available. I might try the Japanese rasp ($35) instead and keep my better half far less unhappier

Zelk

Originally Posted by zelk

I might try the Japanese rasp ($35) instead and keep my better half far less unhappier

Zelk

Yeah - a very sensible attitude!

Let us know how you go. I would expect them to be more like a coarse file than a rasp, so more effective at the cleanup stage than hogging off the bulk of the waste. But maybe better than a coarse file because the open design wshould reduce clogging, which is the bugbear of files & rasps.

Avagoodweekend,

Originally Posted by IanW

Yeah - a very sensible attitude!

Let us know how you go. I would expect them to be more like a coarse file than a rasp, so more effective at the cleanup stage than hogging off the bulk of the waste. But maybe better than a coarse file because the open design wshould reduce clogging, which is the bugbear of files & rasps.

Avagoodweekend,

The tool seems quite versatile, as it has a course and smooth side. Essentially, it looks like a series of hacksaw blades orientated in zig zag fashion. If it doesn't work, I don't think I will be upset for too long. Let you know on Monday.

Zelk

Originally Posted by zelk

Although, I said I would now start shaping the 2nd stool, I changed my mind and continued on with the first one shaping its sides.

I started using a Stanley Surform Planer File, but didn't like using it. I then tried a low angle block plane with an adjustable throat. Allowing for grain direction, the block plane was fine for rough shaping a rounded surface. However, there were times when the planing produced some tear out, as shown.

Are there better alternatives to shaping a rounded surface?

Regards,
Zelk

For that end grain there you've got pictured...I'd definetly actually abandon hand tools and use a light weight orbi.... because end grain doesn't shape anywhere near as well......I'd have one hand on the orbi stroking away continueously (never stop else you flat spot it) other hand holds the seat, with it resting on a blanket on the benchtop with the seat on its edge... sweeping the orbi continueously, turning the seat as you go. Keep your eye along the curve as you go....squinting.......focusing on the high spots. focusing on a nice flowing curve. Its far easier because the seat needn't be clamped to do it. I'd start with a coarse grit first on the orbi and stroke with the grain....fine up to maybe 180.....then once the shapes spot on, to finish off, I'd go over it with bits of of hand sandpaper and stroke with the grain to get rid of any swirling marks the orbi leaves.

Originally Posted by apricotripper

For that end grain there you've got pictured...I'd definetly actually abandon hand tools and use a light weight orbi.... because end grain doesn't shape anywhere near as well......I'd have one hand on the orbi stroking away continueously (never stop else you flat spot it) other hand holds the seat, with it resting on a blanket on the benchtop with the seat on its edge... sweeping the orbi continueously, turning the seat as you go. Keep your eye along the curve as you go....squinting.......focusing on the high spots. focusing on a nice flowing curve. Its far easier because the seat needn't be clamped to do it. I'd start with a coarse grit first on the orbi and stroke with the grain....fine up to maybe 180.....then once the shapes spot on, to finish off, I'd go over it with bits of of hand sandpaper and stroke with the grain to get rid of any swirling marks the orbi leaves.

Jake,

I agree, my 125mm RO sander would do a great job, but quite frankly I don't mind using the hand tools. This afternoon I had a chance to try out the Japanese rasp. For the price, it seems to work quite well and its performance is not too influenced by the direction of grain. As it has two sides, course and fine, I have yet to see how well it hogs of material, I believe it will be a useful tool in the workshop. It would be interesting to know how it compares to the reputable rasps.

Which ever shaping tool I use, the RO will no doubt be perfect for the finishing and as you mention, with courser grits I could shape too.

Regards,
Zelk

Originally Posted by zelk

Jake,

It would be interesting to know how it compares to the reputable rasps.

I've always wanted a quality rasp, and have wondered this too. Nearly bought a japanese rasp one day at carpatec.

Which ever shaping tool I use, the RO will no doubt be perfect for the finishing and as you mention, with courser grits I could shape too.

yep. it does feel a bit like cheating. But its still shaping though. Your results are still governed by your skill. By your eye.

As I see it too, generally when you start laminating you lean towards powered sanders as well, simply because the grains often all over the place. gets harder to read (especially for me, cause its a good way to rid myself of average looking teary timber. hiding its faces)

In the industry nowdays using hand powered tools is considered 'hand crafted' . But IMO, there's just too much of a improvement in time and results by using sanding shapers on hard end grain.

anyway, have a good weekend.

Originally Posted by Woodwould

If I could indulge you just for a moment. There are two principle methods of attaching legs to solid seats:

1. Blind tapered sockets (wider at the bottom) are bored in the underside of the seat with a special (7 degree?) taper bit. The tops of the legs are turned to match the tapered sockets and friction (and a very little glue), hold the structure together.
2. Cylindrical tennons on the tops of the legs protrude through nominally parallel through-sockets in the seat and are wedged from above. The parallel sockets are often just left as is by the uninitiated, but the best solution is to taper the tops of the sockets so the wedged tennons flare out, thereby firmly locking the legs in place.
   Because the wedges are situated at 90° to the seat's grain, the flaring of the top of the sockets need only affect the area of the sockets that the wedges will force the sides of the tennons into.
   
   Therefore, and to finally answer your question, a half-round rasp is a good choice of weapon to carry out the flaring with.

Hi Woodwould,

I was wondering, if my tenon is 30 mm dia and 65 mm long, how much would you have to expand the tenon with a wedge, assuming the dry fit is snug? Should be I be using wedges at all?

Am I better of using two wedges per tenon? I experimented with having one and two wedges per tenon. Using a bandsaw cuts (1mm width), when using two wedges I could expand the tenon to around 1 mm, easily, as opposed to having one thicker wedge which will expand only up 1/2 mm before it causes any stress to the timber, mind you, this is on a tenon while out off its socket.

Regards,
Zelk

The wedges I've used and seen in antique examples have been 2.5mm-3mm thick when trimmed off at seat level and in every case, they've always been single wedges.

You'll need to cut a wedge shape out of the top of the tennon; it's not just a case of making a parallel saw cut in it.

Also, make sure the wedge is no wider than the tennon and radiused to match the tennon, otherwise the corners of the wedge will catch the sides of the socket and could either get hung-up or break in two.

Originally Posted by Woodwould

The wedges I've used and seen in antique examples have been 2.5mm-3mm thick when trimmed off at seat level and in every case, they've always been single wedges.

You'll need to cut a wedge shape out of the top of the tennon; it's not just a case of making a parallel saw cut in it.

Also, make sure the wedge is no wider than the tennon and radiused to match the tennon, otherwise the corners of the wedge will catch the sides of the socket and could either get hung-up or break in two.

Hi Woodwould,

are you saying that there is no need to widen the hole/mortise at one end?

Regards,

Zelk

Originally Posted by zelk

Hi Woodwould,

are you saying that there is no need to widen the hole/mortise at one end?

Regards,

Zelk

No. The mortise should definitely be flared at the upper end.

What I tried to describe is the fit of the wedge whose width should be the same as the nominal bore of the mortise. This is so the corners of the wedge don't dig into the sides of the mortise and get hung up.

If the wedge were to get hung up on the sides of the mortise, it may give the impression of being tight and fully driven home, yet the tennon may not have been sufficiently widened to fill the flare in the top of the mortise, resulting in an unattractive and incomplete joint.

The Japanese rasp is , for the price, quite effective at shaping end grain, without any significant tear out.

I decided to use two wedges for each leg/tenon as it was easier to expand the tenon than if I had used only one. Should one leg break during use in future, I want to be able to remove the leg easily and so have decided not to totally glue the leg to the seat. As mentioned before, gluing the whole tenon could be disastrous when fitting the leg into the seat. I plan to use a little PVA glue at the underside of the seat and a bit of glue on the wedges.

I modified an earlier made jig to support the tapered legs when sawing them for the wedge slots. The same jig was used to cut the legs to length and at the right angle.
Zelk