Curved chair backs- compass plane?
 

Hi,

starting this as a new thread, originally was about finding a 3" pattern
(flush trim) router bit...

************

Thanks for all the comments...a 3" bit seemed like a scary idea to me,
also...

I recently built 4 red oak hi-chairs for the kitchen island, and the
hardest part was the curved chair backs. I cut them from oversized
blanks on the band saw, and cleaned them up with an oscillating spindle
sander, and sandpaper on a curved block of wood. They turned out OK,
but not perfect,and took a LONG time.

I just finished a cherry dining table (48" diam expands to 10 ft) and
want to make 6 cherry chairs to go with it. Have considered steam
bending (never done it) but the tenoning process seems like a potential
problem to me (among the other imagined problems)...

the bandsaw/oversized blank idea is pretty wasteful of wood, but is
probably how I will go...Considering getting a compass plane to help
smooth things out. Any ideas on that, or any of the above?

I have since installed the Carter style BS guides on my saw, so
hopefully I can get closer and smoother with the bandsaw.

advice much appreciated!

david

Curved chair backs- compass plane?
 

Have you checked out the recent threads here about this exact topic?
A compass plane would probably work, but the grain would almost
certainly be going different directions on each side of the convex
curve. Therefore you could plane with the grain "downhill" on each
side, but you'll still have to do some sanding/scraping in the middle
where the grain direction changes.
My advice: spend some quality time tuning your bandsaw to reduce
vibration to get smoother cuts to start with. If you don't have a
bandsaw book (i.e. Mark Duginske or others), get one. Tuning/tweaking
might take a while, but it should pay off during this project alone if
it reduces sanding on 12+ curved chair rails. Your new blade guides
certainly won't hurt either.
Also, if you weren't already planning on it, cut the tenons on your
stock before you cut the curves.
Good luck,
Andy

Curved chair backs- compass plane?
 

Reply to curved back chairs:

Have you considered using your bandsaw to resaw the back of the chair
into narrow slices and then glueing them back together as a lamination
when bending them in mass with a template. I did that with a section
of fir for a chair and it worked fine. I made a template of the curve
that I wanted and glued up all of the slices 3 in my case and then used
clamps to make the bends in the template. After drying there wasn't
any spring back and the surfaces were the smooth ones that was on the
board that I started with. You do lose the thickness of the bandsaw
cuts, but if you get a good clamp job the seams are not really
detectable.

Something to think about.

Al

Curved chair backs- compass plane?
 

"david blumberg" wrote in message
hlink.net...
Hi,

starting this as a new thread, originally was about finding a 3" pattern
(flush trim) router bit...

************

Thanks for all the comments...a 3" bit seemed like a scary idea to me,
also...

I recently built 4 red oak hi-chairs for the kitchen island, and the
snip

help
smooth things out. Any ideas on that, or any of the above?

I have since installed the Carter style BS guides on my saw, so hopefully
I can get closer and smoother with the bandsaw.

advice much appreciated!

david

I use spokeshaves. Veritas is the brand I use.

I cut the curve with the bandsaw and then use the spokeshave on the concave
side. I use shaves and hand planes on the convex side. On the first chair I
made, we relieved the wood in the curve with a back saw and chisels and then
used the shaves.

You cut lines across the grain, defining the curve, break the wood off with
chisels and then smooth it with the shaves. It is quick and very safe to do
it in this fashion.

Curved chair backs- compass plane?
 

david blumberg wrote:


I recently built 4 red oak hi-chairs for the kitchen island, and the
hardest part was the curved chair backs.

snip

Since you are trying to fair out an inside curve, take a couple of
pages out of the boat building community where fairing is a common
practice.

1) Make a couple of profiles from 1/4" hardboard or 1/8" aluminum, if
you can find it and machine it.

2) Saw the blanks as close as possible on the band saw.

3) Knock off the high spots with a 4" right angle grinder equipped
with a rubber sanding pad and 24 grit discs. Use profiles to check
your progress. (Aluminum will leave black marks on the high spots)

4) When close, say about 1/16", switch to a 2" dia x 2" lg, 40 grit
flap wheel. You can use an electric drill but a low cost air drill is
my favorite.

5) When you are within about 1/32", switch to a rubber block and 100
grit to finish.

Using the above, I watched a guy fair out airplane propeller blades to
within 0.001".

I hired him to fair out my boat.

Nobody says it id easy, but it works.


Lew

Curved chair backs- compass plane?
 

thanks, andy...

Andy wrote:
Have you checked out the recent threads here about this exact topic?

I did an archive search a coupla months ago, might have missed that...

A compass plane would probably work, but the grain would almost
certainly be going different directions on each side of the convex
curve. Therefore you could plane with the grain "downhill" on each
side, but you'll still have to do some sanding/scraping in the middle
where the grain direction changes.

hadnt thought of that...

My advice: spend some quality time tuning your bandsaw to reduce
vibration to get smoother cuts to start with. If you don't have a
bandsaw book (i.e. Mark Duginske or others), get one. Tuning/tweaking
might take a while, but it should pay off during this project alone if
it reduces sanding on 12+ curved chair rails. Your new blade guides
certainly won't hurt either.

excellent idea; I think our library has that book and video


Also, if you weren't already planning on it, cut the tenons on your
stock before you cut the curves.

yes, did that on the other chairs.


Good luck,
Andy

Curved chair backs- compass plane?
 

thanks, Al...

That was/is an option I am considering. My concern was having the plies
show (like plywood). Your 3 slices made how much final thickness? I
wonder how many plies I would need for a 3/4" back in cherry?

david

Al Holstein wrote:

Reply to curved back chairs:

Have you considered using your bandsaw to resaw the back of the chair
into narrow slices and then glueing them back together as a lamination
when bending them in mass with a template. I did that with a section
of fir for a chair and it worked fine. I made a template of the curve
that I wanted and glued up all of the slices 3 in my case and then used
clamps to make the bends in the template. After drying there wasn't
any spring back and the surfaces were the smooth ones that was on the
board that I started with. You do lose the thickness of the bandsaw
cuts, but if you get a good clamp job the seams are not really
detectable.

Something to think about.

Al

Curved chair backs- compass plane?
 

lowell, thanks for the suggestion. I had not heard of that technique
before...

david

Lowell Holmes wrote:

"david blumberg" wrote in message
hlink.net...

Hi,

starting this as a new thread, originally was about finding a 3" pattern
(flush trim) router bit...

************

Thanks for all the comments...a 3" bit seemed like a scary idea to me,
also...

I recently built 4 red oak hi-chairs for the kitchen island, and the

snip


help

smooth things out. Any ideas on that, or any of the above?

I have since installed the Carter style BS guides on my saw, so hopefully
I can get closer and smoother with the bandsaw.

advice much appreciated!

david


I use spokeshaves. Veritas is the brand I use.

I cut the curve with the bandsaw and then use the spokeshave on the concave
side. I use shaves and hand planes on the convex side. On the first chair I
made, we relieved the wood in the curve with a back saw and chisels and then
used the shaves.

You cut lines across the grain, defining the curve, break the wood off with
chisels and then smooth it with the shaves. It is quick and very safe to do
it in this fashion.

Curved chair backs- compass plane?
 

Lew, thanks very much for the response. I will consider that...

david

Lew Hodgett wrote:

david blumberg wrote:


I recently built 4 red oak hi-chairs for the kitchen island, and the
hardest part was the curved chair backs.

snip

Since you are trying to fair out an inside curve, take a couple of pages
out of the boat building community where fairing is a common practice.

1) Make a couple of profiles from 1/4" hardboard or 1/8" aluminum, if
you can find it and machine it.

2) Saw the blanks as close as possible on the band saw.

3) Knock off the high spots with a 4" right angle grinder equipped with
a rubber sanding pad and 24 grit discs. Use profiles to check your
progress. (Aluminum will leave black marks on the high spots)

4) When close, say about 1/16", switch to a 2" dia x 2" lg, 40 grit flap
wheel. You can use an electric drill but a low cost air drill is my
favorite.

5) When you are within about 1/32", switch to a rubber block and 100
grit to finish.

Using the above, I watched a guy fair out airplane propeller blades to
within 0.001".

I hired him to fair out my boat.

Nobody says it id easy, but it works.


Lew

Curved chair backs- compass plane?
 

"david blumberg" wrote in message
link.net...
lowell, thanks for the suggestion. I had not heard of that technique
before...

david

Issues 90 and 91 of Woodwork magazine feature articles on making a Craftsman
style rocking chair. The techniques are shown in those articles. Sometimes
hand tools are easier and quicker to use. I use both hand and power tools.

I never mentioned that we use scrapers as well. A well prepared scraper will
remove a lot of wood, leaving a smooth surface.

It's nice to have the option of which technique to use. :-)

I'll post a photo of a recent chair I made in abpw newsgroup.

Curved chair backs- compass plane?
 

I use spokeshaves. Veritas is the brand I use.

I recently did some work in 16/4 cherry with both convex and concave curves.
It had a little tighter radii than you chairs but I experienced the same
problem.

I'll second the Veritas shave idea. IME, shaves to a surprisingly good job
of ensuring a smooth curve (not to be confused with a smooth surface) which
I think is what is eluding you. You would think that you need all of that
sole of a compass plane to control the curve, but I'm not convinced its
necessary. The Veritas shave with a convex sole, is very much like a small
compass plane and it performed well.

Another approach that occurred to me however:

The problem with the OSS is that the drum diameter is too small. If you have
a lathe, you could fabricate an 8" or 10" diameter sanding drum. Although
the surface speed might be but crazy. Just a thought.

One other thought on the abrasive approach: Start with the biggest and
nastiest grit you can find. My initial attempts with the 3" OSS were with
medium grit. It tended to ~divot~ because it was too tempting to apply more
than the lightest pressure. A light touch helps achieve the smooth
continuous motion you need with the OSS.

In the end, I used a combination of shaves and abrasives, shaves really
shine when smoothing (shaping) the curves. My technique is not good enough
for a final surface, so the OSS was effective at smoothing the surface (but
I did have to work through the grits)

-Steve

Curved chair backs- compass plane?
 

I just finished a cherry dining table (48" diam expands to 10 ft) and
want to make 6 cherry chairs to go with it. Have considered steam bending
(never done it) but the tenoning process seems like a potential problem to
me (among the other imagined problems)...

Are you talking about a solid curved back, or just curved rails?
If the former, all I can do is wish you good luck; I wouldn't tackle a job
like that.
If the latter, I went through it and can give you the benefit of my
experience.

Curved chair backs- compass plane?
 

I am a scrapaholic...scraped every bit of the dining table, hi chairs,
and other furniture in the house. I have web access on FW; i'll check
that out, thanks..

david

Lowell Holmes wrote:
"david blumberg" wrote in message
link.net...

lowell, thanks for the suggestion. I had not heard of that technique
before...

david


Issues 90 and 91 of Woodwork magazine feature articles on making a Craftsman
style rocking chair. The techniques are shown in those articles. Sometimes
hand tools are easier and quicker to use. I use both hand and power tools.

I never mentioned that we use scrapers as well. A well prepared scraper will
remove a lot of wood, leaving a smooth surface.

It's nice to have the option of which technique to use. :-)

I'll post a photo of a recent chair I made in abpw newsgroup.

Curved chair backs- compass plane?
 

david blumberg wrote:

Considering getting a compass plane to help
smooth things out. Any ideas on that, or any of the above?

Make your own - rework the base on a cheap S/H woodie. Most of mine are
coffin smoothers, either rounded off to cut concave or with extra bits
attached to cut convex. I'm no fan of cast iron adjustable compass
planes. A #113 is expensive and fragile, a #20 is a big heavy clog of a
thing.

Curved chair backs- compass plane?
 

david blumberg wrote:
thanks, Al...

That was/is an option I am considering. My concern was having the plies
show (like plywood). Your 3 slices made how much final thickness? I
wonder how many plies I would need for a 3/4" back in cherry?

david

David

I lost the width of two or three bandsaw cuts. I plies show less than
plywood because the grain is all in the same direction and is
consistent with the next piece only off set by what the curve changes
the angle. You would need to start with pieces that were longer than
the finished to cut off when you trim them. You might want to start
with the back piece being thicker than 3/4" to get 3/4" as the finished
thickness.

Good luck with your project.

Al

Curved chair backs- compass plane?
 

curved rails...mission style, with 6 square spindles mortised into the
top and bottom rails...

Tim wrote:
I just finished a cherry dining table (48" diam expands to 10 ft) and
want to make 6 cherry chairs to go with it. Have considered steam bending
(never done it) but the tenoning process seems like a potential problem to
me (among the other imagined problems)...


Are you talking about a solid curved back, or just curved rails?
If the former, all I can do is wish you good luck; I wouldn't tackle a job
like that.
If the latter, I went through it and can give you the benefit of my
experience.