Outside stem, steam bending jig size question.

G

gfatula

Curious about Wooden Canoes
Hello friends,

I have decided to finish the Morris rowing pod I am restoring with an "outside stem" as per the original catalog. It didn't have one 40 years ago when I found it and when I re canvassed it then I did not add one. I simply re attached the brass half round to the stem.

I am taking the profile of the ends of the boat, preparing to build the jig for steam bending some white oak. I think I have the oak that will work. Flat grain, eight 6' pieces, 1 1/4" x 1".. Hoping 2 will survive. Ha!

My question is:

Should the jig be the exact size of the stem's profile or should it be a shade smaller for a good fit? Perhaps Roillin has some advice. Anyone's experience is welcome.

Thanks,

George
 
I usually add about 15% curve to allow for springback. But, if you are using airdried white oak, that will be less. If you are using KD white oak, best of luck.
 
Thanks Mark,

I am using air dried white oak. Making the radius of the stem jig a bit "tighter" than the actual profile of the stem makes sense to me.

George
 
I think if you pick the grain carefully and soak the wood for a few days you will find it easier than expected. I have used a home made steamer as well as one of those wall paper steamers with success. tip: as you are bending pull the stem to the form slowly to allow the wood to adapt. Taffy pulled fast will break, pulled slowly taffy will stretch quite a bit. Kind of the same idea bending wood. Go fast to the form and then take it easy. let the wood tell you how quickly to bend it.
 
Dave Wermuth said:
I think if you pick the grain carefully and soak the wood for a few days you will find it easier than expected. I have used a home made steamer as well as one of those wall paper steamers with success. tip: as you are bending pull the stem to the form slowly to allow the wood to adapt. Taffy pulled fast will break, pulled slowly taffy will stretch quite a bit. Kind of the same idea bending wood. Go fast to the form and then take it easy. let the wood tell you how quickly to bend it.
Click to expand...

Thanks Dave, Will do!

George
 
Three thoughts:
1) I've never had success bending stems where the wood's thickness was greater than its height. So I always bend square shapes and shape to fit after bending.
2) Always soak the wood for several days. I use a 3" PVC pipe capped at one end as a water 'tank'.
3) And here's great tip: See if you can get yourself a flexible electrical heating strip. Granger has 'em - look for part # 6THP7, 120vac @ 24" x 1" @ 240 watts. Here's how to use it: Bend the wood as usual on your form. After an hour or so relax the clamps and place the heater between the wood and form & reclamp. Then heat for a few hours. I find I get very little spring-back with this technique. Only don't heat for too long - you end up with charcoal or a fire!
 
Howie said:
Three thoughts:
1) I've never had success bending stems where the wood's thickness was greater than its height. So I always bend square shapes and shape to fit after bending.
2) Always soak the wood for several days. I use a 3" PVC pipe capped at one end as a water 'tank'.
3) And here's great tip: See if you can get yourself a flexible electrical heating strip. Granger has 'em - look for part # 6THP7, 120vac @ 24" x 1" @ 240 watts. Here's how to use it: Bend the wood as usual on your form. After an hour or so relax the clamps and place the heater between the wood and form & reclamp. Then heat for a few hours. I find I get very little spring-back with this technique. Only don't heat for too long - you end up with charcoal or a fire!
Click to expand...

Thanks, Howie.

I was going to start with 1.25" wide X 1". I can easily make them 1" X 1". I thought a little extra width would help.

George
 
Getting ready to steam some white oak stems. Cutting the stem jig to shape this week. I will make it a little tighter than the actual profile. Not sure how to figure a percentage. I plan to cut the stem about 1/4" inside the actual stem profile. What d you think? I also plan to do the steaming in poly tubes. 1"x11/4"x6' pieces fit two to a try on the jig. I will leave them in the poly tubes and keep the steam running after they are clamped down. My steam boiler is a 10 gallon milk can with a wooden plug top and a 2" pvc steam delivery pipe out the top. A propane pot burner is my heat. Plenty of steam.

George
 
Getting ready to steam some white oak stems. Cutting the stem jig to shape this week. I will make it a little tighter than the actual profile. Not sure how to figure a percentage. I plan to cut the stem about 1/4" inside the actual stem profile. What d you think? I also plan to do the steaming in poly tubes. 1"x11/4"x6' pieces fit two to a try on the jig. I will leave them in the poly tubes and keep the steam running after they are clamped down. My steam boiler is a 10 gallon milk can with a wooden plug top and a 2" pvc steam delivery pipe out the top. A propane pot burner is my heat. Plenty of steam.

George
 
Just thinking I have a couple of pieces of wood inside a poly sleeve that I can lay against the form and clamp in place.
 
The main reason for using poly tubes is to allow continued steaming while bending onto a jig or over a form or into the boat. This is most useful for long and/or awkward pieces that may take some time to bend -- the continued steaming keeps the piece from cooling off before the bending/clamping is complete. But unless the poly bag would get in the way of the bending, there seems to be no reason not to use it on an uncomplicated bend.
 
Greg,

Makes sense to me. I have used pieces of pipe as steam boxes in the past. Works fine. Handy for long stuff. This is a one time effort of fairly short stock. I will bundle two strips of oak in a plastic "bag". Hook up the steam and build the form to accommodate the pieces as they start to steam. The form will let me bent two at a time. Clamp them down when they are ready and let the steam work as long as it makes sense. I have 8 good (I think) "blanks". I need two. Once I am set up and boiling I will experiment. A couple of extra steamed unfinished oak stems will make nice decorations. Perhaps an oak heart for an interesting wreath? Ha!

Thank you for the encouragement. The hardest part of this step is finding air dried white oak in eastern Maine. New Hampshire was my source.

George
 
gfatula said:
Clamp them down when they are ready and let the steam work as long as it makes sense.

. . . finding air dried white oak . . . New Hampshire was my source.
Click to expand...

Assuming that your pieces to be bent were steamed long enough when you put them on the form, I don't think there is any advantage to continuing to steam them once they are properly clamped down.

And if it is not a secret, where in NH did you get your air-dried stock?

Greg
 
You must log in or register to reply here.

Similar threads

G
Morris #158 "Outside stems and a substantial keel" questions
2
Replies
23
Views
5K
gfatula
G
Dave Wermuth
Steam bending question/survey.
Replies
15
Views
649
David Satter
David Satter
Douglas Kestell
Cherry outwales failure during steam bending
Replies
15
Views
2K
Douglas Kestell
Douglas Kestell
4
Rib Steam Bending
Replies
5
Views
5K
Raubers Canoes
R
KAT
New stem bands and screw hole spacing...
Replies
10
Views
3K
KAT
KAT
Back
Top