Comments on: Boil-in-the-Bag Plank Bending

By: Michael Olson

Michael Olson — Tue, 12 Nov 2024 12:43:23 +0000

One issue I encountered was heat placement: Heat rises so make sure the heat source is below the bag and parts you are steaming.

By: alex zimmerman

alex zimmerman — Thu, 24 Oct 2024 22:49:45 +0000

I have used a variation of this technique on my last three boats, which were glued-lap plywood. Max thickness of the ply was 3/8” (mm).
Lacking a steamer, I wrap the plank ends in old towelling before enclosing them in heavy (4 mil) plastic. The plastic is arranged to drain excess water just as described in the article. I have an old kitchen kettle which I fill and set to boil. Once the kettle has boiled, I lift the plastic and pour the boiling water over the towels before putting the plastic back over. I refill the kettle and repeat the process. The towelling holds the heat sufficiently between applications of each kettleful. I find that three boilings of the kettle is usually enough, and with my kettle that takes about half an hour. I pull the plank ends in with clamps while the hot towelling is still in place. Once it has cooled sufficiently, I remove the towelling and re-clamp the plank until it has dried.

By: John Homer

John Homer — Thu, 10 Oct 2024 11:06:47 +0000

I have used this technique and it works great. I build Adirondack Guideboats and use it mainly for the gunnels on each end on some designs where the bend comes around and up drastically. For what I do i use plastic sterilization tubing it comes in 2″ through 6″ wide, 100 foot lengths. See link below for details:

https://www.safcodental.com/catalog/infection-control/sterilization-tubing/plasdent-sterilization-tubing?hsa_acc=3454209772&hsa_cam=18137883502&hsa_grp=&hsa_ad=&hsa_src=x&hsa_tgt=&hsa_kw=&hsa_mt=&hsa_net=adwords&hsa_ver=3&utm_source=google&utm_medium=cpc&utm_campaign=PMax_Shopping_50_GP&utm_content=NEWACCT15&utm_term=&gad_source=1&gclid=CjwKCAjw9p24BhB_EiwA8ID5Bin5457YMsuVdZ6n9VrlcfD2Wdv_WdFhXmvUA3WvhflAGvc0LYKG_hoCN0cQAvD_BwE

By: David Peebles

David Peebles — Sat, 05 Oct 2024 20:34:10 +0000

I have had some success bending with dry heat. Sometimes I use a heat gun, but for larger areas, such as a panel of plywood, I have a propane powered heater intended for paint or wallpaper removal. It has a reflector about 4.5″ or 5″ in diameter. You have to keep this kind of heat source moving to avoid scorching the wood. The dry heart method works very well when you have just a few frames to bend (bending batches is more efficient with a steam box).

One advantage of dry heat is that you don’t have to wait for the wood to dry out before gluing or finishing. I have pre-bent thin (1/8″) plywood pieces and then laminated them to make knee braces for a kayak. Once glued, the resulting lamination becomes very stiff and strong. I also backed out a strip of oak with a router before bending it to become edge banding for plywood bulkheads with S-shaped profiles.

When bending strips, I like to clamp one end in a bench vise together with a steel bending strap, then C-clamp the other end before applying heat. When the wood is hot (only takes a couple of minutes), the strap forces the inside fibers to crumple; making the outer fibers take the bend is likely to splinter the wood. The steel binding strap used to bundle lumber works well. I check out the dumpsters at the lumber yard for scrap strapping when I need a piece. It comes in various widths.

It may seem counter-intuitive, but I seldom bother to check grain orientation before bending, except that it should be straight (flat grain, vertical grain–seems to make no difference).

By: Mike Robinson

Mike Robinson — Wed, 02 Oct 2024 18:36:35 +0000

Whew,,, what a job. Now I know why I like stich and glue!