I have built a kitchen counter island that has a cemicircle on one end and is about 28″ wide. I have a cherry board trim that I intend to steam and bend around the cemi circle. The width is about 2 inches.
Any idea on how thick a piece I can steam-bend? Can I go quarter inch? 3/8?
Any advise appreciated.
Jim
Replies
You should be able to bend cherry which is 3/4" thick around a 14" radius -- if you use a compression strap.
Jim,
I don't have any experience with steam-bending, but I do have experience with what I think might be much easier. Consider resawing your cherry and gluing up pieces on a form to your desired thickness. With a 14-inch radius, I would probably glue up two quarter-circle segments and connect them with a small decorative block in the middle.
BJ
Jim, cherry doesn't bend well and unfortunately steaming it tends to alter the color. I've had some luck kerf bending it (when using it for dulcimer ribs)...but for the edging on a counter top, that strategy might be a little frail unless you glue it to a backing of some sort.
If only the face surface shows, I think I'd cut a thin strip of cherry veneer...maybe only about 3/16" thick and laminate bend it over a more flexible substrate. In other words, do a laminate build up with cherry as a moderately heavy face veneer. Slats of ash might be a good choice for the backing...or you could even steam bend a thicker piece of ash, since ash does have excellent steam bending characteristics...and then just face it with cherry veneer...But when steam bending, you inevitably have to deal with the prospects of some rebound...so, a laminate build up is probably the best choice.
Couldn't one also just build up the profile by laminating cherry strips on top of one another? Sure it wouldn't be one solid piece of cherry. But, it would be all cherry.
Regards,
Kevin
Kevin, sure you could use all cherry slats. it would be a bit more expensive and you'd have to keep the pieces a little thinner than if you used a more elastic species for the hidden portion of the glue-up. Cherry is a brittle wood and it doesn't dry bend very well. Steaming it helps improve the pliability, but the risk is you'll affect the color.
In dulcimer making, I've gotten away with soaking the side ribs in cold water over night. The color holds and the ribs become a little more flexible...but it's still one of the more difficult woods to bend.
About 12 years ago I was the finisher/painter at a custom commercial fixture/cabinet shop. We did the lobby of a Portland beer and wine distributer in Cherry. The reception desk had a curved front which we laminated Cherry slats exactly like you described (using cold water for an overnight soaking) to create the curved profile trip pieces. It's been long enough that I don't remember how thin the pieces were. I think they were around 3/8" thick and about 4" wide. Of course it wasn't anything close to as tight a curve as is being discussed here. The cold water did seem to avoid the worst of the color change, as I don't remember it staining any different than the rest. Although... as I recall, we used all steamed Cherry on that job. I dunno if that made a difference or not. It looked like a million bucks when we were done, though.
Regards,
Kevin
Jon -
While I've never attempted anything as sophisticated as a dulcimer, I've read articles about how luthiers use a heated pipe to bend the sides of guitars, etc. That begs the question .... how would a heat gun work to gradually bend a large piece around a form? Something like a laminated stair stringer?
This is one of my planned projects for our new house so it's a serious question. The stair will have three runs (two landings) and I'd like to resaw 1/4" laminations from something like ash or oak which will be 12-14" deep. I'll build some false work forms to bend the pieces, then after they've set, will glue up the final laminations.
...........
Dennis in Bellevue WA
[email protected]
Dennis, you're right about the traditional method for bending dulcimer sides. The Old Masters used dry heat. In other words, they formed the ribs by rubbing them over a hot drum (pipe) until the lignin in the wood softed and made the rib pliable. Once cooled, the rib holds its shape. For best results when using this method, the ribs have to be relatively thin (in the 3/16" range at most) to allow the heat to permeate through the wood before it begins to darken and discolor the surface.
I use a kerf bending technique for a host of reasons...just to name a few; it provides a wider glue surface on the edges of the ribs, without adding much weight or having to laborously install flexible glue blocks...it leaves a little spring in the rib that (theoretically) keeps the soundboard under slight tension...it doesn't risk burning the wood or altering the color of some of the more sensitive species, like walnut and cherry...and it doesn't involve working with a dangerous flame in my comfortably dusty shop.
As for steam bending, I think most woodworkers believe the "magic" in the process is the moisture in the steam and this really isn't the whole story. The moisture in steam does help to soften the cellulose fibers in the wood (as would just soaking the wood), but it's really the heat that allows the wood to reform beyond the normal elasticity limits of the walls of the fiber cells. The heat softens the wood's lignin and this is what allows the wood fibers to slip and slide relative to each other...and then rebond once the lignin cools and becomes rigid again. the other benefit of the moisture in the steam (and maybe the more important one) is that it helps conduct (disburse and limit) the heat, making it easier to bend thicker stock without reaching ignition temperature on the outside surface, while the inside tissue is still cool and rigid.
While it's possible to get very good at steam bending, I think it's a much more difficult skill to master than are the techniques for either kerf bending or laminate bending. Laminate bends and steam bends differ from kerf bends in that they both have the advantage of being permanent...in the sense that they don't need to be perpetually restrained once they're integrated into the project. In many applications, this is a key benefit...but steam and laminate bending techniques, in turn, each have their unique benefits and limitations.
The variability, degree (and unpredictability) of rebound with any given, single piece of wood is greater in the steam bending process and you need to develop some experience in order to manage this variable. Laminate bends tend to hold the shape of the form better, because the multiple pieces in their construction form a compression-tension balance...So, once the form is carefully constructed, the actual process of making multiple, duplicate parts gets to be pretty much monkey work.
If your project allows you to hide the plywood-like appearance of the edge of the lamination, it's definitely the easier way to go...Besides, it allows you to use a cheaper and/or a functionally more forgiving species for the interior laminates.
...Sorry for the length of this response, but you've kicked off a rather subjective topic...Opinions vary. I think mostly along the lines of what happens to be any given woodworker's most commonly encountered purpose for needing bent parts...Or just out of the joy of learning a specialized skill...Steam bending can get to be a hobby in and of itself, but it's not necessarily either a superior technique or always the most practical approach to every bending challenge. I think, in your situation, heat or steam isn't going to be that helpful. You might want to soak the thin strips in preparation for the bend, but I'd go with just a build up of segments, cold laminated in a form. You might need five or so segments to get the thickness you'll need for structural reasons.
Edited 6/15/2003 9:32:29 AM ET by Jon Arno
Jon -
On the contrary, I appreciate the depth (and length) of your replies not only to questions I pose but those of others. The expertise shared here, yours and others, is to be applauded. Thank you.
My application/project will indeed be a laminated section. And with what little experimentation I've done on a much, much smaller scale, I'l fairly confident that with careful selection of the timber(s) and attention to keeping all parts in their original relationship, I'll be able to resaw larger pieces to be reassembled without too much grain interuption thus producing an end product that will be fairly convincing as a single piece of timber.
I've seen examples of both stair stringers and handrails bent through stair pitch changes as laminations, then resawed and bent around forms to match the plan layout. Fortunately this is a personal 'hobby' project thus I'm not planning on trying to make a profit! (grin).
Thanks again for the information. I suspect the laminations will be somewhat thin, on the magnitude of 1/2" or perhaps less, from either ash or white oak. Most of the millwork in the house is ash so I'd like to continue that theme.
...........
Dennis in Bellevue WA
[email protected]
Jon -
On the contrary, I appreciate the depth (and length) of your replies not only to questions I pose but those of others. The expertise shared here, yours and others, is to be applauded. Thank you.
I heartily concur! I find myself looking forward to reading Jon's replies because I invariably either learn something new or am left with a new perspective to ponder. I appreciate both equally.
Regards,
Kevin
Jim
I didn't realize there were so may people out there steam bending wood.
Hey I have steam bent oak - maple- hickory- osage, and have read up on steam bending.
Cherry will steam bend well- use a strap on the back of the bend to keep the grain from lifting and splitting and you will be ok.
1 in. thickness 1 hour steam as far as discoloring make sure the strap is galvanized something that will not rust. No big deal you can do it- a glue up always looks like a glue up
Sorry you wanted to know how thick 3/8 easy- you could bend 3/4 no problem- I bet you might even be able to go up to 2 in. thickness if it was split out so the grain was running the length of the bend.
Edited 6/14/2003 8:57:55 AM ET by I Like Beans
Edited 6/14/2003 9:00:37 AM ET by I Like Beans
Thanks for all the advise.
Well I did it and give myself a C+.
I bent 3/8" and did it using clamps with wood wedges to force the turn. It came out good on 95% of the bend I do have a 3/16" gap over about 3".
Here is what I learned:
Don't use clamps - use a strap to tighten the wood to the form'
The wood sets in about one minute -so apply glue first and work within the time limit.
To bend the wood I steamed it in a flexible plastic pipe, and constantly bent it till I had what I wanted, this was better than simply steaming and then bending outside the pipe- which was my first try.
Aside from that it was well worth the aggravation, looks great!
Jim
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