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Discussion Starter #1
You might remember this project from a couple of years back. My previous attempt at doing a comprehensive build thread on it fell short of my expectations. This being a project that I have fairly well documented with photos lends itself to making another try at it.

The Inspiration:

The design for this project did pop into my head one day but only after thinking about what I wanted to build. I think the basic "Chest on Stand" idea may have been influenced somewhat by studying the work of James Krenov. I just thought that some combination of Bombe and Krenov could be interesting.

Conceptualization:

Google Sketchup is my tool of choice for visualizing my designs. This is what my original sketch. The main difference between the original sketch and the final product was that I eliminated the lower shelf but then added an apron to the stand for rigidity in the legs.

bombe cabinet.jpg

Design Parameters:

I had no client for this project. It was something I just wanted to build for myself so I was free to do as I wished.

Material Selection:

I had purchased some nicely figured Easter soft maple from our local hardwood supplier so I decided that was a good choice of material for the bulk of the construction.

Final Layout:

To accurately measure the curves I drew a full scale two dimensional layout on some scraps of MDF.

P7130329.JPG

Once the radii of the curves was established I made a bending form for glue-laminating the curved pieces. I collect scrap chunks of glue lam beams for cutting these forms from. I cut the radius a little tighter than I want the final product to be to allow for the spring back that will occur once the glue up is released from the form. The thicker the individual laminations are and the tighter the radius, the more spring back will likely occur.

I then made a test lamination and some sample joinery to verify my layout and once satisfied I proceeded to making the actual pieces.

P7130331.JPG

Simple clamping form

P7150347.JPG

Structural Details:

I decided on a stile and rail type carcase frame for the chest body. The end panels would have a middle rail and solid wood panels. This would allow me to install the horizontal frame rails to the end panel rails with long grain to long grain for a lasting glue joint.

The full scale layout made it possible to accurately measure the varying length and angle cuts of the carcass frames.

P7150350.JPG

More to come, Bret
 

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Discussion Starter #2
Making the Curved Ends of the Chest:

This photo shows me checking the thickness on one of the four lams making up the curved stiles. I made the pieces wide enough to rip the lam into two pieces so that I would only need two glue-ups for the four pieces I needed.

P7130332.JPG

This not the actual glue up for this project but this is what it looks like after it's all glued and clamped

P3160738.jpg

After it is taken out of the clamps the fit is checked against the layout. I slightly miscalculated the spring back by about 1/16" overall but I will simply adjust my layout to fit the parts rather than make them over again.

P7130334.JPG

Next, after fitting the router table with a curved fence, I plough the groove in the curved stiles with a straight cutter to accept the panels and the tenons.

P7130336.JPG

I had to make three passes to achieve the final depth of cut but it came out nice.

P7130338.JPG
 

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I love this piece Bret and I'm glad you are revisiting it. I have one (possibly dumb) question though; what does "Bombe" refer to? A person? (Revealing my lack of knowledge here.)
 

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Discussion Starter #4
I love this piece Bret and I'm glad you are revisiting it. I have one (possibly dumb) question though; what does "Bombe" refer to? A person? (Revealing my lack of knowledge here.)
according to Websters "having outward curving lines" referring to furniture.

Bret
 

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Discussion Starter #5
Making the End Panels:

This photo shows using one of my radius templates (which are flexible) to mark the curve of the front which happens to be 20".

P7130341.JPG

Dry fitting the end panel parts to check fit. I did not curve any part of the rails, just made sure they fit good. I figured I would shape them as needed after glue-up. I did do a little shaping to the small panels (reverse raised panels) using a hand plane. I shaped the fronts until they fit the radius and then routed the excess off the back side. You can see this on the previous post.

P7130342.JPG

End panel glued up and ready for shaping on the rails.

P7140344.JPG

Assembling the carcass frame:

This photo show the frames being fitted to the end panels. The top and bottom frames are mirror images of one another but the middle one is wider and deeper due to the curves. They were made using a simple mortis and tenon. The frame rails were fastened to the end panel rails with glue and screws. With the large surface area of long grain to long grain, I felt this was the best way to fasten this together and that no joinery was needed other than an accurate butt fit and even glue pressure.

P7150345.JPG

Bret
 

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Thanks for walking us through the process. Very well detailed and planned smartly. The design looks very firm and that
is a nice example of beautiful work and inspiration. Looking forward to seeing it fully done.
 

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Discussion Starter #7
First Intermission: Me trying to be funny

I'm getting lots of views but nobody is asking any questions. I'm getting lonely on this thread all by myself.

I am positive you will not ask a stupid question but, yes, there is such a thing as a stupid question. It might sound like this "why am I so stupid?" My answer to that might be "because you didn't ask enough questions."

The only reason I do these threads is because I want to share my knowledge, at least the parts I still can remember. Yes, I am a crotchety old guy but I've never bitten anyone, except, well, we won't go there.

I was joking with Bill today. I was recalling that as an apprentice the old guys used to tell me that they had forgotten more than I'll ever know. Well, I'm not getting any younger, there might be some truth to the fear that I may forget more than you will ever know. So ask me some questions. If I don't know the answer, it's because I've forgotten! Ha!

Bret

PS if I don't answer right away it's because I busy doing something else or I'm taking a nap or working in the garden. I will get back to you!

Here is a typical question I would expect to get "dear Mr. Woodworking Genius. What is an enail?" my answer would be "I forgot, you should have asked me sooner"

Hey it's my thread. As long as nobody gets hurt I can do whatever i want.

Now back to the seriousness:
 

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All I can say is I wish I could come over and help on a build like this. So much to learn in the details! I think a lot of us new guys are afraid to do something with curves even though the results are so fantastic. It is helpful to see how you work through this. Any other tips for taking on curved work?
 

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+1 on Shop Dad's question. He took the words from my mouth. Please give details and advice on working with curved stock. I'm really looking forward to seeing this through to the end.

Brad
 

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I spoke with Bret yesterday....

I told him not to worry about not enough posts or questions.:no:
I said that project is so intimidating it would even give old guys like me a run for our money. :yes: Bill
 

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Discussion Starter #11
+1 on Shop Dad's question. He took the words from my mouth. Please give details and advice on working with curved stock. I'm really looking forward to seeing this through to the end.

Brad
As you are aware, I love curves.

I make curves from wood in three basic ways:

1. Cut from solid wood on the band saw.

2. From laminating thin pieces using a curved clamping form.

3. Stack lamination of segments

It is quicker and easier to cut your curves from solid wood but may not be as strong and you may have to use a large piece of wood to get the piece you want, which may force you into segmenting your curved pieces. Curves cut from solid stock also might result in short grain through the work piece at some point.

Laminating curved parts on a clamping form is a great way to make very strong parts using the least amount of wood. It's is helpful to have a good table saw or better yet a band saw that is capable of re-sawing and to have a planer that will plane thin pieces without them blowing up.

Some people have mentioned that they are intimidated by curves. An easy way the get over that is just to make a curved piece.

P7150347.JPG

Start by making a form like in the photo. I use chunks of discarded glue lam beams but any old thing will work such as a few pieces of plywood glued face to face. 6" x 6" x 2feet should be plenty. Draw a simple 30" radius arc from end to end and cut it smoothly and squarely on the band saw. Make sure there is enough meat left on each side of your form so it won't break during clamping. For a lamination like this I would recommend five or six layers tog get to 3/4" total thickness. Six, 1/8" thick pieces, two feet long and how ever wide you want up to you maximum re-saw capaicity but for this exercise 2" wide is fine.

When doing a large glue up you must be prepared and work quickly before the glue sets up. So get everything arranged first. clear the work space, get the clamps out and adjust them to the right opening. For larger glue ups I use a paint roller to apply the glue in a thin layer and fully cover each face of each lamination EXCEPT the ones that touch the form, or the two outside faces. Once the glue is applied throw the stacked bundle in the form and clamp it evenly from both sides with at least three clamps per side, more for a larger piece.

It is helpful to have the form be the same width as your workpieces

I gota go now, I'l finish this later
 

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Bret, i'm always impressed with your work. I love the designs you come up with. How much spring-back can one expect on a laminated piece such as this? Do different hard woods react different to the laminations, was just wandering if most hardwoods can be bent this way? One more Q, how do you go about designing the piece not knowing the exact spring-back the lamination is going to produce, is it kinda trial and error on the first piece out of the form? Thanks for taking the time to help us learn this process.
 

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Following the build and I think it is awesome looking so far.

Young guy question tho:

When making the form, did you make 1 arc 30" in radius and then cut and smooth?

Or

Did you make 2 arcs close together and cut in between and then smooth back to each line to achieve the final product?
 

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Discussion Starter #14
Picking up where I left off.

Thanks for the kind words.

I'm going to finish discussing making a simple laminated arc and then I'll answer some question that were asked.

I said "It is helpful to have the form be the same width as your work pieces" That is because the pieces slide around with all that glue acting as a lubricant. you need some way to get everything aligned laterally which is easily done with a clamp provided the form is the same width as the work pieces. If you have a form that is wider than what you are gluing up then try making the the work pieces a little longer than the form on both ends so that way you can have a little sticking out to clamp laterally.

My glue of choice is TB II, and I use heavy duty clamps and apply lots of pressure. The individual plys should be smooth planed on each side and uniform in thickness.

The amount of spring back you get depends on the type of wood. thickness of the individual plys and the radius of the arc.

This sample arc, if the net thickness is to be 3/4", by using 6 plys of 1/8" each in walnut would have very little spring back, probably about 1/8" overall. But this same arc with three plys of 1/4" thick hickory would spring back maybe 3/8 to 1/2". It's a bit of a guessing game based on experience. I have trouble planing anything below 3/16" thick so I would make this with four plys at that thickness and would expect about 1/4" of spring back.

With radii of 24" or more and net thickness of 3/4" to 1", I have not found it necessary to cut each side of the form at a different radius to compensate for the work piece thickness. For tighter radii and/or thicker net requirements then, yes, both the inner and out radii must be cut to get the form to apply even pressure.

For a simple form, make sure your band saw cuts perfectly square to the saw table and use a good sharp blade suitable for re-sawing. I have a 17" 2HP band saw and I use a 1/4" 3 tpi carbon steel blade and I follow my line as carefully as I can. The form comes off the saw ready to use.

I was introduced to curve laminating early in my career. One of my first jobs was making wooden water skiis, gluing. loading and unloading the hot presses. I used an automated glue spreader and heat blankets between each ski. I could press 48 skis at a time using six very heavy duty presses with 8 skis in each press and I could cycle through the process 4-5 time each shift.

Bret
 

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Brett, first thanks for such an informative thread!
One the subject of springback, I was wondering. Do you approach your work based upon doing the glue ups first and then adjust around that? Also given what you know about wood species and their
springback tendencies do you ever adjust the radii? to compensate for springback.
One last thing. Have you ever put a laminated arc under load to get it to fit into a frame and if you have what were the results?
Eric
 

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Discussion Starter #16
Brett, first thanks for such an informative thread!
One the subject of springback, I was wondering. Do you approach your work based upon doing the glue ups first and then adjust around that? Also given what you know about wood species and their
springback tendencies do you ever adjust the radii? to compensate for springback.
One last thing. Have you ever put a laminated arc under load to get it to fit into a frame and if you have what were the results?
Eric

Great questions.

I do my layout of the project first and then try to hit the radius right on but (as in the case of the Bombe Chest) I might adjust my layout if I don't get it perfect.

Certain projects, such as a round top door jamb, require the arc to fit exactly. But in the case of a door jamb, there is some flexibility and the trick is installing it properly in the field. But in the case of curved cabinet doors with curved inset doors, you have to get it spot on if the cabinet carcass was built first.

I didn't really understand the last question enough to give you an answer. Rockers and splats come to mind.

PB200192.jpg

PB080145.jpg
 

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I have one (possibly dumb) question though; what does "Bombe" refer to? A person? (Revealing my lack of knowledge here.)

That's where the bombs go in a military plane before dropping them on the enemy. :eek: (sorry, but often times its better to ask a dumb question than to get an even dumber answer!)

Loving this build. Loved it before and missed out on the finish. Hoping to see it all the way through this time.
 

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Nice build Bret- you do so many bent laminations and make it look easy. I have a question. I am making some jewelry boxes- right now working on prototype but have found that white oak bends easy- 6.5 radius-1/8" lams. mahogany and cherry- not so hot- 1/16"- 50% breakage. Question is- what trouble am I going to have with soft maple- or how about hard maple- walnut??? Here is a picture to show you what I mean- if inappropriate- just say so and it will be gone.
PS beautiful chest- don't stop- I am learning a bunch.
 

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Discussion Starter #20
Nice build Bret- you do so many bent laminations and make it look easy. I have a question. I am making some jewelry boxes- right now working on prototype but have found that white oak bends easy- 6.5 radius-1/8" lams. mahogany and cherry- not so hot- 1/16"- 50% breakage. Question is- what trouble am I going to have with soft maple- or how about hard maple- walnut??? Here is a picture to show you what I mean- if inappropriate- just say so and it will be gone.
PS beautiful chest- don't stop- I am learning a bunch.
No problem, I will get back to my thread eventually.

Mike, your created some problems to solve. I think white oak is a good wood for bending, without breaking. A test to judge the bendability could be to take a piece of the subject wood 1/4" x 3/4' x 18" and try to break it in two. Some wood are more brittle than others such as walnut, cherry and maple. Others bend a long way before breaking such as white oak, ash, hickory, black locust.

That's is a pretty tight radius you are working with. I'm surprised you are having luck with 1/8" lams. What are the recessed panels made of? You know, your project might lend itself more to a stacked segmented curve. It's small enough so it would not have too many segments and you could alternate the miters to make it real strong. I think it would be faster and might even look better?

Bret
 
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