Best method of making accurate bevels.

[Beau]

If it is part of a horn on a speaker would one side be invisible? Just wondering if you could kerf some veneered board to the curve.

I am guessing this curve will be joined to some sides on the ends. The snag I see is you are building a wide board in solid wood that is going to want to expand and shrink. You will need to devise a way to allow it to do this if my guess is accurate.

 

[simonms]

Jacob and Beau, thanks for your insights, very helpful.

Jacob, unfortunately my drawings are not wildly inaccurate guess work, they are precise transcriptions to the actual object itself. I do realize that the bevels are all differing by tiny amounts from stave to stave. All I am assuming is that it was planed to fit, but I could be wrong on the actual process as I have no way of knowing, just pure guess work.

I have made this curve by laminating ply over a former in a vacuum bag but this is not the tradition method and that is what I want to attempt to build.

Beau, thanks and certainly movement is going to be a consideration, the poplar wood I have been quoted for is quarter sawn and kiln dried so was hoping that might get me off on the right foot but am painfully aware that this will still mean that things will move but my experience here is non existent being the first time I have considered making something like this. As I have said I am hemmed in with my methods of construction and it's clear kerfs was not used.

 

[Jacob]

Jacob and Beau, thanks for your insights, very helpful.

Jacob, unfortunately my drawings are not wildly inaccurate guess work, they are precise transcriptions to the actual object itself. I do realize that the bevels are all differing by tiny amounts from stave to stave. All I am assuming is that it was planed to fit, but I could be wrong on the actual process as I have no way of knowing, just pure guess work.

OK planed to fit, but not by setting up a machine or a hand plane to precisely cut each piece with its fine variation in such a way that they would all go together like a jig saw. Have you looked at both faces of the original? The back would give a clue. Have you any photos?
My guesses are either:
most likely they would all be undercut by the same amount such that the top face would show a tight fit but the back would be less tight - but barely noticeable as the angle is very small and full of glue. Clamped tight.
Or they were planed at 90º and clamped even tighter.
Or planed at 90º but each piece eased to fit as it was dropped on to the former. Each piece would then have one edge at 90º but the meeting edge slightly eased to fit at the angle. Your "precise transcriptions" would not have found this unless you had done some very fine lab work on a demolished original.
Whichever method the material would start over sized in thickness but brought down smooth after the glue had gone hard.

 

[simonms]

I don't have any photos to hand but my process was to measure the width of the front and back face and draw in the bevels so the drawings are a good reference I believe, there is no way to actually see the cross sectional cut lines as the sides are covered. The only datum I had was the start angle which was measurable then just adding on the distances as they came from the from top and bottom. It's the most accurate process as I could manage given what I had to go on. From what you are saying this drawing is showing that constructing this would be a non starter so am struggling to figure out whats going on here.

 

[worn thumbs]

I'm a bit surprised this thread has gone on so long.How do you suppose the fellows who built this Dragon managed to get tight seams?

 

[simonms]

Jacob, thanks for you insights, I completely agree with your assessment, I would never have been able to tell if we were looking at 90 degree bevels or 91 degree bevels but thats all I had to work with. What you have suggested may well be true and is a great insight and just what I am looking for, your experience is something that I have not got so thanks again.

I m likely making the mistake of looking at cad drawings and not the reality of building. Could we consider that one face might be at 90 and the next or adjoining slat might have been carefully planed to butt up against it. Working from the cabinet not the drawing so to speak, I think this might certainly be a case of choosing my best approach from all of your help and just seeing how that works in reality. Poplar doesn't seem too expensive a material so that is a plus.

Any thoughts on movement and best methods to combat this would also be interesting.

 

[MikeG.]

....How do you suppose the fellows who built this Dragon managed to get tight seams?.......

Beautiful.

By offering up and adjusting. That option has been dismissed (by being repeatedly ignored). Again, we've spent more time prattling about this than it would have taken to do the job, by a factor of about 10. The thing I'm waiting for is to hear that it's going to be a painted finish, as indicated by the choice of poplar, rendering the entire conversation pointless.

 

[Jacob]

I'm a bit surprised this thread has gone on so long.How do you suppose the fellows who built this Dragon managed to get tight seams?

Exactly!
Carvel built and then smoothed, a.k.a. "fairing in"
https://en.wikipedia.org/wiki/Carvel_(boat_building)

 

[simonms]

Cheer up Mike, I have made it clear that I am asking for advice on something that I have never done and from that perspective what might appear an obvious method to an experienced woodworker, I have to look into it and understand what it means. One might expect a slightly more lenient approach from advisors considering my lack if experience, read between the lines a little. I don't believe I have dismissed anyones suggestions, certainly there are 3 practical posts I have already acted upon regarding squaring up boards, buying a particular plane and Jacobs recent post regarding methods of joining. Now that I understand what Jacob is saying then your first posts make sense to me, if I have come across as dismissive it is certainly not intentional.

You may think this is un necessary prattle but to me it's very valuable and gratefully received advice. I certainly don't want to cause problems or continue in this manner so may I respectfully ask for constructive suggestions.

 

[Jacob]

So that's covered three very trad methods of making things look perfect:
under cutting,
offering up,
finishing (plane, scraper, sanding) after joining.

 

[simonms]

Yes, thanks Jacob and i understand in theory what all of those methods entail so I hope in realty I might be able to get some half decent results. If it were not for the help here I would have likely used the rail saw, probably slightly undercut on every bevel on my drawing but now I think I will re draw leaving 90 degrees on one edge then plane to adjust as I go....as Mike was describing on page 1

 

[custard]

I'm a bit surprised this thread has gone on so long.How do you suppose the fellows who built this Dragon managed to get tight seams

Isn't that comparing apples with pears?

Presumably the bloke building the Dragon was planking over ribs/frames, so no glue-up challenges, where as the original poster faces a quite tricky cramping and gluing job.

Furthermore the Dragon looks like carvel construction, so it's far from gap free as it'll need the caulking hammered into the seams.

I always think with woodworking projects there is such a thing as "appropriate viewing distances", which in turn dictates the required fit precision and quality of finish. The OP's projects and the Dragon are at different ends of that spectrum, I see plenty of fine boat varnishing every time I wander around my local marina, but what's first rate varnish work on a boat would be considered third rate on a violin. Same rules apply to fit quality.

 

[MikeG.]

.........Furthermore the Dragon looks like carvel construction, so it's far from gap free as it'll need the caulking hammered into the seams.....

It's much more likely to be cedar strip construction, which is really a form of veneering in that the strips are only 3-5mm thick, and likely glued to a ply substrate. If not, as in canoe construction, for instance, then the same thickness cedar strips are edge joined (offer-up-and-adjust, again) over a series of temporary frames. They are then epoxied over, so whilst there is no caulking, the joins don't have to be perfect to be watertight.

My approach to the construction that the OP has taken on would be to make a couple of formers (just cut from the flat from MDF), then offer up each piece in turn, adjusting the edges as I went. I would glue up one piece at a time (ie wait for each join to set before moving on to the next), using tape and/ or string as clamps. Depending on the finish, you could even pin the timber to the formers, temporarily, and/ or fix temporary battens to the formers and wedge from those. I wouldn't however, have taken on a project I didn't have the skills, knowledge or tools to attempt.........and I list those requisites in a descending order of priority.

 

[Jacob]

I'm a bit surprised this thread has gone on so long.How do you suppose the fellows who built this Dragon managed to get tight seams

Isn't that comparing apples with pears?

Presumably the bloke building the Dragon was planking over ribs/frames, so no glue-up challenges, where as the original poster faces a quite tricky cramping and gluing job.

Furthermore the Dragon looks like carvel construction, so it's far from gap free as it'll need the caulking hammered into the seams.

I always think with woodworking projects there is such a thing as "appropriate viewing distances", which in turn dictates the required fit precision and quality of finish. The OP's projects and the Dragon are at different ends of that spectrum, I see plenty of fine boat varnishing every time I wander around my local marina, but what's first rate varnish work on a boat would be considered third rate on a violin. Same rules apply to fit quality.

Same "standard" just scaled up or down. OP would be working with small pieces on a former (in place of ribs and frames) so it'd be a lot easier than building a full size boat!

 

[simonms]

Thank you Mike! Great advice, we all have to start somewhere, believe it or not I am not a total cretin in terms of woodwork it's just that I have never done anything like this before.

I am going to adjust my drawings and post them up so that you can give the approach thumbs up or thumbs down depending on my understanding of the methods described.

 

[MikeG.]

If you do proceed along those lines, then you must be working on the 3rd piece before you glue the first join. By that I mean you must have planed up both edges of the second piece before you glue it in place, as you won't have access to the free edge of the piece again once its other edge is glued to the preceding piece. So you'll be needing to do a series of dry fits well ahead of the gluing.

 

[simonms]

Thanks again Mike, I will be certain to do that. The actual method to make the adjustments are still not decided but I am wondering if the shooting board idea (obviously my previous drawings on the design would have to be doctored somewhat) would be the way to go.

Maybe its just a matter of suck it and see and re evaluate if necessary.

 

[worn thumbs]

I'm a bit surprised this thread has gone on so long.How do you suppose the fellows who built this Dragon managed to get tight seams

Isn't that comparing apples with pears?

Presumably the bloke building the Dragon was planking over ribs/frames, so no glue-up challenges, where as the original poster faces a quite tricky cramping and gluing job.

Furthermore the Dragon looks like carvel construction, so it's far from gap free as it'll need the caulking hammered into the seams.

I always think with woodworking projects there is such a thing as "appropriate viewing distances", which in turn dictates the required fit precision and quality of finish. The OP's projects and the Dragon are at different ends of that spectrum, I see plenty of fine boat varnishing every time I wander around my local marina, but what's first rate varnish work on a boat would be considered third rate on a violin. Same rules apply to fit quality.

The better Dragons,such as this Borresen ,were tight seamed.The majority of them were built years before the much cruder strip planking technique became common and as Jacob says you ought to use a former.There is also the high probability that when you don't have a former the shape will vary almost from minute to minute with moisture changes.

 

[simonms]

Mike was correct in his assumptions that the originals were painted but I am trying to avoid that if I can hence the pursuit of good bevels.

 

[OscarG]

This thread made my brain hurt...not hard!

Can you please post pics when this is finished? curious to see what this will become.