In the pictures, a complete shell, with circle for roundness, a close up from the only seam I sanded a bit to see if it is tight. (The ones next to this one are still rough and not exactly same height, and therefore look like they are not tight, but they are). last one shows two staves with the routerbits I used. I think there are better choices on bits, but I have these and this looks promising I think.



My thoughts on this one are that a round edge doesn't need the 100% accuracy that you need with anglecutting. Round is round and will fitt by nature, always. If the diameter is bigger as the thickness of the wood you are able to set the staves in any angle (to an limit offcourse, but ya know) you like. If you have a routerbit with wich you can cut a 180 degree rounding in one go you will be king!!



randyb:

That's a cool idea Koko.

Basically, with glue, as long as you are getting a good contact between your two surfaces you are going to get a good bond that is stronger than the wood around it. Looking at this, I would figure you have a good chance of getting that to glue up well and hold.



lunarsnare:

I have never built a stave shell, however just looking at this, I like this a lot better then gluing flat edges. More glue surface left to go thinner on the final machining of the shell wall? Very coolÉ. Can't wait till you have it glued and shapedÉ



Well this is just a thoughtÉ

What about running your piece of wood through a shaper before it is all cut to length.

One side the concave and the other side the matching convex profile that may be very accurate and less cumbersome in the long run.



Woodrow:

This is quite clever. I hope it works out. It could be an easier way to produce stave shells for all of us.



CSpencer:

Very clever. I only see one possible problem. Often when rounding a shell on a lathe (or a router jig) you end up in a situation where you're removing slightly more material from one side of the shell versus the other. This can be caused by a slightly out of round shell or by having the shell mounted slightly off center. When this happens the width of the staves ends up varying slightly. To clarify, I'm not talking about the width (thickness) of the shell wall varying. That would be a huge problem. I'm talking about the width of individual staves, as in from left to right. With beveled seams the variation is extremely small, less than 1/16", so it certainly isn't noticeable and it has no effect on the tone or strength of the drum. With your rounded seems the angle of the seam at the outside of the shell is steeper, therefore the variation in the width of the staves could be much more. Plus, with the rounded seams it will be difficult to get the raw shell round to begin with, which will worsen the variation I'm describing.



Of course, it's a problem you can avoid with very careful gluing and mounting and judging by your other posts you do everything very carefully. Even if there is some variation it may still not be enough to notice, although you may not know until you mount the hardware.



koko:

Hi cspencer.

I have to think over your reply to be sure I really get your point. On 1st hand I think this:

You are right that by rounding the shell the staves start to differ in size if not completely round. I believe that is the case anyway, as you also state and you accept a 1/16 difference. If I follow you right, your concern is sound, strength and looks. If the rounded staves are all the same width in the beginning I think the variation in width will not be any bigger or smaller as with normally beveled edges. For now I don't see the effect from rounded seams making this worse.

The raw shell has to be round to begin with, which I achieve by inserting a round template while setting up the staves. At the test run I noticed that the gaps can differ, but by gently slapping the corners it was quite easy to get them even and thereby rounding the raw shell.



I don't understand the steeper thing, but that is a lanquage problem. I'll ask my brother if he gets this. He is the smarter and more precise from us 2.



CSpencer:

"Steeper" was perhaps a poor choice of words. I'll try to explain myself:



Picture a stave with beveled sides. The widest part of the stave is at the outside of the shell and the narrowest part is at the inside of the shell. The difference, which is caused by the beveled edges, is around 1/4". Now, consider a stave with rounded edges. The widest part will be at the front and back faces. The narrowest part will be through the center. The difference between the widest and narrowest part will be much greater than a beveled stave. Judging by your pictures, I'd estimate the difference to be about 1/2". It is partly because of this larger difference that the staves could vary in width more after being machined.



By "steeper" I was referring to the angle of the bevel. A typical 20 stave shell has a bevel angle of 9 degrees. In other words the seam meets the front of the stave at an 81 degree angle. This is pretty close to perpendicular (90 degrees). With your design the rounded seam meets the front of the stave at a much smaller angle, around 45 degrees judging by your pictures. I think that this smaller angle could cause the width of your staves to vary more. With a smaller angle the amount of material removed from the outside of the shell will have a larger impact on the location of the seams relative to each other.



It could be that in practice it still won't be enough to be noticeable. I suppose you won't know until you try it.



koko:

I am very, very, very impressed by your thinking. As you said: "You wont know until you tried it". I tried it. Not all the way but enough to see you are making a strong point here!!!

First: This second explanation helped a lot, but somewhere you mentioned 1/2" difference. By this I thought: or I still don't understand what you are saying or you "misjudged" these close up pics. Only way to find out was to build another shell with common edges. Well, I did. It gave me the opportunity to check accuracy of the drawing a friend made (and made available for you all at the builders manual section "Stave layout PDF" by Rjhanes) and to fully understand what you where saying. I made another shell pretty much the same size as the one with rounded edges. By doing so, I could check what you are saying. The inserted circles are the exact same size and there is hardly any play.

While setting up, I noticed that the "hassle" is about the same, but at different moments. Setting up the normal staves was a bit harder than the rounded ones, but rounding the shell was a bit harder than with the normal staves. Equal hassle to me. Now the concern you thought of. It seems to be there, but by no means in the distance you thought. As the pictures show, the rounded ones can give more gap, but only 1mm difference opposed to each other. On the outside you can really see this happening. I couldn't get the staves to match exactly and the differences did vary. This variation is caused by the rounded staves' needs to be put in correct angle and the normal staves don't.

I think that you may need thicker raw staves with the rounded edges.

Conclusion so far: Normal staves are less hassle to get placed in a circle by its nature, but more hassle to set up and more hassle to cut in the correct angle, although with a template that is not so hard to overcome. The rounded staves are more hassle to get into a full circle, but less hassle to get up and have a longer seam wich will always be a perfect match by its nature.



Seems that the real issue here is the variation in width as you mentioned. (And I am realy impressed by that strong thinking). As shell building will always require 100% accuracy on the job, I think in the end you may end up with about the same variation, but rounded edges are a greater risk for this matter, but only if you are able to create 100% accurate normal edges. (If not 100% your normal shell will also be out of round to a certain degree and with that the width will vary).

As far as sound is concerned I call the experianced on that matter to reply.

For now the only thing I do in my shed will be cleaning and then go for a holiday. After that I will build two shells with two colors of wood, to see the real difference in width.

I thank you Cspencer for your strong thoughts. To me this is what Drumshed is about: sharing thoughts and ideas 'till we have found the best!!



Sam Bredeson:

My dad tried to get me to make a stave shell like this, but I couldn't get over how the shell doesn't round itself. I could never get putting a circle inside to make it round enough. Nice job on yours though! If done correctly, I think this method would work great.



koko:

Hi Sam. The shell will never round itself and that is a downside of this method. I have set up a dry run only and made the round template to a perfect fit by gently making it smaller and smaller in diameter 'till it slid in. The router is my best friend nowadays, because you can take off less then 0,5mm at a time with it. Your dad seems to be no girly, but a clever man who should post here!!



crankz1:

Another very cool idea koko!

There's nothing wrong with thinking outside the box and trying new things.

I can see this as working quite well with your router jig. I'd incorporate the inner circles (you used in glue-up) into the hub assembly that runs on the roller bearings. Seems as though this would be a good way of maintaining run-out accuracy. Provided, of course, that the hub assembly is true and dimensionally accurate. Odd width staves may pose a problem though.



koko:

Now that this thread is in focus again I would like to add some extra experiences I got a couple of weeks ago.

The beams have to be the same thickness and that has to be pretty close too. When you do the round going outside (convex?) with the bit like I had to use you need to go two times. That takes real good adjustment of the height of the bit. It needs to be in the middle. If your beams are not same height that means you have to adjust height every time. With the MDF this problem didn't show of course, but with the maple floorboards from my mother's house it came up.



The routerbit itself needs to be sharp and in perfect shape. Especially the round bit to do the inward going (concave?) round... is prone to wear out in use. Especially with hard wood like Purperhart.



TheIronCobra:

Just started doing these bevels for the first time, and then got called into work. Anyway, Koko, this is amazing and I'm putting you up for the Nobel prize this year.



Hmmmm, interesting developments...... Decided on the most important factor in this method GOOD QUALITY ROUTER BITS.

Needless to say, I've destroyed my crap quality bowl cutting bit (luckily on MDF) and have gone to buy some good ones.



koko:

I use old routerbits for the first cuts and at last change for the best and do the final run with these. Save a bit of money, but more importantly, save the shape as long as possible.



TheIronCobra:

Tried milling up some mdf pieces in this method AND IT WORKED - to a certain extent.....

Few questions if you will..



1 - Where did you get those clamps from? they look cool and useful



2 - When using the bowl cutting shaped bit in the router table, did you use the same radius bit in comparison to the roundover, or did you do multiple cuts with the bowl bit?



My roundovers were alright, but I had to do multiple cuts with the bowl bit and found it hard to be accurate and make it fit.

I think ill just go and buy a same radius roundover to my bowl cutter and should IN THEORY fit perfectly in one another.





koko: I did use two matching bits. (Diameters the same. The one which leaves you with a hollow shape (concave,convex, always confused) in your piece of wood is prone to wear. Especially the top because that piece is taking the most cuts. From what I see at your pictures it looks that yours is worn out. That is why I wrote I use old bits for the first cuttings and only switch to the newest bits for the last cut. (Less wear or risk for a worn out bit).



Make sure when you do one that leaves you with a round piece of wood, that you set your router height very accurately, precise in the middle.



TheIronCobra: What I meant was, was the total diameter of the bit (convex) big enough to round the inside of the wood or did you have to adjust your router fence and cut multiple times to get the roundness all the way to the edge?



Was thinking of buying a big ass bit to compensate for this, but if you have a better method (which you probably do ) would you share?



koko:

The routerbit last shown cuts the round in one last go. (Only adjustements that are made are for the bit rising out the routertable. If you would make the whole depth in one go that would be very agressive on the wood and router). NO adjustements at the fence, especially NOT at the fence.



jbfrench75:

Don't you think that round bevels can move with time, even with glue ? I would be afraid about that.

Don't you think it could be better to use finger joint bit?



koko:

Ohhh, freak jeahhh, a fingerjoint would be the thing to use. I met Gert from Lignumdrums (Belgium) and he showed me two staves being cut with a fingerjoint. Men, even without glue it was very strong already. The problem is you need to have a specialy made fingerjoint bit for that.

The bit has to be cut at the correct angle 10000% right. And those bits only fit in a different kind of router. EXPENSIVE.



About your concern of the joints moving, no I don't believe that can happen. With this method you are able to achieve such a tight joint that the only thing you have to do is tighten it securely while the glue is curing and of course there should be glue everywhere. That specifically doesn't mean you have to use as much glue as you can, but as much as needed for covering the joint. If there is too much glue you risk not being able to force it out while clamping. Take in account that you're always at the end of open glue time before you are able to set up the shell.



Wato:

I thought this joint idea out independently after seeing Flute & Bead Bit Set used for canoes, but used 3/4 inch bullnose and round nose router bits to make the interlocking staves. The timber is Jarrah (I am located in Australia). 65 mm wide 21 mm thick decking was used for all staves except the bass drum staves which were cut from wider 25 mm thick pieces.



The round edges allow the staves to rotate for self alignment and the joints will be stronger than simple butt joints. Also, the joints will be inclined to the final surface making any filling a lot easier and better.



For assembly, bases were made from 16mm MDF screwed to 16 mm plywood. A circular groove, with accurately machined inner and outer diameters, was routed then into the MDF (only) for inserting the staves. This and other info was calculated using a spreadsheet.

Looks complex, but is simple in practice since the bullnose routing is done to get the "stave width" dimension measured with calipers. Dry assembly pic shows top and bottom strap clamps which pulled the staves together using a circular lid corresponding to ID (removed for pic).

Glue up was piece at a time using sieved jarrah saw dust added to West System 105 epoxy to form a paste. The "Glad Wrap" around outside helped minimize leakage out of vertical joints. Epoxy was scraped back into internal joints as it thickened while hardening.



The bass drum is 20 inch dia. Pretty scary if they were to break apart while spinning on a lathe. However the staves are glued solid into the 32mm thick bases, which could be used for mounting onto a lathe face plate and the lids could be fixed to the other end to help keep everything together, at least while doing the outside.



They have been sitting around for more than a year now. Had a guy setup with large metal lathe but he pulled out after the build. Have thought about Koko's jig too. But it would be so much easier to use a metal lathe.