Bottom-cleaning VS spoilboard router bits

[Dax Liniere]

Hey gang!

(I considered the post title "Master woodworkers: Do you prefer your bottom cleaned or your boards spoiled?" XD )

I'm making a jig to turn the outside of a drum shell. (sketch below)

The system relies on a router table and uses a threaded rod to pull the drum shell through at an even rate (hand-cranked).

I'm looking at router bits for this task and figure that 1" is probably a good diameter, but I have discovered that bottom-cleaning bits have a very slight V-shape to their flat bottom cutters, compared to a spoilboard surfacing bit which looks completely flat.

What would be the best choice for this situation?

This is how I've started the timber shell: https://www.youtube.com/watch?v=aaVSylbRQ4U
Gah! Can't attach photos in this group, here's the sketch: https://www.facebook.com/daxliniere/posts/10215559743181408

All the best,
Dax.

[Erica Calogero]

Hi Dax,

I'm not a master woodworker but I did work as an architect for a few years and even with the diagram it took me ages to figure out how your set-up works. Am I right in thinking that the decagon of the drum (the drum face) is perpendicular to the page in the drawing? So that the handle on the threaded rod rotates it as well as moves it laterally in the x-axis? That's quite a clever design, not seen one like it.  Anyway, if that's the case I would say you need to go with the bottom cleaning bit as the spoilboard bits mostly look like they're for CNC finishing of large flat surfaces. I don't think the degree of V-shape matters too much, but if you want to know the technicalities, Dean or Liam can lecture you at length on that subject, even though they're metal workers as I believe the priciple is the same.

Anyway, if I were doing what you're attempting, I would prefer to have a continous sharp edge from side to side of the bit. That's my two cents for what it's worth.

Best,

Erica.

[stephen o'brien]

End grain to end grain is the most feeble of orientations for a joint, should 've used the grain rotated by 90 degrees.

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[stephen o'brien]

A much easier way of constructing this would've been to cut the timber into staves, and use a rounding bit for the edges.

[Erica Calogero]

I was going to say use very fine ply and go on a steam-bending course. But I guess you want to use that historical wood...

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Erica Calogero

www,ericacalogero.weebly.com

[Dax Liniere]

Hey Erica,

How are you going?

Yes, that's right, it's more about historic value, though I do believe it could sound quite good. Either way, it's my curiosity that's driving me on this project! :D
You are correct about how the jig works. It's not an original idea, I saw a guy doing this on YouTube, but he didn't have one fixed nut on the frame so he had to manually move it along the X-axis after he did one rotation. Seemed obvious to weld a nut to a plate and screw that plate to the jig, so that's what I've done.
I ended up using chunky M20 threaded rod which was carefully selected as the straightest at the builders' merchant. (<1mm over 1000mm)

I'll go ahead and get the bottom-cleaning router bit. Thanks for the advice. :)

Hi Stephen, thanks for your replies and taking the time to do that CAD drawing. I've never seen a stave drum produced that way, commercially or otherwise. Seems like a lot of wastage and a lot higher chance of something going wrong, wouldn't you say? Also, as I understand it, the fewer seams on a drum, the clearer its tone (larger pieces offer more shell resonance).

As for the end-grain gluing, what you've said is 100% true of traditional PVA glues, but PUs like the one I used have exceptional end-grain-to-end-grain strength. Plus, if it falls apart, I can always use my biscuit joiner on it. I might do that on the next shell, hopefully getting some more historical timber from another famous studio in the next couple months.

Thanks everyone!

All the best,
Dax.

[Scott Young]

I am not a woodist so this might be totally bunk.

Do you guys have a box joint jig? That might improve the strength of the joints and make for a certain artistic flair on the next one. 

Another possibility if you have a CNC router, you could set it up to cut the inner and outer profiles, but you would need to be spot on with the alignment of the router. 

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[Erica Calogero]

Scott and Dax,

Scott's idea would be good, but I don't think extra strength will be required, as it's just a drum and I don't think it's going to be taking huge stresses and strains. Also it will have those rings of steel around it, I don't know what the technical drumming term is. Anyway, we have a sled for the table saw but not a box jointing jig for the table router that I'm aware of. However, best to ask the self-appointed resident master woodworkers who are: Stephen O'Brien, Jonathan Hodgson and Dean Forbes as I've been locked out of the wowodworking tool cupboard.

Good luck with the build Dax.

All the best,

Erica.