Cutting v. Steam bending

[pcastag]

Anybody know the difference in terms of longevity, sound etc? With so many variables in sound (shape, wood, skin etc) it would be hard to do an A B comparison, but just wondering what people know about the subject.
PC

[bongosnotbombs]

According to my experience, the argument for carving staves is that since they are not steam bent they don't want to return
to their original shapes.

The argument for steamed and bent staves is that they are structurally more sound because you don't
cut through the grains, and the grain stays continuous.

In my opinion, both approaches are sound. The carved approach usually uses thick enough wood to compensate
for cutting through the grain of the wood, and the steamed guys usually use bands and other mechanical means to
prevent the wood from bending back to it's original shape.

I've heard and seen several examples of each type, and I've never been able to tell any substantial or appreciable differences between
the two construction methods.

[Tonio]

hmm, here we go down that road again

Not to disagree w/ BNB, but with the current adhesive quality, I think the use of bands to keep the shape may be of a old skool approach. However looking @ old GB's spit city shells its hard to say, even their last few years of existance, they seem to have that tendacy.

I have heard an opinion that carved congas have a different tone in a negative way (hollow sound), which I don't buy. I think the overall design e.g. shape, hardware, skin/crown, approach is what makes the tone. I'll bring it up again, but IMO the tone is based on the "choke" degree of the skin/shell variance.

It is intriguing subject, however.

It would seem that the cost of carving would have a higher overhead, due to the quantity/size of stock required. When I went to pick my Isla's from Mario, he had a big waste dumpster full of unused spent stock. The stock used must have been pretty hefty in size. Considering the shell shape, perhaps a 3x6 pcs of stock is cut out? Vs a bent can probably use a 1x3?

So what would be the difference in cost, the labor? Bending seems to be a large task at hand, yet carved-stock and a band saw would be less time consuming with higher overhead. It seems carving would be less labor and higher continuity.

I guess time will tell in the end.

T

[bongosnotbombs]

hmm, here we go down that road again

Not to disagree w/ BNB, but with the current adhesive quality, I think the use of bands to keep the shape may be of a old skool approach. However looking @ old GB's spit city shells its hard to say, even their last few years of existance, they seem to have that tendacy.

T

You may be right there T. But I have always thought that even though the glue itself may be strong and not
fail, sometimes the wood immediately adjacent to the seam can fail. Like when you pull two things apart and
a bit of one pulls off and stays with the glue?

but then again the only seams I have had split were on pretty old drums, so you may be right. However I did have a metal bottom band on a very new drum split, but the drum was intact.

One difference I have seen between the two styles of cutting staves is in appearance. The grain of the wood is different because the grain is cut across in the carved staves. Look at pictures of Islas and Mopercs and you can see the difference, especially when compared to Matt's or Jay's drums. The Islas and Mopercs have a kind of solid look to the word versus the grain you can see in the others.

[bongosnotbombs]

I was just thinking about this subject today and I remembered, not all woods
can be steam bent. I think I remember hearing that the African mahogany Matt
Smith uses can't be steam bent.

[Joseph]

My interest in this subject caused me to do a bit of research.
Found an interesting article: http://www.leevalley.com/wood/page.aspx?page=43626&category=1,42172&ccurrency=3&sid=
Probably more than most would care to know about steam bending.

Some salient excerpts:
"...Two rules of thumb are:
1. Exotic woods do not bend well.
2. Softwoods do not bend well and should be avoided..."
I read "exotic woods" as tropical hardwoods (like African Mahogany). Doesn't say you can't bend them, just that they don't bend well, some may bend better than others. Has to do with lignin(component of wood fiber) & cellular structure.

"....Questions that you might want to ask yourself before deciding to steam bend a curved part of your project are:
• Is the curved part structurally important?
• Is it visually important that the grain follow the curved shape?
If both answers are "No", maybe a bandsawn shape will do. From a design point of view, try to avoid steam-bent parts that have unanchored ends that are not fastened down. Humidity changes can cause the extended piece to "wave" a bit...."

• "...Will I be shaping the piece afterwards?
Laminating a curve from thin strips of wood may cause problems when applying the finish. Any glue that is exposed during shaping will not accept the final finish in the same way as the wood. Also, the laminates are always under stress and, if some are cut away during shaping, the curvature may change. Steam-bent parts, on the other hand, have no memory of ever being any other shape, unless immersed in water....."

That last sentence was surprising to me. I always thought the bent shapes were under stress.
Explains why we see bent wood shells (built with modern techniques and adhesives) sans exterior banding.

[bongosnotbombs]

Steam-bent parts, on the other hand, have no memory of ever being any other shape, unless immersed in water....."

That last sentence was surprising to me. I always thought the bent shapes were under stress.
Explains why we see bent wood shells (built with modern techniques and adhesives) sans exterior banding.

Good article. That sentence is intriguing.

The Volcano Percussion guy has a different opinion. The quoted article mentions "immeresed in water", makes me wonder about the effects of humidity.

Conga drums are traditionally made by assembling all the staves together at once during steam bending. Simultaneously, steel bands are pounded down around the staves to force them into position to form a drum. Consequently, when dry, the staves will always be under stress, wanting to spring back to a percentage of their original position. Coupled with constant changes in temperature and humidity, the joints can be weakened. This is the primary reason some drums delaminate after time.

http://www.volcanopercussion.com/Conga_Anatomy.php

[KING CONGA]

The staves on my Requeña were no doubt under constant stress.
A picture is no doubt worth a thousand words.

[s'chopp]

I was just thinking about this subject today and I remembered, not all woods
can be steam bent. I think I remember hearing that the African mahogany Matt
Smith uses can't be steam bent.

Can anybody confirm if matt carves staves for his mahogany line?

thanks

[bongosnotbombs]

Per my friend taikonoatama who has a set of Ritmos in African mahogany, they are cut and not bent, purportedly because African mahogany cannot be steam bent. Hell of a set of drums.

[FFaria]

Being a long time woodworker/woodturner i think i can add to this topic. When you steam wood you must allow for springback. Otherwise the staves are allways under preassure.
Builders who steam their shells the way wine barrels are made over a steam kettle with hoops are not allowing for springback the staves are always under pressure. Even with the aid of glues and hoops.
When the wood starts drying out the joints will eventually fail. Hoops just prolong the inevitable.

Wine Barrels don't separate because their not allowed to dry out. The wine inside keeps the wood hydrated .
The staves expand and form a tight seal. The barrels are also rotated regularly to keep wine impurities down and to keep the wood wet at all times.
Wine is stored in dark humid conditions ideal for keeping the wood from spliting.
I've noticed some builders are using mechanical means along with glue to keep shells from separating. I've seen steel pins, splines, tongue and groove, dowels, biscuits. These will improve the joint, better then relying
just on glue. Steel pins are just for alignment purposes.
I personally like the cut stave method because all inherent wood stresses are remeved. Most people may not realize that laminate strip and steam bent staves once you turn them on a lathe you are cutting down into the wood fibers
exposing all end grain All that steam bending to just end up with a cut stave in the end. Steam bent and laminate staves are stronger to a cut stave as long as you don't alter its shape.

With proper joinery technique, quater sawn wood, low moisture content, good quality glue, and a good wood sealer, the cut stave method is definitely the way to go.


Just my personal opinion.

[Tumbas]

This is a godsend...

I was just asking a friend about this very thing, this evening.

I join this forum and VOILA!

I learned something new!

Great info... thanks!

[dende]

I personally like the cut stave method because all inherent wood stresses are remeved. Most people may not realize that laminate strip and steam bent staves once you turn them on a lathe you are cutting down into the wood fibers
exposing all end grain All that steam bending to just end up with a cut stave in the end. Steam bent and laminate staves are stronger to a cut stave as long as you don't alter its shape.

With proper joinery technique, quater sawn wood, low moisture content, good quality glue, and a good wood sealer, the cut stave method is definitely the way to go.


Just my personal opinion.

Um, Not exactly. only the surface has been cut through, and you still have all that interior continuous grain as long as you follow the original shape (bent shape) of the drum.

Ive never seen Laminate staves, like plywood? it doesnt seem good for large drums for me, but im kind of a hippie when it comes to drum construction.

as this topic is about forming the shape of the drum, what do you all think about fire bending staves, like in this video ( http://www.youtube.com/watch?v=RdjOyBrPGx0 )?

[Jerry Bembe]

Interesting points.

LP uses the laminate construction for the interior/exterior and Siam Oak (Rubber wood) particle board in between.

In Uruguay they use a form of fire bending as well with soft wood that is relative to pine. They march with these drums so they need to be lightweight.

The cut staves are more stable but there is still the potential for warping and twisting as the wood ages. Wood will be wood. If this is a problem then choose fiberglass. Also with cut staves there is significant waste of wood. This can be an issue with rare and valuable woods like those used by Volcano and others.

I personally like the cut stave method because all inherent wood stresses are remeved. Most people may not realize that laminate strip and steam bent staves once you turn them on a lathe you are cutting down into the wood fibers
exposing all end grain All that steam bending to just end up with a cut stave in the end. Steam bent and laminate staves are stronger to a cut stave as long as you don't alter its shape.

With proper joinery technique, quater sawn wood, low moisture content, good quality glue, and a good wood sealer, the cut stave method is definitely the way to go.


Just my personal opinion.

Um, Not exactly. only the surface has been cut through, and you still have all that interior continuous grain as long as you follow the original shape (bent shape) of the drum.

Ive never seen Laminate staves, like plywood? it doesnt seem good for large drums for me, but im kind of a hippie when it comes to drum construction.

as this topic is about forming the shape of the drum, what do you all think about fire bending staves, like in this video ( http://www.youtube.com/watch?v=RdjOyBrPGx0 )?

[bongosnotbombs]

The trade off with cutting staves is you actually cut across the grain when you cut the peice of wood into a curved shape, that is the grain will not be continuous as the saw cuts through it to make the curve. Thus at the ends and in the center the grain lines are much shorter, and nowhere does the grain travel the full length of the stave. This could potentially be problematic due to the stress caused by the hands and floor playing the drum could lead these shorter lengths of grain to separate or create fissure like cracks. A steam bent stave has full continous grain.

I have drums made by both methods and both methods work well to make durable great sounding congas.