Rib thicknessing

[Stephen Perry]

I have done by hand, with a Wagner power planer, and with a drum sander in the drill press. Hand is best so far. However, I acquired a thickness planer and was wondering how thin one can cut with one of those. Anyone use these for ribs?

[Jim Adwell]

My thickness planer will go down to, well, nothing, with an MDF insert. Practically, it depends on the wood, the planer, and the sharpness of the blades. I routinely plane softwoods and the less problematic hardwoods to .06" (a Porter Cable 12" cheapie planer from Home Depot).

[billhay4]

Jim must have a real good planer. Mine tends to eat the kind of wood I use for sides when I get much below 1/4" whether I use a backing board or not. That would be walnut, figured maple and the like. The thickness sander is very slow but it gets me there.
Bill

[Mandoborg]

I'm definetly with Bill on this one. On figured woods, I would even think about going less than 1/4 inch. And that's with an auxiliary table. It's a safety issued. I've seen it all go to heck fast in just one pass going thinner than that !

[Mike Conner]

Dewalt planer with a 3/4" plywood board. The blanks are fastened to the plywood at the ends using carpet tape. I send the whole assembly through planer. Here's some walnut ready to start



I start at about 0.100 to 0.125", and can plane down to my target 0.077" making very shallow passes of about 0.010" or so. I've lost a couple sides here or there. I start with 3/4" to 1-1/2" boards ripped on a table saw, so there are a couple of spares in play to replace any suicides. Success so far with walnut, plane red maple and curly red maple. The curly was scary.

[Jim Adwell]

Like I said, it depends on the planer. In my experience the bigger more powerful industrial planers do not do nearly as well planing that thin as the smaller home shop planers, for some reason. The best results I've gotten were with an inexpensive 10" Ryobi planer 25 years ago, even with some curly maple and curly koa if I went slowly and took a lot of passes. The big 24" industrial planer at the shop I worked for back then would tear up pretty much any type of wood under about 1/4", though.

I've been planing wood thin for a lot of years. Maybe it's just learned skill, but I wouldn't hesitate to try almost any kind of wood. When it does go bad, though, the result is pretty exciting. Eye protection and standing off to the side is important.

[Dave Cohen]

Look, you don't want to use a thickness planer to plane curly maple or other figured woods to 0.070" or 0.080" thickness. Unless everything is perfect, the knives are extremely sharp and perfectly straight, and the cutterhead is in perfect balance, there will be tear out from the wild grain, not to mention that planers tend to eat thin pieces of wood. The probable reason that a portable planer like the Ryobi mentioned above did better is that those things have essentially router motors. The best tools for thicknessing ribs are either thickness sanders (either in the form of drum sanders like the Jet or Supermax versions, or wide belt sanders - much more $$), or a hand plane, as you have already found out. You can run the thickness planer experiment for yourself if you are determined to do so, but be prepared for the possibilities of injuries and/or ruined wood.

[Stephen Perry]

Good point Dave. Probably not worth the effort. I can use to get a clean side, then slice and thin as usual working on the other side. I'll be going to .040" or thereabouts. Oh well, it's still a fun tool I'm not used to, certainly does save time on some things. A table saw etc would be nice, too, but then I'd need a big shop!

Thanks all!

[Pete Jenner]

I don't own a thickness sander so I've been using my bench top ryobi thicknesser for maple ribs and thin ebony veneers.
I tape the stock to a board about 12 mm thick with double sided tape. It takes many passes to get where I want to go but as long as I only take a tiny fraction of a millimetre off at a time, I don't have a problem. The double sided tape releases easily with acetone. From there I hand sand and finish with a card scraper.

[Stephen Perry]

Wow, I can see that working. Might be faster for me with a plane and jig!

I'll try a few. I sharpened and set up the planer, so it works very nicely, but that might not be sufficient!

[HoGo]

Planers are extremely sensitive to correct setup. ANything is hair away from prefect and it will tear or eat especially figured woods.
For best results try planer with those "spiral blades" - I don't remember the official name for that but it is whole different animal for highly figured woods. Almost like sander.

[Rob Roy]

Since I use figured wood for ribs, the planer is problematic- curly maple will explode if you go too thin. I have a friend with a very nice thicknessing drum sander, but doublestick-taping down the rims. measuring with a caliper as you sand, etc turned out to be a lot of work. I actually run the 2x stock on the tablesaw with a thin kerf ripping blade to about 0.080' and then finish with a card scraper. The fastest and easiest method of come up with.

[Dave Cohen]

Planers are extremely sensitive to correct setup. ANything is hair away from prefect and it will tear or eat especially figured woods.
For best results try planer with those "spiral blades" - I don't remember the official name for that but it is whole different animal for highly figured woods. Almost like sander.

Adrian is referring to a "helical cutterhead". Those things are smoother and slightly more forgiving that straight planer knives, but still not as safe as a drum sander or wide belt sander. Assuming an aftermarket helical cutterhead is available for your particular planer, expect to pay in the neighborhood of $800 minimum for one. For that, you could pay a significant part of the price of a new 16"/32" open-ended drum sander.

[peter.coombe]

Jeepers creepers, some of you guys are taking risks. Using a planer, any planer, to thickness ribs down to 2mm is damn dangerous. The wood is likely to explode and bits fly out, so make sure you are wearing a full face mask if want to risk it. I use a drum sander, they are not all that expensive to buy.

[Pete Jenner]

Risk is my middle name. Can't afford more tools.

[Stephen Perry]

I'm used to wood bits flying around! Have a mask, gloves etc. Probably just use my old approach plus a two strip planing jig!

Now neck blocks - they'll be flying through the power planer!

[Dave Cohen]

If you think that you can reliably take a piece of curly maple down to 0.040" = 1 mm with a thickness planer, then I have a bridge to sell you. Even if the planer doesn't eat it, the probability of tearout is high, and if you get tearout on a piece of curly maple 1mm thick, you might as well throw it away. Another thing no one has mentioned: at least some thickness planers have blunt-toothed rollers for feeding the stock through the machine, and those rollers can leave marks, as can the planer knives themselves. Planers were not designed for producing finished surfaces, and they especially were not designed for thicknessing pieces of wood as thin as violin ribs.

I probably should just let you run this experiment for yourself It shouldn't be necessary to mention how much a piece of instrument grade figured wood costs. It's your money.

[Larry Simonson]

After some practice, I've had success using a cheap oscillating spindle sander fitted with a homemade adjustable fence (similar to the Stu-Mac model) to thin curly maple sides, and it is also very useful for many other jobs.

[Pete Jenner]

If you think that you can reliably take a piece of curly maple down to 0.040" = 1 mm with a thickness planer, then I have a bridge to sell you. Even if the planer doesn't eat it, the probability of tearout is high, and if you get tearout on a piece of curly maple 1mm thick, you might as well throw it away. Another thing no one has mentioned: at least some thickness planers have blunt-toothed rollers for feeding the stock through the machine, and those rollers can leave marks, as can the planer knives themselves. Planers were not designed for producing finished surfaces, and they especially were not designed for thicknessing pieces of wood as thin as violin ribs.

I probably should just let you run this experiment for yourself It shouldn't be necessary to mention how much a piece of instrument grade figured wood costs. It's your money.

Well 1 mm is a bit thin for mandolin ribs but 2 mm is quite doable on the thicknesser.

[Larry Simonson]

Pete, I don't think anyone said it is impossible (your love will have to wait), if fact some have said they're doing it.

[Dave Cohen]

Well 1 mm is a bit thin for mandolin ribs but 2 mm is quite doable on the thicknesser.

.

Not impossible, but certainly risky. Not all curly maple is made the same . The most highly figured pieces, will have deeper curly figure, which is in turn harder to plane without tearout. So, do you really want to risk ruining your best (and most expensive) pieces of wood? You may very well get away with using a planer some of the time, but there certainly will be some failures. Say you are successful 9 times out of ten. Do you really want to throw away 10% of your materials and materials cost, and risk injury while you are at it?

I am not in general a champion of "conventional wisdom", but in this case, the conventional wisdom is based on the experience of many. I, too, have run this experiment (long ago), and my sad results were in agreement with the conventional wisdom.

Iirc, your Ryobi portable planer has a rubber feed roller, which is in your favor. At least you will not have roller marks to deal with. But, any planer is cutting intermittently. There are 3 or 4 knives on the cutter head. Each time a knife comes around, it makes a scooping cut on the workpiece. The faster the cutterhead rotates, and the slower the feed rate, the less you see the effects of the scooping cuts. Nevertheless, it still leaves something of a "hammered" surface, and the wood is somewhat compressed where it is hammered. All of that has to be addressed afterwards, and it is a lot more to deal with than if you use a hand plane or a drum sander. For me, another headache would be releasing the double-sided tape, especially on something 1 mm thick. On a drum sander, I routinely make wood binding strips as thin as 0.025", occasionally even 0.020". No double-sided tape, just a backer board made from some scrap. And most important, no injuries or scary accidents.

[Pete Jenner]

Yes, rubber feed rollers. When I sell a mandolin I'll get a drum sander but until (and it may be years) then I'll just have to suffer the slings and arrows of outrageous exploding maple. Just as well I have this suit of armour.

BTW, I've never the maple (or spruce) to be very expensive. IMO it is too cheap but that's an argument for a different day.

[Steevarino]

I have a Delta 13" planer that takes wood safely down to about 1/8". If it starts to chip-out, I just leave it a little thicker, and then run it through the wide belt sander. Also, if the wood chips a small amount while running it through the planer, you can sometimes send the wood through the planer at an angle Not straigt-in) to get a bit of a shear-effect from the straight planer knives. Works for me, anyway.

If you have some sort of a sander, and a tablesaw with a good thin blade, you can resaw your rim sets from a larger piece, and then run them through whatever sanding process you have. I joint the edge, resaw, re-joint, etc., until the board dissapears, or the grain goes wonky. If you go this way, remember to draw some diagonal lines along one end of the board before you resaw, so you can keep them in the correct order once they are a bunch of strips. Kinda like this . . .

[oldwave maker]

Good point on marking them, Steve.
Still using the $299 performax 22-44 bolt -on for your radial arm saw, wouldn't do brazilian rosewood guitar backs on it, but for maple, walnut, mesquite, koa, etc sides it is certifiably old, slow, dusty, and cheap, just like its operator........

[Rick Lindstrom]

Stephen-

If you decide to fool around with this, there is a trick you can use to enhance your chances of success- chamfer the ends of the rib pieces slightly so that you have a sort of "ramp" for the feed rollers to roll smoothly onto at the beginning of the piece, and off of at the end. This will help avoid knife snipe and possible ruined stock.

Here's what happens- when you feed the piece in, the knife starts cutting and then there is a slight bump or hesitation as the stock tries to lift the out-feed roller and get under it. This is one of the points where the knife can cut too deeply ("snipe") or blow up the piece in the case of thin stock.

The second tricky point is when the end of the stock passes out from under the in-feed roller. If you have a sharp, square end on the stock and a rubber roller, the roller can actually lift the stock (especially if it's thin) into the knife causing another snipe point or worse.

These effects are somewhat mitigated if you have your thin stock stuck down with double sided tape to a heavier "carrier" piece, which I would do in any case. But cutting a 45 degree chamfer on the ends eases the stock in and out of the rollers much more smoothly.

You can demonstrate this easily with a piece of 3/4" scrap stock- plane it once with the ends cut square, then chamfer the ends and take another cut of the same depth. You should notice that it enters the rollers more smoothly and exits without snipe.

If you measure the distance between the axis of the feed rollers and the axis of the cutter head on your planer, it will be the same distance that snipe happens from the ends of the stock, roughly.