Getting Mahogany Flat
Very hard woods with alternating grain patterns sometimes develop waviness when sanded with wide-belt equipment. Here's an extensive discussion of the characteristics of Mahogany, and of ways to approach it using both hand tools and power equipment. November 12, 2005
Question
Does anyone have tricks for sanding mahogany (Honduras) and keeping it flat? Hardness variations can be quite extreme in some of the more "ribbony" boards. Even very careful machining and sanding can yield unexpected, bad results, like waves and dips when finished and rubbed out. It seems to me that it's very difficult to get consistency when material removal rate (machine and hand) can vary so much from one inch to the next. I see this problem in tables all the time.
Forum Responses
(Cabinetmaking Forum)
From contributor L:
The ribbons are caused by the grain reversing itself within the wood. Whenever this happens in wood, you can expect to have some milling problems. Also, if you buy the wood and store it for 6 months or so, it will be more stable than fresh from the mill. Yeah, I know - not very practical. But when I do it, I can cut a 1" strip and watch the kerf stay right at 1/8" as the board gets cut. Real nice to see that. When I cut my fresh wood, I give it a full 3/16" extra so that when it bends, I can joint it out to straight again. So, you are not alone in this problem (as you knew) - wood is an active substance that can do unpredictable things at times - you just have to deal with it. If you want perfectly flat, use veneered MDF.
From contributor F:
Not knowing what type of finish sander you use, I can only say that with the half sheet 505's (Porter Cable) I use, pressing too hard and sanding too long will lead to unevenness between the late wood and early wood in the boards (also rounded edges). This is not for everyone, but I (one man shop guy) have changed the way I prepare solid wood before finishing. I have discontinued the practice of wide belt sanding of frame assemblies because of the cross grain scratches, which lead to excessive sanding. I don't use a portable belt sander, either, for similar reasons. My frame making process aims for very flush joints followed by a little work with a well tuned bench plane at the joints and a bit of scraping with a well prepared card scraper. This yields better results and is faster (for me). I finish up with 150 and 180 grits using a light touch on the half sheet sander. I hope this doesn't get all the high production guys riled up, because I know it's not for everyone. It is just a discovery I made after using belt sanders and wide belt sanding on frames for over 25 years.
From contributor D:
It really makes my soul sing for joy to hear other professionals talk about how old school hand tools actually increase their production, quality, and bottom line.
From contributor J:
I'd like to join the club, too. I am a one man shop and having just finished two jobs involving custom doors and panels, I have new appreciation for my hand planes. I glued up all the 2-1/2" wide frames by 1-3/4" thick, then set about flattening them with my planes. Did I mention that both jobs were hard maple? I know it's not as fast as a big widebelt, but it is far more affordable for a little guy and very satisfying at the end of the day. I won't be getting rid of my jointer and planer anytime soon, but it is nice to occasionally pull out the hand tools and make shavings instead of dust.
From contributor K:
Contributor F gave away our secret weapon when he started talking about the card scraper. It took me 10 years to discover that little tool and now I can't live without it. That's the best thing in the world for working stock like your figured mahogany, but it's got to be tuned right.
There's a great point in this thread. Many of us (not all) who learned cabinet making in production shops never really learned how to use hand tools like planes, scrapers, spoke shaves, etc. I'm playing catch-up now. As craftsmen, we sure don't need to lose that knowledge.
From the original questioner:
I should have been more specific. I'm talking about table top flat, most specifically rubbed out tabletops - dining, conference, etc. High end stuff. Any table makers know what I'm talking about? I appreciate all responses, but I wouldn't want to take a hand plane or scraper to a 50"x144" tabletop, especially if it had to be rubbed finish. I don't think my hand plane game is quite there yet.
From contributor D:
If you want to elevate your craftsmanship, you really should learn how to at least smooth the top with something like a number 4 smooth plane. Either buy a good one (Lie-Nielsen, for example) or take the time to tune up an older one. It really is worth the time. You can also use the skill as a marketing point, if you choose. You probably also know that the look can be significantly different between a hand planed board and a sanded board. I don't say one is better than the other, just different. However, I don't think you should write off mastering hand planes just because someone else is using them on his kitchen cabinets.
You can also look at the cost savings to your shop. LN smooth plane with all the goodies and sharpening stuff tops out at $500. Life expectancy is +100 years. 50" top of the line wide belt sander = tens of thousands (?) of dollars up front plus abrasive belts at $ per belt x belts per year. Life expectancy = 20 years? Less or more?
It may be easier to run the power tool, but don't just give up on the hand tool because you haven't mastered it yet.
From contributor F:
The first part of my post gives some key advice about avoiding uneven sanding of late wood and early wood while using a half sheet vibrator type sander. It also asks what type of sander you are using.
Also, fine furniture type table makers would definitely take a card scraper and\or a cabinet scraper to a tabletop of any dimension to help get it flat. A card scraper is much easier to learn to prepare\sharpen than a hand plane and well worth the effort to learn.
Trust us - we're not some cave men out here with dirt floor shops and nothing but hand tools. We have lots of machinery and power tools, too! Machines don't replace hand tools, they supplement them and vice versa.
Actually, if you're looking for advice on furniture making that does not require the use of any hand tools, you are asking for the advice of the low end makers, not the high end makers.
One last tip for flattening a wood surface with sand paper: Make a wooden sanding block that fits your hand and glue some 1/8" thick sheet cork to it. Hold sand paper tightly and sand with the grain for a much flatter surface than can be gotten with power sanders.
From contributor R:
Sounds like African mahogany, which comes from Honduras also. I can run Honduran through the drum sander and it's fine for woodworking. I have had high and low spots in African mahogany when using an air orbital and hand held belt, but with a satin sheen it flew just fine.
From contributor E:
Get yourself an air file.
From contributor G:
Ditto. The air file (usually used in automotive applications) will do the trick. Make sure you have a hard rubber backing and angle it about 15 degrees from the grain. Once you get it flat, clean it up with a RAS or a card scraper.
From contributor A:
Are you sure it is truly Honduran? The only Honduran currently available is what is coming from existing stocks here in the US, since there has been a stoppage on shipping out of Honduras for some time now. Lots of suppliers out there shipping African (which has a much greater banding issue) call it Honduras.
Either way... Besides getting it flat, when you have the band runouts (the "fuzzies"), you can capture them with a 1 lb cut of shellac, and that makes working them easier with a scraper.
From the original questioner:
I apologize if it sounded like I was discounting hand tools. I wasn't at all - just saying that on a big top, getting a gloss finish, I personally wouldn't try it. I do know how and often use tools like hand planes, spokeshaves, scrapers, etc., just not for surfacing big shiny tables. I'm good, but not that good, and I would really love to meet someone who could achieve a flat surface with something like a card scraper and a sanding block. That would blow me away. When I say flat, I mean flat. A buffed out gloss finish will tell you just how good your surface prep really is. An eye opener, you might say. I have yet to meet my expectations and I can get wood pretty dern flat. So I'm always trying to get better, but it is wood, and the variations that come with the material do limit its capabilities. As stated before, with satin, it's fine. If they stopped making gloss finish, I'd be just fine with that.
To answer the African or Honduran question: I notice this on new lumber, lumber before the "embargo", and on 100 year old antiques. So some of it, at least, has been Honduran. The African stuff that I've knowingly used looks different to me - it seems pinker.
We use a 26" drum sander (various grits 100, 150, 220) after machine, planning, then the usual arsenal of electric hand sanders, mostly random orbit. How wide and long is an air file? How do auto standards compare to furniture?
From contributor P:
What am I missing here? This situation is what wide belt sanders were made for. You can just kiss it in the last few passes and it will be as flat as it can possibly be. Then finish immediately. Over time it will probably develop waviness again, but nothing can stop that. Your other alternative would be veneers - personally, I would be very nervous with a 50 x 144 solid top, as it would warp in a heartbeat.
From the original questioner:
Good god! Not solid - that's with leaves. And it was just a hypothetical number. What makes a wide belt better than a drum sander? And who makes a good one? I've skimmed, but haven't seriously looked into them. Any hand sanding after the wide belt? I take a few final light kiss passes with the drum. And yes, I know 26" isn't enough. Also, we do veneer.
From contributor V:
Most widebelt sanders have a combination head that has both a hard rubber contact drum (used for calibrating the wood to precisely the same thickness), and a platen that will give a longer scratch pattern in the finer grits. Widebelts also have four corner jacks for raise/lower and a larger feed bed. They are also heavy sheet steel with some cast iron. This makes for stability and accuracy. Drum sanders are usually thin sheet steel, two jacks, small beds, etc. Most times a drum sander is overwhelmed, and the drum rides up and over the boards and does not actually thickness the wood. A wider board will get less removed than a narrow board, and thicknesses will vary all over the place. Our Butfering can take off half the thickness of a pencil mark without any finessing. Everything comes out dead flat when properly sanded, irregardless of grain directions.
From the original questioner:
Thanks, everyone!
From Gene Wengert:
One key to prevent the indentations is to use brand new sandpaper, which reduces the pressure overall, as well as provides even pressure across the sanding machine. Another key is to minimize pressure, which can be translated into minimizing the amount of stock you want to remove. Too often, sanders are used to do the job of a planer or jointer. Third, if you sand in one direction with a species like mahogany that has spiral grain (same as ribbon stripes), you are actually sanding with the grain or against the grain at the same time, depending on location. You will find it easier to push fibers down in the "with the grain" direction, so you will see the unevenness. Again, light cuts and light pressure will help.
Regarding supplies of Honduras mahogany, as much of their wood is from plantations, it seems funny that it would be included in a boycott. They survived the boycott of Green Peace and others in 1996. I wonder if someone could give an internet source that has information about the extent and details of the present stoppage that was mentioned. If it is true, it seems that the forest owners will be motivated to burn down the forests, as they have no economic value if the timber cannot be sold. I would think that if the trees had good value, then the owners would be encouraged to preserve more of the forest.
From contributor V:
I don't have a ready source for the slow/no shipping of Honduras mahogany, but the story does verify what I have seen and heard as the recent chapters in this species' history. I think if you check with Thompson Mahogany, or J Gibson-McIlvain, you'll find the supply of Honduras has tightened enough recently to force a 40% increase and a limiting of accepting new customers for the species.
Satellite monitoring has indicated wide spread illegal logging, and when pressured to resolve the problem, Brazil stopped all export of the species, tying up millions of dollars in international trade.
This spring, when ordering 10/4 pattern Honduras, I heard "Don't have any, don't know when we will have it" for the first time in nearly 30 years. When I recovered, I learned that I can still get it - at a price.
As I hear it, Honduras mahogany is a solitary growth tree - not in groves - and requires roads or, lately, helicopters to gain access to the tree and the logs. These are all old growth trees, not plantation. While there are many Honduras mahogany plantations in existence, the slow growth and (so far) limited commercial success makes a harvest many years distant. Again, all as I hear it - not having first hand knowledge.
