Can someone point me to a technique for making 8-sided table legs?
I knew how to once, and have forgotten!
How do I know I once knew? I’ve found a set in my wood store, made in the 80s, they’re perfect octogons but warped. I know I made them, just can’t remember how!
I’ve just ordered a Minimax 12 inch under and over jointer/thicknesser, and judging by the machine marks on the old legs, I used my once-ownd and long-since-sold British under and over to make the original legs.
Malcolm
New Zealand | New Thinking
Replies
A fairly easy way is to start with square stock and rip off the corners at a 45 with a table saw. You just have to do your layout carefully. You can leave the ripped corners a bit strong and clean them up with a single light pass on the jointer. You can tip your jointer fence to a 45 and do the same thing with knocking off the corners, but it is more difficult to control the equal facets if the stock isn't perfectly straight or you have to make multiple passes. Of course there are other ways with hand planes, hand saws, shaper cutters, router cutters but the saw is the most consistent.
Beat it to fit / Paint it to match
Are you just trying to do straight octagons or tapered ones?
If they're just straight, you should be able to do them on a TS with the blade set to 45 deg. Four cuts and voila - an octagon. You might want to cut them a bit proud, then clean them up on the jointer. The trick is getting the TS fence set exactly so all 8 sides end up the same width.
If you're just trying to figure out the layout to get 8 equal width facets, I did some messing around with trig formulas and came up with the following:
If your square stock is W x W in size, then
1) F = W x (SqRoot(2)/(2 + SqRoot(2)) or W x 0.4142136
F is the width of each facet of the octagon
2) X = (W - F)/2
X is the distance in from each corner to set your layout lines
If you build it - he will come.
Thanks guys
In the back of my mind is a clever technique that ensures the 8 sides are all exactly the same width ... I seem to recall published at some time in FWW
MalcolmNew Zealand | New Thinking
Kiwi
Get the leg cut to a square. Cut a square out of hardboard the same size as the end of the leg. Mark the center of both (corner to corner lines) and drill a small hole at center using the same drill for both. Now pin the hardboard piece to the end of the leg using the drill bit as a pin. Rotate the hardboard until it is 45° to the leg and draw your layout lines. Should be a perfect octagon. If the legs will be tapered I would saw them to an octagon first then taper them on the jointer so all eight sides would be the same regardless of the taper.
Rich
The Professional Termite
Edited 2/24/2005 8:20 pm ET by Trialnut
kiwimac.......
What I do to cut an octagon on the TS. Crank the blade over to 45 degrees. Lay one flat of your squared leg stock on the blade. Slide the fence over against the leg blank. Then lay the blank flat on the saw table against the fence and proceed to cut the coners off.Be not afraid of going slowly. Be afraid only of standing still. chinese proverb
BINGO!
I think that's the one!
I suppose I should have been able to figure it out for myself.
There must be quite a few people like me on this network ... good gear, quite competent, long list of projects to make ... and no workshop time?
MalcolmNew Zealand | New Thinking
Why taper on the jointer. Seems to me the bandsaw is the way to go? No?I also saw a neat way to taper using a planer - basically you mount your stock at an angle on a "sled" made out of plywood or other scrap. - Brace your stock so it does not flex under the pressure of the planer rollers then send it through over and over until you're down to your desired thickness. Pretty clever actually.Mark
Measure it with a micrometer, mark it with chalk, cut it with an ax.
Mark
If you cut the taper on a bandsaw you still have to clean up the cuts on either a jointer or with a handplane. Cutting the tapers on the jointer is not only faster than using a bandsaw but the cleanup cuts are already done. A bandsaw cut would not all be the same distance from your intended finish line so your cleanup cuts would ride the highest points first and therefore not all be the same depth. Not a problem with a handplane but extra puttering with a jointer. I am sure I could taper four legs on eight sides each on the jointer in less time than would be required to build a sled to use with a planer, and feel it would be a better job. With the planer you could get some flexing and distortion of thinner legs from feed roller pressure. You would get none with a jointer. Hope this explains it, if not I will try to explain further.
RichThe Professional Termite
Thanks, but I'm puzzled, Let's say I'm doing a pencil post bed with tapered octagons - the octagonal portion of the post is about 4 feet long (below that it is square for bed frame connection) - the square portion is 3" x 3" the end of the taper is about 1.5" x 1.5" (if it were square). So how is this done on the jointer so that all sides are the same?Thanks,
Mark
Measure it with a micrometer, mark it with chalk, cut it with an ax.
Mark
I guess I'm puzzled to. How are you going to do those with a planer or cut the octagon on the tablesaw to begin with? In a case like you are talking about I would either make the leg in sections (my preferred method) or cut the tapered octagon on the bandsaw and finish with hand tools. Depends also how the transition between Octagon and square is designed. The way the original question was posed and first answered led me to believe we were talking just tapered octagons with no special "stuff" on the ends. I am sure no matter what method is offered there can always be exceptions where it will not work. That is part of the fun of woodworking is finding a way to easily do the impossible. I have a preference toward machine tools but am not at all adverse to using hand tools when I think it will be quicker.
RichThe Professional Termite
YEs I agree, woodworking is often about solving new and different challenges with the tools and skills you have on hand.Regarding the taper:
Assuming I'm doing them on a sled in my planer - mind you I have not done this yet, I've only read about it. But it made sense to me and since I just got my planer, I'm dying to try out the process. Also the process I read about was for square tapers not for octagons.If I was to attempt this, I'd set up my sled to support the stock for it's length at the angle of the taper. So if the taper is 1.5" to 3" (1.5 inches over the stock's length) The narrow end of the taper will be mounted 1.5" above the thick end. The planer needs to be cranked up high. Then you plane off a bit at a time - keep running the sled through, and lowering the cutter head.First cut the tapers on the flat sides of the square stock. The first two can be done without adjusting the sled. The other two will require that the narrow end of the taper be raised to account for material removal.Then adjust the sled so you can rotate the stock 45* from it's starting point. (a "V" block on the sled perhaps) Cut the first two tapers again. Then adjust the narrow end again, upwards to account for material removal.I guess the process is complicated but I think it would result in a repeatable process. My biggest concern with the Jointer method is repeatability. That is also my concern with the bandsaw process.Mark
Measure it with a micrometer, mark it with chalk, cut it with an ax.
Mark
As a pattern maker I have been cutting tapers on the jointer for many years and from personal experience I can assure you it is not only very fast but also very accurate and repeatable. I would trust it over a sled in a planer every time. Not saying the planer method doesn't work or isn't accurate I just know the jointer is faster and feel there is less chance for error, less chance of the part tipping or something and messing up the cut. Plus, it does not require resetting (like the sled)to do the second half of the tapers. All eight sides are done at the same setting. Grab some scrap and experiment. I am sure you will find what method you like best. I have done it both ways and didn't take long to decide which way I prefer. Like I said before, I know I can have a set of legs done in less time than it takes to build the sled and most likely in less time than it takes to design or draw it. ;o) Just my personal preference, but I'm a lazy person so always look for the easiest way to get r done while still maintaining quality. Have fun with it and if you need any input on the jointer method I'd be glad to help.
RichThe Professional Termite
Rich, can you describe the process for tapering on the Jointer?Thanks
Mark
Measure it with a micrometer, mark it with chalk, cut it with an ax.
Mark
Start by cutting the leg to the shape you want (square, octagon whatever) with the size being the largest dimension of that feature when finished. For an example lets do an octagon table leg that's 2" across the flats at the large end and 1" across the flats at the small end, 30" long with the taper starting 5" down from the top. We would be removing a wedge that goes from 0" to 1/2" thick off each side. That is a rather aggressive cut for the average home shop jointer to take in one bite so lets divide it into four cuts of 1/8" each. Set the depth of cut for 1/8". Be accurate on this setting because any error here will be magnified by the number of cuts. In this case four cuts so an error of .004" would give you a total error of 1/64" when done. Probably acceptable for most work but you get the idea. The error will only show up on the small end of the taper.
Now clamp a stop to the infeed table that is 25" from the center line of the cutter head (length of taper). If this is longer than your infeed table other methods of setting a stop or reference can be used but I won't go into them now. Remove the guard or fasten it back to expose a little over 2" of cutter. You could remove the guard and move the fence over to leave a little over 2" of cutting width. Grab a leg and holding it close to each end set it down on the machine by setting the small end of the taper against the stop block and lowering the large end down to the outfeed table, then feed through in a normal manner. Once you are aquainted with the mechanics of the process then fire up the jionter and make the cuts. I usually make a cut then rotate, make a cut, rotate untill all sides are done X number of cuts rather than take four cuts, rotate, four cuts, rotate. This removes stock evenly and reduces the possibilty of stress induced warpage. Thats all there is to it. I will say this is not a process for the timid or someone who is not experienced on a jointer. It is not dangerous but does require more skill and attention than normal use. I think trying to use push blocks on this process would severly lesson the degree of control and make it easy to mess up the part. There is just not enough surface width to get a good feel with the block and keep it from rocking.
There is of course a certain amount of error produced which can be compensated for. The error depends on the mouth opening of the jointer. The wider the mouth the greater the error and the wider the mouth the more pronounced the start of the cut will be. This can be allowed for and then take a final very shallow cut without using the stop to clean up after the tapers are cut. Practice on some scrap to see what fudging needs to be done. Hope this does the trick for you.
Rich The Professional Termite
Thanks,
Looking forward to giving it a try. Yes 1/8" seems like a big bite for my jointer. Also, my infeed bed is not 25" long but I have ways of putting a stop in place that would allow for the longer post.Best,
Mark
Measure it with a micrometer, mark it with chalk, cut it with an ax.
Mark
If your bed is not long enough to have all the tapered section on it to start you will need to cobble together a table extension or the cut would end up curved as well as tapered. (Think of the possibilities that opens up.) I have the luxery of a 6' long 20" jointer so seldom have that problem. Each method of tapering has it's advantages and drawbacks and bed length is the drawback of the jointer method. If I was running into this very much I would build a permenant extension for the infeed table. I have a tendency to keep forgetting about the limits of smaller machinery when spouting off about what method is fastest. Perhaps with smaller machinery the planer sled or bandsawing the taper is a better method when the taper is longer than the jointers infeed table. 1/8" really isn't that much of a cut for something like this even on a small machine because the cut is only about 1" wide. Have fun exploring the possibilities.
Rich The Professional Termite
Rich, here is the sled idea done in pictures - clearly conceptual at this point. I'm sure there are bugs in this design that would need to be worked out.Mark
Measure it with a micrometer, mark it with chalk, cut it with an ax.
For tapers as you describe (top and bottom oct. tapers on a pencil post bed) you can make a jig that works with either table or band saw. Can't do it on the jointer or planer in this application...
Edited 3/14/2005 12:12 pm ET by EXHIBITOR
Straight, I am trying to figure the length of each side of a 22" flat Lazy Susan turntable.
The same formulas would work for a flat octagon too. If your starting square is 22" then:
1) F = 22" x 0.4142136 = 9.1126992" or aprox 9-7/64" F is the width of each facet of the octagon Note: this info doesn't do much for you other than you need the rsult in step 2. Well - I just thought of this - I guess you could skip step 2 if you had centerlines drawn on your piece and marked off half of this measure on either side of the centerline. Either way you'd end up with marks "X" far in from each corner.
2) X = (22" - 9.1126992")/2 = 12.8873008/2 = 6.4436504 or aprox. 6-1/2' then subtract off around halfway between 3 and 4/64" X is the distance in from each corner to set your layout marks
Put 2 marks on each side "X" distance in from each corner then connect the marks that are 45 degs across the corners and you should have an evenly laid out octagon. The easiest way would probably be to use a combo or speed square to connect the marks. I double checked my math back when I first worked out the formulas, but let me know if this doesn't look right. I'll go back thru it again if I made a mistake.If you build it - he will come.
Mac,A picture tells a thousand words.Here's how to lay out dimensions to get all sides the same width.In this diagram, the square is your stock, the radii are layout lines drawn as shown. I left one as a circle to aid in understanding.Cheers,eddie
That looks like a decent way to do it without any math. But how do you keep the point of a compass precisely located on the corner points to be able to lay out the arcs?If you build it - he will come.
Many ways Douglas,
If you use a compass, use one with a sharp point and just put a couple of scrap blocks against the end of the billet.
One of the easiest ways is to use a pencil gauge and butt the stock against the arris, pivoting off the arris.
Must fly - they're waiting for me at work
Cheers,
eddie
eddie,
It's easier for me to draw a circle as big as can be contained within the square. Draw 45* lines, tangent to the circle, cutting the four corners. There's your octagon!
Regards,
Ray
This sounds too easy, I kile it!!!
Mike,
kile it, you'll like it!!
Regards,
Ray
Thanks Eddie! Where you been? This question has been about for, like, ages!
Your method is the most elegant layout approach. The "lay it against a 45 degree blade and move up the fence" is the best straight to the machine approach.
That's all I need. Thanks everyone.
Good old knots, eh!?
Malcolm
New Zealand | New Thinking
your distance X is the distance from the center point of the square to the corner. Set your compass to that distance and Skip the math.
No - I hate to throw more math at you, but the "distance from the center point of the square to the corner" would be W times the Square root of 1/2 - which is quite a bit longer. I attached a diagram showing the dimensions that match up with the formulas I used. Please forgive the quality. I freehanded it with MS Paint.
I think Ray (joinerswork) came up with the best no-math method - at least on small enough stuff where a normal compass could do the circle. On bigger stuff, I think the math method might be quicker for one-off octagons, but if I had to do multiples it's probably worthwhile to make up a trammel arm and do Ray's circle method. Course there's still some things the math method will do for you that the others wont. Like for material estimating - Ex: if MIKE wanted to edge band the facets on his lazy susan and wanted to know the width of the facets before cutting the octagon. Could mean the difference between making one vs. two trips to the woodstore if he cant know the widths until after he's cut it.
If you build it - he will come.
the distance from the center point of a square to corner is the hypothenuese of 45 degree triangle with legs = 1/2 side of square. For the 22 inch model = 11 inches. The length of the hypothesis = square root of 2 * leg = 1.414 * 11 = 15.556. marking this distance from the corner would leave 22-15.556 = 6.44 from the opposing corner - the same value as your formula calculated. You get get the length of a facet by the diffence 22 - 12.88 = 9.12 or by calculation because now the facet is equal to the square root of 2 * 6.44 = 9.11. The total length for banding would be 9.11 *8 = 72.88 so you better buy 7 feet.Some ancient greek far superior in intelligence to me came up with the using this method to create an octangon with equal sides
Wilson – Sorry if I implied you couldn’t handle more math. It’s a bit surprising how many folks will do anything possible to avoid it. Looks like I may have mistakenly lumped you into that camp.<!----><!---->
No arguments with your results. We're both getting the same values in 2 steps. Just going about it in different ways. I used the Greek's (Pythagoras) math tricks to come up with the first formulas I posted.<!---->
My initial (invalid) concern with your reply was that someone would take my directions: "Put 2 marks on each side "X" distance in from each corner then connect the marks that are 45 degs across the corners" and substitute your definition of X (your distance X is the distance from the center point of the square to the corner) for mine and get something that didn't work out to an octagon.<!---->
Without the additional info marking this distance from the corner I didn't immediately realize what you intended to do with that number. Someone could have used your X definition and still come out OK. They'd just be marking on the farther (your method) vs. the nearer side (my method) from where they were measuring. Either way our layout marks end up in the same places. My own personal bias against using a compass/dividers for this kind of stuff stopped me from realizing what you were getting at. I just have a tough time getting accurate results with them when the pivot points are right on a corner or edge, so I was looking at the problem differently.
Maybe we need to get a separate forum section for "Stupid Math Tricks" ?
<!----> If you build it - he will come.
Thanks, I tried it today and it worked. Not the first try but eventually.
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