uneven boards.

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I'm making a side table.
The top is Queensland Maple (a cabinet grade hardwood) I joined three 200mm (8"?) boards together with a biscuit joiner, For reasons probably related to my shortcomings in the talent department the surface is uneven and I need to fix it.
I believe I have two options. 1. A jig I designed a while ago which will pass a router over the whole surface at a constant height. which will make the boards flat and square, but will add a lot more time to the final finish 2. Go out and buy a belt sander and do the job that way.
Are there others I haven't considered, if so what? What would be the best?
Oh and buying new timber and joining it properly isn't an option atm. Q Maple is spendy stuff.
TIA
Mekon
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with. That is what causes unevenness for me with biscuits. Anyhow, some people claim they can use a belt sander like a scalpel, getting great results. I have never had that experience; I only use it for hogging off wood. For your problem I would use a ROS with 60 grit. It will take a while and the surface won't be flat, but it will work. If your budget allows, find a lumberyard or woodshop with a large planner or sander (as appropriate to the amound of wood you need to remove) and pay them a few dollars to fix it. Should cost about the same as a belt sander.
The router device will reduce some local high spots, but won't do much for low spots. To do it with a router you would have to build a frame to put the whole assembly in, and run the router in a carriage along the top of the frame. That would be very time consuming and unreasonable unless you planned on doing a number of them.
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Mekon (in JJE7g.25064$ snipped-for-privacy@news-server.bigpond.net.au) said:
| I'm making a side table. | | The top is Queensland Maple (a cabinet grade hardwood) I joined | three 200mm (8"?) boards together with a biscuit joiner, For | reasons probably related to my shortcomings in the talent | department the surface is uneven and I need to fix it. | | I believe I have two options. | 1. A jig I designed a while ago which will pass a router over the | whole surface at a constant height. which will make the boards flat | and square, but will add a lot more time to the final finish | 2. Go out and buy a belt sander and do the job that way. | | Are there others I haven't considered, if so what? What would be | the best?
Were I in your shoes, I'd take the top to a local cabinet shop and have them run it through their big sander - specifying that you'd like it flattened and that you'd like a fine grit finish pass. Ask if they'd mind if you watch - they almost certainly won't, and the experience may change the way you think about "flattening".
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto
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wrote:

ditto. Find a cabinet shop with a 30" wide belt. They shouldn't charge much for a single panel.
Frank
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Mekon wrote: > I'm making a side table. > > The top is Queensland Maple (a cabinet grade hardwood) I joined three 200mm > (8"?) boards together with a biscuit joiner, For reasons probably related to > my shortcomings in the talent department the surface is uneven and I need to > fix it.
<snip>
As Morris suggests, time to find a commercial drum sanding shop.
Forget a belt sander, you can't get there from here.
Lew
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Belt sanders are to the sanding world what skew chisels are to the turning world - a lot of people seem to be afraid of them. I've flatten panels with belt sanders very successfully. First, a good belt sander(or any sander for that matter) is designed to operate under its own weight, you don't have to push down on them, just guide them. (I like the Bosch 3" x 21" because it has a low center of gravity and not tippy like some of the bigger ones) If it doesn't seem to be taking off as much as you would like, don't push down, just go to a coarser grit. I usually start at 60g.
Start by drawing pencil lines cross-grain. This will reveal low spots as you work. Sand 60 degrees diagonal to the grain making several full passes. Then reverse the diaganol and make the same number of passes the other way. Be careful not to round over edges. Repeat this proceedure untill all low spots are gone. Resist the temptation to work on any specific area and just think full passes. When all low spots are gone, make full passes with the grain until all diagonal scratches are gone. Spritzing with alcohol and viewing panel in a raking light will help reveal scratches. At this point I proceed to 80g, 100g, then 120g with the grain to further reduce the scratch pattern. Then I get out the random orbit and go 120g, 150g, and sometimes 180g and done.
Next time, don't rely on bisquits for alignment. They are designed to be a bit sloppy so the bisquit can expand as it absorbs the glue. Besides, a well jointed panel glue-up doesn't need the added strength of bisquits since the glue joint will be stronger than the wood anyway. I've gone back to the old tried and true clamping caul method. Good luck whatever you decide.

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Max Mahanke wrote: > Belt sanders are to the sanding world what skew chisels are to the turning > world - a lot of people seem to be afraid of them. I've flatten panels with > belt sanders very successfully.
<snip a belt sander technique described by Max>
If you truly want to flatten a top with hand techniques, borrow the "long board" method used by boat builders to fair a hull.
Start by spraying a spit coat of something like black lacquer on the surface.
Make a long board from 1/2"-5/8" plywood, say about 4" x 48" with some handles on one side.
Glue some 24 grit (flooring paper) to the other side with rubber cement and you are ready.
Start sanding at 45 degree angle and alternate at +/- 45 using full strokes.
Continue process until black is gone.
Check your work with a fairing batten such as the back side of a 3/4 x 3/4 x 1/16 x 96 aluminum angle which will allow you to measure the flatness to less than 0.0010".
Continue process until your arms feel like they want to fall off. When they do, your top is flat<G>.
Finish out using a ROS and progressively finer grit paper.
Now you know why I suggested going to a commercial drum sander shop.
Lew
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Lew Hodgett wrote:

with a bendable sandpaper backer is a far cry from what the OP is looking for.
Dave
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Just goes to prove, the first liar never has a chance. Your method is definately superior if your going for .001" even tho I think a 4' board on a side table is a bit over-kill. I'll admit that the belt sander is not the method to flatten a conference table but for side tables I'll stick with it. I've gotten side tables flat enough (and in less time than the long board method) to take a high-gloss rubbed finish that looks perfectly flat in raking light. I like to save my poor old arms for rubbing out finishes which power tools are not that good at. But to each his own.
BTW, Klingspor Abrasives does recommend a 60 degree angle for the most efficient stock removal and I've found that to be true.

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Max Mahanke wrote: > Just goes to prove, the first liar never has a chance. Your method is > definately superior if your going for .001" even tho I think a 4' board on a > side table is a bit over-kill.
<snip>
SFWIW, took over 4 years to fair out a 55 ft sailboat.
Standard long board consisted of two thicknesses of Luan door skins, about 4" x 48".
You could twist those boards to follow a compound curve.
The 24 grit paper would wear out in less than an hour sanding epoxy based fairing compound.
BTW, used at least 3 boxes of 24 grit floor paper. Would buy it from a flooring distributor and cut pieces as req'd.
If I hadn't found a guy with a lot of talent, I'd still be trying to fair out that boat.
Did it once, never again.
BTW, the long board was only for final hand strokes.
Lots of time with a 9" right angle sander equipped with 16, then 36,then 60 grit.
IMHO, wearing a hair shirt in direct sun light would be easier than fairing a hull.
Lew
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: If you truly want to flatten a top with hand techniques, borrow the : "long board" method used by boat builders to fair a hull.
: Make a long board from 1/2"-5/8" plywood, say about 4" x 48" with some : handles on one side.
: Glue some 24 grit (flooring paper) to the other side with rubber : cement and you are ready.
: Start sanding at 45 degree angle and alternate at +/- 45 using full : strokes.
: Continue process until black is gone.
: Check your work with a fairing batten such as the back side of a 3/4 x : 3/4 x 1/16 x 96 aluminum angle which will allow you to measure the : flatness to less than 0.0010".
You're gonna want to do something to that 4' piece of plywood to make sure it remains dead flat, otherwise it's going to follow whatever peaks and valleys the boards have. It'll make them smooth, but not flat, unless you rigidify things.
    -- Andy Barss
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Andrew Barss wrote:
> You're gonna want to do something to that 4' piece of plywood to make > sure it remains dead flat, otherwise it's going to follow whatever > peaks and valleys the boards have. It'll make them smooth, but not flat, > unless you rigidify things.
If you can get a piece of 1/2" (9 ply) or 5/8" (11) ply birch ply to bend when being used as a 48" long, long board, you are a hell of a lot better man than I am, which is entirely possible.
You are also using it improperly.
Lew
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: Andrew Barss wrote:
: > You're gonna want to do something to that 4' piece of plywood to make : > sure it remains dead flat, otherwise it's going to follow whatever : > peaks and valleys the boards have. It'll make them smooth, but not : flat, : > unless you rigidify things.
: If you can get a piece of 1/2" (9 ply) or 5/8" (11) ply birch ply to : bend when being used as a 48" long, long board, you are a hell of a : lot better man than I am, which is entirely possible.
: You are also using it improperly.
I'm completely confused. You say that a 48 inch long, four inch wide piece of plywood is capable of staying flat enough to make another board flat to within a few thousandths of an inch. This implies that the piece of ply will not flex, beyond a couple thousandths, as you apply pressure to it using a couple of handles.
Steel would do that. Plywood would flex at least an order of magnitude, probably two, beyond that. That is, I would expect a four-foot long piece of half-inch ply to easily flex at least a tenth of an inch along its length as you apply differential pressure to it.
Do you really say what I think you do?
    -- Andy Barss
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Andrew Barss wrote:
> > I'm completely confused. You say that a 48 inch long, four inch wide > piece of plywood is capable of staying flat enough to make another > board flat to within a few thousandths of an inch. This > implies that the piece of ply will not flex, beyond a couple thousandths, > as you apply pressure to it using a couple of handles. > > Steel would do that. Plywood would flex at least an order of magnitude, > probably two, beyond that. That is, I would expect a four-foot long piece > of half-inch ply to easily flex at least a tenth of an inch along its length > as you apply differential pressure to it. > > Do you really say what I think you do?
Perhaps this will help.
You use a long board in conjunction with a fairing batten.
Take a few strokes with the long board, then check your work with a fairing batten.
Using the back edge of a 3/4" x 3/4" x 1/16" x 96" aluminum angle as a batten, you litteraly look for daylight between the work surface and the angle.
A 1/32" gap looks bug enough to drive a truck thru <G>.
Lew
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: Andrew Barss wrote:
: > You're gonna want to do something to that 4' piece of plywood to make : > sure it remains dead flat, otherwise it's going to follow whatever : > peaks and valleys the boards have. It'll make them smooth, but not : flat, : > unless you rigidify things.
: If you can get a piece of 1/2" (9 ply) or 5/8" (11) ply birch ply to : bend when being used as a 48" long, long board, you are a hell of a : lot better man than I am, which is entirely possible.
To clarify, are you talking about a piece of ply which is 5/8" in the dimension perpendicular to the surface being flattened? or is it rotated so there is 4" perpendicular, and a 5/8" surface with sandpaper on it?
I can imagine the latter being inflexible to the extent you describe it, but no the former.
    -- Clarifyingly yours,
            Andy Barss
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Same process as using jointer p;ane. Yes, it works well.

With you until this point. You can use this to tell if the panel matches the aluminum reference piece to within .001 but it won't tell you if it's flat. That piece of aluminum will not be anywher near that close.

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Mekon wrote:

Dave
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snipped-for-privacy@hotmail.com says...

Hmmm, the reason could be right there - most of our antipodean timbers are not quite stable enough to go joining 200mm boards together without getting into problems with them warping and making everything very uneven. If at all possible, I'd recommend you rip the boards down to between 75-100mm before joining.
I've even got into trouble joining 6x2 totara for a coffee table top, I was careful of how the grain ran (alternating direction), after joining I put a s/steel ruler over the top and you couldn't see light under it -- 6 months later the thing had assumed a zig-zag shape.
What I am trying to say is: you may well get it flattened now, but it may no longer be flat in a little while. Check the individual boards and make sure the trouble really does lie with the joining. Consider breaking it down and flipping every other section if the boards are misbehaving.
If, on the other hand your problem is simply a wee step between boards, then I personally would clean up with a finishing plane and then a cabinet scraper. My Ulmia plane takes off very fine shavings and is much quicker than a belt sander :-)
-Peter
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"Mekon"

1. Send it out as other have said. But then can you say you built it? 2. Buy a widebelt sander and sand it yourself. Very expensive. 3. Make a router carrier and surface it. Not to hard, time consuming, but if you build it right, it will work on many other projects. 4. Buy a belt sander and again, sand it yourself. BTW, not all that difficult. See Max's post. 5. Sand it with a ROS. This idea will take you the rest of your life and it still won't be flat. 6. Get some winding sticks and a good hand plane. This too will take some time but you will be rewarded with the lessons learned and personal satisfaction of doing it by hand.
The real lesson learned, use cauls to clamp the top flat. I rarely use biscuits or dowels on long grain to long grain glue ups.
Dave
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