Biscuit joiner problems

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Even when I clamp down the wood on a flat surface when I use the joiner, an d the wood is planed to the exact same thickness, my joints are 1/64 off al ong the full length of the joint. This has happened almost every time. It's just not logical that this is happening. Any helpful thoughts?
Thanks,
Mike
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If the biscuits do not fit relatively tightly in the slots they will allow up and down movement. Do not reference the bottom of the joiner to the work surface.. Always use the joiner fence for indexing.
This can also happen if the boards are not perfectly flat.
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On 5/27/2013 12:57 AM, Leon wrote:

Either the fence or the bottom are useful. just as long as you use the same for both joints. 1/64 is not extreme, but not perfect. As Leon said if the biscuit is not tight then you have a potential error. I always nudge the boards as my biscuits are variable. I use them to prevent sliding when I use them. Mostly when edge joining I don't...
--
Jeff

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On 5/27/2013 12:28 PM, woodchucker wrote:

Because after using the bottom of the jointer for many years and having inconsistent results I finally determined that if the board/panel is not perfectly flat of not setting perfectly flat on the work surface the alignment can be thrown off. A small piece of 1/32" thick debris under the piece receiving the slot can throw that slot off by that amount. When you use the fence as the reference you only have to worry what is between the fence and the work and you can see what is in that location. If the board is not perfectly flat the fence dies not exaggerate the whole deflection as would happen if the joiner was on the work surface and the board had as much as 1/16" bow.
On paper it makes sense to use the bottom of the joiner on the work surface. The paper does not take into account other factors and if any of the debris escapes the cut the likely hood of the work surface being contaminated increases the odds of a problem. The relatively small joiner fence eliminates most of the problems.

Yeah, that is what I said.
I always

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On Sunday, May 26, 2013 11:57:07 PM UTC-5, Leon wrote:

Thanks for the good insights everyone. I have not been using the fence beca use my work table is flat and the pieces went through the thickness planer and appear to have exactly the same thickness. It seems logical to me that the biscuit joiner will make the same cut on all pieces, but I'll try the f ence!
Thanks again.
Mike
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Regardless if the work bench is flat the wood may not be flat. Just because your wood was sent through a planer does not mean it is flat, it mostly means that it is smooth and a uniform thickness.
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On 5/26/2013 10:55 PM, Michael wrote:

Sounds like you're not using the same reference face uniformly for all pieces to me...
--


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Is it possible that rather than the slot distance from the edge being off 1/64, that the slots are not parallel to the edge? i.e. the axis of the slots in the 2 mating boards is not parallel? I don't have easy access to it right now, but as I recall, there is an adjustment for this on my deWalt plate joiner.
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On 5/26/2013 11:55 PM, Michael wrote:

the wood is planed to the exact same thickness, my joints are 1/64 off along the full length of the joint. This has happened almost every time. It's just not logical that this is happening. Any helpful thoughts?

However the same principle applies. ALWAYS cut the slot to the same relative surface. ie if you are cutting a picture frame always cut the slot with the face up,
As I said I don't have a biscuit joiner but if the fence defines the depth of the biscuit slot then the same surface of the should always be against the fence. If a cabinet face frame then the outer surface.
I avoid this problem by not centering the biscuit slot. I put it so that top edge of the slot is below the center line of the piece that I am cutting. By cutting them all against the same face, then mistakes are immediately evident.
With long pieces, you can have problems by not feeding the piece into the cutter square to the fence. ie so the slot is cut at an angle to the end of the piece. This can be exaggerated if you start the feed at and angle and end the cut square.
This is the reason I use a router table. It is easier to insure the piece is flat on the table square when you start the cut, and don't have to worry able wobbling the biscuit joiner. (Understand this goes out the window on a slot into the face of the board, But the possibility of wobble is still there.)
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On 5/26/2013 11:55 PM, Michael wrote:

the wood is planed to the exact same thickness, my joints are 1/64 off along the full length of the joint. This has happened almost every time. It's just not logical that this is happening. Any helpful thoughts?

Lots of good advice so far. I would add that I had a similar problem when I first started using a biscuit joiner. What I did to resolve it was clamp the piece so it couldn't move when I was cutting the slot. That allowed me to concentrate on holding the fence flat on the reference surface and the machine tight against the piece.
Mike
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Yes, and make sure it is at the edge of the bench so you are using the fence properly for alignment and the tool does not rest on the bench.
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My biscuit joiner fence is not parallel to the blade. Check yours. If there is an adjustment for the De Walt 625(?) I would love to hear it.
wrote:

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On 5/27/13 10:12 AM, TinWoodsmn wrote:

Hammer? :-)
--

-MIKE-

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On 5/27/2013 11:12 AM, TinWoodsmn wrote:

Hmmm. don't know, but what about making a shim? Make it on the tablesaw.
--
Jeff

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On 5/27/2013 10:12 AM, TinWoodsmn wrote:

May I suggest the adjustment that involves you wallet and a trip to your local Festool Dealer? LOL.
Fence being parallel to the blade is an absolute necessity.
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ABSOLUTELY, that will bite you if you don't pay attention to that small detail.
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"Leon" wrote in message wrote:

...and keep your fingers out of there too. I know someone who biscuit slotted their finger... makes a mess and interferes with alignment. ;~)
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On 5/27/2013 9:45 AM, Mike wrote: ...

For small pieces, I do the opposite--I've a cradle on the bench for the joiner and I bring the work to it.
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On Sunday, May 26, 2013 10:55:51 PM UTC-5, Michael wrote:

along the full length of the joint. This has happened almost every time. It 's just not logical that this is happening. Any helpful thoughts? Thanks, M ike
Possibly? Check to make sure there isn't some loose debris interferring with alignmen t, randomly getting between the tool and work piece, or something stuck on the center of the tools upper facing plate, to cause a slight teetering eff ect, if the slot is not parallel to the face.
Sonny
Sonny
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"Michael" wrote:

------------------------------------------------------------------------------------------- What you are trying to do is like trying to push on a rope.
I surface my table stock 13/16" proud and don't sweat trying to line up the boards as the glue-up proceeds.
I let the glue cure a week, then it's off to the drum sander and the top is sanded to 3/4" final size.
Makes life a lot easier.
Lew
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