Thread: biscuit joiner accuracy

If you have to make a number of these boxes and they are of a similar size I would consider doing what the profesionals do- make an asembly jig to hold things in the right place.
I am going to guess that you are making speaker boxes or cabinets of some sort so you would be able to construct your cube in stages. First asemble the 4 sides into a square and hold them with clamps, then glue in the base, then the top.
The biscuits are there to hold the timber together and strengthen the glue bond. I doubt that biscuits would make an accurate asembly system because they are not designed to do that, in fact I have found that the slight gap left around the biscuit to ba a blessing when it comes to getting things lined up and square.
You may find that even the Makita will need some minor adjustments to make it "spot on".
Good luck.
PS.
I use a GMC jointer. They also make a doweling jig that looks a bit like the biscuit jointer but drills the holes for dowels instead.

I agree, it sounds like more time on making some simple jigs would be the remedy. I have a makita which is good, I also purchased a 'less than permanent' ozito which to date works just as well after I removed the plastic fence sole plate and glued on a mdf fence sole plate.
These are not highly accurate machines that will make up for shortcoming elsewhere in the work. From reports the angle grinder attachments are more than capable also.

These may give you a few ideas:
http://www.woodworkingtips.com/woodtips/sntip57.html
http://www.woodworkingtips.com/woodtips/sntip58.html
http://www.woodzone.com/tips/sqblock.htm

(I'm allowed to say "less than permanent", aren't I?)

I am but joining MDF to make cubes of roughly .6m a side and am finding it impossible to get everything line up EXACTLY using biscuits.

AudioMan

The POINT with biscuits is that thet DON'T need to be as accurate as dowels. Dowels are VERY difficult to set accurately and they rely on dead accuracy both in the vertical and the horizontal planes. Biscuits, on the other hand, only require accuracy in the horizontal plane (that is, they need to be cut level so the two cuts match). It is ON PURPOSE that they have a 2-3 mm amount of sideways movement. This enables you to adjust and perfectloy allign the two pieces of wood/MDF before the glue dries.

Consequently, the vital area for all biscuit machines is the angle of the blade, not really the fence, per se. As long as the blade cuts at a perfect horizontal, you will match cuts on opposing sides. You don't need a fence for this if you are resting the sole of the machine on a flat surface. Obviously you would also prefer an accuate fence. If the machine you have is not working as it should, then replace the machine or adjust the fence (most do). The de Walt's fence has a reputation for excellence. Incidentally, it is the same one as on the GMC, so if you are only looking for a machine for occasional use, consider this one (I have one and it works flawlessly).

These machines are BY FAR better than dowels (which still have a place in joinery). So don't give up on this idea.

Regards from Perth

Derek

Audio Man,

If you have an accurate table saw, try this method:

1. Cut each side to the exact dimensions.
2. Install a timber fence against your metal fence.
3. Tilt your saw balde to an accurate 45 degrees, burying the top of the blade into the timber fence.
4. Adjust the height so that the intersection of the blade and the timber fence exactly coincides with the thickness of your MDF panels.
5. Chamfer each panel on all four sides.
6. Lay out your panels butted edge to edge except for the top and bottom. Chamfers are down.
7. Join the panels accurately with duct tape - making a hinge.
8. Flip the four panels over - gently.
9. Run a bead of glue down each 'V'.
10. Fold the whole assembly into a box hinging on the duct tape.
11. Square up if necessary and clamp.
12. Add the top and bottom panels.

The end result should be a perfectly joined cube without any edges showing.

I can't take credit for this idea as I read it somewhere...but it works well.

I have received some very valuable advice here, thankyou all very much!
I am now looking at which jigs to use, now that I have been put on the right path!

Well, Mate....
You have been put on a path. Only time will tell if it is the best path to take. If all goes to plan you will find an even better way of doing the job and then you can share that with the rest of us, that way we all keep learning.

i looked into biscuits when they first showed up and have used them a few times. i bought a cutter to fit my router that i use in the triton, but honestly i don't like them. i find that they don't swell up into the cut like they are said to do. i soaked a few biscuits in water overnight and then measured them and they were still the same size. if they did swell up, how do they not split the board apart??? especially mdf that is so weak edge-on. i find that a loose plywood tongue glued into a groove on both parts is both a more accurate and much stronger joint, and as the ply tongue doesn't swell, the groove can be cut to the exact size of the ply for a tight fit. once the cutter is set, all the grooves are exact, so set-up time is just as quick as a biscuit cutter. just make sure that the groove is slightly deeper than 1/2 the width of the tongue so there is room for the glue to squeeze out, and clamp from one end so the glue can escape. for joints where the ends show, just stop the groove short each end and cut the tongue to fit.

As some one said before you I guess you are building speaker cabinets.

all previous comments withstanding.


One thing I learned early in speaker building dont expect things to join up perfectly, i mean perfectly.

A second dont get too complicated in your construction methods unless the job is realy worth it.

Buscuits are not a real help in speaker construction.

If you are building pretty vineered boxes the mitre & tape method is worthy and effective.

If its a cheaper job and you can use filler & sand rebated joins are the go. The box then becomes self jigging.

make the joints tight , fill & sand the edges for a perfect finish.


Final secret
accuracy, accuracy, accuracy. especialy squareness.