On 01/09/2014 10:19, James Harris wrote:

Some background :

http://wiki.diyfaq.org.uk/index.php?...iscuit_Jointer

Any recommendations for a reasonably good DIY biscuit jointer? I wouldn't
have asked but, surprisingly, even looking back over the last year I cannot
find a uk.d-i-y post with the word "biscuit" in the subject. Maybe there is
another name for a biscuit jointer...?

Biscuit jointers are usually just called that. There are some similar
but different systems that have other names, but they are not really
comparable.

There is a massive difference in price between DIY models - which cost, say
£60 - to more advanced models - which cost, perhaps £250. For example,

http://www.screwfix.com/p/erbauer-er...230-240v/33513
£60
http://www.axminster.co.uk/makita-pj...iscuit-jointer £280

The job of the jointer is deceptively simple - cut a slot in a bit of
wood. The problem comes from the accuracy required... unless the machine
is *very* accurate, you immediately lose much of the advantage the
system offers.

The latter is far too expensive for the use I would get from the tool but is
there anything I should be aware of and look for in a cheaper model that
would make one DIY version better than another? The only important setting I
can think of is a fence that can be depended on to remain parallel to the
cutter blade and, perhaps, dust collection would be a boon.

Getting the slot parallel to the edge is a must, and something sadly
that many fail at. Even a tiny error will be magnified very quickly
(imagine fixing a nosing to the front of a composite board shelf - the
nosing may be several feet long - but must remain aligned with the shelf
along its length).

The fence and plunge arrangement must also be spot on with no slop in
the mechanism - since again you want consistent and accurate alignment
of the edges.

I have the Ferm jointer - and one has to take care setting it up to try
to keep it square enough. In the final analysis its not really good
enough. Its still usable for some tasks, but not as good as it ought to be.

I have seen material saying that biscuit joints are strong but even with the
extra glue surface I wonder what difference a small piece of wood can make.
The biscuit slots don't seem to go very far into the timber to make a really
strong join. I know that biscuits are supposed to be compressed when
manufactured so that they expand in the joint when wetted with glue but,
even so, is the main idea of a biscuit join to *align* boards reliably
rather than give strength?

It depends on what you are expecting. They will not yield the same
strength as proper mortice and tenon for example. However they make
assembly of cabinets and alignment of edges very much easier. So for
tasks like fixing this face frame to the edge of a ply side panel:

http://wiki.diyfaq.org.uk/index.php?...and_cupboar d

they work well.

They don't have a huge pull out resistance - but still better than the
woeful performance of a simple butt joint. They are also not great in
torsion. So for example, form a "tee" joint and apply leverage to the
free end of the tee, its easy to break the biscuits free.

They are very strong in shear however - so things like adding support
for shelves they do well:

http://wiki.diyfaq.org.uk/index.php?...Small_bookcase

Use to support a cross member of an H section for example, you could
quite probably stand on the cross member and they will take the load.

The other nice feature is that they accurately align in only one plane
at a time - so it allows a bit of wiggle room during assembly along the
longitudinal axis. (unlike say a dowel joint which needs to be pinpoint
accurate in both axis at once).





--
Cheers,

John.

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