Biscuit jointing ?

[waterworks]

I have a Rexon biscuit jointer I've never used lurking at the back of the tool cupboard and now a job has come up for it , the blade is 100mm diameter and the tips measure 3.8mm , what size biscuits do I need for it ?

 

[Rhossydd]

Standard Biscuits vary in width and length, not thickness. There should be an adjustment for the depth of cut on the machine, usually three options, and you buy the biscuits to suit the depth of cut which in turn will depend on what you're jointing.

 

[Hugh M.]

Something like this:

That’s on a fairly generic Erbauer. Set to size 20.

 

[waterworks]

I will be jointing 200 x 50 boards edge to edge to make a workbench top.

 

[Phil Pascoe]

So you need 20s.

 

[Blister]

I sometimes have problems with biscuit's
Dunk them in my coffee and sometimes half of it fall is the cup

 

[robgul]

Biscuits are OK, I use them a lot, BUT they don't "penetrate" very far into the boards being joined - they're more for "location/alignment" than "strength" - for something like a worktop bench I'd consider dowels* with a bit more depth into the boards.

*cheap drilling jigs are available

 

[Inspector]

I will be jointing 200 x 50 boards edge to edge to make a workbench top.

Then why use biscuits at all? Alignment would be the only reason as they won't add anymore strength to a long grain to long grain joint. If you are going to surface the top then just be careful with the glue up and only glue a few at a time, no wider than your thcknesser. Take a final thickness pass to clean them up and then you only have to get one or two joints perfect to complete the glue up. If you feel you must use the biscuits for alignment the smallest are enough and only a few down the length.

Biscuits originated for assembly of cabinets from sheet stock to replace dado/housed joints to simplify and speed up the fabrication. They are a strong joint when used that way.

Pete

 

[recipio]

It's probably made with a 3.8 tolerance to give a snug fit for the biscuit. Try one for size. If it's too tight heat the biscuits for 20 seconds in a microwave and you should be ok. Just out of interest Lamello are the only company who make interchangeable biscuit blades. A 3mm blade is available for thin boards.

 

[Sideways]

So you need 20s.

The Lamello biscuit jointer manual on my lap agrees.
Set for a size 20 biscuit, the machine cuts snug grooves 12.3mm deep at the centre.
The size 20 biscuits are 56x23x4mm. So you have about 0.8mm space around the long edges of the biscuit to let the glue flow.