I've just bought a biscuit jointer (plate jointer in some circles), but I'm having problems so I thought I'd check with the various woodwork skilled people here.

First, let me say this is the first real wordwork I have done since the age of 15. All the wordwork I did at school didn't involve any power tools (actually that is wrong, there was a band saw and a table saw, but we weren't really encouraged to use them). So, I could be doing something stupid...

I need to replace the double glassed partition in my back door (because we are getting cats and this seemed to be the easiest way to fit a cat flap). The panel is 530x675mm, so I obviously can't get a piece of dark hardwood that size at my local timber yard. So I bought two metres of 20mm thick hardwood and a biscuit jointer so I can join the pieces.

The biscuit jointer I bought was the Clarke International BJ600 (heh, that could be a character from a porn parody of Terminatior). It is a all in jointer, not one of these ones that fits to an existing angle grinder. It cost me about £70.

Now to the problem. The jointer has a fence height adjustment which adjusts how far from the edge of the wood the cut is. It adjusts with knob and has a hand tightened lock nut to secure it.

Unfortunately the lock nut does not secure the fence. As soon as you cut into the wood the lock nut loosens and the fence moves. The result being that your cut ends up anywhere but where you want it. With each cut the fence moves further.

Am I doing something wrong? I have tightened the lock nut as far as I can, I can't see what else I can do.

I'll have to take it back to the shop on Monday, unless anyone has some suggestions?

Why does Norm never have problems like this