cutting slot/track in MDF

[sokar]

Hi folks,

I'm trying to build a floor standing cupboard with 15mm MDF from Homebase. I need to cut two slots/tracks near the front edge, top and bottom to take some 3mm hardboard as a sliding door. I was bought a JCB router about 3 years ago but have never even opened it. I'm guessing you can tell I'm not too experiened in all this by now

Is the router the best tool to do this with and if so, what bit would you recommend I use. Money is an issue here as well I'm afraid and I don't want to have to spend silly money on a bit I'm only going to use once. It's already cost me £40 in MDF, sealer and paint

Any gurus out there kind enough to advise?

Many thanks

 

[Scrit]

Hi Sokar

Your grooves should ideally be a bit oversize, so for 3.2mm (1/8in) hardboard (hardboard is all Imperial as far as I know) so you'll need a 3.5 or 4mm cutter.

Personally I prefer to cut grooves for hardboard/thin MDF backs using either a circular saw or a biscuit jointer. The biscuit jointer cuts a 4mm groove (ideal for 4mm MDF). The saw cuts about 2.8mm (3.2mm if on my table saw), so if a wider groove is needed I run a piece of 2in electrician's tape along the fence, make a cut, remove the tape (wiping any sticky bits with lighter fuel) and make a second cut. This widens the groove by about 0.5mm (width varies depending on tape).

Either way it might still be necessary to "ease" the edges of the hardboard (at the back, out of sight) with a block plane/surform/wood block and coarse sandpaper to get 3.2mm hardboard into the groove.

Cutting a groove with a 3.2mm cutter in a router is a delicate task - do not cut more than 2mm extra depth per pass to a depth of 5 or 6mm - so 3 passes are necessary to achieve the required groove depth. And do not push the router too hard as the small cutter is delicate and will break easily.

Remember that the workpiece should be to the left, the router is pushed forwards and lightly to the left against the fence, you need to adopt a stable working stance and the workpiece needs to be clamped down onto something firm, level and flat and about waist height.....

Good luck

Scrit

P.S. Lots of things can be used to seal MDF edges including thinned paint, "white" French polish and dry wall jointing compound....

 

[sokar]

Thank you VERY much Scrit - that's some excellent advice. I have a circular saw somwhere in the garage so will try it on an off cut and see what kind of groove thickness I get.

Many thanks