Finishing edges on cupboard doors (MDF)

[Sarah_W]

I'm making up cupboard doors for new cupboards I've created in the eaves. I'm going to jigsaw the doors along a straight guide then route them to give a good, straight finish. Is this the best way?

[Simpo Two]

It would work if you use a fence for the router, but it would be easiest if you used a circular saw - one straight cut using a guide clamped in place. I have a cordless model, rather lightweight in the scheme of things BUT it has a very thin (1.5mm), fine blade which leaves an excellent edge.

The cut edge of MDF is very fibrous and absorbent and will easily show knocks - you may be OK with that; if not you could adjust the size and add a moulding with mitred corners.

ETA You could also use a jigsaw as planned and then plane the edges straight, but the plane will need to be sharp to avoid fluffing up the MDF, and you'll need to be good with it not to get the edge angled.

Edited by Simpo Two on Wednesday 4th November 09:48

[andy43]

Either use a fence on the router with a square cut bit as above - will help straighten out a wiggly jigsaw cut as well, or use a radiusing router bit with a bearing on it if you just want to round the sharp edges off. The bearing just runs along the wood and keeps the router in position.

[annodomini2]

As has been said a circular saw or a table saw will typically give a better finish.

You could use the Router with a straight cutting bit against a straight edge to smooth this off.

If you want to add a profile to the edge with the router, where the bit uses a bearing along the edge of the piece make sure its how you want it before you begin.

Couple of tips for cutting MDF:

1. If possible do it outside
2. Where a dust mask

MDF dust is just as bad as asbestos!

[robinhood21]

If you have not yet purchased the MDF, measure the required details and, pop along to a good timber merchant or big DIY store and let them cut the MDF to the required size.

[DB7 pilot]

Sarah,

Ideas from the other chaps are perfectly good, but an easier way, if you're not that comfortable with the power tool option is a sharp block plane, the trick is not to stick the blade out too far. It'll fit snugly into the palm of your hand and a couple of sweeps will take the worst kerfs out of the edge of most MDF boards, then finish with 80 grit sandpaper over a timber block, a five inch piece of 2" X 1" will do. Don't forget to put a light arris on the edge/corner as paint doesn't cling to a sharp edge.

I then find that the first coat of paint will get 'sucked' straight into the fibrous edge, for that I'd use acrylic primer (2 coats), then finish in your desired colour. I find acrylic primer puts a 'skin' across the worst of the MDF edge and will save more coats of an inferior primer. Lightly, (very lightly) sand between the primer coats for a better finish using 150 grit paper.

By the way, I've had a joinery workshop for over twenty years and cut up a couple of tonnes of MDF a week, so I'd suggest that if you work in a ventilated room, maybe open a window and don't lick the edge of the board once you've sanded it, then you'll probably be o.k. with a particle mask for your project.

Good luck.

Mark.

[B17NNS]

Get your MDF from a B&Q wehouse. They offer a cutting service. Cut edges very good, a light sand and your away and onto painting.

[Sarah_W]

Thanks for all the ideas folks - stupidly I've already bought the MDF so have lost the option to get it cut for me. I don't have a crcular saw, so will go down the jigsaw then block plane route suggested.

Thanks again :-)

S