08 March 2009

Mitre tape...

I managed to get quite a lot done over the weekend on the cherry table, but this job is pretty complex and is seeming to take forever without any real progress being made. The shots show my arrangement for making mortises using the router...I use a pair of 'arrows' marked on the wood that line up with the sub-base on the router so I don't even have to look at what the cutter's up to, it's just a bit of a pain to square up the mortises when they're cut. The reason I do them like this is that they're dead true and also that the top edge is straight so none of that slightly jagged effect that you get with a machine mortiser or even with a chisel. Another shot shows the router being used to make the bottom of the halving joints flat and true, cheating I know but it's guaranteed to make them spot on. The third woody sort of shot shows the wide rails that go into the legs and you can see the long mortise for them as well as the mitres on each corner...and therein lies a tale. I'd made up a rebated chisel rest with one end shot in true at 45 deg and I'd used this successfully on another project last year. When I used it this time though, I found that the mitres were at least 5deg out when I checked them...so what's going on? I rechecked the block and found that it was slightly out so I planed it again on the mitre shoot to get it accurate and then tried again on the cherry. When I tested the corners for a second time the bloody things were still 5deg out! I was totally baffled...the mitre chisel rest was spot on but the actual corners weren't...totally infuriating. Calming down and trying not to hurl tools and timber through the door, I had a good think about how to get round this seemingly insurmountable problem. The only way I could see to solve it was to skew the mitre block by sticking three layers of masking tape into the rebate at the far end (which had the effect of raising it) and then using a LN block plane to true up the mitres rather than a chisel, so it took three attempts to get these mitres accurate. It was worth doing though as at glue up time I'd have been more than slightly miffed if the joints hadn't pulled up.

1 comment:

Anonymous said...

With all those pieces, Rob, it looks quite complicated - but no doubt you have a cunning plan ;-)


Paul Chapman