mitre problems

[kennethwilson]

Hello
I have recently begun framing but am a lifelong woodworker.
I use an older S/H MORSO machine and an as yet unidentified underpinner (it is Blue!).
My problem is that my mitres are consistently very slightly open towards the inner corners.
I take great care with measurements and matching opposite sides and the Morso has newly sharpened blades, so
where is the error creeping in? On the underpinner, I usually have to reduce to guides from 45
in order to close the mitre, but of course this has knock-on effects.
Dare I risk undoing the present Morso guides to test its accuracy for 45degree cuts?
Any advice you experts can give would be much appreciated.
Ken Wilson

[prospero]

Hi and Welcome Kenneth.

Try searching in the search box for "Left Fence Tweak" or variations of same. It's a classic Morso fix.


Here's one pearl of wisdom....

.....you maybe need to tweak the left-hand fence. Usually it needs fine-tuning by swinging it slightly towards you. I'm talking a gnat's eyebrow here. It's handy to have a strip of scrap timber to set the machine properly. About 3" wide is ideal. Or if you have a few offcuts of wide moulding, even better. Mitre 4 short pieces the same length and dry fit them together. If there is a gap on the inside, swing the left fence toward you a tad. Cut 4 more. If there still is a gap, tweak it a bit more. If you start getting a gap on the outside, you have tweaked too far. Not very scientific, but it works. Eventually you develop a feel for setting this up. Forget about using angle gauges and such. You can set the angles to dead 45 deg, but it doesn't mean they are going to cut 45 deg. Wood is springy stuff and a tiny deviation in angle will be magnified x4. You might also have to tweak the left fence more as the blades get dull.

[kennethwilson]

Thanks for that. I will give it a try.
Kw