Open joints can be caused by either or both your guillotine and underpinner. But if this has only just started to happen with the newly sharpened blades then it must be your guillotine that needs attention.
You say this is the first time you have had your blades sharpened. First you need to check if the blades have been hollow ground. The face of the cutting side should curve slightly inwards. When fitting the blades make sure they are perfectly aligned, both the same height and neither one more forward than the other.
If the Morso has had any
left hand
fence adjustment previously then it was probably to compensate for dull blades. I would reset the fences. Place a long steel rule in contact with your measuring scale and also up against the RIGHT
fence. Both should be inline, adjust if necessary. Now slide the rule over to the
LEFT fence and adjust so it is inline with the RIGHT
fence. The measuring scale and both fences should all be perfectly inline.
Now cut a square test frame from a WIDE FLAT moulding and cut upside down so you don’t have to use the rebate supports. Lay the frame on a flat surface and you should be able to see if the joints are open either at the front or back. If there are obvious gaps then make a
LEFT fence adjustment. Reduce the size of your square frame and cut all the corners again. When you think the corners look right go ahead and join the frame to make a final check.
If the face of the frame looks perfect and there are still gaps at the back but on the side of the frame only, then this could be an underpinner issue.
As to which way to move the
left fence… I can’t remember!
You’ll work it out!
I think Prospero will remind us
EDIT: Featurepiece got in before me
