Question Mitre joint fixing

What sort of finish? If it's a smooth and glossy surface then any fillings are likely to only partially
disguise the problem. I hate this type of moulding for this reason. Liming wax is one way. Although
if it's a big gap then it will eventually pick up atmospheric dirt and stick out like a sore thumb.
Another way is to use a non-solvented grab adhesive. Force into the gap and wipe off the excess.
You can paint this stuff when dry with white acrylic paint.

The elegant solution is to fix the cause of the gaps. (Sorry for the lame answer.) :confused:

Welcome to the G btw. 🙂
 
If you anticipate gaps you might paint a bit of white acrylic onto the offending area before joining and wipe off the excess that is squeezed out. Like with the wax, as Peter pointed out, acrylic will develop pores that will get soiled over time.
You might also try gluing and clamping the joints before inserting the v-nails, though it does seem a bit counter-intuitive. Don't let the glue completely set before putting in the v-nails as the process might cause the joint to fail.
What is your saw setup? Maybe you need to look at that as part of the solution, as well as making adjustments to the fences on the v-nailer.

And welcome to the G!
 
Welcome to the G!

I use cc paste which comes in white and black (maybe more colors these days)
You can also use a filler that hardens and paint it after. It all depends on the moulding and how big the gap is of course.
 
You can also use a Japanese pull saw to tweak the fit of your miters (before joining, obviously).

A handy tool is sandpaper adhered to a metal plate 1/32-1/16 thick. The one pictured below was made by Stanley 13/4 wide x 10" long. Stanley no longer makes the tool but you can make one simular using something like a cake frosting tool with sandpaper adhered to it.
Works great truing up miters while in a framing vise.
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The elegant solution is to fix the cause of the gaps.
IMHO this is the only correct answer. Its one thing to do this for a one off but if this is recurring the only thing to do is to correct the root cause. The Reef didn't supply any additional information on this. Perhaps they can supply some more information.
 
I’d buy chops until I could have the problem fixed. If you have bad corners, look at sharpening, adjusting, whatever else, until you’re confident with your cuts. Painful, but necessary.
 
The smallest little thing can cause big problems. Recently I have had more back chipping than normal on my EMN-12. But not both sides. The front cut was always good but the back end would chip a bit. It took me a while to find the problem. My right saw blade lagged about 1/32" or less from the left. That is, when then left blade had fully cut the moulding, the right still had a tiny bit to go. I guess that because the inner cutout was only attached on one side, the tiny bit left would vibrate and chip. Or so it would seem. In any case, you can never fully get rid of chipping, but you can minimize it.

Problem solved and fixed.
 
How are you cutting your moulding - saw, chopper? what type of saw? if you are using a chopper when was the last time the blades were sharpened?
 
To echo previous replies -

With a Morso the most common cause of gapping is dull blades. Once the pristine edge has gone
the blades will tend to cut slightly 'off-track'. Particularly if you have been cutting hard wood or
very thick synthetic gesso. The solution is the 'left-fence tweak' which I have explained to people
xxxxty times. Amazing how many framers don't know about it. Forget setting the blades to an angle
gauge. You can do this until the cows come home but the fact is the angles are so fine that you will
never get the blades set right this way. Except by dumb luck.

If the cut face is a fraction of a degree adrift then the error will cumulate over 8 faces. People get
baffled as to why the gap (typically on the inside) only occurs on the last join. If you think about it,
the first three joins will always be tight even if the angles are off. That's because the ends are free.
you simply can not tell that the corner is 89.99º. But when it comes to the last corner the faces will not
be parallel. Hence the gap.

You cannot correct the angle on the right hand blade. That is set in stone (or metal). One way is to lay a
stick in the cutting position tight against the left fence. Then slacken the bolt and deflect the far end of the
stick about 3" toward you. That will likely cure the prob. It will compensate for any angle deviation on both blades.
Theoretically, this action will produce a different length on the right/left lateral miter faces, but in practice this
anomaly is sooooo small that you will never notice it.

The principle is the same on saws. I have two chop saws set inline. One does the left end and the other the right.
I slide the stick though and cut the right end. Then slide it further up to a stop and cut the other end on the other saw.
This not only saves swinging the head (which is likely to disturb the angle setting) but allows very fine calibration.
Saws of this kind that have a fine tuning adjustment on the set indents are few, if any. With my setup there is enough
play in the holes where they are fixed to the bench to skew the left hand saw a tad until it cuts true. It's worth taking
time to calibrate equipment.

My ideal situation is to end up with the two final faces ever-so-slightly apart. The natural springyness of the v-nails
will make other corners flare out slightly. Pulling the last two faces together neatly cinches up all the corners all the
better for the glue bond. 😁

** If you try this tweak and subsequently get gaps on the outside, you have tweaked too far. 😕
 
An ounce of prevention is worth a pound of cure. Or, more accurately in this case, an mg of prevention is worth a KG of cure.

But, if it's too late, CC or CJ paste are viable options as long as it's not "too" (subjective term) bad.

If it's "too" bad, send it back or do it over. After all, all the customer cares about is what they get. They have no interest whatsoever in who/what/where caused the problem.
 
Don't forget about one of those miter sanders.
I have more than one company whose miter cuts always need to be sanded true.

Sometimes it is just that their blade wobbles a tiny bit as it goes into the wood which causes that tiny gap at the inner edge of the corner.

Roma's chops are notorious for needing a sanding.
Don Mar's almost never need sanding.

Sometimes my own chops need a tune up with the sander... depends on the wood.

The pull saw Mar mentions works great for moulding that is a bit warped and won't close up at the last corner join.
 
..yet one more reason to not have Decor on the wall. :nuts:
 
..yet one more reason to not have Decor on the wall. :nuts:
That sounds vaguely like you prefer bare walls.

Or maybe you prefer "real" art.

Or maybe you were referring to a company.
 
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