Squaring a Morso Chopper


Grumbler in Training
Sep 13, 2005
Thomasville, NC
Anybody know the best way to adjust the fence on a chopper to ensure that it is square? Seems like mine might be off just a bit. I used a 45 degree square with it pushed up against the fence and touching the blade. There must be a better way of doing this. Sure would be nice to be a little more accurate. Thanks..Ron
I have a Meter long metal straight edge which I have used and that did the job….

This subject was discussed in the past search the archives and you should find some interesting tips……

One tip it to adjust the left side first ….I know this helps but I cannot for the life of me recall why…..

Good luck


Long straight edge along the torque rail will straighten out both sides.
Straighten the right side to align with the torque rail, then slide your straight-edge to the left to match the left swing arm to match the right arm and torque rail.

If all three rails are in alignment, it doesn't mater if their are 90.1 or 89.9 degrees to the centerline of the blades. The blades will always be 90 degrees to each other and if the miter on the left is 44.05 and the miter on the right is 45.05, you will never see it with a naked eye.
Ron when you say yours may be off a bit do you mean that your mitres are poor i.e. opening at the front or back when joined?
If so make sure that the right fence is aligned with the measuring arm as described above but adjust the left fence either forward a bit or back a bit depending on whether your mitres open at the front or back.

Open on the front(inside) move fence back
Open on back (outside) move forward.

We adjust the left fence constantly depending on the moulding and even on which blades are in use.
We use a lot of synthetic mouldings and we've found that the best way to achieve a good join is to adjust the left fence sometimes to quite a degree to get the best results.

The exact angle is unimportant but the finished join certainly is.

Hope this helps

The extension fence is adjustable, so you can't use it as an absolute reference point. Also, even though theoretically the short adjustable fences should be perfectly in line with each other I have not found that to always be the case. The following procedure produces cuts that many of our customers claim are the best they've ever seen. It uses the simple principle that two 45° angles make a 90.

(first, make sure your blades are properly sharpened and the locking bar is holding at the last position).

Use a piece of 1 x 4 or other similarly wide and flat stock. It does need to be perfectly straight, flat and of consistant width. Cut both ends of a short piece (maybe 6-8" tip to tip) on the same side of the chopper. That is, cut one end, flip it end-for-end and cut the other end so that both ends of the piece are cut using the same knife and fence. Put the 45° angles against a regular square and keep adjusting that fence until you get it perfect.

Then do the same thing with the second side.

As a test, cut four pieces the normal way (right cut on left side of chopper, left cut on right side of chopper) and hold together. It should be perfect.
I generally use a six to ten foot length of Nielsen profile 97 or 99 as a “straight edge”. Remove the stop from the right side of the chopper, lay the Nielsen rail the length of the chopper and fiddle with the “adjustable” fences until they all just touch the moulding rail without any gaps.