Grizzly shapers putting a dip in the end of our stock

[rudy de haas]

Something is causing your wood to pivot as soon as the end clears the infeed fence. To beat that I'd suggest first ensuring that the feeder pushes against the outfeed fence, not the infeed; and, if that doesn't suffice, clamp a guide to the edge of the shaper table on the outfeed side to prevent that end of the wood swinging away from the outfeed fence. It's dirty, but it works because it stops the pivot and doesn't get anywhere near the fence, the feeder, or the cutter.

[peter gagliardi]

It hasn't been determined what the root cause is yet. Have you checked planarity of both halves of the fence with a known precise straightedge?
If no, you need to.
If yes, and they are indeed straight, and you are butted into the cutterhead on each side as close as possible- hopefully with wood plates, and it still happens, it can only be one of two things.
1. Your outfeed fence is set back at a smaller diameter than your smallest cutting circle diameter.
2. Your feeder wheels are not in a good location linearly in relation to the fence opening.

Are you using a 3 or 4 wheel feeder, and how long are your parts?

I have metal fence plates, I run almost exclusively with the factory fence setup vs an outboard fence, and have done so for about 20 years.
Accurate setup is the key.

You can accurately dimension parts without a back fence, but you have to be diligent in setup and stock prep.
I mill my door parts about .015- .030 over width, and dimension to width with the split in and outfeed fences.

It is fundamental to good shaper results to have an accurate fence.
Without addressing the root cause, and skipping to a backfence, you are just kicking the can down the road so to speak.

[Joe Calhoon]

Accurate fence on shaper is a must if you want precise snipe free parts. Fence plates square to the table and coplaner with each other before offsetting. It’s like a jointer with the fence plates being the jointer bed.

We use the outboard fence a lot for window parts. Easy to get snipe free cuts on the Martin using the offset fence but you can get a slight wedge effect even with no snipe. To keep precision in slot and tenon work the outboard is best. For house doors with various width parts we sometimes use the split fence.

07751899-EE10-42CB-A33D-760A97D4C781.jpg

For outside frame profiling that that might be similar to cabinet door edges we use a add on fence that is milled with a 1mm offset. (Our normal removal) This is a 8” diameter cutter and also serves to close the opening when taking the whole edge.

DA6D856B-C3FA-48A2-9971-B882DEAFBFA7.jpg
B178F03F-30A6-4BA4-B5B8-09167F67B411.jpg
If not removing the whole edge we bridge the cut with the Aigner fence. We have a add on for that when using our small diameter Freeborn cutters. This is also a good solution if you do not have a finger fence.
005E947D-56BB-4484-8FB6-AF72368B0B26.jpg
D75A28CA-F8C0-485A-8069-A1D2F6F01439.jpg
80354B56-4A45-429B-9070-D2FF45EAB03D.jpg

The add on fences are are easy to attach with no screws and less than a 5 minute setup with all. We do not use dedicated shapers.

I second making wood plates coplaner by running across the jointer. We used to do that with a Italian shaper, works well.