Unusual jointer alignment issue?

[Jim Eisenstein]

I've been using a Grizzly G0856 8" jointer with a helical head for
a while now. Basically, the machine works well, although I've had some
difficulty setting the outfeed table height as accurately as I'd like. In short,
if the outfeed table is at the correct height relative to the cutters at the near
edge of the table, it will be about 0.005" too low at the back edge 8" inches
away. This is not a big problem when face jointing wide stock, but it can
lead to snipe at the tail end of narrow boards being edge jointed for a glue-up.

The usual first suggestion is to check to make sure the infeed and outfeed tables
are perfectly parallel and apply shims to the ways on the outfeed side if they
are not. I've very carefully checked this on my machine and find the tables are
parallel to better than 0.002" across their entire width.

Another possibility is that the rotation axis of the cutter head is not parallel
to the tables. I've never seen this discussed, no doubt because it is easily fixed
on a cutterhead with straight knives. When the knives are adjusted to be parallel to
the outfeed table it doesn't matter if the rotation axis is slightly off.

With a segmented cutterhead like mine, this fix is not available; each
carbide insert is attached to the cutterhead in a fixed position, there is no wiggle
room.

I've solved this problem on my machine by inserting 0.005" brass shims under
one of the two cutterhead bearing blocks (the near side, in my case). This removed
the misalignment of the rotation axis relative to the tables and allows me to
set the outfeed table height correctly across its entire width.

Hopefully this will be useful to others owning jointers with segmented heads.

[Mel Fulks]

Jim, I’ve seen that situation many times , but have not used a helical jointer. Mfg,s don’t want problems. Most jointers are, or were sold with
outfeed table a bit low because many like that set -up since it does not make the material “climb” …that is ,remove less wood at the trailing
end than the front (starting end). Those with less than precise demands are happier with snipe and often just use a longer board …then just
cut off the snipe. Doesn’t make for good accuracy or thrift …but it’s easy, and cuts down on long telephone calls . Experienced users know
that just a little wear off full sharp , can make material climb ,and they know how make fairly fast slightly lower outfeed table.

[Maurice Mcmurry]

Well done on your troubleshooting and fix Jim. Also well explained. Grizzly make so many machines they have to be moving through quality control very quickly.

[John TenEyck]

You get snipe when the cutterhead is too high or the tables aren't coplaner. If your tables are coplaner I'd say the root of your problem is the cutterhead being too high. If your tables are coplaner then it matters not that the end of the outfeed table is lower than the cutterhead as long as it's the same height at the cutterhead. The board is still taking a linear path.

John

[Jim Eisenstein]

Thanks, John. The issue was not at the far end of the outfeed table; it's that it was not possible to have the outfeed table match the cutterhead
height front to back. The reason turned out to be that the cutterhead axis was not parallel to the tables. Shimming the cutterhead solved the problem.

[Ken Fitzgerald]

Jim, based on what you have posted here, I agree with your fix.

To be honest, the first time I read you initial post, I read it as you put the shim under the cutters, not the cutterhead bearing block:o. When I saw your reply to John's post, I went back and reread your initial post.

[John TenEyck]

Thanks, John. The issue was not at the far end of the outfeed table; it's that it was not possible to have the outfeed table match the cutterhead
height front to back. The reason turned out to be that the cutterhead axis was not parallel to the tables. Shimming the cutterhead solved the problem.

I, too, misread your first post. My apologies. Carry on.

John