Reverse Glue Joint snipe

[John Keane]

I am using a Reverse glue joint router bit in a table mounted router. with a Incra jig and a zero offset fence. RPM = 10000.

Problem: snipe. First cut at 1/16th or 1/8th is ok. Each subsequent cut has snipe for the last inch. I have tried it with offsets of 3 hundredths negative on the infeed and the same on the outfeed and still get snipe on all after the first cut.

I would like to master using this bit without cutting the boards long enough to cut off the snipe. It seems apprentice to cut boards longer than necessary just to allow for snipe.

[Chris Padilla]

Did you make a dedicated fence/zero clearance insert for the bit? That might help. Otherwise, plan to cut the snipe out or add beginning and ending backer boards.

You are losing support on your piece and thus the cause of the snipe.

[Steve Clardy]

I've always used a straight fence. No snipe

Never seen the need for a offset fence.

[Charlie Plesums]

Many of the glue joint bits cut the entire face, sort of like a funny shaped jointer. Therefore the outfeed fence has to be even with something on the cut wood, to hold the wood steady after it leaves the infeed fence.

Easiest solution... don't cut the entire face...adjust the depth to kiss but not cut some portion of the work, that can ride on the outfeed fence.

Second easiest solution... cut off the snipe

Not very easy solution... adjust the outfeed fence to be exactly even with the low point of the cutter (the high point of the workpiece) after it is cut. Sort of like adjusting the jointer so the outfeed table is exactly even with the knives.

[pat warner]

Yep a glue-joint bit has "joint" in its name because the stock is to be jointed & milled in one shot. Fence has to be offset for that, but not much.

See Jointing on the Router Table for some setup tips.

Still screwed up? Could be the cutter. Would be happy to run a few feet to diagnose if problem persists. It is not uncommon for these cutters to be ground poorly, not at all.

[John Keane]

Pat, your comment "jointed and milled in one shot." I have been operating under the policy of multiple passes with minimal removal per pass e.g. 1/16 or 1/8 per pass. Since the first pass is without snipe, your comment suggests that I make one pass. At what depth of cut?

[pat warner]

JK, darn good question.
Usually these cutters swipe ~ 3/16 - 1/4 to produce their entire profile.
But it is a full thickness and power hungry cut, even for 3HP.

If you don't waste the whole thing with an offset fence in play, the work will bash itself into the outfeed table. So for your fundamental question:
If you have a 1/4 glue joint, I'd waste no more than .260". Any more is a waste of energy, cutter, wood, & time.

But your intimation of a staged cut is correct. Even for 3/4 stock, .260 X .750 is a ton of wood to waste in one pass. I would do this if I had a lot of stock to join/joint.

1) Waste the first 1/8-3/16 with the fence straight.

2) Offset (& reset) the fence x .010 then take the finish cut.

Routers

[glenn bradley]

I'm with Chris. I keep my fence boards within about 1/16 to an 1/8 of the bit. For some profiles, I use a sacraficial fence and make it a ZC. No snipe either way.