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Leon[_7_] Leon[_7_] is offline
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Default Planing Across The Grain, Just To Prevent Snipe

On 4/8/2019 4:08 PM, DerbyDad03 wrote:
On Sunday, April 7, 2019 at 1:11:11 PM UTC-4, Leon wrote:
On 4/7/2019 9:31 AM, Jack wrote:
On 4/6/2019 11:58 AM, Leon wrote:
On 4/6/2019 9:33 AM, DerbyDad03 wrote:
On Saturday, April 6, 2019 at 9:29:08 AM UTC-4, Jack wrote:
On 4/1/2019 10:03 AM, Leon wrote:
On 3/29/2019 7:05 PM, DerbyDad03 wrote:
I'm still trying to learn things about my planer....

I need to plane some poplar down by no more than 1/32". However, the
boards
are already cut to length and have tenons on the ends. (Don't ask)

I really want to avoid any snipe on these boards so I'm thinking of
using
the Sacrificial Board technique. Here's my idea:

Cut a groove in the sacrificial board, insert the tenons in the
groove, and
run it all through the planer.Â* With the setup shown below, I can
easily run
4 boards through at one time. (I'm only showing 2 in this example) My
only
concern is that the sacrificial board(s) will be planed cross grain.

https://i.imgur.com/s3bxz1G.jpg

Â* From a safety perspective, is there any reason I shouldn't try
this?

Yes, I know I could do the same thing with a sacrificial board
running
with the grain, but I'm sure this question will start an interesting
discussion, as usual.


Typically snipe happens because of the play in the cutter head.Â* Or
the
material is not PERFECTLY flat.
I always lifted the board a bit as it entered the planerÂ* and again on
the out feed side I lifted the end of the board as the material exited
the planer.
Typically, it happens because of the feed rollers.Â* Only one roller
apples pressure at the beginning and end of the cut, creating uneven
pressure.Â* You can tell because the snipe is always the length of the
distance of the in feed/out feed rollers from the blades. Lifting the
work piece at the beginning and end of cut tends to offset this
somewhat.

To eliminate the problem is difficult, and best done by allowing
room to
cut off the sniped ends.Â* If that is a problem, then run sacrificial
boards. If that is a problem, then cutting at an angle can reduce the
length of the snipe as the board will be supported a bit more through
the feed rollers.

--
Jack
Tolerance is the virtue of the man without convictions.

Thanks for jumping in so late and repeating everything that has
already been cover in this
thread. In terms of a synopsis, it's not bad.


FWIW I have never ever experienced snipe as badly or in the
quantity/length as Jack indicated.

If the cutter head pivots, and the cheaper the unit the worse the pivot,
you get snipe.Â* As the wood goes under the in feed roller the cutter
head pivots higher in the front lower in the back, and NOT EVENLY.Â* This
results in the the cutter cutting deeper.

This is new to me.Â* I didn't know the cutter head pivoted. To me, the
cutter head should be rock solid, no pivot whatsoever?Â* Otherwise, how
do you get a level cut if the cutter is moving around on uneven surface?
Not saying you're wrong, just that it is a new one to me.

I lift the work as it goes in to keep the end of the board low until the
cutter begins to cut. Then on the opposite end I lift slightly again as
the board is near the end of the cutting operation.

Yes, that is what everyone seems to do.

Many manufacturers include a cutter head lock to help.

So on my Delta 15" stationary planer I have rollers on the bed of the
planer too.Â* One on each side of the cut.

The in feed pulls the work into the planer and then the work rides up on
the roller.Â* This essentially angles the work higher on the in feed end
in relation to the other end of the board.Â* Then the cutter cuts deeper,
snipe, until the work travels far enough be pushed down on to the lower
rollers and under the out feed roller.

Yes that makes sense.Â* Those rollers should be set to not lift the work
up enough, if at all, to cause snipe, no?


I agree. I think it is a feature on some planers that are probably
intended for lots of work with out much worry of snipe. Probably
intended for a high production setting where a lot of heavy boards are
being processed.



On the opposite end the reverse happens, but left alone through the
whole process I only get/got snipe on the very ends of the boards and
never over about 3/4" in length.

3/4" snipe would not bother me at all, unless I was planing a board
already cut to length, which I try to avoid like the plague. I routinely
cut off more than that w/o snipe, just to clean up the edge, square etc.


So yes! If I am going to plane a board I try to do it before squaring
the ends. I don't have to pay attention to lifting the boards so
closely. ;~)


Just FYI...

This is an unbiased review of the Wen planer that I have. If you start
at 3:15, he talks about the snipe and at about 3:40 there's a picture of
a sniped board. That picture is consistent with what I get. As you can
see, it sure is a lot more than 3/4". 3/4" would be nice. ;-)

Lifting helps somewhat, but it doesn't eliminate it all. With shortish
boards, a diagonal feed helps a lot - really a lot. I need to play around
some more with sacrificial runners, leading and trailing boards, etc.

https://www.youtube.com/watch?v=byHKLOqJeUM

The "short" in feed and out feed tables do little to nothing to prevent
snipe on bench top planers. They hold the end of the boards up.

If a planer does not have the ability to lock down the cutter head the
whole cutter head assembly can rock and that is simply just one more way
to introduce snipe, depending on how much slop there is in the design.

So the guy reviewing the planer indicated that they put a scrap in the
front and back of the work. That will work IF the person feeding the
stock keeps the opposite ends of the boards lifted. The scrap pieces do
nothing to prevent the work from pivoting the ends of the boards up off
of the planer bed. They just help to keep the cutter head from pivoting
when the actual work passes under the cutter head.

Ideally boards being fed should be supported their entire length on both
sides of the planer so that they do not bow under their own weight.
When the boards bow the ends lift until both the in feed and out feed
rollers are in contact with the work.

Because I don't have supports that long on both sides I do the next best
thing, I lift the ends of the boards to counter act the bow and to
insure that the leading and trailing ends are flat against the planer
bed as each end is only being held down by one or the other feed roller.