Benchtop planer question

Its a little fickled in my opinion. I need to adjust the feed rollers a little bit. It doesn’t really leave a fine finish but I have a double 50” drum sander to make it money! 

But to answer your question, I’m so used to snipe after 20+ years that I always plan for it ahead of time. 

I’ve got it tuned in good enough to where a few passes through the sander and they are gone 🙌 

Weird timing with this thread for me. Been using mine the past week or two for the first time in like 2 or 3 years after finding some window and door sill rot to deal with. It's a 20? year old Mastercraft, which I think is a rebranded Delta. It only seems to snipe on the trailing end. 

Which is likely a useless thread contribution. Except maybe to add to the 'it's everywhere'...

I'll give it a go.  First off, I was never the best at what I did but I was very good.  I've had the privilege of working with people much smarter than me from multiple backgrounds.  I am the first to admit, I have forgotten more than I know.  All my life I have constantly had to retrain myself on things I've already learned over and over.  I haven't run millwork since 2015.  I would never claim to put someone in their place on any subject or anything.  But maybe I can put some things into perspective in an understandable way.  At least in the way I view and understand them.  

Snipe.  I've never had to deal with snipe that much unless it was close to having to perform maintenance on a machine.  I've been lucky to work with planners that had multiple heads such as the first being a thickness head and the second being a finishing head. The finishing head generally removes snipe, if there was any.  Or double side planners.  Those are cool but not my favorite.  

Snipe in production.  There is a 1000 ways to design an line depending on the product you are making.  But the first stage of every process is to produce a workable kant to go to a profile machine be that a molder, CNC, shaper or a finger jointer.  Assuming varied width wood stock the fist step is always thickness planning.  Then straight line, precision end trip (maybe chop) then gang rip.  Chop can be before or after gang rip (pros and cons depending on the part).  So in that run any snipe if existed would be eliminated in the precision end trim.   

Knife marks per inch (KMPI)  This is really interesting and more technical than one would think.  I speak molder talk more than planner but they essentially do the same thing.  Many times I've set up a molder to surface 4 sides which basically makes it a 4 head planner.

Lets talk about dominant knife while we talk about KMPI.  There will always be a dominant knife and there are a couple of reasons. First off it is physically impossible.  There is a lot that goes into grinding knives and creating profiles.  Generally on a head there will be 4 knives that are ground within .005.  They can be so close that you can never see a difference by the eye.  But they will never, very rarely weigh the same.  We grind out spots and scale them to as close as we can to have them balanced just like a car tire. Then they are installed on a head with a .005 tolerance of one another.   Also never will a knife be installed that is as sharp as a razor.  When we grind them, they for sure are razor sharp.  But if we installed them without deburring or slightly dulling them they would heat up and wear very quickly, enough to screw up a profile dimension. Maybe even chip.  It is also impossible to deburr them all the same.  So there is always a variance.  But this is not the reason for a dominant knife.  

Here is a brain twist.  All knives cut.  There is always a dominant knife.  But! the dominant knife is not always the same knife.  It is not called the biggest knife, the longest knife.  It is called the dominant knife.  How does this happen? 

We have a knife set at 25 degrees spinning in a circle into a moving surface.  If it was a hockey puck sliding on flat ice it would always be in contact with the flat surface leaving one long flat line.  The puck would be moving and not the surface but in our case the surface is moving and we are not always in contact to the total depth of the surface.  We are not a flat like a hockey puck, we are a 25 degree knife spinning at 6000 to 10,000 RPM in a circle.  Lets just say the footprint of the knife is .005. There is only a minuet period that a knife is reaching total depth on the surface.  The surface has to move or we would be like a sewing machine hitting the same hole.  If we were to move and leave a perfectly flat surface, we would have to be moving as a rate the same as the footprint of the knife.  I'm not doing the math but at 6000 RPM and a footprint of .005 we would be moving at something like 6 inches per minute.    

What gets lost in trying to describe this is that most of the milling is happening on the upcut of each knife.  (Every knife is removing material on the upcut)  As a knife hits the surface (AND MAKES A CUT) at total depth it is not always the same knife and it is never the same knife on every rotation.  The surface has to move.  As the surface moves and it is timed out that a knife hits the surface at total depth (and makes a cut), there is a period where a knife reaches total depth (in the void of the dominant knife) but does not make a cut.  But that knife will make a cut into the moving surface on the upcut.  That is how we get mill marks and that is what we call knife marks.  Our feed rate controls the number of knife marks per minute.  

If you was cutting a profile on a molder, something of depth, and you put a strobe or timing light on it.  You will see knives on the upcut.  You would likely never be able to see a knife making dominant cuts at total depth.  

It really is kind of a neat thing.  

So the first problem is running a conventional cut vs climb cut. Albeit, this is safer as the cutter pushes back when the drive rollers lose grip vs letting the material pull in and fly through the machine. When you conventional cut the blade slides along the flat surface until there's enough pressure to force it in the material, generating heat in the blade like flick mentioned. To small of a cut and more sliding, more heat. Climb cut, the cutter bites right away causing thet heat to leave with the removed material. In addition, you can see the conventional finishes it's cut, lifting the material (creating the snipe) vs climb cut pushing it down and away eliminating the snipe.

I get your point that you're not going very deep but you're still cutting at an upward angle. The more I think about it, the more issues I believe need to be considered. Remember though, the less deep of a cut, the harder it is for the leading edge to get into the material because the the wedge is so slight. 

I'm pretty sure it's a safety issue. The neighbor, when he got his TimeSaver, he set it a bit too low and the belt grabbed the part and shot it out the back of the machine, flew 15ft and impaled the part in the wall. Many of those planers sell to amateurs that would kill themselves. The belt on the TimeSaver runs in the direction of what would be a climb cut for a tool.

Hey Borg,

Being an electrician, maybe you could confirm for me. If I run a motor (load) off 2 meters, The meters will run equally (with a very small difference of one might have slightly longer wiring). And if that's the case, instead of having 1 200AMP breaker on one meter, I'd install a 100amp breaker on each meter.

TM

So I know this is an old thread. Been noodling on this. I believe the "dominant" blade as you call it, which leaves the "Knife Mark" will always be the knife/blade that follows the dullest blade. The dullest blade will have the hardest time initiating a cut as it will slide before it actually cuts into the material leaving a higher surface. Then along comes the next blade and because that material is marginally higher it's very easy for the next knife to enter the material earlier and pull a deeper cut making the "mark". If you only have 2 blades, of course it would be the sharp blade but if you had let's say 4 or 5 blades, it would be the blade that follows the dullest blade. which brings me to the question, if you only had 1 blade, how would you achieve knife marks?

TM

Calling @FlickitFlat what u say?

Bumped this back up to show my solution to sniping.

Working on an 90" long, edge grain maple top for a custom dresser.

Built in two pieces, 8' long with a few long tails. Leaves the snipe in sections that will be cut off when sized. 

Then dowled together when glued up.

Actually, every piece is doweled to the next with 4-5 1/2" oak dowels.

Long tails help to give you handles for moving, and flipping this heavy beast. 

Started with 8/4 boards. 

Milled clean to whatever dimension it took.

Straight edged one edge using a homemade 8' fence on my tablesaw. 

Ripped 1 1/2" strips, planed the cut faces to 1 7/16", then after gluing up the two pieces, planed both to 1 3/8".

Wish I had a festool domino machine.

I could have done a one time glue up, and saved a coupe of days of gluing and dowling one piece at a time, waiting 3hrs +/- before unclamping, and gluing the next one.

Sounds like their patent has expired, and Kreg has a battery powered verision for $450.

Beats the $1,200 + the cost of a vacumm system for the festool model.

Used a domino machine in the past for some fast assembly on some huge tops, glued up at one time.

^^^

show off!