planner defect KP312

[philoufelin]

Hi All,


I'm new to using a plane (I have a Makita KP312) and I can't get the result I expected. I have some defects (see in the photo) and I'm trying to understand where they come from. The blades are freshly sharpened. I wonder if the defect doesn't come from the adjustment of the said blades. Regarding the defects, we can see in the photo that there are lines (drags) that continue throughout my beam. Additionally, the surface is not nice after the knots.


 

Any recommendation?

[realzed]

It appears to me that there are some nicks in the blades that are causing what I see as lines left after the planning..

[Don P]

Those tearouts are from the knives hitting steeply rising grain surrounding the knots, very common, go roll thru the piles at the building supply. And it sounds from the line comment that there are some knicks in the knives leaving lines down the board.

In other words getting the knives really up to snuff is the first order of business, they are not really sharp, you need to be really sharp to get what you are wanting. Abrasive planing is the commercial way out of the problem, grind it smooth with progressively finer belts. Just need a spare quarter million and a stable for it. Get spectacles and strong light sharp, slow down, more knife marks per inch=shallower shorter tearouts. Play with sliding down the piece with the planer sitting a bit sideways, shearing the fibers off more, you are whacking into fiber there that instead of laying flat is standing up in your direction, you're rubbing the cat the wrong way. So also try turning the board around, stroke it the other way. The defect will be on the other side of the knot then but find which direction has the least wild grain. I think you are planing towards the roots, try planing towards the top. When you look at a tree that bunching fiber above the limb is pretty crazy too as you can see there. It is to an extent a no win situation. Using a jack plane is a good way to get a handle on what the wood is doing.

For real fun try planing something with interlocked grain like gum. The tree grows spiral right for a few years, then spiral left for a few. You can turn the board around and the tearout s simply move over 1/4" to the side. Sometimes it is hard to win. Wicked sharp, shallow bites and let it cut is your best tool.

[dougtrr2]

If the defect you are referring to is the tearout around the knots, that is pretty "normal".  The grain is changing direction around the knots and you can't help but encounter end grain.  End grain and planers don't play together well.

I also agree that you may have already picked up a nick or two in your knives.  Those straight lines like that are a dead giveaway.

Doug in SW IA

[doc henderson]

I agree and for nicks, you can just offset the blades a sixteenth of an inch, if allowed by type.  An exaggerated example is trying to plane a cookie.  the whole back end of the cookie will chip off.  a spiral of helical cutter may work better, and a drum sander is better.  that is how I "plane" stock down to an eighth inch.  also, softer wood is more prone including ERC and soft maple.  MC can play a role and high is better than dry in most cases.




 
 

 

[YellowHammer]

You certainly have multiple nicks in the blades, so that brings into question how sharp the blades really are.  I have seen many "resharpened" tools that were very "not sharp."  With planers, sharp needs to be "real sharp" to prevent tearout like you are seeing, as in knife blade sharp where you are in danger of getting cut if you touch them. 

Otherwise, reduce the thickness of the cut, and change directions of the board to plane downhill.  You may also have over dry wood, which also causes tearout.




   

[beenthere]

philoufelin
Welcome to the Forestry Forum.

May also be the angle the sharpened blades. A number of issues that it could be. Less depth of cut may help too.

And Doc's remedy, if possible, to slide a blade to one side or the other just a fraction of an inch will help remove the results of the blade nick showing as the steady line.

[doc henderson]

yes, if they are really sharp, you should be afraid to rub you finger on the edge to test.  maybe have a band aid or steri strip available.  you can try to hone them with a sander and a fine grit like 320.  I always hit the back side after a grinding to remove any burr.

[bluthum]

It's probably just my interpretation of the pics but the lines look more like indentions in the wood rather than raised areas caused by blade nicks. Indentions [mashed in grooves] can be caused by some issue with the bed. On my old Powermatic sometimes that happens if a chip gets stuck in the bed roller slots.

As has been pointed out chunks pulled around knots are going to happen but will be worse if the wood isn't dry like 6-8%. Even 12% moisture machines much worse than properly dried.

[21incher]

I think it looks like a drag also. My little Bosch sometimes gets sap on the plate and a chip will stick leaving marks like that. I would clean and wax the baseplate to start. Then replace the blades.

[beenthere]

There is an older USDA Technical Bulletin No. 1267 that is pretty good about the angles for sharpening planer blades for different woods.  E.M. Davis was the author.
Machining and Related Characteristics of United States Hardwoods - E. M. Davis - Google Books

[Oth]

That's a helluva a lotta portable planer for a beginner at planing, definitely nicks in your blades as said before. Make sure the surface you're planing is free of dirt/debris and that you don't set down the planer on the ground with the knife/bed side down or you'll pick up debris that way and you'll be constantly dealing with new nicks. That said, a 12" portable plane is not exactly a finishing tool, it's a dimensioner.

[Larry]

The lines are caused by a nick in the blade.  Either sharpen or shift one knife over slightly to eliminate.  The end grain tear out behind the knots can be caused by dull knives, the wrong cutting angle, or maybe both.  In a commercial setting the planer guy would resharpen the knives and possibly alter the cutting angle by grinding a micro bevel on the back side of the knife to alter the cutting angle.  Different species of wood require different cutting angles for optimum performance.....out of the factory planers have a compromise angle to work with either soft or hardwood.

In my small shop if my segmented insert planer was causing tear out behind the knots, I would run the wood through my small wide belt sander and call it a day.

[Brad_bb]

If you are trying to get a smooth finish on your beams, you need to belt sand them after planing.  I use a 4x24 belt sander.  I stick to good sandpaper brands too.  There's a small learning curve to the belt sander so you get a flat surface and don't dig in anywhere. 

I plane my hardwood beams with my mill mounted planer.  It has straight knives so there is a subtle chatter from the mere nature of a straight blade not being in contact 100% of the time.  So for a smooth finish, need to belt sand them.

[Don P]

On that end we've also rented a floor sander and racked them up. Oh, and hired a convict to sand, a work release center was right down the road  :D.

[philoufelin]

Hi all,

With the blade well sharp, the defect disappears. But it seems that I have issue with blade heigth adjustement. I follow the instruction of this video to adjust them :
planer blade adjustement - Google Search
But, the back plate of my makita KP312 sticks throughout the pass. Should I increase the height of the knives or polish the plate so that it no longer sticks?

[doc henderson]

how does the manual say to adjust them.  I use planer blade setting tools. 

[philoufelin]

The user guide mention that the blade should be perfectly parallele to back plate. I tried and I had the same issue, it's why I adjusted a bit higher then the back plate.

[doc henderson]

I think it needs to be parallel, but not the same height.  did i misread that?  It does need to protrude but not hit the base obviously.  i.e. needs to protrude the same on each side.