Whether to Reverse Planer Blades
Short answer: Don't do it. Long answer: Take a look at spiral cutterheads or a widebelt sander. July 10, 2009
Question
When I run hardwood (maple especially) through my 16" jet planer sometimes I get boards with little tiny holes in certain areas of the board which is a pain in the neck to sand afterwards. I bought new blades but still the same problem. If i only reverse the blades, would the planer cut sort of like climb cutting? I needed to ask before I experiment. If not, how can I avoid or minimize this problem?
Forum Responses
(Cabinetmaking Forum)
From contributor A:
By turning the knives around you are simply changing the cutting angle - in a detrimental fashion.
From contributor B:
I agree with Adam – don’t reverse your knives. Have you tried taking a deeper cut? Sometimes when you take too shallow a cut the feed roller will leave marks or holes.
From contributor K:
Have you considered upgrading your planer to a spiral cutterhead? I put one in my 20" Grizzly (essentially the same planer) and the results are great. It’s a better finish and the cutter lasts much longer. It would pay for itself in sanding time before long.
From contributor P:
Those little defecst are one of two things: light tear out or dents from inadequate dust collection. I suspect it is tearout. Maple is very prone to this. Very sharp, honed knives can fix this, but not 100%. Flipping your knives will change the rake angle to negative and leave zero edge strength. This will give horrid results and break down the knives very quickly. You may be able to tweak the pressure bar a bit, that may help depending on the machine.
From contributor T:
I agree with contributor K, the spiral does a great job on maple, little if any tearout. The other thing you can try is to dampen with a sponge. I don't like to do it with rust and all, but it may help.
From contributor Z:
First off you have to be a little off tilt to even attempt that. Second it won't be like a climb cut because the head is still rotating in the wrong direction. Try to imagine putting a blade in your table saw backwards and feeding it. Your problem is a combination or poor dust collection and dull spots on your blades.
From the original questioner:
Where can I get a spiral head? Do they carry these for jointers as well?
From contributor T:
Mine is a Byrd, I ordered it from Grizzly as I recall. Keep your tables waxed, or use something like topcoat on them so your material slides freely, that can help too.
From contributor K:
Sometimes you can also flip the board around and run the other end first. A change in grain direction will sometimes help.
From contributor A:
I also have 20" grizzly. Do you know which spiral head you got? I have 12" grizzly jointer with spiral and it is fantastic. They show two spiral heads in catalog for planers. I was in another shop and his grizzly planer had a spiral head and left lines 1/2" apart along entire length of board. My jointer does not leave those lines.
From contributor S:
This has come up before but given the current economic climate and the downward movement in machine prices these last year’s why not get a simple widebelt to take care of the tearout? A spiral head is only going to give you a tear out free planed finish that still needs to be sanded and might need to be sanded more because of steps. A widebelt will greatly increase your yield where there are reversals in the grain that no head can handle. Even if your budget is limited the majority of expense in widebelts is anti-dubbing (for veneer sanding) and width. Older sanders did not have anti dubbing and narrow width sanders are fine for sanding solid wood. No spiral head can flush door joints so you are way further ahead with a widebelt.
From contributor G:
The cutting angle of most small planers is a little low for most hardwoods and probably a little high for most softwoods. One thing you can do that helps is use a diamond stone on the back of the blades and hold it up about 5 degrees and change the cutting angle a little towards scrapping. This will use more horse power and generate more heat but does help with the tearout. Of course the thickness sander is the ultimate fix and the spiral blades next best. Do not reverse the blades in the head.
