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+-- Thread: Hollow ground planer knife angle? (/showthread.php?tid=7350488)
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Hollow ground planer knife angle? - Pirate - 09-26-2019
Got an extra set of knives with the Parks planer, I just bought.
They are hollow ground, with no micro bevel.
Should there be a micro bevel? And if so what angle, and how wide should it be?
Thanks for any info
RE: Hollow ground planer knife angle? - EdL - 09-26-2019
When I used to run knifed planer heads, none ever had a micro bevel.......
Ed
RE: Hollow ground planer knife angle? - fredhargis - 09-27-2019
It's not something that's usually done, I'd skip it.
RE: Hollow ground planer knife angle? - Admiral - 09-27-2019
(09-26-2019, 06:05 PM)Pirate Wrote: Should there be a micro bevel?
I've never heard of this, seems like gilding a lilly to me, and it would likely not make much difference.
RE: Hollow ground planer knife angle? - jteneyck - 09-27-2019
(09-26-2019, 06:05 PM)Pirate Wrote: Got an extra set of knives with the Parks planer, I just bought.
They are hollow ground, with no micro bevel.
Should there be a micro bevel? And if so what angle, and how wide should it be?
Thanks for any info
Whether or not you add a micro-bevel, the angle needs to be what the manufacturer specifies where the knife hits the wood. If the knife as it now is is at the correct angle adding a micro-bevel will cause the heal of the micro-bevel to compress the wood behind where the point is cutting. The resultant compression marks are darned hard to sand out.
John
RE: Hollow ground planer knife angle? - Pirate - 09-27-2019
Parks manual doesn't mention knife angle.
I've read 40 - 50 degrees.
Problem is. The hollow ground edge measures 35 degrees, across the edge. But with the hollow grind, the actual angle at the edge must be 30 degrees or less.
I've heard with a hollow grind and micro bevel, it's easier to hone knives in place, because the edge is narrower, than a flat grind.
RE: Hollow ground planer knife angle? - Pirate - 09-27-2019
Just checked knives in the machine. Had to use a 30x pocket microscope to see it! They have a micro bevel.
Now just need to find micro bevel angle.
RE: Hollow ground planer knife angle? - jteneyck - 09-27-2019
(09-27-2019, 11:51 AM)Pirate Wrote: Parks manual doesn't mention knife angle.
I've read 40 - 50 degrees.
Problem is. The hollow ground edge measures 35 degrees, across the edge. But with the hollow grind, the actual angle at the edge must be 30 degrees or less.
I've heard with a hollow grind and micro bevel, it's easier to hone knives in place, because the edge is narrower, than a flat grind.
I think that's far too wide a range. I had a planer that required a 45 deg bevel, another at the same time that was 42 deg. I once forgot and sharpened both sets at 42 deg. The one that required 45 deg planed poorly and left those compression marks I described earlier.
If you go to OWWM.org someone can point you to the manual for that machine if you don't have one.
The problem with the micro bevel approach is once you hit a nail, staple, or piece of dirt you have to grind the knife back more than had it not had the micro bevel, so you will get less sharpenings out of a set of blades if you put a micro bevel on them each time. My observations showed no improvement in cut quality.
John
RE: Hollow ground planer knife angle? - Pirate - 09-27-2019
Are you talking about a flat ground knife with and without a micro bevel, or the same with a hollow ground knife?
With the hollow grind, I don't think an edge with less than 30 degrees would last long.
The knives in the machine, hollow grind and micro bevel, are still very sharp.
RE: Hollow ground planer knife angle? - Timberwolf - 10-01-2019
(09-26-2019, 06:05 PM)Pirate Wrote: Got an extra set of knives with the Parks planer, I just bought.....................
They are hollow ground, with no micro bevel.
Should there be a micro bevel? And if so what angle, and how wide should it be?
Thanks for any info
A micro bevel has the effect of "blunting" the edge while making it stronger...Edges get more "blunt" are they are used...No point in starting out with a blunt edge..let nature take it's course...
