Minimizing Tearout on an Old Crescent Planer

Advice on tuning and sharpening tweaks to reduce tearout on an older crescent planer. March 13, 2009

We are experiencing excessive tearout after setting up our older crescent 24" 4-knife planer with new blades. Especially with maple (not figured) but also with white pine. This is our first time setting up this machine. We have newly sharpened blades and lowered the feed rollers on the table down from where they were (1/8 inch high for rough lumber feeding I assume). I have tried adjusting the chip breaker down but found no improvements.

Forum Responses
(Solid Wood Machining Forum)
From contributor H:
Your knives may be projecting too far. The grind on your knives may be incorrect.

From contributor L:
I have an 18" Crescent pony planer. Those are the two woods that I have always had trouble with. I allow more thickness for the widebelt. Maybe they are difficult wood for all planers? Who makes a helical for these?

From contributor B:
There are manuals available on the link below. I agree the knife projection could be the problem. Set it up per the manual and the problem should mostly go away.

From contributor R:
Could be that the angle of the knives in the head are set for softwood. I had the exact same result when buying a Yates American out of a school shop. I found out that I could have a front grind put on the knives to change the effective cutting angle for hardwood, I think the front grind is at 10 degrees and about an eight inch flat.

From contributor R:
You may be interested in this.

Front Bevel

From contributor L:
It seems that I had asked my sharpening service about this. I believe there was a general grind that they recommend for all woods. I have been putting off going over the planer and insuring the set-up was correct. I did this some time ago. I had bought an original manual from the machine shop that owned the Crescent rights.

Becoming more and more production oriented, I had left the planer on a faster feed rate. I had forgot about this. I slowed the feed rate down to about 15 fpm and took a lighter cut. The finish was a lot better (even on pine). The time element was terrible though.

I like to join rough stock for door panels, then plane and cut to size. This leaves plenty to thickness. I could order lumber 15/16 thick . This could work. I should plane the first two passes on the fastest feed rate. Then slow the planer down to produce a better surface for beginning sanding. I have had a problem with feeding rough stock. The bed rolls are about 1/32". The rolls are not quick adjusting. I have heard of raising the bed rolls to 1/16 to 1/8" for rough planing and using a quick removable platen that can be added to bring the bed to an appropriate height between, in front of and behind the bed rolls.

From contributor R:
Adjusting the bed rolls is only needed if the stock is not flat. Higher bed rolls will let stock that has a cup or bow, stay on the rolls and not contact the bed. A few thousandths will work as good as an eighth if the stock is really flat. Bed rolls will not affect the quality of the cut with the exception of the amount of snipe at the beginning and the end.

From contributor S:
So I read the manual and had to lower the chip breaker, pressure bar, and top rollers after lowering the bottom feed rollers. I also had the original knives sharpened and put them back in the head deep enough to leave a 4 1/2" cutting circle as per manual. I am getting a much better finish cut, and I think my next step would be to address the knife angle or front bevel idea to get a better cut on maple (which we use a lot of here in northern MI). Now if I can just get my phase converter to keep running without blowing fuses.

From contributor L:
I have used a phase converter all my woodworking life. I use a starting circuit on larger motors, 15 HP and up, on each machine. Otherwise, I would run out of amps. I have a rotary converter for most of the shop, 7.5HP and smaller motors. Itís turned off when I run the larger motors on some machines.