Speed Testing the Granberg Grind

[mtngun]

I reground one of my 3/8" ripping chains to Granberg style, kinda, sorta, almost, and except.

Granberg does it like this, with the scoring cutters having a different top plate angle and different raker depth.

For my first test, I used a 10 degree top plate angle for all cutters, and used an FOP on all cutters. That simplified the grinder setup and ensured that all cutters would be the same length.

Speed tested on a bone dry and somewhat punky ponderosa cant, 12 1/4" wide, the same kind of cant I've used for all of my previous speed tests, and the usual 066BB & 36" bar.

However, this time, instead of timing the entire 8 foot pass, I divided it into three 24" mini-tests. I've come to prefer the 24" mini-tests because you don't have to pause to fiddle around with wedges, etc., and it seems accurate enough.

Results in chronological order: 0.69, 0.62, and 0.57 inch/sec. Average 0.63 inch/sec.

That compares to 0.62 inch/sec the last time I speed tested regular 3/8" ripping chain. In other words, no significant difference.

The saw had no problem averaging 10,000 rpm in the cut, about 500 rpm faster than it had done with regular 3/8" ripping chain.

The chain cut straight, there was no problem with it cutting crooked as Aggiewoodbutcher reported. No insult to Aggie intended, but since he is the only one who reported a problem with Granberg style chain cutting crooked, I have to suspect that his chain must have had an issue with unequal angles or unequal lengths.

To my eye, the cut was neither smoother nor rougher than regular ripping chain.

I'll regrind the scoring cutters to 25 degrees, and retest. I don't think it'll make any difference, but since I have gone this far, I might as well try it.

 

[mtngun]

OK, scoring cutters ground to 25 degree top plate angle, and FOP'd.

Clearing cutters still at 10 degrees/FOP.

In chronological order: 0.62, 0.60, 0.59 inch/sec. Average 0.60 inch/sec.

To my way of thinking, 0.60 vs. 0.63 inch/sec is not statistically significant.

Revs seemed higher this time. I tried to maintain a steady 10,000 rpm, but it was very sensitive to feed. Sometimes it "bogged" down to 9500 rpm while other times it was hitting 11,400 rpm -- and still throwing chips, which is unusual for this powerhead.

Finish still seems no better or worse than regular ripping chain.

Conclusions:
-- Granberg grind does not cut significantly faster than Woodland Pro ripping chain.

-- Granberg grind does seem to spin 500 - 1000 rpm faster than regular ripping chain.

-- In my opinion, Granberg grind offers the same benefit as skip chain -- less power is required, so the saw can spin a little faster -- without the rough finish that goes with skip.

-- I'll continue to use this particular chain, but don't plan to make any more. There's just no measurable improvement to justify the effort.

 

[wigglesworth]

Cool thread. I have seen that Granberg chain, and wondered if it was any count. Interesting how it increased the working RPM, yet the cut time stayed the same. Im assuming it's a result of the less cutters.

 

[mtngun]

I'm using the Granberg'd chain to mill a few small logs that have been taking up space around the house.

A small, very dry doug fir. The finish here seems rougher than WP ripping chain, not that it's a problem.

The heat is unbearable, so I'm not wearing PPE today. Can't wait till I get the woodshed built so I'll have a shady spot to mill and split wood.

My FastTach croaked this morning. First, the battery would pop out of its holder when I taped the tach to the saw for hands-free tuning. I'd reposition the battery, then it would promptly pop out again. Somewhere along the way part of the display died. I'll have to contact the manufacturer on Monday and see if they offer any support.

 

[john taliaferro]

90 here today i am going to the cold shower for ever . or tell i get wrinkled fingers and blue . johnt

 

[smokinj]

Filling 96 here...Great post again Mtngun.

 

[Stihlman441]

Are you for real about the heat,22 deg c that's fantastic temp 40 deg c + is unbearable.

 

[mtngun]

Are you for real about the heat,22 deg c that's fantastic temp 40 deg c + is unbearable.

I'm just giving you guys a hard time. Thought you might enjoy that.

But truly, I cannot handle the heat. I'm not used to it.

The hottest it has ever been here, since I've lived here anyway, was 85 F (30C) in the shade. That was bad.

Anytime it is over 65 F (18C) I don't feel like working outside. I have to take lots of breaks and drink lots of ice water to avoid dehydrating.

I prefer to mill in the fall when it's around 40 - 50 F (5 - 10 C).

I'll have another pic or two later. The Granberg grind is leaving a rough finish on doug fir. I guess it just depends on the species of wood, the powerhead, etc., but I'm not impressed with it.

 

[mtngun]

Doug fir cut with the Granberg'd chain. These are about 14" wide. Some roughness, but not enough to complain about. As the chain got duller, the finish became smoother (left to right).

Milling at home. The construction site in the background will become the woodshed/barn.

After 1 hour of run time, the Granberg'd chain had slowed down noticeably. I should have swapped it out, but instead I filed it on the Alaskan, which didn't help much. Nonetheless, I ran it for the rest of the day, ending up with 11 doug fir slabs.

 

[BIG JAKE]

Good test-I don't believe I'd have ever bought any anyway. It's a grind that is over complex. If it yielded significant gains in either finish or speed that'd be one thing but that is not the case it seems. Still, it's always best to test an idea-the proof's in the puddin'!

 

[BobL]

Re: . . . . . .. As the chain got duller, the finish became smoother (left to right)."

Certain chain cutting speeds can synchronize with the cutting width and may produce a rougher finish than for a different width. As the chain gets duller the chain speed drops and the chain and cut width drop out of synchronicity so the finish gets smoother.

If this happens again try angling the bar to change the cutting width and you should get a smother cut. The bar has to be angled a long way to achieve this.