3120 vs 395 cutting speed

[xpuser]

Have any of you ever done a test between the 3120 and 395 on your CSM to see the difference in cutting speed between them on the same size log with the same size bar and chain. If not can someone tell me how many feet or inches per minute you average on a 20" - 24" log with either saw. I am new to this site so if this information is already on here please direct me to it. Thanks for your help and I enjoy reading all the information you all share on this site.

 

[mtngun]

All my speed data can be found by searching for "inch/sec."

I don't recall any 90cc vs. 120cc shootouts. Normally a 120cc saw is used to run a longer bar, not to gain speed on small logs.

 

[gemniii]

All my speed data can be found by searching for "inch/sec."

I don't recall any 90cc vs. 120cc shootouts. Normally a 120cc saw is used to run a longer bar, not to gain speed on small logs.

And here are some gleanings from a few. Sometimes you have to look in prior posts for the saw.

Here are the speeds for injecta-sharp with the half sharpened/half dull 25 degree top plate, all in doug fir:

slab #1, 15" - 16" width including bark, 0.4 inch/sec.

slab #6, 15" - 16" width including bark, 0.3 inch/sec (slowing as it dulls)

slab #10, 10 1/4" cant, 0.57 inch/sec

By slab #10, it felt like it was cutting slower, and the RPM's were only 7500 - 8000 most of the time. Also, the chain tension was getting a little sloppy.

I decided to take the injecta-sharp off and install a freshly sharpened WP lo-pro ripping chain. Here's how it cut on the same cant:

slab #11, 10 1/4" cant, 0.85" inch/sec.

-- mini speed test during pass #9, 14" wide including bark, 0.54" inch/sec.

-- speed test during pass #13, 14" wide, 0.36" inch/sec. Definitely sloooowing down.

-- speed test on the final pass #16, 10" wide, 0.55" inch/sec.

-- RPM's with sharp chain were typically 8000 - 9000, dropping to 7000 - 8000 toward the end of the day, as the chain dulled.

Statistics:

-- 2.2 hours CSM run time.

-- swapped chain after finishing first log (6 slabs).

-- seemed happiest and cut fastest at 8500 - 9000 rpm, yet I had a tendency to lug it as low as 7000 rpm. It takes a delicate touch to maintain the higher rpms, though it never actually bogged.

-- mini speed test, pass #3, 16" wide, 0.42 inch/sec.

-- speed test, pass #3 on another fresh chain, 16" wide, 0.29 inch/sec. Slower than previous test because the aux oiler needle valve had plugged, and I didn't notice until the test was over. The aux oiler makes a difference ! ! !

-- speed test, pass #5, 17 1/2" wide, 0.25 inch/sec. Sloooow.

Statistics:

-- 2.2 hours CSM run time.

-- swapped chain after finishing first log (6 slabs).

-- seemed happiest and cut fastest at 8500 - 9000 rpm, yet I had a tendency to lug it as low as 7000 rpm. It takes a delicate touch to maintain the higher rpms, though it never actually bogged.

-- mini speed test, pass #3, 16" wide, 0.42 inch/sec.

-- speed test, pass #3 on another fresh chain, 16" wide, 0.29 inch/sec. Slower than previous test because the aux oiler needle valve had plugged, and I didn't notice until the test was over. The aux oiler makes a difference ! ! !

-- speed test, pass #5, 17 1/2" wide, 0.25 inch/sec. Sloooow.

I haven't kept track, but let's say 6 cords.

BTW, the slabs may get used for barn siding. If not, they'll end up as firewood.

Some data, in chronological order:

-- lo-pro pass #3, 15 1/4" wide, 0.39 inch/sec.

-- lo-pro pass #4, 14" wide, 0.46 inch/sec.

-- lo-pro taken off after 0.9 hours, injecta-sharp installed

-- injecta-sharp pass #2, 13" wide, 0.37 inch/sec.

-- total 1.8 hours run time on 066.

-- about 1 1/2 gallons fuel and 1 gallon bar oil.

The 066 felt like it was running a little slow today, and the speed tests bear that out. During the last couple of passes, it was intermittently stumbling. It'll need a good checking out before heading to the woods again.

I've been using an FOP on the rakers lately, and as with the 3/8" FOP, the lo-pro FOP is a little too aggressive for this powerhead. Revs are not as high as I think they should be. I'm not sure what the solution is, but I'll stop filing the rakers for a while.

I haven't kept track, but let's say 6 cords.

BTW, the slabs may get used for barn siding. If not, they'll end up as firewood.

Some data, in chronological order:

-- lo-pro pass #3, 15 1/4" wide, 0.39 inch/sec.

-- lo-pro pass #4, 14" wide, 0.46 inch/sec.

-- lo-pro taken off after 0.9 hours, injecta-sharp installed

-- injecta-sharp pass #2, 13" wide, 0.37 inch/sec.

-- total 1.8 hours run time on 066.

-- about 1 1/2 gallons fuel and 1 gallon bar oil.

Total haul was 8 boards and two 8x8 posts, plus firewood and slabs.
The thinned 3/8" nose sprocket continues to work well and spin freely.

Once again, the injecta-sharp lo-pro ran for an hour before it slowed enough to warrant changing. A total of 1.1 hours run time and 9 passes on the injecta-sharp.

Then I finished the day with regular lo-pro.

All together, 1.5 hours run time on the 066.

Today the saw was tuned to 12,700 WOT with the 36" B&C. Typical RPM in the cut was 8500.

As usual, it seemed to cut fastest around 8500 - 9500 RPM, but human nature wants to push the saw as fast as it will let you push it, so I often found myself lugging it down to 7000 RPM. At least this top end is not fussy about RPMs.

Mini speed tests, minus the forgotten auxiliary oiler:

injecta-sharp pass #2, 13" wide, 0.44 inch/sec. Seems too slow, perhaps I wrote down the wrong number, but I have to go with what I got.

injecta-sharp pass #3, 15" wide, 0.36 inch/sec.

injecta-sharp pass #8, 13" wide, 0.46 inch/sec. By this time the chain was getting dull, yet the cut speed was faster than pass #2, which is why pass #2 doesn't seem right.

lo-pro pass #1, 13" wide, 0.62 inch/sec.

e woods ported 81 cc saw

Here's the speed test data.

pass #2, GB'd 33RP, 22" wide, 0.182" inch/sec. Did I mention it was sloooooow ?

pass #2, GB'd 33RP, 22" wide, 0.178" inch/sec.

pass #3, GB'd 33RP, 24" wide, 0.146" inch/sec. Like watching a glacier melt.

pass #1, 33RP, 20" wide, 0.245" inch/sec.

pas #1, 33RP, 22" wide, 0.195" inch/sec. This glacier was melting slightly faster than the GB'd glacier.

Here's the speed test data:

Chain #1 (GB'd 7.7 deg)
-- @ 0.6 hours, 12" wide, 0.39 inch/sec

-- @ 0.7 hours, 12 1/4" wide, 0.39 inch/sec

Chain #2 (33RP 8.7 deg)
-- @ 0 hours, 13 1/4" wide, 0.29 inch/sec

-- @ 0.1 hours, 13 1/2" wide, 0.28 inch/sec

Chain #3 (33RP 6.6 deg)
-- @ 0 hours, 12 1/4" wide, 0.38 inch/sec

It's hard to make direct comparison because the widths were different, but the stale GB'd chain was cutting just as fast as the fresh 6.6 deg chain in similar widths.

All the speeds are pitifully slow compared to lo-pro.

All the speeds are much slower than the 066 did in a 12 1/4" pine cant, even though the Oly felt strong and had no trouble maintaining 9000+ RPM. I'm puzzled as to how the Oly spins the chain just as fast as the 066, yet the cutting speed is slower ?

Four different chains were used, and this is what we'll call them.

chain #1 -- 33RP with 6 degree raker angle
chain #2 -- 33RP with 7.5 degree raker angle
GB'd -- 33RP modified to GB style, 5 - 6 degree on regular cutters, more on scoring cutters.
virgin 33RP -- I will measure and post the virgin geometry later.

The hours referred to in the results is the run time on that particular chain at the time of the speed test.

chain #1, 0.7 hours, 15", 0.30 inch/sec
chain #2, 0.1 hours, 15.5", 0.32 inch/sec
GB'd, 0.1 hours, 16.5", 0.33 inch/sec, 9500 rpm
GB'd, 0.5 hours, 16", 0.233 inch/sec, getting dull after only 1/2 hour.
GB'd, filed, 17", 0.185 inch/sec, my filing in the field sucks.
virgin 33RP, 0.1 hour, 17.5", 0.375 inch/sec
virgin 33RP, 0.6 hour, 19.5" 0.286 inch/sec.

I think there's one more test hiding somewhere, maybe it'll turn up when I edge the boards.

Chains #1 and #2 liked to spin at 9000 - 9400 rpm.

GB'd liked to spin at 9500 - 10,000 rpm.

Virgin 33RP liked to spin at 8800 - 9200 rpm.

Virgin 33RP was by far the easiest chain to bog, and it spun the slowest. It was obviously taking bigger bites than the other chains. It wasn't excessively boggy, I'd say it was "just right" for this powerhead. The other chains could stand to be slightly more aggressive.

GB'd dulled the fastest. On a previous day in the woods, I noted that GB'd had dulled the slowest, so I'm not drawing any firm conclusions based on a single experience. The tree fell in some bare dirt, and some dirt got embedded in the bark -- dirty bark will dull a chain instantly.

Chain #1 was swapped after 1.4 hours.

Chain #2 was swapped after 0.8 hours

GB'd was filed after 0.7 hours, and swapped after 1 hour.

The virgin 33RP had logged 0.9 hours when I called it a day. It had perhaps one more decent pass left in it.

The winner of this shootout was clearly virgin 33RP. Even though it was not particularly sharp -- you can often see glint on the cutters of new WP chain -- it took big bites and cut fast.

I don't understand why virgin 33RP, with its lame raker angle and glinty cutters, was actually more aggressive than my experimental chains. There must be something different about the geometry of virgin chain, something besides the raker angle. I will study the virgin chain very carefully and try to figure it out.

It's like gleaning from the forest floor.

 

[BobL]

Have any of you ever done a test between the 3120 and 395 on your CSM to see the difference in cutting speed between them on the same size log with the same size bar and chain. If not can someone tell me how many feet or inches per minute you average on a 20" - 24" log with either saw. I am new to this site so if this information is already on here please direct me to it. Thanks for your help and I enjoy reading all the information you all share on this site.

This might sound like a fair test but it does not take advantage of the best cutting features of either saw.

Any test will in the first instance also depend on the hardness of the wood.

Let's stick with your test first (same 20 - 24" width, and same chain).
In really soft wood I would expect the 395 to outcut the 3120. This is because the 395 should still be able to maintain a slightly higher chain speed in this width of cut.

As the wood gets harder there won't be much difference between the two saws as the 395 chain speed will drop while the extra torque of the 3120 will keep cutting.

However, if the 3120 is run with lower rakers than usual it will cut more wood and should keep up and and maybe even out cut the 395. Using that chain on a 395 will just bog it down and it my not even cut.

In wood smaller than 20" there is a limit that the rakers can be dropped so the 395 will once again have the advantage due to it's higher chain speed. Over ~30" the 3120 will have the edge.

So what you thought was a fair test does not take advantage of the ability of the 395s chain speed or the 3120s torque and to optimize the cutting speed for either requires a different chain.

If you are only going to be cutting 20-24" wood I would stick with the 395 for other reasons, eg lower fuel consumption and less weight, but it can still mill 36" log if you needed it too. If you are venturing consistently above 30" then the 3120 would be the way to go.

 

[mikeb1079]

i agree with bob l. one of my early misconceptions about chainsaw milling was that a bigger saw would always be faster. i have both an 066 (92 cc) and an 075 (111 cc) saw, which are basically the stihl equivalent of the 395 and 3120. up to about 20" or therebouts the smaller saw is actually faster due to the higher chain speed. over 20" the bigger saw catches up and eventually beats the 066. so in my experience, the biggest saws really only shine in large hardwoods. as for the inches/second times i've never actually kept track. some days it seems like i'm flying and some days like a old truck chugging up a steeeep hill.

 

[xpuser]

Thanks for your replies you have helped in my decision on which saw to buy. I did not mind spending the extra money for the 3120 if it was going to make a big difference in how fast I was able to cut, but since 90% of my logs will be in the 20" to 24" range with only an occasional 30" to 36" I thank I will go with the 395.

 

[BobL]

Thanks for your replies you have helped in my decision on which saw to buy. I did not mind spending the extra money for the 3120 if it was going to make a big difference in how fast I was able to cut, but since 90% of my logs will be in the 20" to 24" range with only an occasional 30" to 36" I thank I will go with the 395.

Good decision.

BTW, unless you are peeling off a lot of 5/4 thick boards from a narrowish, long cant the speed of milling is not usually the limiting step in CS milling. The time needed for setup, sharpening (or chain changing) and managing larger pieces won't go any faster no matter how fast the saw is.

 

[TSRuff]

Thanks for your replies you have helped in my decision on which saw to buy. I did not mind spending the extra money for the 3120 if it was going to make a big difference in how fast I was able to cut, but since 90% of my logs will be in the 20" to 24" range with only an occasional 30" to 36" I thank I will go with the 395.

Bob beat me to the punch here, but there are so many variables that go into how fast each saw will cut in a specific situation that it is almost impossible to say which one is "faster". I took the route of looking at what situation I will be milling in most often, much as you did, and chose the 3120 as I am usually in 30" white oak or 24" black ash, and that definitely is helped by having a 120cc saw.

When I am milling things up to about 18" my 372 is faster than the 3120, but in a 36" oak it is about 1/2 the speed.

The way I look at it thought, I love big saws, and either one is a great choice. You can make people with Wild Things quiver in fear !!!

 

[xpuser]

Thanks again, your experience saves allot of money and time for us that are just getting started. Thank you for your time.

 

[mtngun]

up to about 20" or therebouts the smaller saw is actually faster due to the higher chain speed. over 20" the bigger saw catches up and eventually beats the 066.

If both saws are spinning at 9500 rpm in the cut, why is there a difference in chain speed ?

If anything, the bigger saw should be able to run an 8 pin rim, moving the chain even faster.

Or else the bigger saw should be able to run more aggressive rakers, and take bigger bites.

The bottom line is, I haven't seen a 90cc vs. 120cc shootout, and if someone were to attempt a shootout, seems to me quite a bit of tweaking of rims and chains would be required.

 

[BobL]

If both saws are spinning at 9500 rpm in the cut, why is there a difference in chain speed ?

I check the specs - Mtngun is almost 100% right.

A 3120 has max power at 9000 rpm and is coil limited to 9500 rpm. Running a 3120 with it constantly bouncing off the rev limiter won't see it developing much power so it's best to sit it at 9000. The 395 runs develops its max power at 9600 rpm and while it can spin a couple of thou RPM higher that this , it ain't happening in 20"+ wide wood.

If the both use a 7 pin 3/8 sprocket the chain speed for the 3120 will be 66 ft/s and the 395 will be 70 ft/s. The 395 has the edge.
BUT
Running a 3/8 8 pin on the 3120 will give a CS speed of 75 ft/s. Although the applied power loss at the bar will be 14% less , this is more than made up for by the power adavantage of 18% for the 3120.

I'm getting a big sense of Deja Vu - Haven't we gone thru all this before somewhere????

 

[mtngun]

I'm getting a big sense of Deja Vu - Haven't we gone thru all this before somewhere????

We've talked about it, but it hasn't been tested and verified.

Prolly because most people would rather make lumber for projects rather than cants for speed tests. Still, inquiring minds would like to know ..... ? ? ?

Another issue is that, even if a 120cc saw doesn't cut faster, it doesn't have to work as hard, and should last longer.

Then again, you can rebuild 3 or 4 90cc top ends for what it costs to rebuild one 120cc top end.

Or another way of looking at it is, if you can afford a new 120cc saw, you can probably afford a used bandmill, so why muck around with a CSM, unless you need to mill monster logs ?

Personally, I think used powerheads are the only way to go on a CSM, so I'd go with whatever used bargain I could find, as long as it would do the job and parts were available.

 

[huskyhank]

The 3120 is a better milling saw than a 395 in proportion to its displacement. So the 395 is a "10" and the 3120 is a "12".

I base this on having asked the same questions earlier this year and finding the answer from experience. I have a great old 2100 and its a really good saw for milling. But I bought a 3120 and its just better. The 3120 is heavier and it uses a bit more gas, but its just better. It is simply more powerful. I have 2 of them now, one new one I got a super deal on and a used one thats about 7-8 years old with the 11,500 limit. The old saw was better than the new one until I "de-limited" the new one. Now they are pretty much equal. Super torquey and very powerful. I might want to sell my old 3120. Let me know if you are interested.

The limiter is aggravating when using the 3120 as a regular saw. If its not under a good load the constant limiter bouncing is noticeable. In milling though, keep it just off the limiter by how you feed the saw and its not that big a a problem. And this can be changed if you want to use the saw for other uses.

Mtngun is right - you can run an 8 pin on the 3120 where you might not on the 395 and the 3120 and will cut faster in same size wood.

A 3120 with a 32" bar, 8 pin sprocket and a 36" Alaskan mill will be very hard to beat for milling 24" wood. And its really nice to handle. (as CSMs go) Get a 42" bar for the bigger logs up to about 39" or so with a 36" Alaskan.

 

[BobL]

We've talked about it, but it hasn't been tested and verified.

Prolly because most people would rather make lumber for projects rather than cants for speed tests. Still, inquiring minds would like to know ..... ? ? ?

That's another small driver for me making a second big CSM mill. I would like to have two CSMs fully set up and ready to cut and be able to open up a log and then test out two different saws without having to swap them in and out of a mill.

 

[gemniii]

That's another small driver for me making a second big CSM mill. I would like to have two CSMs fully set up and ready to cut and be able to open up a log and then test out two different saws without having to swap them in and out of a mill.

But Bob, with the difference in weights of the mills how would that be possible?

 

[BobL]

But Bob, with the difference in weights of the mills how would that be possible?

Good point! . . . . I guess I could adjust the slope to account for the weight difference. or hang a few lead bricks off the BIL mill (don't laugh - I really do have some lead bricks to try this idea out)

 

[Sawyer Rob]

Good point! . . . . I guess I could adjust the slope to account for the weight difference. or hang a few lead bricks off the BIL mill (don't laugh - I really do have some lead bricks to try this idea out)

Doesn't everyone? Here's a ton of them,

Yes, there really "is" a ton of lead bricks there.

Rob

 

[mtngun]

Dang, Rob, you've got a lot of toxic waste sitting there. Tell ya what, since we are friends, I'll dispose of it for you, at no charge, if you ship it to me.

What do you do with it ? I'm a bullet caster myself, and there's no such thing as too much lead.

 

[Sawyer Rob]

Dang, Rob, you've got a lot of toxic waste sitting there. Tell ya what, since we are friends, I'll dispose of it for you, at no charge, if you ship it to me.

What do you do with it ? I'm a bullet caster myself, and there's no such thing as too much lead.

I swage and cast both... You never know when the British might try to come back! lol

Rob