Chain mill pico bar modification, pico spur question

Hello
I'm new to the site but not new to milling. Been running a homemade Logosol style mill with smaller saws and standard chain for a while but finally picked up an old Stihl 066 I'm working on getting up and running with a 3/8 .050 bar and picco chain. Apparently Baileys is the only distributor of Logosol bars in the US. I called Baileys last week and tried to order a 20" 3/8 pico bar but the rep said it would be 3 weeks. He sold me a carlton 20" 3/8 .050 bar and some 63PMX chain and said it would work fine. He also told me I did not need a pico spur as my standard 3/8 rim would work. He claimed to be in the business for 50 years and knows milling. Anyway, I got the bar and chain and it is obvious the chain does not ride properly on the sprocket tip of the bar. The .050 strap gap on the chain is too narrow for the .062 sprocket teeth on the bar so the chain rides way out on the tip and does not come anywhere close to the tip rails. The bar groove is perfect. I do not understand why there is a .062 sprocket tip on a .050 bar.

Question is since logosol bars are so hard to come by, has anyone ever tried modifying a standard 3/8 .050 bar by filing down the width of the sprocket teeth to accept PMX chain? Too late, I already did and looks like it will work fine, but I am wondering if anyone else has done the same? What is your experience? I know 3/8 pico is a little light weight for milling, but I'm really attracted to the narrower kerf and faster cut speed.

Also, what is the general consensus regarding using standard 3/8 rim sprockets vs the 3/8 pico spur drum recommended by logosol?

Thank you...
Troy
Redding, CA

Standard 3/8 rim is different than 3/8 picco. It works(kinda) but I would not run it on a mill. I can not believe some one from Baileys would say it works fine, seams like a lot of liability , just to make a sale?

I know it is not the same, but when I did the swap over to the 63PMX chain, I wanted to order a Logosol bar, but was told the same thing. I went on their recommendations and used a new 3/8" rim, on a std .050x3/8" Oregon powermatch bar, and have milled about 2000 bd ft with the setup so far, and I am not worried at all about the minor mismatch, Using a new rim, the chain and rim run together after a short run it, and a few chain adjustments (typical of new chain). The chain ride on the sprocket tip, is Ok so far, I have not noticed any premature wear on the chain, and the sprocket tip will just reshape over time. The chain has no tendencies to jump off, and I have had zero issues with it since the change over. I understand the liability issue, I am just giving you a report of what i have done, and that it works for me, I will continue to march on. I really like the feed rate increase of the picco chain over the 3/8" chain I had on it before the swap. Good luck with your swap. If you go teh Logosol bar route, it definitely is the best way to go, but from what I understand, though the bar tip is replaceable, new tips are like hens teeth as well, so if you are going to wait anyway for a special order to fill, I woiuld order an extra sprocket tip at the same time, so you arent dead in the water when it comes time to replace the tip.

Welcome to A.S.! (Oooops! - just realized that you have been a member for a while - just have not posted before. Change that to, "Congratulations on your first post!")

Heres a thread related to your question - might find something interesting or helpful:

http://www.arboristsite.com/milling-saw-mills/121746.htm

Philbert

Philbert

That was an exhaustive thread but quite informative however I am still unclear if its ok to use a standard oregon 3/8-8 ring sprocket with 63 PMX. I think what I got from it all was the bar sprocket tip may have been what has caused mtgun all the driver peening problems. That understood, I think I have done the right thing by filing my sprocket tip teeth narrower to accept the picco chain right? As far as the drive sprocket, I have ordered an oregon rim and drum set 3/8-8 for my 066. Hopefully there will be no issues with peening the chain. I do have a used .404-7 rim I could turn down though. And apparently Danzco may still sell picco rims for the 066! I think I will call them to be sure. Thank you everybody for your input. Any additional input also welcome. I wont be doing a lot of milling, but I like to be geared up in case I get the urge and have a need.

troy

I would encourage you to reach out to the guys in that thread and discuss it directly with them. They have the experience with this, and might also have some updated information, especially as it relates to milling.

Philbert

austringer said:

Question is since logosol bars are so hard to come by, has anyone ever tried modifying a standard 3/8 .050 bar by filing down the width of the sprocket teeth to accept PMX chain? Too late, I already did and looks like it will work fine, but I am wondering if anyone else has done the same? What is your experience? I know 3/8 pico is a little light weight for milling, but I'm really attracted to the narrower kerf and faster cut speed.

Also, what is the general consensus regarding using standard 3/8 rim sprockets vs the 3/8 pico spur drum recommended by logosol?

Click to expand...

I thin the sprocket nose teeth to fit lo-pro and it works fine.

When I tried running lo-pro with a 3/8 rim, it peened the drive links within minutes. Other people claim they run a 3/8 rim with no issues, so go figure.

Mtngun

I have already thinned my sprocket tip as implied earlier, however I still have the drive sprocket to deal with. Although I'm sure some may have had success with running a standard 3/8x8 rim, I'm sure there is a reason Logosol sells the special 3/8 picco spur. In some of your other posts, you said you turned down "A 7 pin 404 starts out at 1.521" OD and gets turned down to 1.435", a 0.086" reduction", but you also mention a turned down 404 x 8 rim. I did not see the turned dimensions of the 8 pin rim. Of the two turned down 404 rims, do you have a preference? I have a 7 pin I could turn.

Thanks
Troy

If the chain is sharpened correctly (with aggressive rakers) the saw will work hard to pull a 7 pin. I've yet to find a use for an 8 pin.

Perfect and thank you. Looks like I will try turning my 404 x 7 to the dimensions you quoted in the other thread. Playing with the picco chain on the stock rim, it makes sense to turn it down. Im still waiting for more saw parts. Probably get to milling in a week or two.

Troy

austringer said:

... I'm really attracted to the narrower kerf and faster cut speed.

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To be honest, the kerf of a 3/8" Picco chain is not that much narrower than an ordinary 3/8", probably about 0.02".

Another issue is the chainsaw sprocket. Stihl does make a (spur) sprocket for 3/8" Picco for the MS 660 (Stihl P/N 1122/06, see picture), but the standard 3/8" sprocket works quite well. This is not true the other way around, i.e. a 3/8" chain will ride high on a 3/8" Picco sprocket.

View attachment 297179

I am milling everything below 15-20" diameter using a 25" Stihl hard-nose ("DUROMATIC") bar and a 3/8"/.050" picco chain on an Alaskan and Mini mill, which works very well. Stihl P/N 3003 000 5531. Don't know if it's available in the US.

View attachment 297180

Happy milling

mortenh said:

To be honest, the kerf of a 3/8" Picco chain is not that much narrower than an ordinary 3/8", probably about 0.02".

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I've measure it on a number of occasions and it's 0.05" (detailed discussion here).
It does not sound like much but it means fewer fibres that the saw needs to cut through.

As Mtngun puts it.

So either way, the LP kerf is about 15% smaller. I'll buy that. Thanks for the data.

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BobL said:

I've measure it on a number of occasions and it's 0.05" (detailed discussion here).
It does not sound like much but it means fewer fibres that the saw needs to cut through.

As Mtngun puts it.

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My bad.

I was looking for the link you provided but couldn't find it.

So you are right. It's about 0.05" (13%) narrower kerf. But I'd still claim that it's not enough justification in itself to use a low profile (Picco) chain for milling.

mortenh said:

So you are right. It's about 0.05" (13%) narrower kerf. But I'd still claim that it's not enough justification in itself to use a low profile (Picco) chain for milling.

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My tests in a cant showed that lo-pro cut 15% - 25% faster than 3/8. I'll take a 25% speed increase any day.

the standard 3/8" sprocket works quite well.

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A 3/8 rim peened the drive links in just a few seconds on my setup. Your mileage may vary.

mortenh said:

My bad.

I was looking for the link you provided but couldn't find it.

Click to expand...

Click on the "here" in my post

So you are right. It's about 0.05" (13%) narrower kerf. But I'd still claim that it's not enough justification in itself to use a low profile (Picco) chain for milling.

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If you could boost the HP of your saw by 13% by changing the bar and chain and sprockets would you do it?

BobL said:

Click on the "here" in my post

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I know that. What I meant to say was that I couldn't find it UNTIL you posted a link to it.

BobL said:

If you could boost the HP of your saw by 13% by changing the bar and chain and sprockets would you do it?

Click to expand...

Comparing Apples and Pears!

If you are cutting 2" wide slabs, you are wasting 0.05"/2" = 2% less material out of your timber.

And as I said, I AM using a 3/8" LP bar/chain. But if I wasn't I wouldn't be rushing out and investing in new bars and chains.

With regards to cutting speed, I have not experienced any great difference in cutting speed between 3/8" and 3/8" LP setups. I reckon the speed is more dependent on having a sharp chain than anything else.

mortenh said:

. . .I AM using a 3/8" LP bar/chain. . .

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A fussy point, which may be interest to some (it's A.S., right?) . . .

I was once talking to an Oregon rep about low profile chain, and it was clear that we were not communicating clearly. Finally he said, "OH! You mean Low Profile chain!" Turns out that they make a version of their full-sized 3/8 inch pitch, round ground-full chisel chain that is designated 'LP', or 'LPX'. "3/8 LP" meant that chain to him. Never occured to me.

Anyway, if you are talking about running non-standard combinations (low pro/'Picco' on standard 3/8 sprockets, turning down .404 sprockets to fit low profile chain, etc.), it may be helpful to know that this is another point where some people might get confused with what you are describing, or where you could end up with the wrong thing.

Philbert

mortenh said:

Comparing Apples and Pears!

Click to expand...

Not really - cutting 13% less fibres every second means 13% less backload so there is in effect 13% spare power

If you are cutting 2" wide slabs, you are wasting 0.05"/2" = 2% less material out of your timber.

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Sure but that is not why most people are doing it.

I haven't done this on my big bars and powerbeads because the LP stuff seems to stretch too much but if folks are setting up a small to medium size alaskan from scratch I think its worth doing.

mortenh said:

With regards to cutting speed, I have not experienced any great difference in cutting speed between 3/8" and 3/8" LP setups. I reckon the speed is more dependent on having a sharp chain than anything else.

Click to expand...

Maybe you need to work on your sharpening technique ?

Wow, I thought ya-all were just a bunch of average woodcutters. I didn't realize I was getting help from millers with aptitude exceeding the average educated engineer! Quite the technical discussion...

In hindsight I'm sure it would have been much easier, cheaper and more versatile for me to stick with standard 3/8 chain ground to 10*, but since I bought the 3/8 picco chain already, and thinned the sprocket tip on my bar, I felt the need to research the proper drive sprocket. Although many have stated they have run a standard 3/8x7 rim with picco chain, I decided to experiment per mtnguns recommendation. What I found is my new picco chain tightly wrapped around the new oregon 3/8x7 standard rim tended to rise out of the drive slots when turned by hand. It did not appear to be a good fit. However, the 404x7 rim turned to 1.435" fit perfectly with little to no movement. Also, the chain driver tips aligned perfectly the entire circumference of the inner clean-out holes in the rim. Of course this does not mean it will work better as I have yet to run it on the saw, but the turned 404 rim is the obvious choice at this point.

Interesting note for those who wish to try is I was able to easily turn the 404 rim without a lathe to what I believe to be quite accurate tolerances. I should have taken a picture, but anyway I slid the rim onto a 12" piece of 7/8" solid round stock, shimmed the difference with beer can shims (appears to be about .005 dif between the inner dia of the rim and the round stock od), taped the rim tightly to the center or the round stock, laid the round stock between a couple homemade vee blocks and used a sander mounted on an angle grinder to do the milling. I was able to tightly brace the grinder on the bench to ensure accurate positioning while the slight offset of the wheel caused the rim to turn very slowly which provided for a perfect finish on the outer diameter of the rim. Considering it is hardened steel, I couldn't have done it any better on any metal lathe I have ever used. Hoping to do a little milling today, however it will be a while before I will be able to say with certainty the 404 rim works well.

Thanks...
troy