Thread: Long bars for a 880

Sag can be a real issue for the big bars. My biggest is 60", but it is an older form large wide bar (the shop had it for years so sold it to me for a song) doesn't sag much but is very heavy, the newer ones I've seen don't seem as wide and hence will can sag more.

For sag, I use a "L" shaped piece of timber screwed to the log, after the mill is set up ready to cut with bar again the log (first diagram). I take it off before the rear chain hits it, when the bar is almost half way into the log and supported by the cut (second diagram). The chainsaw is OFF when you attach and remove the jig.

Interested to know if it would stay straight throughout the length of the log ?

Long bars are always looking for an excuse to crown or sag, so you need to be very particular about chain sharpness and raker set, and bar dressing.
My preference when excessively big slabs would be to cut them out vertically, using a westford rail mill style setup. It's a lot easier on the back then the hands and knees stuff on bottom slabs, and you can take a slab off each side as you go to relieve tension. Slabs just fall off to the side when they come off that way too, which makes picking them up with a forklift or similar easier.

My newer protop GB bars don't seem as good as the older ones, a little softer. I suspect they might now be made in China. The old titanium ones however are probably the best thing I've ever bolted to a powerhead.

Originally Posted by Barterbuilt

Interested to know if it would stay straight throughout the length of the log ?

Sometimes they stay straight for a while then they dip, usually sag, but I have had a couple crown.

Hi there.

Before my Lucas Mill days began, I spent many years chainsaw milling with an old 090, with various bar lengths up to 60". I used to try all sorts of things to shim the bar flat, but it was Dudley at Lucas Mill's who showed me the trick of shimming with squares cut from an aluminium can. This has been the easiest and most accurate method of flattenning the bar I have found.

However, as metioned earlier, a mis-sharpened chain, poorly dressed bar, loose chain, etc, can bring all that effort undone anyway.

The other thing to consider is that a bar cutting a slab 1.5m+ wide slab with a few mm of sag won't really effect the slab if it racked dead flat until it is dry. The very slight cup in the slab of a few mm will easily press out over the years once the full weight of the racked timber is on it. More often than not, people go to pains to get dead flat slabs off the saw, only to rack them poorly and degrade the quality of the slab. A slab with a 10mm twist will end up thinner after machining flat both sides than a slab with a 3mm cup in the middle.

However, the aim should always be to cut them as flat as possible and rack them properly for a premium end product.

Cheers

James.

The widow makers first appearance. MS880
The new 50 and 84 " bars. Sheeesh, looks a lot bigger in the flesh.
Wifey laughed at me and waved little finger.

Now to finish the mills for them.
I think I will make a dedicated mill for them both, save swapping around.
Plenty of time as I want to run half a dozen tanks of fuel through it before I use it to mill with.
That's about 50T of wood the way that thing cuts.



mini-84 inches.jpgmini-50 and 84 inches.jpg

can of industrial lubricant for size ( unofficial sponsor )

hopefully your arms don't fall off before you get the 50 tonnes of firewood cut

I thought my 60" was big, that 84" is a monster, hope you have the strength to lift it

You may want to investigate options for tensioning the bar

Ya gotta be sh#t'n me?! Were'd you find that 84 inch bar? That thing would be spinning some chain. I'm running a 880 with a 52 inch bar that takes 10 foot of ripping skip a tooth. Can't read the brand, what is that beast? I gotta get me one of those for a job I'm supposed to be doing. Cheers.

Originally Posted by Barterbuilt

The widow makers first appearance. MS880
The new 50 and 84 " bars. Sheeesh, looks a lot bigger in the flesh.
Wifey laughed at me and waved little finger.

A few years ago on another forum guys were showing off their long bars so edited their their pics as shown

Originally Posted by dai sensei

I thought my 60" was big, that 84" is a monster, hope you have the strength to lift it

You may want to investigate options for tensioning the bar

Definately going to be a two person lift, especially when attached to the mill. But any slab comming off that bar will require some mechanical assistance anyway. Not sure about tensioning the bar? I may investigate having it free floating of sorts and the shim idea from James sounds good.

Originally Posted by feralwoody

Ya gotta be sh#t'n me?! Were'd you find that 84 inch bar? That thing would be spinning some chain. I'm running a 880 with a 52 inch bar that takes 10 foot of ripping skip a tooth. Can't read the brand, what is that beast? I gotta get me one of those for a job I'm supposed to be doing. Cheers.

Are your eyes painted on? GB, fair smack in the middle. 206 drive links
Contact Sawchain from this website, he has them. They are on special this month too. https://sites.google.com/site/sawcha.../gb-guide-bars
Where abouts on the north coast are you? should catch up one day if your in the area.


Also to answer the sag question. If you suspend it on packers either end it sags about 10mm. Although I suspect that having chain on it will stiffen it up quite a bit. 100ft roll of chain should be here next week, so I'll update when I get one fitted.

Cheers