(11-14-2018, 01:21 AM)ianab Wrote: Yup, go big if you want to get into chainsaw milling. Up around the 90cc that John is using.
But at the price of those big pro grade chainsaws you are getting up closer to the price of a small band sawmill.
Now if you happen to have a big chainsaw already, or come across one cheap, then why not. But a little $3,000 Woodland sawmill is a LOT easier to use than an Alaskan mill, and has a little 4 stroke motor that can hum away all day and not risk burning it up.
Like woodwork shops, the sky is the limit for sawmills too. But you can buy a sawmill that "works" relatively cheap if you don't need the speed and log size of the bigger machines.
My mill has a 3ft log dia limit, which is a bit of a problem here, but I'm not complaining as I got a heck of a good deal on it, and it otherwise does what I need it to.
I couldn't agree more, Ian. I started with the chainsaw and Alaskan mill because it was by far the cheapest way to mill lumber at the time. But nearly 15 years later chainsaws have gone up in price by nearly 50% while bandsaw mills have not, so the difference in price of entry is not as great, though it's still at least 2 to 1. The problem with low cost bandsaw mills is the size of the log they can handle. You can put a 26" diameter log on some of the smaller Woodland mills, and others, but they can't cut slabs that wide. For a furniture maker that's no problem, you don't want the bark anyway, so by rotating the log a few times you can get the cant small enough to cut boards. But if you want slabs then you need a bigger bandsaw mill and the prices go up in a hurry, whereas if you buy a big chainsaw to start with you can add a longer bar to it and cut slabs even 6' across if that's what you want. It all depends on what you want to do.
I'm seriously contemplating building a chainsaw mill driven by a 4 stroke engine. I'd actually prefer to use an electric motor but a 10 HP single phase motor draws a lot of amps., and the unit isn't really portable either. But if you have ever watched the Snik mill in action you know how fast and smoothly a chainsaw can cut. So for portability I think it's going to have to be a 4 stroke motor, which will be cheaper to buy, too, but require a beefier frame. I was doing some comparisons in torque for various options. My 385XP makes about 43 lb-in of torque at 9600 rpm and the big 3120XP is 58 at 9000 rpm. 2 stroke motors certainly are a marvel of power to weight. A 5 HP electric motor has 91 lb-in of torque at 3450 rpm, but it will be down to 33 at the chain sprocket. You would need at least a 7.5 HP to get equivalent sprocket torque to the chainsaws. And it's actually the same for a 4-stroke engine. You need 7.5 HP at 3600 rpm to give you 49 lb-in at 9600 rpm at the sprocket.
When you compare all this to the bandsaws we have in our woodworking shops it all makes pretty good sense. A good rule of thumb is 1 HP will give you 3 or 4 inches of resaw capacity, if you want to get it done efficiently. My 16" resaw bandsaw has a 5 HP motor on it, so 3.5 inches/HP. So if you are looking at a bandsaw saw mill it's going to be pretty close to the same requirement. Green wood cuts easier than dry but, still, if you want to cut a 26" diameter tree into slabs you are going to need at least 7.5 HP to do it efficiently, and twice that would be a whole lot better. The Woodland mills are actually pretty powerful for their maximum cutting width of 19". The smallest engine on those smaller mills is 9.5 HP, so that's only 2"/HP, meaning it will cut pretty quickly.
In my case, I'm looking at least 12 HP and more like 15 to 18 HP for a chainsaw mill. And if I can find a simple, low cost way to use a horizontal shaft motor I could adapt the frame to a bandsaw mill later if I want to.
Musings for a future project.
John
