one man cucular sawmill

[Lewis Branden]

We are making a one man circular sawmill and are having problems with the blade.
Does anyone know witch way the crown (the pushed out part) of the hammered blade go? Does it go against the log? or away from it?
and is there a right handed and a left handed blade?

and what rpm does the blade have to go?
do you measure the rpm from the shaft?


Thanks

[Chuck Saunders]

Hi Lewis,
Don't quote me but I think the crown is away from the log. Yes there are leftand right blades. The speed of the blade is dependent on what speed the blade is hammered for. You can measure the rpm anywhere and it will be the same. Shaft is easier.
Chuck

[Travis Johnson]

We are making a one man circular sawmill and are having problems with the blade.
Does anyone know witch way the crown (the pushed out part) of the hammered blade go? Does it go against the log? or away from it?
and is there a right handed and a left handed blade?

and what rpm does the blade have to go?
do you measure the rpm from the shaft?


Thanks

Lewis, on our sawmill anyway the crown part of the sawblade is away from the log. As you probably already know, when coming up to speed the centrifigual force brings the blade out straight. The thing is, most of the time the log acts as a backing plate or straight edge. The outside, or slab side is where you want the sawblade to dish too.

The left and right hand blade depends on how your sawmill is set up. On our mill, it is a left hand mill as the sawblade is spun from the left hand side, and the blade is also on the left hand side of the log. At least I think that is how they are defined.

As far as RPM's go, I think our circle mill is direct drive (same pulley speeds) and the old 327 Chevy we had powering it had to be in 3rd gear to get the speed of the carriage and speed of the sawblade just right. If that is indeed the case then the RPM would be around 1750. That sounds about right because most high-speed line-shaft equipment (my 1880's ish jointer) from decades past was designed to run about 2000 rpm.

Just keep in mind there is a massive difference between RPM and inches per minute at the cutting teeth of the sawblade. A lot of people get this confused. RPM will always stay the same on a solid shaft no matter what the diameter. What does change though is how fast those teeth are turning. In other words a 36 inch sawblade turns the same speed as a 52 inch sawblade (2000 rpm for instance) but the 52 inch sawblade is going to put almost twice the amount of teeth into the log because the RIM SPEED measured in inches per minute, is going to be faster.

Finally one more thing. As much as I want to help you out here, and as much as I hate to send you away from the Creek, there is a better place to take your questions. The www.forestryforum.com (http://www.forestryforum.com) is the place to ask these questions. These guys have built their own sawmills and can answer your questions better than I ever could. Like you, many have built their own mills, bandsaw and circle mill alike. Myself, I just own an old 1901 Lane Circle Mill (http://www.railroadmachinist.com/Sawmill_Lane.html)that has seen better days :-)