[TheForge] Band saw

[ries]

Actually, Andy, I dont think those little bandsaws have much crown-  
they have a lip on the back of the wheel that acts as a backstop for  
the blade, and then the action of the saw downforce pushes the blade  
back against that lip. So rather than having a crowned wheel, that the  
blade auto centers on, like a vertical bandsaw does, there is only one  
possible position for the blade on the wheels- fullly seated back  
against the lip.
Usually when they throw blades, its because the side bearings are not  
adjusted tight enough, and the blade slews in its guides.
Again, this is different from the vertical bandsaws you are  
discussing, where something like a Cool Block is used. In a vertical  
bandsaw, the blade often doesnt quite touch the Cool Block, or just  
kisses it. But in a small horizontal saw, there is positive side  
pressure on both sides of the blade from the roller bearing guides, so  
that you kind of ease the blade into a bearing gap that is just  
slightly smaller than the blade thickness- the blade should have a  
VERY tight fit in those roller bearings.
Then, when it comes to the wheels- the cheapo ones, the ones from  
harbor freight and so on, often dont have bearings at all on the  
wheels- just a bushing- and often not even a bronze bushing.  
Obviously, bearings are much better- my Jet has bearings on both  
wheels, which is one reason I like it better than the cheapos. It also  
has a back stop for adjusting the angle of the top wheel, which some  
do not.  But there is no "tracking" adjustment per se- just a blade  
tension knob, which I understand, on these little saws, should be  
tightened as tight as you possibly can hand tighten em. Grant, whose  
page I linked to, once actually used a blade tension gage, and found  
that the tightest he could get it by hand was at the very bottom end  
of the acceptable blade tension.

Obviously, you have much better taste in bandsaws, as the advice you  
were giving applies to $10,000 D0-Alls, but not to $300 Rong Fu's.

In checking, it appears Grant's page is down- here is a link to a  
wayback version of the same page-
http://web.archive.org/web/20050814083326/http://www.tinyisland.com/4x6bsFAQ.html

Ries



On Aug 29, 2008, at 4:14 PM, Andrew Vida wrote:



> You should examine the wheels to verify that they have enough crown.  
> If they are flat you will have fits trying to keep the blade  
> tracking. The main function of the guide is to keep the blade in  
> position when cutting, but a secondary function is to aid in  
> maintaining the blade on the the wheels as well.  Crown is  
> absolutely essential on at least one wheel, the one that adjusts the  
> tracking.  Crown should be subtle, but definitely noticeable with  
> the naked eye.  I would try to examine a well functioning saw and  
> note the crown.  If yours is flatter, I would not hesitate to re- 
> profile it.

The guide is the other really important aspect of a bandsaw.  If the  
guides that came with it suck, then invest in a set of Cool Blocks.  
They are well worth the few dollars.

Also, the bearings on which the wheels rotate are critical.  They must  
be tight so that the blade will track - if they are wobbly you will  
have unpredictable tracking and tracking adjustment.  Speaking of  
tracking adjustment, a good one will be very linear and predictable.   
If you don't have one like that, it isn't the end of the world so long  
as once you lock things down the adjustment doesn't change or does so  
in a predictable fashion.  These are the few quick things one can do  
to tune up a band saw.  I've worked almost exclusively with very  
expensive saws, so I have not had to mess too much with bad designs  
and poor-ish quality, but adjustments must be made even to the finest  
equipment and failures occur there as well, so you will have to get to  
know your tool almost no matter what sort you buy.





Ries Niemi
Industrial Artist
http://www.riesniemi.com/