I've had a problem with getting good vertical blade alignment for quite awhile now.? In that, while I can get the blade vertical, it also is displaced.? In other words, it doesn't have just pure twist, it's pushed to one side or the other.? This makes it difficult to get proper alignment in the other axis, and also leads to strange interactions between blade tension and blade tracking.

I did some testing by clamping a short length of aluminum flat stock to the blade and then used it to twist the blade so it was exactly vertical (this was done with the blade guide assemblies removed, but the mounting brackets were still installed).? This showed me how far off the 8mm screw holes for the blade guide assemblies were, since they should be more-or-less in line with the aluminum flat.? I observed a number of things that were wrong.? For the bottom blade guide bracket, the 8mm hole was in line (this was good), but the dovetail boss wasn't parallel to the bar.? It was so far off that it was impossible to adjust the blade guide to avoid moving the blade around in order to get the blade vertically aligned.? I also found that the upper blade guide bracket's 8mm hole did NOT line up with my aluminum bar, so it, too, would cause the same problem.? Now, it would be possible to machine the bottom support bracket to improve the situation but that wasn't going to work with the upper bracket.? Plus, I really didn't want to modify the OEM brackets, just in case something went wrong.

For these reasons I decided to make two replacement blade guide brackets.? I had originally considered making a trunnion-like arrangement that would only permit adjustments around the blade-neutral axis, to get nothing but twist, no displacement -- but that was getting complicated and looked like it would require making new blade guides, too.? Instead, I came up with a relatively simple change to the OEM blade guide brackets that would add additional adjustment range, enough to produce something a lot like the trunnion scheme.

The following photos show a lot of what I did to accomplish this.? FYI, the replacement mounting brackets consist of two parts.? One is the vertical part (when the saw frame is vertical), which is bolted to the saw frame; and the second is the support piece, where the blade guide with its three ball bearings is attached.

This photo shows the lower vertical part, after marking the location where the OEM bracket's 8mm hole intersected the aluminum bar when twisting the blade for verticality.? I used this to (eventually) determine where the horizontal support piece needed to be attached.? The 8mm screw hole actually is centered on the edge of the vertical bar, but this isn't an issue because the 8mm mounting hole will be drilled/tapped in the horizontal piece.


The piece below is the horizontal piece.? I drilled/tapped an 8mm screw hole centered on one axis, and .350" from the left edge (MK2 version, mentioned below).? This hole is used to mount the blade guide assembly.

I aligned the piece so its 8mm hole was over the mark on the edge of the vertical part, and rotated it so its long axis was parallel to the aluminum bar when the blade was twisted to get proper vertical alignment, then used a sharpie to draw the outline of the vertical piece.? This was used to determine where I needed to drill the mounting hole for screwing the horizontal and vertical pieces together.


The photo below shows the two pieces screwed together, from a side view.


The photo below shows the assembly from the top.? Note that the horizontal piece looks a bit different.? It is the "MK2" version, after I learned a few things.? The rounded corner is there to provide clearance between the saw blade and the mount piece.? A nice benefit of using this two-piece approach is that I can rotate the top horizontal part, providing additional adjustment range.


The additional adjustment range works pretty well, at least on my bandsaw.? Here's a photo showing the current setup, looking down the blade toward the two blade guides:

The result is a vertical cut that is pretty good.? And I didn't have to do much adjustment to get the work-holding vise at 90 degrees to the blade, either.