Most saws are set at a 45 degree twist from the bed (mine measures 45.3 degrees) and you would need to set the blade twist 90 degrees to the bed. I would think only a 2 or 3 degree adjustment each way would be enough. This would allow a range from 42 to 48 degrees to dial in the blade adjustment as needed.

On Sep 15, 2023, at 12:17 PM, Mark Kimball <markkimball51@...> wrote:

?Has anyone here determined the blade twist angle necessary to get a vertical cut?? I'm trying to create a model of the blade guide assembly.?

Hi John,

The 40 degree angle is closer to what I measured when I looked at the angle between the blade guide support's square dovetail and its body.? That's part #84 in my Harbor Freight owner's manual.? It's called the "lower blade guide bracket seat" in my manual.? But I wasn't sure if the plane of the bracket seat's body is anywhere close to vertical (when the body frame part #62 is horizontal).? Apparently it is.

I also saw that when the blade is twisted to be vertical the plane of its wide dimension passes through the M8 hole in the bracket seat.? That makes a lot of sense!? However, it doesn't seem to be exactly parallel to the long axis of the dovetail.? ?Maybe that's to account for the necessary clearance between the saw blade and guide bearings?? With zero clearance the blade and guide bearing axes would be parallel, but adding clearance would result in needing some additional "twist offset" on the part of the blade guide.? More clearance = more angular offset.? But how large is that angle?

Knowing that the bearings are 9mm long, for .005" clearance I calculate less than 1 degree. .010" would come to 1.6 degrees.? Not much to worry about I'd say.? So the dovetail alignment issue may be an observation error on my part (I just eyeballed it), or perhaps a minor design error.

Mark

Hi? Mark

The human eye is pretty damn good at seeing squareness and parallelicity so I don't doubt that groove in the bracket seat is not parallel to the arm it slides on. I've seen it on ones I've dealt with too.?

Unfortunately the parts are not made with much precision. I believe the manufacturers build in so much slop (they call it 'adjustability') that you can mostly get it adjusted correctly, but I've had to file the corners of a bracket tongue to get enough twist to align a blade vertical on a brand new machine.

For the purposes of your drawing the assumption that they should be parallel is correct - jv

On Sun, 17 Sep 2023, 5:08 am Mark Kimball, <markkimball51@...> wrote:

Hi John,

The 40 degree angle is closer to what I measured when I looked at the angle between the blade guide support's square dovetail and its body.? That's part #84 in my Harbor Freight owner's manual.? It's called the "lower blade guide bracket seat" in my manual.? But I wasn't sure if the plane of the bracket seat's body is anywhere close to vertical (when the body frame part #62 is horizontal).? Apparently it is.

I also saw that when the blade is twisted to be vertical the plane of its wide dimension passes through the M8 hole in the bracket seat.? That makes a lot of sense!? However, it doesn't seem to be exactly parallel to the long axis of the dovetail.? ?Maybe that's to account for the necessary clearance between the saw blade and guide bearings?? With zero clearance the blade and guide bearing axes would be parallel, but adding clearance would result in needing some additional "twist offset" on the part of the blade guide.? More clearance = more angular offset.? But how large is that angle?

Knowing that the bearings are 9mm long, for .005" clearance I calculate less than 1 degree. .010" would come to 1.6 degrees.? Not much to worry about I'd say.? So the dovetail alignment issue may be an observation error on my part (I just eyeballed it), or perhaps a minor design error.

Mark