It's been a slow slog, but I think I have fixed my saw vertical and horizontal saw cutting issues.? ?Currently, I'm able to cut in the vertical and horizontal at less than .001"/" (my goal).
My saw had a number of issues.? These include:
1. The holes in the saw frame and table casting bushings were way too large for my pivot shaft.? ?The clearance was something like .006".? It should be less than .001" for this sort of application.? The hole on the left and right hand of my saw frame and table casting bushings were different diameters (as looking at the vise hand wheel).? ?Luckily, the left saw frame hole/table bushing and the right saw frame hole/table bushing were close to the same size.
2.? The pivot shaft was not parallel to my table, hence I was cutting about .020" out of square (primarily in the vertical orientation).? My table was low on the left hand side.
I machined a new pivot shaft and it fit *really nice*.? ?I decided I didn't want to mess this up and decided I needed to lower the right hand side of the table.
I put shim stock under a 1.5" diameter steel shaft on the left hand side and determined that I needed in excess of .030" shim to cut square.? ?I started to file the table by hand.? I got over 1/2 of the way there by filing by hand, but then I decided to break out the Makita angle head grinder and finish the job.? ?I used a flexible disk, 80 grit, in the Makita and ran it lightly over the table, measuring often.? I used the file to indicate the high spots and also partially flatten the table.? ?I then followed up with the grinder on the high spots, filed more, etc. etc.? ?I'm pretty sure that my table is within .002" from flat on the entire table and less than .0015" on most of it.??
Key things to note when doing this:
1.? You have to keep aligning the blade guides before each time you make a test cut (after filing/grinding on the table).
2.? You have to have your blade tension constant.
3.? You have to cut two pieces:? One before the measurement piece to properly get the cut piece to represent the new saw setting and then the piece you will be measuring.
4.? The vertical and horizontal measurements affect each other.? ?When I was dialing in my vertical, I had to dial in my horizontal too.
If you want to make your saw cut more square, it can be done.? ?My goal was to have everything within .001"/".? When trying to achieve this, you need to have everything correct and you need to move in on it slowly.? ?I chose to file/grind my table rather than follow John V's recommendation of reducing the size of the pivot shaft.? This is because my saw frame holes and table bushings were so messed up.??
Ultimately, I achieved around .0005"/" on the vertical and .0004"/" on the horizontal (average over 5 measurements).? ?Note, that due to the surface roughness, measurement repeatability, inadvertent swarf under the part being cut, etc., I would say that this measurement can vary +/-.0015" (or better).? You have to make multiple measurement on successive days to really know the average machine setting.
I finished the work last night and made another cut today.? ?The red line was the top of the piece after the initial piece was cut off.? I used the line for a gage to rotate the shaft 180 degrees for the parting cut.? ?This part came out .0002"/" for the vertical and .00016"/" for the horizontal.? ?I figure my micrometers are measuring on about 1.25" diameter (my part is 1.5" diameter).
