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Bridgeport 815 grinder 7" version, table flatness z/Traverse shallows 8thou+

countryguy

Hot Rolled
Joined
Jul 29, 2014
Location
Mich, USA
Dad/Son newbs. He's a recent collage grad trying a home shop CNC Startup. We bought some used auction items to support him and doing the inspect and repair dance. Got him a horizontal saw... and an inexpensive manual BP-815 surface grinder (they more or less gave us). 7" wheel, Walker magnet. It's a pleasure to have one for small tasks so far.

...the but- As we put the mag indicator on and ran the Z traverse outwards w/ magnetic chuck removed (starting all the way in) this thing fell .008 in like 6 inches? X is not as bad but still over a thou.

Have the 22page manual. Searched and read as much as we could online for flatness and solution's but this just seems like something is out of adjustment or worse?
- Wondering if the traverse screw to handle assy- maybe pulling the table down as we wind outward?
- column to table obtuse? cannot even see how to square it... but taking larger table off tomorrow.
- Ways ? Not sure how to see if the traverse way's are ... warped? bent?

Folks here are just wizards on so many things... thought I would ask the PM braintrust.

Ohhhh...sidebar- if this BP is not going to get happy again- We saw a Kent SGS 816 recently very close by us... We see the Surface Grinder being a great shop tool... wondered if they are a step in the right direction for quality?
 
Dad/Son newbs. He's a recent collage grad trying a home shop CNC Startup. We bought some used auction items to support him and doing the inspect and repair dance. Got him a horizontal saw... and an inexpensive manual BP-815 surface grinder (they more or less gave us). 7" wheel, Walker magnet. It's a pleasure to have one for small tasks so far.

...the but- As we put the mag indicator on and ran the Z traverse outwards w/ magnetic chuck removed (starting all the way in) this thing fell .008 in like 6 inches? X is not as bad but still over a thou.

Have the 22page manual. Searched and read as much as we could online for flatness and solution's but this just seems like something is out of adjustment or worse?
- Wondering if the traverse screw to handle assy- maybe pulling the table down as we wind outward?
- column to table obtuse? cannot even see how to square it... but taking larger table off tomorrow.
- Ways ? Not sure how to see if the traverse way's are ... warped? bent?

Folks here are just wizards on so many things... thought I would ask the PM braintrust.

Ohhhh...sidebar- if this BP is not going to get happy again- We saw a Kent SGS 816 recently very close by us... We see the Surface Grinder being a great shop tool... wondered if they are a step in the right direction for quality?

Sounds like the spindle axis is not parallel to the table surface. This could be any number of things and you just need to work through and determine which it is.

- The spindle axis should be perpendicular to the vertical (Z) column ways.
- The Y axis (front to back) should be parallel to the spindle axis
- The X axis ways should be perpendicular to the spindle axis
- the table should be ground flat, and thus be parallel to the ways it rides on (X & Y)

Ideally you would work through these items one by one and verify them, with
whatever tools you have available.

You might check the mag chuck back on the machine, and see whether the mag was ground
to compensate for the spindle/ways/table as it is currently? Or just mic the thickness of the mag chuck and see if it is uniform in height or varies inversely to the measurements you're seeing.

If you are only concerned with grinding parts flat, you might not need to fix any alignment problems you find, so long as they are consistent and you can get a flat grind on the mag chuck.
But if it were me I'd want to figure out what's going on a bit before I ground of .008" from the mag chuck.

-Phil
 








 
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