Circular spirit level & vibration?

[homebrewed]

I'm using a diamond grinding wheel mounted in my 4" angle grinder to flatten the top of a large hunk of basalt that was used as a support pier for our old barn. I want as much contact area as possible but it's proving to be challenging to get the contact area both flat and in the desired plane (perpendicular to a vertical stud-to-be-sistered-in). I had the thought of attaching a circular level to my grinder to make that easier, but I'm wondering if the grinder vibration will cause problems with the bubble, perhaps shaking it up into a froth. So my question is if anyone has tried this, and, if so, how it worked out.

The (HF) grinder has a handle that can be screwed into either the left or right side of the tool, so I had the idea of using the unused hole to attach a bracket that holds the level. I can bend/rotate it to get the level's "0" parallel to the diamond grinding wheel. Sounds pretty cheesy but hopefully the results will be better than eyeballing it with my AMD-affected eyes. That's the idea, anyway.

 

[benmychree]

level does not necessarily equal flatness of a hopefully plane surface.

 

[Provincial]

Grinding on rock by hand is slow, hard work. It also produces large amounts of dangerous dust.

Check out the option of packing the surface with grout. Structural grout is often used to increase the bearing strength of uneven surfaces.

I placed two prestressed concrete sections in excavated recesses in soil to use as support for prestressed bridge sections. The 6' x 16' sections were 12" thick. We excavated the recesses as close as possible to flat and horizontal bottoms, compacted crushed rock to make the bottom easier to final grade, then placed bricks that were carefully leveled to hold the prestressed bottoms barely off the surface of the crushed rock. We then filled the recess with structural grout slightly higher than the top of the bricks and lowered the prestressed sections onto the bricks. This gave us a perfectly flat surface with almost 100 square feet of contact surface with the soil. These served as the bearing area where prestressed highway bridge sections were used to build a 16' wide bridge for log truck and heavy equipment access. Final load was about 3.5 pounds per square inch.

You can easily find grout that is stronger than the wood members of the building, so it will certainly transfer the load. Consider increasing the bearing surface of the wood to make an even stronger load-bearing contact area.

 

[Eddyde]

I agree With Provincial.
Non-shrinking Grout is available at most big box, building suppliers for less than $10 for a 50lb bag. Put a strip of Ice and water shield between the wood and grout. Should be good for a couple of hundred years.