I want to make a precision rotary table for surface grinding VMC spindle spacers/
Parallelism required within 0.002 mm
Andy from Workshopshed
"Making and repairing things in a shed at the bottom of the garden"
I think I can point you in the right direction with a simple tool modification to achieve what is needed.
You have to start with a Drill Press but it has to be the style with the round table, the following mods will be needed.
Replace the spindle bearings with something higher quality of a deep angular contact design set up to control endfloat, simple enough with some machine tools to make preload spacers if needed.
Secondly the spindle needs modifying so as to be able to attack a cup style grinding wheel.
Third one must then modify the round drill press table to be mounted on tapered roller bearings with adjustment to remove excess play.
Once all this is done one simply offsets the table in relation to the now hand spinable drill press table which can also have an external brake clamp fitted if desired.
To true up the table to the grinding wheel one simply spins the table by hand and lowers the Cup Grinding stone down and it will guarantee after grinding that the stone and table are perfectly aligned, The offset oif the table to the grinding stone will guarantee the grinding stone will by itself keep the table spinning.
Appropriate speeds are selected first and if desired lowered by pulley ratio changes to a suitable speed the resulting finish will be blanchard ground as is used on flywheels, Flip the freshly ground item over and parrallism will be guaranteed.
Workholding use common sense smaller parts can use a magnetic chuck larger items such as Vehicle Flywheels can be either securely clamped or bolted thru the table via the crankshaft mounting bolt holes.
This idea was to originally avoid the expense of purchasing a commercial Flywheel grinder that are in excess of 12~15,000 Dollars Australian.
Even with new parts to build this grinder it should be well under a thousand dollars for a flywheel grinder, One could also mount an XY axis table and either manually operate it or power it for conventional surface grinding duties, making sure to use coolant so as to maintain accuracy as the workpiece gains heat and potentially expands.
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