</font><font color="blue" class="small">( What type of stone grinder are you using to sharpen on the machine without removing the blades? )</font>
I don't have a
chipper/shredder anymore so I'm not using anything - but I would think to maintain the correct angle you would almost certainly have to pull the knives off the unit.
</font><font color="blue" class="small">( an you tell me what the air gap should be between the rotating blades and the stationary. )</font>
No - but your manual should. If you don't have a manual email Wallenstein and ask.
</font><font color="blue" class="small">( I can see the gap with the cover open, but can you all tell me what happens if the blade gap increases from sharping the blades on the machine for touch up sharping. )</font>
I would think that performance would suffer - basically the anvil provides a hard, rigid surface for the log to rest against as the rotating knives peel off chips - increase the air gap far enough and the log/branch, being a rather flexible thing (at least when green) as compared to steel will want to bend or flex in the direction of knife rotation. The knives would move from peeling or slicing to more of a shearing action which would probably require more force (power) than the peeling/slicing would - this would probably become more noticable as the knives became less sharp.
</font><font color="blue" class="small">( What type of shop or company will sharpen this type of blades?)</font>
There are shops that are dedicated to sharpening - in the Yellow Pages of my phonebook they are listed under 'Sharpening Service'. Beyond that, any machine shop that has a wet surface grinder ought to be able to do it.