Fly cutting on the mighty comet

[jakes_66]

I was using a half ass way to secure the head to the table , the block finish came out perfect imo. I’d assume if my Gibs were out too I’d have issues with the block too no ?

A couple of things, surfacing iron parts is very different than surfacing aluminum. I use high speed steel with an aggressively positive rake angle and WD40 for lubrication on aluminum. Good fixturing is challenging, but it is a must for aluminum cylinder heads. Minimal tool stick-out on the flycutter will reduce chatter on the interrupted cuts as the tool passes over the water ports, bolt holes and combustion chambers. After zooming in on your photo I can see your chips are not cleanly cut, they are rolling over and clinging to the edge of the combustion chamber in the direction of the cut. Try the aggressive rake angle and hone the tip of your HSS. Try WD40 if needed.

I recommend brazed carbide (dry) for the cast iron, usually C1 thru C4 grade does the trick. Cast iron naturally absorbs vibration, therefore you won't notice as much chatter in the deck of your block. I still think I see a 'halo' around one side of each cylinder in the direction of the cut. This could be a tool 'bounce' in the direction of the interrupted cut. I think your machine is capable of decent cuts on these parts, but it must be adjusted properly.

 

[sasanifab]

This is the jig I purchased , I
Going to add some supports on the other side but it’s pretty rigid