metalmagpie
Titanium
- Joined
- May 22, 2006
- Location
- Seattle
I have a 718 surface grinder now for a few weeks. I haven't been happy with the grinds I've been getting. I have tried several approaches and I am writing to summarize what I had to do to eliminate the waviness. I'll provide more details and pics later, but for now here's a picture of my final finish, considerably enlarged. There are longitudinal lines but almost zero waviness.
The aluminum heat sink is there to allow my phone's camera to focus.
Here is what I needed to do to eliminate the waviness:
level the machine
lubricate the ways correctly
tighten the wheel adapter flange nut really tight
do a precision balance on the grinding wheel
dress the wheel
use a single point diamond that's still sharp
dress the face, MUST be deep enough
dress the sides of the wheel
last dressing pass no infeed at all
break wheel edges after dressing with dressing stone
touch wooden stick to wheel to get 'hangers'
The finish is also affected by the longitudinal traverse speed, crossfeed amount, and depth of cut. However, I could not prove to myself that these affect the waviness.
Similarly, the choice of wheel makes a difference in finish but I didn't see any correlation with waviness. I switched back and forth between a 46H and 100K wheel. Quite different, but again didn't touch the waviness.
Finally, I had heard that 3 phase power from a rotary phase converter is not as good as the power provided by a VFD. I have a machine with a VFD and an auxiliary receptacle, so I was able to plug my grinder into the VFD or use the power from my RPC at will. I didn't see much difference at all between the two.
I will have more to say later about how I did the wheel balancing. My results showed that balancing the wheel helped to eliminate waviness (aka chatter, cogging etc.).
metalmagpie
The aluminum heat sink is there to allow my phone's camera to focus.
Here is what I needed to do to eliminate the waviness:
level the machine
lubricate the ways correctly
tighten the wheel adapter flange nut really tight
do a precision balance on the grinding wheel
dress the wheel
use a single point diamond that's still sharp
dress the face, MUST be deep enough
dress the sides of the wheel
last dressing pass no infeed at all
break wheel edges after dressing with dressing stone
touch wooden stick to wheel to get 'hangers'
The finish is also affected by the longitudinal traverse speed, crossfeed amount, and depth of cut. However, I could not prove to myself that these affect the waviness.
Similarly, the choice of wheel makes a difference in finish but I didn't see any correlation with waviness. I switched back and forth between a 46H and 100K wheel. Quite different, but again didn't touch the waviness.
Finally, I had heard that 3 phase power from a rotary phase converter is not as good as the power provided by a VFD. I have a machine with a VFD and an auxiliary receptacle, so I was able to plug my grinder into the VFD or use the power from my RPC at will. I didn't see much difference at all between the two.
I will have more to say later about how I did the wheel balancing. My results showed that balancing the wheel helped to eliminate waviness (aka chatter, cogging etc.).
metalmagpie
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