Hi folks,
Just me again. While I was on the subject of getting valves to seal properly I though you might like to see how I finish
my valve faces. After turning the valve stem and finishing to size, diameter, then I cut the 45 degree valve face with a form
tool I ground on a 45 degree angle. After this I part off the valve from the stock clamped in the lathe. An old friend of mine Lloyd Butler (now deceased) told me never to invert the valve in the lathe stem first to cut away the stub from the parting off operation. He seamed to think that when the tool used to turn off this stub gets close to center the strain on the stem,
which is what we are holding from, will deflect and bend the valve. Lloyd build over 100 models and they all ran well, so I have always heeded his advice. I just take a fine file and remove this stub by hand very gently. Now we have what looks like a valve, but theres a good chance it won't seal to the seat just yet. The surface of the valve face must be very smooth,
and it won't be from just machining. I take the valve and place it in the lathe headstock stem first in a true running collet
that fits the stem well. next I use my 45 degree square head clamped to my toolpost to indicate. Your toolpost should be 45 degrees to your lathe bed by doing this. Using india stones then 400 - 600 grit wet or dry sand paper wrapped around a flat
piece of steel, use the toolpost as a guide to keep your stone at 45 degrees. Lightly keep presseure on the stone to keep contact with the toolpost and gently move the stone back and forth while moving the lathe carraige away from the headstock. when you touch the valve face with your stone set the carraige stop or readout to 0. continue to stone until
all toolmarks are gone then use the sandpaper to help refine the finish ever further. I check my valve faces with a magnifier to make sure of proper surface finish. Since adapting this method I have had very little trouble getting my valves to seal the first time. Once again I hope this info helps and don"t forget to work safely. Dave
Just me again. While I was on the subject of getting valves to seal properly I though you might like to see how I finish
my valve faces. After turning the valve stem and finishing to size, diameter, then I cut the 45 degree valve face with a form
tool I ground on a 45 degree angle. After this I part off the valve from the stock clamped in the lathe. An old friend of mine Lloyd Butler (now deceased) told me never to invert the valve in the lathe stem first to cut away the stub from the parting off operation. He seamed to think that when the tool used to turn off this stub gets close to center the strain on the stem,
which is what we are holding from, will deflect and bend the valve. Lloyd build over 100 models and they all ran well, so I have always heeded his advice. I just take a fine file and remove this stub by hand very gently. Now we have what looks like a valve, but theres a good chance it won't seal to the seat just yet. The surface of the valve face must be very smooth,
and it won't be from just machining. I take the valve and place it in the lathe headstock stem first in a true running collet
that fits the stem well. next I use my 45 degree square head clamped to my toolpost to indicate. Your toolpost should be 45 degrees to your lathe bed by doing this. Using india stones then 400 - 600 grit wet or dry sand paper wrapped around a flat
piece of steel, use the toolpost as a guide to keep your stone at 45 degrees. Lightly keep presseure on the stone to keep contact with the toolpost and gently move the stone back and forth while moving the lathe carraige away from the headstock. when you touch the valve face with your stone set the carraige stop or readout to 0. continue to stone until
all toolmarks are gone then use the sandpaper to help refine the finish ever further. I check my valve faces with a magnifier to make sure of proper surface finish. Since adapting this method I have had very little trouble getting my valves to seal the first time. Once again I hope this info helps and don"t forget to work safely. Dave
