Truing a Face Plate

[wallyw]

Rarely us HSS these days. However when I did it was not optimal for cast iron. Purchase a brazed carbide tool grade c2. Will withstand the pounding from interrupted cuts.

Looks like you are out 16 and a half thousands. run your rpms up to about 250, moderate feed and 0.005" cuts until true. Once true take a diamond hone to the bit. Increase radius some and insure that it is sharp. Finnish cut of 0.0002 with a slow feed at about the same RPMs or higher.

Wally

 

[Badge171]

Thankyou all.
The diameter is 8". The cut was.010. Didn't seem especially heavy. I did lock the carriage. Wish I could lock the top slide too. When you say large radius, how large? Some say 1/32", others say different. I really would like to get this done without turning it into a pail of chips.
Al

Just a thought , but can you lock the top cross slide with the gibb adjusting screws
frank

 

[batt]

Dear Person

I use a brazed tip used for stainles steel ... very hard but brittle ... grind it with good rake clearance front and back and say 60 deg point, then I file a ... say about a .5 mm radius with a diamond file, make sure you do not roll the edge, the diamond files I use are just cheap ones from some discounter... ground flat on top.
Set up in lathe with leading edge about 30 deg to face plate, about .005" feed and face off from the centre to the outside. for finishing .002 to .003" depth of cut, rpm low, when you have done first cut have look at the edges of the slots in your face plate and look for chatter ... if chatter is there the only way to get rid of it is to decrease rpm or / and decrease radius on the tool, more likely it is best to decrease rpm ... do not finish with freshly sharpen tool but on the second cut ... tool will slightly wear on the first cut.

Batt



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Dear People

Thought I deleted second picture ... it did not appear on my post when I went to edit it out ... still there when I reposted it ???

Batt

 

[ronzo]

try grinding an HSS with a nice fat radius taking very light cuts, I'd say a medium rpm with a slow feed. Once the high spots are knocked
off, then it should be a piece of cake. I suggest locking the carriage with the gibs snugged up a bit. Or perhaps soften the slots with
a file a little. Or a flap disk on a grinder or air tool.........................

Breaking the edges of the slots is good advice. Not only does it soften the interrupted cut but it helps to get under the scale in the slots.
Ron