Truing a Face Plate

A

Allan

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I bought a Tools 4 Cheap face plate for my lathe. A nice product but it had about .0165 runout on the face. I tried facing it with an 3/8" HSS tool. I used eyeball relief and rake angles in the "moderate" class. I found that the interrupted cut from the slots and holes caused the tool to chip or wear. The smooth centre portion turned quite nicely but once the slots started the tool was finished. Should this be a back gear project? Any advice on grinding angles? or tool material?

The face plate does not appear to be cast iron as it turned some rather longish curly chips and left no black crud on the ways.

I would really like to get this right before the face plate is only 1/4" thick ; ) Thanks in advance.

Al
 
I would suspect cutting speed more than tool if the center cut well. The interrupted cut should not bother HSS that much if you are taking a light cut. You probably need to slow down as you go out away from the axis.
 
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.........................
 
GK1918 said:
Or perhaps soften the slots with a file a little. Or a flap disk on a grinder or air tool.........................
Click to expand...

That's a nifty trick, I can see how that would make a big difference...:thumbzup:

Bernard
 
Use a very slow speed and carbide on cast iron. You don't mention the diameter of the face plate. Much size at all and HSS will get dull and mess up your cut. Cast iron is hard on HSS tools.
 
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
 
Soften the edges at the break, use a carbide cutter, slow the spindle speed, slow your feed rate. All have been mentioned. Using HSS on cast iron is rough but can be done. Use a large radius at 1/16 or larger. The key is the word "SLOW".

"Billy G"
 
No telling what the face plate is made from. I didn't see the part about the long chips and no black crud. Never the less,use a carbide tool if your HSS isn't making it,before you DO wear out the face plate trying to cut it. The radius on ordinary brazed carbide lathe tools will do.

You know,these cheap brazed lathe tools are really supposed to be honed sharper. I don't usually bother to do that,but thought I'd mention it. Use a fine diamond hone.
 
Thanks to all who helped. This is a great place to learn from the experience of others. As the old Aviation Safety Letter said, "Learn from the mistakes of others. You won't live long enough to make them all yourself."

Last night's session went much better. I slowed it down as slow as it would go on back gear. Still a bit rough, like tearout, but bordering on glassy. Would more top rake help? I ground the top rake with my Dremel. Honed with small stone and followed up with Arkansas stone. Not terribly precise but better than free hand at the grinder or belt sander.

I am quite determined to build the grinding rest that Ted Hansen had in Machinist's Workshop June/July 2013 issue. This would give better control and predictability. I don't have the means to mill the required slots but I'll talk to a local shop and see what they would charge. I can probably get one long slot cut in the plate and then cut them to size after. Only one set up fee then. Thanks again for all the advice.
Al
 
It is always a good idea to put some load on the plate from the tail stock while truing a face plate. If you can push a live center into, say a button of brass on the face plate. and put some pressure on the face plate you may get better results. If there is end play in the spindle. the face plate will pop back out a little every time you interupt the cut causing chipping and uneven cut. And lock the cariage before you start the cut.
 
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