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All,
Just started to try and face my 4 jaw backing plate before fitting the 4 jaw, only to find that it seems much harder than the HSS Im trying to face it with.
Within 10mm or so of starting to face its dulling / grinding the HSS to the same shape of the faceplate, i.e. flat!
Is this a job for Carbide or am I doing something fundamentally wrong?
Pointers and advice please!
Thx
J
Think I've solved my own problem...
SPEED. I had too much I it.
Engaged the back gears, re-ground the tools and all seems much better now!
Thx
Jon
Do yourself a favor and search for HSS cutting tool angles (this will give you a base line to work to when sharpening,it should also include the theoretical angles required for different materials).
Also do a search for cutting speeds of different materials when using HSS (it may only show carbide,if so only use around 1/4 of what is said),there should also be a formula for working it (rpm ) for the diameter of the material.
Normally when I face cast I run 2 to 3 times quicker than when I am turning.
Ok, update from my experience today...
Slow is good!
I guess it was my inexperience showing early on this morning. I forgot to look at my speed tables and was initially running WAY to fast. A quick reference to what the turning speed should have been for my diameters put me in the 40 - 150 rpm area. I don't have a tacho on the lathe so I put a paint mark on the 4 jaw backing plate and did my best to count the revolutions for 5s, multiplied it by 4 and estimated that I was now running about 80rpm.
I took light cuts and felt how it went. I soon got that I could see and hear where it wanted to be - a bit quicker near the centre and slower as I got to the outside - VFD was great for this!
I didn't know about turning vs facing speed- good tip. Thanks.
Jon