Another Wheel Spacer Question

[faavs730222]

Hi, I am still busy with my wheel spacers. The progress a a bit slow. I have a couple of questions.

After I drilled the holes. I fitted the spacer on the wheel hub. It fits nicely over the hub and wheel nuts, but it is too thick. The wheel hub don't protrude. The thickness of the spacer is 38mm, so I am machining it down to 30mm to give the wheel a 8mm shoulder to rest on. My problem is that the holes are all drilled and I am taking interrupted cuts now. I dialed in the spacer on the chuck, but when I take facing cuts over the holes it vibrates. I tried HSS tool bits , but the holes eats it up. I had the best luck with Carbide inserts but at 380rpm it makes sparks, and if I feed it from the outside in it begins to cut taper after the holes.

How do I prevent the sparks? Lower RPM?
How do I prevent the Vibration? Lower RPM? Smaller cuts?
How do I prevent the tool from cutting taper? Tool blunt?

 

[rgray]

I'd do it on a milling machine. Maybe touch it up after with a surface grinder.

 

[Randall Marx]

How about plugging the holes with steel rods using a light press fit? Then you can cut an uninterrupted surface as you face it to thickness. Afterwards, press the pins out. NOTE: this is just the first thought that came to mind...take it for what it's worth, just a suggestion. Good luck!

 

[Wreck™Wreck]

An interrupted cut is always difficult, the tool shown would not be my first choice. As you have already assumed slow it down but the finish will suffer.

A tool with less angle in the cut will work much better such as an 80° diamond insert, there will always be an artifact on the surface after the interruptions.

Todays job, as cast bronze rings 28" OD X 24" ID, the OD finishes at 27.375 +.000 - .005, the ID at 25.562 +.005 - .000, an interrupted cut until the you are past the cast surface, had to remove 3/8" per side, this did not make the boss happy.
Rough castings


Nearly finished part, the estimated lathe time is 17 hours for 4 parts, I am already at 22 hours on the lathe work alone, however the castings were Customer Supplied and a good deal larger than needed.