Issues Machining plasma cut steel and large chamfers

[ryanbez]

Very new to CNC and machining and still have a lot to learn. I have been attempting to machine a 3/16" deep 45 degree chamfer in 3/8" thick steel plate that was cut into an 8 inch diameter disc on the plasma. I am attempting to chamfer around the entire edge.

I am wondering how people account for the hardened edges from the plasma? Also what might be the best way to go about this operation? I have found a recipe that works but does not seam ideal and i believe it can be much approved upon as im just starting to understand basic speeds and feeds. I have been thrown into the fire and told to use what we have to figure it out. I have been using a 1/4 inch 5 flute endmill in a ramping toolpath stepping down 3 times and moving outward as cutter ramps down. I then come back with a 45 degree .391 max depth cut index-able chamfer mill in a single pass to finish chamfer. I have produced okay parts but believe my speeds and feeds are off and I can cut down on tool wear and cycle time(takes about 12 minutes currently) with a better recipe and tool paths. The edges from the plasma seem to make things tricky as well. I am looking for any input and advice to help and keep me on the right track. As I do not have much experience. here is a link to the tool https://www.mscdirect.com/product/details/00306514

Similar Threads:

• Need Help!- LARGE 5 X 10 STEEL ROUTER BUILD
• Need A Quote- Large 1040 steel spindle
• Large OD Alum or Steel Tube
• Large Steel Channels
• Newbie- Large Stepper Issues?

[spumco]

Also very new to CNC, so take this with a grain of salt...

This may be a situation where conventional tool path (instead of climb milling) may be appropriate. If you get under the hardened layer it will probably cut better and the tool last longer. Consider a rather wide WOC and cut the perimeter on first to get under and rid of the hardened layer. Maybe a slow pass with slow SFM and kind of treat it like a slotting operation. After that, you can step up and in using climb milling and finish with your chamfer tool at more appropriate speeds/feeds. You might also consider using a larger end mill, preferably a stubby one with a short flute length so it doesn't deflect as it bangs through the crust.

I'm sure someone more experienced will be able to provide better or more comprehensive advice.

[84scrambler]

If you have slag knock it down with a grinder or sanding wheel. Also trying taking a 2 tool approach. Use a stubby carbide or toroidal cutter to cut the bulk of the material out and finish it up with the chamfer tool. Chamfer tools are expensive and if you want a nice finish save if for the last little bit that way you can ensure numerous parts with a clean finish. Also if time is important I have found that a stubby carbide endmill runs a little faster then the toroidal but the toroidal was cheaper.