1/16 Ballnose speed and feed rate

[tagguy]

Hope someone can give me direction on speeds and feeds for 1/16 ball nose bit.
I know there are a lot of variables. I have a Piranha XL (shark) which has a Dewalt router. The bit is 1/4 diameter, has a tip radius of .0313

Currently it is set up like this.(I'm pretty new at cnc, so any suggestions are welcome)

Pass depth= .015
Step over= .0056 (9%)
Clearance passover=.09 (143%)

12,000 RPM's
25 IPM
15 Plunge

I'm cutting a 2.5D Basketball plaque for my grandson out of hardwood. (Afromosia)

Any help with thes parameters would be appreciated

Mike

[martin54]

Mike I can't comment on your current figures as I know nothing about your machine or its capabilities sorry

But it might be an idea for you to ask this question on the shark forum since there will be a lot more people on their with your set up

https://www.nextwaveautomation.com/forums/

[redwood]

As Martin stated, your machines capabilities will have a lot to do with it. If you are using a finish toolpath, depth setting doesn't come in to play. Use a roughing toolpath if your depth of cut is significant. Your settings would be a little slow for my machine. Your stepovers should be OK.

[rscrawford]

That seems pretty slow to me. You will dull your bits prematurely at that feed rate.

I know a Shark won't move very quickly, but on my larger machine I would run that bit at 300-400 ipm (X,Y,Z axis) and 18000rpm. At 0.005" per pass, your machine will not feel much if any resistance from the cut. So I'd go as fast as your machine is capable of going without losing steps. Not sure what a Shark will do, but hopefully its faster than 25ipm.

[martin54]

That seems pretty slow to me. You will dull your bits prematurely at that feed rate.

I know a Shark won't move very quickly, but on my larger machine I would run that bit at 300-400 ipm (X,Y,Z axis) and 18000rpm. At 0.005" per pass, your machine will not feel much if any resistance from the cut. So I'd go as fast as your machine is capable of going without losing steps. Not sure what a Shark will do, but hopefully its faster than 25ipm.

I didn't really look at the figures to be honest as this is really something the individual needs to work out for their own set up & is a part of the learning curve (at least that's how I see it). But yes 25 ipm on any machine is very slow

My own feed settings are very conservative ( I already know that much) but rscrawford's post show just how little I really know, based on what he has posted I could probably more than double my feed settings Obviously need to increase spindle speed as well but since that is only set at about 14000rpm that isn't a problem.
Speed isn't a real issue for me BUT often when looking at machining times I wish they were a bit quicker. Time to go back to some more experimenting I guess

[Adrian]

Thing to bear in mind that 2.5/3d work is a blend of all three axis constantly moving so the plunge rate (and the short movements) will nearly always constrain the actual speed reached which may be well below that which is actually programmed.

[Leo]

Fast or slow is relative.

It's more to do with chipload.

25 IPM can be just right - as long as RPM produces the right chipload.