Feeds & Speeds

CAD/CAM/CNC
1

I am new to CAM and following the Titans of CNC Building Blocks. All is going very well!!

Quick question. I am up to the Titan 4M. I have a 2HP benchtop milling machine that I converted to CNC. The max spindle speeds is 3200 RPM. Most of the speeds & feeds in this Building Block Series are based upon 4000 RPM.

Other than simply scaling my speeds and feeds by about 75%, would I be better off calculating the correct speeds and feeds based upon the depth of cut and width of cut for each toolpath? How do I know the depth and width of cut for each of these toolpaths? Any suggestions would be helpful.

Thanks… Richard

2

You need only to change the SFM or RPM to about 3000 RPM. If your feedrate was defined as chip load and not inches per minute, then Fusion 360 will output you the correct feedrate in IPM. Double-check your feedrates in each process to make sure you have the correct # of flutes and feed per tooth about .003" for roughing and .0015" for finishing.

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3

I would take some tests cuts on an extra piece of stock. A lot of the smaller machines don’t have the torque to talk bigger cuts. The rigidity of your machine has a lot to do with it also. So clamp up the stock program a strate line cut similar to the part you plan on cutting. Start out slow then crank it up untll you have issues. If you’re using a collet watch out for milling tools pulling out.
Most of all have fun with it.

4

Hello Stephen,

Thanks for the quick reply. I am not sure if I am completely following you.

When you say double check your feed rates to make sure you have the correct # of flutes and feed per tooth. If I enter a tool in the tool library correctly, doesn’t Fusion know my number of flutes for that tool?

Titan Gilroy creates the feeds and speeds on the fly by entering RPM and feed rates. On the current Titan 4M for example, with the adaptive tool path he enters 4000 RPM and 25 IMP feed rate. This results in .002 feed per tooth. This is slightly less aggressive than .003 you are recommending but I get the idea. If I am following you, then as long as I enter 3000 RPM and my feed per tooth is in the range that you are suggesting (or match the feed per tooth that Titan ends up with) I should be fine. Is this correct?

Two questions:

  1. I am using mostly YG1 aluminum specific (AluPower) end mills. Titan is basing his speeds/feeds on higher end tooling that probably handle greater surface feet per minute. Can I still use these recipes with my tooling on my 2HP 1000 lb. benchtop mill?

  2. Does it make sense for me to disregard these feeds/speeds and simply calculate based upon depth of cut and width of cut using a speeds and feeds calculator?

Thanks… Richard.

5

Sorry, I got a little long winded in my explanation, hope this video explains the process to match your tool with the cutting data for that tool. Home | Autodesk Knowledge Network

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6

Thanks Stephen. I understand the relationship between feed per tooth, feed rate and surface speed. I was just trying to see if there is a simple way to adjust Titan’s feeds and speeds to my environment. I think Rumpelstiltskin is correct that the best approach is to experiment with IPT values and see what works best for my machine and tooling.

Thanks for your help… Richard

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7

@RichardSalzman This widget might be of help to do some trial and error computations. Milling Horsepower Calculator (custompartnet.com)

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