Odd question for my old machine

Added some pics for clarity.

snoozer77 wrote:

Hi Hatch. In Fusion, if you change your spindle speed, your cutting feedrate stay's the same, but your feed per tooth will increase. You need to change your feed per tooth to the value you require, then your cutting feedrate will come down. This is a cam setting, not a linuxcnc one, as Tommy said. Hope this helps. Matt

OK So in F360 when I saw the "Surface Speed" reduce by over 3x because I dropped the spindle speed. I thought that was my CAM program saying "OK we need to move the table slower now to accommodate the slower spindle speed!" -But maybe I was wrong.

I'm at work right now but I will get some pics for you tonight when I'm home. If I'm understanding you properly, will I actually see a difference in the F codes when my CAM picks things up properly and adjusts for my spindle speed?

Yes, f values will change. I use a large machine with slow spindle speeds (1800 max). I find that good results can still be obtained using slower surface speed, if the correct feed per tooth is programmed. Saying that, would love to have a nice high speed spindle on her to get the small jobs done that little bit quicker.

Maybe I have something wrong with my CAM Setup in F360 then? I will try to get some pics for you guys and help you see what's happening. I do see it changing the "Surface Speed" but maybe that's not enough? You're saying that I should see it change the F codes in my .ngc file?

Maybe you are confusing the difference between "surface speed" and "cutting feed rate".

"Surface Speed" is simply the circumference of your cutter times the rpm, and has nothing to do with how fast the tool is moved when cutting, just how fast it is spinning.

"Cutting feed rate" is the speed that the tool is moved around. (this is set by the F code in the G-code)

I think Todd may be on to something. The feeds and speeds are as he explains. 2 different things that need to work together. In your first post you mention letting fusion choose your feeds and speeds. Fusion doesnt actually choose anything. It has sample tools with default feeds and speeds, but for best results, you need to modify them to the values reccomended by the tooling manufacturer (as a starting value), to suit your machine, machining conditions and material you are using. Most tooling catalogues have alot of useful information regarding this. When i started with fusion, i watched NYCCNC's you tube channel. He also has alot of general machining info as well as fusion tutorials. Good luck. Matt

Hahaha, that makes me feel better Andy. Im sub'd to your youtube chanel, thought that was something that i might be able to do if we ever needed the high RPM. We have got a BT50 spindle speed increaser with 1:4 ratio, which works well enough for small end mills that can use a bit more surface speed. Its a large 6m bed mill that isnt really designed for high speed small stuff, but every now and then, we get a large job that needs small slots and things. Your spindle setup would probably come in handy. What do you think of it (quality, power)after having it for a little while now?