Need help with settings

New Home Forum Getting Started Cut Speeds and Settings Need help with settings

This topic contains 7 replies, has 5 voices, and was last updated by Profile photo of Mike Mike 1 month, 4 weeks ago.

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  • #19157
    Profile photo of Mike
    Mike
    Participant

    Hi,

    I’m trying to mill out 3d shapes from planks of pine using Fusion 360, however I’m really unsure what speeds I should be using for things.

    All of the formulas I’ve seen online require you to know what RPM you’re using first. How do you decide what RPM to use? My Kress 800 FME doesn’t have a digital RPM display (it just has a dial) so I can only really guess what RPM I have. Is that accurate enough?

    I’m using an 8mm flat carbide end mill and my spindle does between 10,000 RPM and 29,000 RPM. What would be the best settings for me to use to do pine?

    I’m getting confused because the terminology in fusion is a bit different from estlcam. In fusion I have the following fields:

    Spindle speed (RPM)
    Surface speed
    Cutting feedrate
    Lead-In feedrate
    Lead-out feedrate
    Ramp feedrate
    Feed per tooth
    Plunge feedrate
    Feed per revolution

    A lot of the guides I’ve seen online say things like “Make sure you use a conservative/sensible value”, but nobody says what a sensible value is 😉

    Any advice would be hugely appreciated

    #19186
    Profile photo of PJM
    PJM
    Participant

    I’m in a similar boat. I’ve looked up the bits that I have for the required feedrates, chip load, etc.

    As an example:

    – Onsrud (40-100 series) 1/8″(3mm) upcut 2 flute bit,
    – Cut depth same as bit diameter (3mm),
    – Chip load for softwood .005-.007 (use .006),
    – My router is 20-24krpm (use 20krpm),
    – (Feed rate) Inches Per Minute (IPM) = RPM x # of cutting edges x chip load = 20000 x 2 x .006 = 240 IPM
    – 240 IPM x 0.423333 = 101.6 mm/s

    At .005 chip load this would work out to 84.67 mm/s and at the high end of .007 it would be 118.53 mm/s.

    I’ve tried it and it’s very fast. Are people following manufacturer specs for bits or are they slowing things down intentionally? What is recommended?

    #19188
    Profile photo of vicious1
    vicious1
    Keymaster

    If you are unsure you should follow the estlcam guide. It is free, and simple. Fusion is not for beginners. If you follow my guides you will see the numbers I use, or others on their videos. When you get the hang of it and have a sense of things then try out fusion.

    I would start with a much smaller bit, 3mm is good to learn with and very forgiving. 8mm is more of a roughing bit.

    You will see for all my cuts I use between 12-20mm/s on a 1/8″ bit and vary the depth of cut and spindle speed depending on material. If you are really new to this a single flute bit is even more forgiving and more suited to our high spindle speeds and machine rigidity

    #19189
    Profile photo of vicious1
    vicious1
    Keymaster

    You are going too slow if your material is melting or burning, too fast if your cut is ugly or you break something. Start with a 2D pen drawing, then mill some foam, then soft stuff like pine. By then you will probably have a good sense of what it should sound and look like while it is cutting. Experience is key, Hard numbers are not given by many because every machine will require something different.

    #19207
    Profile photo of wichitapilot
    wichitapilot
    Participant

    I second Ryan’s advice on this. Experience and testing are key factors. Once you have done some testing you will know what a good cut sounds like. Personally I do not follow the suggested equations for the tools just for the fact that I am not comfortable with my machine moving that fast. I use Fusion 360 a lot and really like it. There are some settings that are mentioned in the first post that either don’t matter (Spindle RPM) or they are calculated based on some of the other inputs. I would only worry about:
    Cutting feedrate
    Lead-In feedrate
    Lead-out feedrate
    Ramp feedrate
    Plunge feedrate
    Here is what I do for Pine:
    1/8″ Up or Down cut 2 Flute End Mill
    Depth of Cut: .1
    Cutting Feedrate: 35 in/min
    Lead in and out feedrate: 13 in/min
    Ramp and Plunge feedrate: 13 in/min
    I have a Dewalt 660 and a speed controller and I am guessing that I am running it at about 16k – 18k.

    Let me know if I can offer any advice for Fusion 360.

    #19246
    Profile photo of Mike
    Mike
    Participant

    Great, thanks for the advice.

    After 12 hours of messing around with trial and error in Fusion 360 I seem to have found my machines limits for the wood I’m using, although I’m still struggling to judge how to balance the relationship between “depth of cut” and “cutting feedrate”. Is it better to do for deeper cuts at a slower speed or shallow cuts at a faster speed? 🙂

    As for Fusion – I’m loving it so far. A few dodgy tutorials on YouTube sent me down a bad direction to start with, but I’m starting to understand it much better now. I love being able to define various strategies for different parts of the model.

    Unfortunately, my better half has banned me from playing with it until I get the dust issue sorted, so I guess everything is on hold for a while 🙂

    #19247
    Profile photo of Barry
    Barry
    Participant

    You need a dust shoe.

    #19261
    Profile photo of Mike
    Mike
    Participant

    Yup! Working on one now. 🙂

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