Speeds and feeds questions

New Home Forum LowRider Troubleshooting – LowRider Speeds and feeds questions

This topic contains 5 replies, has 3 voices, and was last updated by  Ryan 1 month, 1 week ago.

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  • #102817

    Tyler
    Participant

    Trying to dial in my feedrate as I have had some problems with it in the past. I have been doing some searching and have come across some different information. Posted here in the milling basics there is a section that says we should be using climb milling, but, I have read multiple other places that, unless you have a very rigid machine, you should be using conventional. As far as feeds go I will attach a couple pictures. One one calculator I am getting 3mm deep, 45mm/s, at 16000RPM to get an optimal chip load. I have a feeling this will not go well and bind the machine up but it falls within that spec. Using the calculator in Milling Basics I get 3mm Deep, 21mm/s, at 21000RPM. I am going to be working mainly with particle board. What do yall run at?

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    #102819

    Ryan
    Keymaster

    3mm deep, 45mm/s, at 16000RPM

    Those are not the only variables. There is more to it than that. Chipload is a major factor as well.

    #102826

    Tyler
    Participant

    3mm deep, 45mm/s, at 16000RPM

    Those are not the only variables. There is more to it than that. Chip load is a major factor as well.

    As I understand it you can calculate chip load from those variables.

    Chip load = Feed rate/(RPM x Number of Teeth)

    Chip load = 106IPM/(16000 x 2)

    Chip load = 0.0033

    Edit: I should state this is your chip load at the depth of the diameter of your bit. Being this is a 3.18mm diameter bit the depth of cut would be 3.18mm.

    #102893

    Ryan
    Keymaster

    I know it seems a little backwards but I highly recommend you not use a calculator until you know what a good cut sounds like then you can use one to get close with a unknown material. That way you can plug in what works for your build and works backwards.

     

    You are giving no information about the size of your machine or spindle.

    If you insist on using the calc, adjust the setting on the first federate page. Make sure when the settings on all 4 pages are reasonable and the cutting load is under 1kg. There are 8 variables that I am counting. start with the Number I have on the basics, and only adjust the rest, keep an eye on the load.

     

    #102920

    Greg
    Participant

    FWIW I went down the rabbit hole of sinking a lot of time into calculators and formulas for feed speeds and experimented while cutting aluminum trying to get good chips ejecting without welding them to the mill, but my experience with MDF was similar.

    Short version is.. always use single flute mills and I don’t think the chip load calculations apply that well to the low rider. Long explanation follows.

    I had two issues.. first is to get recommended chip loading even with a single flute mill the recommended speeds possible with more rigid machines with spindles that can handle more force than the dewalt but the lowrider sometimes needs a fairly shallow cut depth to achieve these speeds. I’ve wondered if maybe this is not the best approach since all the wear is on the very tip of the mill plus a very shallow depth of cut can take longer.  Second, even at the lowest RPM the dewalt router can do you’re still needing to throw around the carriage pretty fast to get even the lower end of recommended chip load.. maybe too fast.    There is one similar router that you can set slower.. I think it’s a Makita.   There is also someone that makes a PID you can install on a router to have your board set any slower RPM you want.  You can go to a spindle but that’s opening up a whole other can of worms with water cooling or heavier spindles.

    Like Ryan says.. start conservatively and work your way up.   As you do you might see problems like burning, broken mills, skipping belts, etc.  but at least you are only dealing with one problem at a time instead of many.

    #102947

    Ryan
    Keymaster

    Nicely put. If I ever use the linked calc I just tweak all the settings and pay close attention to load. Once you know a good load your machine can handle the rest kind falls into place. I favor deeper cuts, for the endmills sake, and slower speeds.

    Router PID’s are nice, I do like mine but I would have to say they only really help squeeze a little more performance, 5-10%, out of the machine it lets you run safely near the raged edge. I don’t think I am going to sell any more of my design for a while, it needs a revamp to be more useful for our kind of use. Since we do mostly one off’s we need to have on the fly control with a knob or buttons not just Gcode.

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