Maching Maximums.

This topic contains 8 replies, has 3 voices, and was last updated by  Ryan 4 months, 1 week ago.

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  • #31076

    Christopher
    Participant

    I was wondering what you guys push your machine to do as far as feed rates and depth per cut when it comes to plywood/wood. And what type of spindle you use.

    I designed a tealight holder for my wife. It’s 300mm by 80mm, cut into 3 sections. Fusion 360 estimates my toolpaths as taking 4+ hours at 400 mm/min with a depth of cut at 3mm. That doesn’t seem right. Granted there’s 5 pockets, 38 mm round and 14mm deep. Maybe I’m just choosing inappropriate toolpaths but I have a feeling I may be just babying the machine.

    #31077

    Ryan
    Keymaster

    How did you come up with those numbers? What are the dimensions of your machine? What spindle? What diameter , how many flutes, what style is your cutter?

    MAybe a picture of your estlcam screen so we have a better idea of the parts being cut.

    There are obviously tons of variables and I can’t just give you exact numbers, but I feel you are going slow and shallow, but please fill in some of the details before you just start changing things as maybe it is what is appropriate for your machine. If you watch any of my videos I list my specs and speeds all of which are much faster. Also if you start using mm/s it really might help to visualize the speed. 400mm/min is more difficult for me to understand than 6.6mm/s but again maybe that is just me.

    #31087

    Jeffeb3
    Participant

    That seems like a really long time, even for 400mm/min.

    I was just cutting the front/back of the MP3DP at 15mm/s, 1mm per pass and it’s about 225mm,45mm. I cut to 13mm deep. It took ten minutes.

    There are no pockets in it. Still even if your part took 2.5x longer, it would be done in 25 minutes, which is off by a factor of 10 from 2 hours.

    Is there a preview in fusion 360? You aren’t surfacing the entire piece or something are you? Do you have a good grasp on the step over on your pockets? You could be spending too much time there.

    #31121

    Christopher
    Participant

    Let me try to answer as many questions as possible.

    My numbers? – Totally winged them. Feeds and speeds confuse me no matter how much I read
    about them.
    Machine size – 42″ by 24″ And I don’t see any flex.
    Endmills – 1/8 & 1/4 2 flute spiral Flat nose endmills, 1/8 2 flute spiral Ball nose endmill.
    Yes, all three were used. 1/4 for larger pockets, 1/8 flat for small pockets that
    fusion wouldn’t do with the 1/4. And Ballnose for the fillet on the top piece.

    I don’t use Estlcam. I could never get the hang of it.

    Spindle is a harbor freight knock off of the 660. I’ve never had it bog down.

    I am not surfacing the entire piece. There is three pieces of cabinet grade ply that will get
    doweled together. All three pieces stay their original thickness. Just pockets and a 2mm fillet on the top piece.

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    #31123

    Jeffeb3
    Participant

    Oh, I thought it was one piece about 300×80.

    It does seem that with the speeds and depths you mentioned (400mm/min and 3mm per pass), my back of the envelope estimate is 45 minutes without the pockets. The pockets definitely will add in a lot though. 3.5 hours seems like too long for those pockets.

    The rough computation is (300+80+300+80) * 5 cuts deep * 3 parts / 400 mm/min =
    28 minutes. Multiply by 1.5 to add in a bunch of travel and acceleration stuff.

    What I meant about surfacing is: I remember a fusion tutorial where the CAM automatically tried to treat the part as 2.5D and it wanted to mill the entire top surface. That would add up quickly. I was wondering if you’ve seen the simulation, or another drawing of the gcode (in repetier perhaps) to look for anomalies like that.

    Maybe one of the numbers I have is wrong.

    #31125

    Christopher
    Participant

    Fusion WILL do that if you have a top offset enabled. I turn it off and reset it to 0 mm. With it anytime you do an adaptive clearing toolpath it automatically wants to shed that offset off the topside of the workpiece before actually performing your true cut. The default is 1mm.

    4 hours seems ridiculous. I could pop a forstner bit in my drill press and crank these out quicker while still having to measure everything and map out my centers.

    #31131

    Jeffeb3
    Participant

    It sounds like you have your cam knowledge under control. The numbers just don’t add up to me. I don’t want to put words in Ryan’s mouth, but I think he’s also saying you could probably go faster.

    Another option is to just mark the center for your forstener bit with a little hole. Also, cutting out the hole entirely is faster than pocketing.

    #31162

    Christopher
    Participant

    What’s the max speed for the movement of the X and Y before the arduino chokes out? It’s got to be somewhere in the 800 mm/min range.

    #31200

    Ryan
    Keymaster

    I have the firmware max at 190mm/s. There is math behind this shown here, at the end https://www.vicious1.com/software-updates/.

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