Cutting steel with mpcnc

This topic contains 14 replies, has 4 voices, and was last updated by  Kevin Lopez 1 year, 1 month ago.

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  • #39766

    michael
    Participant

    As a step towards a printer like ability3d.com (steel 3d printer with cnc quality) i did a test cutting steel. I used a carbide endmill. Endmill would get red hot but was successfully cooled with a water squirtgun.

    The point of failure seems to be in the collet of the dewalt 660. When enough force is applied the endmill comes out of the collet. Another failure point seems to be the belts skipping and the motors not being powerful enough.

    Any thoughts?

    #39770

    Ryan
    Keymaster

    Hmmmm, I’ll just jump into two things here. Trying to break the record for hardest material cut with a MPCNC requires a much shorter machine, preferably shorter on all axis.

    You will need constant cooling, a lot of it. If your bit gets red even one time it is garbage.

    Manually feeding it will not work either.

    I am pretty sure you can drill steel with an MPCNC but cutting steel is going to take a perfect set of circumstances.

    #39771

    michael
    Participant

    did you see the video from 4:28? I’m cutting steel there albeit small cuts.

    Why is the bit garbage after getting red hot? Is it because of annealing?

    #39772

    Kevin Lopez
    Participant

    I did once cut some steel. Okay maybe not quite. I ground a flat spot on a super hard motor shaft. My file rubbed off of it indicating that it had to be really heat treated hard steel. I did it by clamping the motor and then manually jogging the bit slowly but surely. The result was what I wanted, it did carve out a perfect flat spot.

    I think the mpcnc can cut steel…but Ryan is right it will take some serious coolant and certain conditions. With really light trochoidal passes I think it can but not at a speed that would be worthwhile.

    #39773

    Ryan
    Keymaster

    You should try a Adpative/tricoidal type cut, a straight cut is the hardest cut to perform on any material as you are cutting with 50% of the bit adpative/tricoidal cuts with 25% or less, the part you want and gives you time to keep it cool and get the chips out of the way.

    Red means it has gone way to far past the point of no return. If you use a bit and it is permanently discolored it is probably worthless. When it gets to hot the the cutting edge is even hotter and instantly gets destroyed on contact.

    #39774

    Kevin Lopez
    Participant

    Had molten aluminum and tried melting it off over the stove…no go Lol. The carbide turned blue and I trashed it. I also tried 7075 aluminum which is basically the strength of mild low carbon steel. An endmill with a coating might help too.

    #39775

    Barry
    Participant

    did you see the video from 4:28? I’m cutting steel there albeit small cuts.

    Why is the bit garbage after getting red hot? Is it because of annealing?

    It will screw up the grain structure of the end mill. Carbide either needs zero coolant, or constant coolant. Going back and forth will break them. The rule with machining is the only thing that should ever glow is the chips. If the bit, or the part is hot enough to emit it’s own light, you’re doing it wrong.

    Fun fact, the stuff starts out as a powder.

    #39776

    michael
    Participant

    I bet that if we were to use nema 23s, either leadscrews or bicycle chain instead of the rubber belts, and dewalt 611 for the spindle we could get a serious steel cutting 3d printer and change the world.

    #39777

    Ryan
    Keymaster

    I doubt it.

    #39778

    Kevin Lopez
    Participant

    There has been a lot of talk on nema 23s. That’s not the bottleneck of the system. You will get some nasty deflection before you run out of torque.

    #39779

    michael
    Participant

    I doubt it.

    Well if the stock mpcnc is already cutting steel albeit with very small cuts then a nema 23 with leadscrews or bicycle chains and dewalt 611 can only get better.

    #39782

    Ryan
    Keymaster

    If you can get it to work I would love to see it. It is just not one of the things I want to spend any time on right now.

    #39783

    michael
    Participant
    did you see the video from 4:28? I’m cutting steel there albeit small cuts.

    Why is the bit garbage after getting red hot? Is it because of annealing?

    <span class=”et_quote_sign”></span>

    It will screw up the grain structure of the end mill. Carbide either needs zero coolant, or constant coolant. Going back and forth will break them. The rule with machining is the only thing that should ever glow is the chips. If the bit, or the part is hot enough to emit it’s own light, you’re doing it wrong.

    Fun fact, the stuff starts out as a powder.

    <iframe src=”https://www.youtube.com/embed/95yS7W66-BI?feature=oembed&amp;wmode=opaque” frameborder=”0″ allowfullscreen=”” name=”fitvid1″></iframe>

    amazing stuff

    #39784

    michael
    Participant

    There has been a lot of talk on nema 23s. That’s not the bottleneck of the system. You will get some nasty deflection before you run out of torque.

    The forces with the 1/8 endmill are actually pretty small. I havent noticed deflection. I do plan on making steel cast parts in case of deflection.

    #39792

    Kevin Lopez
    Participant

    Should of been more specific. I meant deflection of the whole machine pretty much. The bit will barely deflect cause well, it’s carbide and were not pushing them that hard. For example, I cut aluminium 1/4 inch in one pass. (6.35mm doc) and never even get close to running out of stepper power. And that’s not even with the steppers or drivers getting hot.

    Idk you can try it and show us but if you want to cut faster I don’t think the steppers are what’s holding you back.

    Cast parts would be pretty neat.

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