MPCNC with Double Belt Setup

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This topic contains 42 replies, has 17 voices, and was last updated by  Leon 6 hours, 31 minutes ago.

Viewing 13 posts - 31 through 43 (of 43 total)
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  • #72628

    Aaron
    Participant

    2) I use a helix with a low angle to ramp down into the material, however, especially in steel, that causes a lot of chatter. What do you guys use for metals like aluminum or even steel?

    Amazing results, bravo!

    If you have trouble with plunging, what you could do is to first use a regular drill bit for making a hole, and then come back with a milling bit to do the rest, starting from this hole.

    I think that’s pretty much the only method unless you find some kind of fancy bit.

    Actually, I think that’s what he’s doing now, that’s where I got the idea to try it out on my own machine.

    #75791

    Leon
    Participant

    I didn’t found much time in the last weeks to work on my MPCNC, so sorry for the lack of updates.

     

    2) I use a helix with a low angle to ramp down into the material, however, especially in steel, that causes a lot of chatter. What do you guys use for metals like aluminum or even steel?

    Amazing results, bravo!

    If you have trouble with plunging, what you could do is to first use a regular drill bit for making a hole, and then come back with a milling bit to do the rest, starting from this hole.

    I think that’s pretty much the only method unless you find some kind of fancy bit.

    Actually, I think that’s what he’s doing now, that’s where I got the idea to try it out on my own machine.

    Exactly, except that I can’t use regular drill bits as these are too long for my machine. However single flute end mills seem to work just fine for that.

     

    Atleast I did some progress over the last weeks, the z-axis finally got a cable chain:

    DSC06098

     

    And the electronics found a home in an old computer case:

    DSC06099

     

    The front and back panel are 0,8mm sheet metal, obviously cut on the MPCNC. I did one test cut with thick paper first and then adjusted some distances. The final part fits beautifully:

    DSC06100

     

    3 users thanked author for this post.
    #87327

    Thorsten
    Participant

    Hi,

    I am currently going for the Mafell as Spindle since they optimized it for 71db loudness. Which tool holder did you use? The Mafell is a bit wider than the rest so I feel like most 43mm tool holders might not fit…

    thanks in advance

     

    Thorsten

    #96664

    c0
    Participant

    I have operated a CNCrouterparts CNCPro machine milling 6061 aluminium sheet metal (2mm-10mm thick).  Our magic formula for success:

    • Amana tools 51373 single ‘O’ flute cutter 1/8 inch dia, 5/16 inch cutting height, 1/4 inch shank (ToolsToday USA)
      [!] Highly recommended (am not affiliated with either Amana nor ToolsToday).
    • 18000RPM spindle speed.
    • 1300mm/min (50 inch/min) feedrate.  Increase to 1600mm/min (65 inch/min) if stable.  Probably want to halve these values for a MPCNC.
    • Too slow feedrates will dull a cutter.  Too high feedrates will break a cutter.  I’d rather dull a bit over time than break it straight away, so best to go slow at first.
    • Lead in/out feedrate = 50% of feedrate.
    • Plunging feedrate = 25% of feedrate.
    • 2mm depth of cut.
    • 1 or 2 finishing passes.
    • [!] Isopropyl alcohol mister (use a simple spray bottle to continuously spray a mist over the cutter whilst cutting for cooling as aluminium gets very sticky/gummy when hot and tends to weld itself to the cutter).
    • [!] Fusion 360 > 2D Contour operation > Geometry > Select “Tabs” > Triangles instead of rectangles (triangle slope = less plunge = less wear on cutter).
    • [!] Fusion 360 > 2D Contour operation > Passes tab > Select “Passes” > Left (Climb milling).  Do not select Right (Conventional milling)
    • [!] Fusion 360 > 2D Contour operation > Linking tab > Select “Ramp” > Ramping angle: 20 degrees.
    • Screw down sheet onto spoilboard around perimeter (50-100mm distance between screws) and in center of some of the larger shapes being cut out as otherwise chips will make their way underneath sheetmetal and lift the sheet causing excessive vibration if not careful.
    #111983

    Josef Mouris
    Participant

    Hi all, first post here and just to let you know I tried to make Tom Sanladerer aware of this double belt system. I feel like this really could be something good without having any experiences with it.

    After doing that I started thinking….. the belt that is basically just double sided taped on to the angle iron is flat. It never bends. It is also held by the clamps at each end, right? (Could use a tensioning device)

    And the main argument against steel core belts is they don’t like bending back and forth right?

    So I was thinking about a total re-design. Why not tension / tape  a steel reinforced belt onto a 1 X 1/2” box section. Use 12mm wide belt on the 1/2” side. On the other side you have a set of bearings. Run a 15mm wide motor output pully wheel directly on the top. This is the 4 sides done. Still use the same 25mm stainless steel tube core setup. The box section is actually cheaper then the stainless tubing, fairly smooth and has some weight to it. No belts get bent so can be steel core and tensioned to the max.

    Your thoughts welcome…. will do a drawing when time permits.

    #112036

    Barry
    Participant

    Hi all, first post here and just to let you know I tried to make Tom Sanladerer aware of this double belt system. I feel like this really could be something good without having any experiences with it.

    After doing that I started thinking….. the belt that is basically just double sided taped on to the angle iron is flat. It never bends. It is also held by the clamps at each end, right? (Could use a tensioning device)

    And the main argument against steel core belts is they don’t like bending back and forth right?

    So I was thinking about a total re-design. Why not tension / tape a steel reinforced belt onto a 1 X 1/2” box section. Use 12mm wide belt on the 1/2” side. On the other side you have a set of bearings. Run a 15mm wide motor output pully wheel directly on the top. This is the 4 sides done. Still use the same 25mm stainless steel tube core setup. The box section is actually cheaper then the stainless tubing, fairly smooth and has some weight to it. No belts get bent so can be steel core and tensioned to the max.

    Your thoughts welcome…. will do a drawing when time permits.

    So basically a poor man’s rack and pinion setup?  How do you keep it tight to the belt?  That’s why we wrap the belt around the gear now, so it can’t slip.

    #112198

    Josef Mouris
    Participant

    Yes, a bearing or two on the other side should take care of that. As long as the box section is fairly uniform in size it wouldn’t skip on the belt. The last bunch I had in my workshop for a completely different purpose was very smooth.

    See the quick and dirty sketch.

    #112212

    Jamie
    Participant

    With a large pulley I can see this working, but I agree with Barry, at least for a small pulley this might be trouble.

    As it happens, I am contemplating alternatives to reduce belt stretch, so this is something I’m interested in.

    You might be able to make a little “tank tread” with a short closed-loop belt running inside-out.  This is an awful drawing but trying to show the bumpy side is the side with teeth.  There would be three idlers.  The drive gear has a healthy amount of wrap, and the track has plenty of engagement with the tank tread.

    tank_tread

    Attachments:
    #112241

    Leon
    Participant

    Hey,

    it took some time, but here’s the latest update of my MPCNC:

     

    combined

    Enclosure made with 20mm aluminum profiles and 4mm acrylic (still with protective cover). Table welded from 50x50x3mm steel.

     

    DSC06943

    Electronics cabinet features two RAMPS-controlled 230V outlets for the spindle and compressor. The RAMPS/Arduino board can be connected to an external laptop or to the included Raspberry Pi which runs cncjs.

     

    DSC06940

    I think adding an air blast is one of the best things one can do, at least if the machine is used mainly for aluminum. It’s really nice to be able to let the machine do its job without babysitting it the whole time and vacuuming chips.
    If you look closely at the carriages, you can spot some wipers on the steel rails. I machined a lot of plastic and the chips tend to get stuck on the rails, where they would be compressed by the bearings. This causes the motion to get really rough and left marks in the parts. The wipers kept away the majority of those chips and are essentially just a small plastic part with some cloth on the inside.

     

    As you may have noticed, I removed the double belt. It worked ok for some time, but then the glued belt started to curl up at some places. Additionally, as I have already mentioned in a previous post, it’s not really easy to tension the belt. Too little tension -> loose belt. Too much tension -> the angle iron will be pushed down and the two belts don’t engage each other anymore.
    I did try a few different designs, but in the end I just wanted to be able to use the CNC and not tinker with it anymore. Therefore it now has a single 9mm belt. And to be honest, I don’t see any difference to the double belt. Backlash is the same (0,03-0,04mm) and rigidity also didn’t changed noticeably.
    I still think that a double belt is an interesting drive mechanism, but the MPCNC just isn’t the right use case. Just look what Bell-Everman is doing with their double belt system.

    1 user thanked author for this post.
    #112251

    Barry
    Participant

    Just throwing this out there.  You want the belt on the bottom.  Chips will settle on it otherwise.

    #114011

    Bill
    Participant

    Dang, I like the look of a well done wiring job. I wish I had the patience to do it myself. 🙂

    #114558

    Andreas Eicher
    Participant

    Hello Leon

    Nice work there!

    I have printed the original and the double belt parts from your videos on youtube.

    Now I see you have changed it back to single belt, are the belt tensioners you use made for your double belt corner?
    Can you upload this on thingiverse too?

    THX MAN!

    #115044

    Leon
    Participant

    Can you upload this on thingiverse too?

    Here you go: https://www.thingiverse.com/thing:3875362

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