Delta experts: feedback appreciated



  • I wanted a delta with aluminum top plates (instead of aluminum corners with extrusions), linear rails and a 4th axis for a flying extruder. There are various designs out there like this one, but none of them fit my needs exactly, so I am making my own design.

    Specs:

    • Duet, Smart effector, Magball arms.
    • 240mm heated bed.
    • 2060 700mm extrusions.
    • 600mm MGN12H rails & carriages.
    • E3D Gates 6mm belts, 16t pulleys.
    • 5 or 6mm aluminum plates on top and bottom.

    To do:

    • design endstop mount.
    • design idler mount (16t motor pulley fixed on a 5mm axis riding on bearings).
    • design bed mount.
    • design 4th axis parts.
    • insert smart effector, carriages and magball arms into design.

    I have already built a V1 without the flying extruder axis. This design builds on some errors I made in the V1.

    Tonight I am going to (try to) insert the effector + arms into the design (so they are moveable in Fusion).

    I don't have an engineering background and am learning Fusion360. So all feedback is appreciated: https://a360.co/2BoJbIp



  • I'd use 9mm belts. They are about half the stretch of 6mm belts.

    9 (or 10) mm pulleys and idlers and such are a tiny bit hard to find, but if you keep searching they are out there.

    What is your plan for diagonal bracing? That will do MUCH more than the heavy extrusions and top/bottom plates.

    And, last, see if this does you any good. May or may not because your plate based design may not match any of the corner choices. Still, it will give you a rough idea of bed / arm / tower relationships.

    http://danalspub.com/DKcalc/?he=655&ve=1500&dr=720&lr=1000



  • Here's a link to my build. I had the same specs except for the 4th axis for the extruder, my verticals are longer, the bed is larger.

    The idler bearings were an issue, I went through 4 iterations. Basically nothing would be "proper" until I came up with this.

    Also I don't mind if you totally take my endstops.

    As far as the bed mount, I'm doing something similar but with 3 points and the slots are in the mounts themselves. I would change this however.

    I'll be doing a kinematic mount.

    https://cad.onshape.com/documents/92c6e4f3dd6190ac11f6da6d/w/0a9aab1733ca8499a69fa3d0/e/2379fd41a484d79fff420d7c



  • @Danal Thanks for looking. I realise 9mm belts would be better, but I already have all the 6mm e3d gates parts. Would be a shame to put them away.

    I don't have any plans for diagonal bracing. I chose these extrusions because the rails fit right in the middle, and 2020 is too fragile. I could try to come up with something if it really is necessary.

    I have used your site a lot to figure out the relationships of the design. They were very helpful.



  • @blt3dp Wow, almost the same design, except you have the motors on the bottom. Thanks for the link. I just used it to measure the distance between your bed and the towers: yours is 74mm, mine is 75mm. So I must be on the right track.....



  • Hi, what exactly are you missing in standart kossel style designs?

    I have frankensteined together a delta over the year based on a kossel and i noticed that all the different systems (rails, arms, effector, flying extruder etc) dont interact much, meaning I can freely (re)design every system without risking the intergrety of the whole printer.

    If you want alu top plates, that should only effect the way your belts idlers and motors are fastened to the plate. endstop mounts you'll find many designs in the usual places, same with bed mounts.

    Looking at your design: I like the frame with the 5 pillars. That looks robust and probably doesnt require crossbracing. Although a frame can never be ridgid enough and crossbraching with wires is easy and cheap.
    The only thing im asking myself here is: isnt that frame expensive? the 2 extra extrusions + two heavy alu plates?

    Cheers 🙂



  • @sungod3k I just wanted something I designed myself really. Just going through the design process and learning Fusion is a lot of fun (for me). I just noticed that in my design the arms would stretch out over 20deg on the edge of the bed. Just took me a little effort to correct that.

    Also, with fewer parts, cut to exact dimensions, I know the frame is easier to square.

    The frame itself isn't expensive. The V1 plates only cost me €15 (the alu corners from robotdigg cost me more than that) and the 700mm extrusions are €8,70 a piece (V1 had 3 extrusions). It's the rest of the parts that add up to the costs.



  • I see, there are 2 or 3 different calculators to check the min arm angle, but with your detailed model you can see right away what the angle is in any position. Just make the footprint smaller until you reach 20deg.

    As for learning fusion, thats indeed the right way to go. I am still tweaking parts here and there^^

    Mind sharing the link to the alu plates? when i look on ebay everything over 2mm thickness is super expensive 😄



  • @sungod3k Yes, that was great. I only saw that today after creating ball joints. I moved the hotend to the edge of the bed opposite the tower and could just read the arm angle. Great stuff. I already modified the dimensions, but it messed up my effector assembly. Will redo that tomorrow.

    Sorry, don't have a link to aluminum. A friend cut the parts for me, and charged 15€ including material. I guess for him they were small scrap parts.



  • I updated the design. Opposite the towers, the min arm angle is now 20.7deg. And towards the tower, at the edge of the bed I can barely fit a 4010 blower fan (1mm clearance to the belts). It all just barely works, and I really want to maximize the build volume.

    I am thinking of another way to mount the carriages, like this: https://a360.co/2BhIiRJ
    I would need to adjust the carriage, but I would provide some more room for cooling fans. Good idea or not worth the effort?



  • I am also thinking about a delta with alu top and bottom plate. I own a Rostock, and I cannot imagine anything being more rigid (unlike the rostock!) than screw-pulled direct alu to alu contact. Of course the cuts need to be very precise, but if they are there is really not a lot of room for play or mis-alignment. Even with just 3 verticals.

    The motors at the top is a good idea. Like the rails it keeps the belts short as possible. I would however make the the plates round. That makes it VERY easy to bend-fit a plexi or acrylic sheet between the V grooves, in a way they follow the curve of the plate. Easy chamber, without the need for hinges and mounting materials!



  • Making the plates round would be fairly simple, although I have no plans on making a chamber.

    Just updated again. Moved the carriage adapter in front of the belt. Now I have 23.6deg angle on the edge and more clearance near the towers: Minimum of 18mm between the edge of the smart effector and the belt.



  • I think I am almost done with th ebasic frame layout.

    I just received an email about the Zesty Nimble V2. I did have a nimble before, but wasn't 100% satisfied.
    Now I am in doubt about the extruder setup:

    • Fying extruder
    • Nimble V2
    • Or 4th axis extruder?


  • Drew up a first concept for the 4th axis extruder mount:

    Delta_small_v4_2019-Oct-21_09-10-24PM-000_CustomizedView28560289120.jpg



  • So, I would like some feedback/ verification:

    With a 240mm bed, I now have:

    • 25deg at the edge of the bed, opposite a tower
    • 85deg, at the edge of the bed, nearest a tower
    • 61deg in the middle of the bed.

    Are these numbers ok?



  • Yes, the "rule of thumb" limit on low angle is 20 degrees (and that always occurs opposite a tower). You are comfortably away from that. None of the other angles really matter.



  • @Danal Thanks, I thought I saw DC42 mention somewhere that the center or high angles can have an affect on resolution. But it's hard to find any info on that. Thats why I asked for verification.

    I can still put a 260mm bed in this setup, and the low angle then is about 22deg.



  • @bartolomeus said in Delta experts: feedback appreciated:

    I think I am almost done with th ebasic frame layout.

    I just received an email about the Zesty Nimble V2. I did have a nimble before, but wasn't 100% satisfied.
    Now I am in doubt about the extruder setup:

    • Fying extruder
    • Nimble V2
    • Or 4th axis extruder?

    I have used Nimbles on all my printers and they have worked well for me.

    What problems did you have?

    It would be much simpler than a flying extruder.

    Frederick



  • I would go big. 22 is fine.



  • @fcwilt said in Delta experts: feedback appreciated:

    @bartolomeus said in Delta experts: feedback appreciated:

    I think I am almost done with th ebasic frame layout.

    I just received an email about the Zesty Nimble V2. I did have a nimble before, but wasn't 100% satisfied.
    Now I am in doubt about the extruder setup:

    • Fying extruder
    • Nimble V2
    • Or 4th axis extruder?

    I have used Nimbles on all my printers and they have worked well for me.

    What problems did you have?

    It would be much simpler than a flying extruder.

    Frederick

    I never totally got rid of the wave pattern on the surfaces, even after I used the specified grease and also after they sent me a new worm gear.


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