First build - large Hex framed Delta - 3DR Mega style March 13, 2016 07:47PM |
Registered: 8 years ago Posts: 177 |
Re: First build - large Hex framed Delta - 3DR Mega style March 13, 2016 08:31PM |
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Re: First build - large Hex framed Delta - 3DR Mega style March 13, 2016 10:29PM |
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Re: First build - large Hex framed Delta - 3DR Mega style March 13, 2016 10:47PM |
Registered: 9 years ago Posts: 475 |
Re: First build - large Hex framed Delta - 3DR Mega style March 14, 2016 12:03AM |
Registered: 8 years ago Posts: 177 |
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dc42
That's going to be a nice machine! A few suggestions:
1. Do not use printed corners, they are not rigid enough for a large printer.
OK 240v heater it is, I better add a DC/AC SSR into the parts list then....I do Christmas lighting for a main hobby, and never run "smaller" supplies, the smallest I have for general duties is 350WQuote
dc42
2. Yes use a 240V bed heater. That in turn allows you to use a smaller 24V power supply to power everything else.
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dc42
3. Nema 17 vs Nema 23: I guess it depends on the mass of your flying extruder. Without a flying extruder, Nema 17 motors should more than adequate, unless you think the greater belt mass is going to be a problem.
So would a "long" Nema 17 be better? Can I go to 28V to the board? (have plenty of 27V supplies then can easy go to 29V)Quote
dc42
4. The existing Duet should in theory be able to drive 1.8deg/step Nema 23 motors with a low enough current rating (below 2A) using a 24V supply, however you might not achieve such high speeds as with Nema 17 motors. Don't try to drive 0.9deg/step Nema 23 motors from the Duet, because I expect they would need more than 30V to reach reasonable speeds. The next-generation Duet will probably have drivers rated at a higher current than the existing Duet, but it will still be limited to about 30V.
Or you can use external DSP-based drivers attached to the expansion connector of the Duet.
Interesting idea and I like the concept but that heads back to the Bowden feed and it's (imo) various issuesQuote
dc42
5. Another possibility: instead of a flying extruder, as you have 3 spare vertical towers, put another stepper motor, belt and carriage on one of them, and attach the extruder to that. The firmware would need to be changed to keep the extruder at a sensible height depending on the effector XYZ position.
Re: First build - large Hex framed Delta - 3DR Mega style March 14, 2016 12:14AM |
Registered: 8 years ago Posts: 177 |
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PRZ
Plastic corners cannot give you bending stiffness, but if you stabilize the printer either by bolting panels or making a cross-bracing, they will be sufficient. The hexagon design is quite practical for that.
I am for panels because I prefer enclosed printers, especially if you print ABS. Also, heavy wood panels dampen vibrations and noise.
In principle, the height of a flying extruder don't vary much because as an average, the height of the effector vary very slowly.
So, their inertia is somewhat negligible for loads, you only have to live with their dead load. You can probably get an extruder for 250/300g all included, which could be easily lifted by Nema17, because one column will rarely carry more than 40% of the effector weight.
With standard boards, I am for Nema17, because you cannot improve with Nema23, and lose microstepping precision (the microstepping intervals are said being more accurate on Nema17 than Nema23). If you get in trouble, limit the travel movement speed.
Also, I am for larger minimim arm angle (say 23~25°) instead of usual 20°, which limit the maximum carriage speed at the cost of slightly longer arms. That is also better for printing accuracy at large diameter.
If using traxxas style links, you shall find a mean to increase friction, as this dampen vibration and limit banding effects. spring between arms is not elegant, but that helps.
You may use ball and socket from Igus, they have way too much friction for a normal delta, but that may do the trick for a large unit and being all plastic, they are very light.
You may have a look at the italian Wasp printers, they exist in large size, use flying extruders and Igus components. They are near of what you want to do.
Also, some have developed light extruder for delta with small steppers, but that may limit the retract speed.
If really at the limit, you may slightly increase the voltage near the board maximum (30V) , but I may be afraid of back EMF from steppers.
For a 24V setup, use 12V fans, that is easier to handle. A DC/DC converter cost nothing.
Re: First build - large Hex framed Delta - 3DR Mega style March 14, 2016 12:19AM |
Registered: 9 years ago Posts: 916 |
Re: First build - large Hex framed Delta - 3DR Mega style March 14, 2016 12:24AM |
Registered: 8 years ago Posts: 177 |
Re: First build - large Hex framed Delta - 3DR Mega style March 14, 2016 12:36AM |
Registered: 8 years ago Posts: 177 |
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nebbian
Flying extruders are excellent, especially if you want quality prints. The extruder itself doesn't really move when the effector does, it just sort of stays in the middle and tilts. It gives you the benefit of a short bowden cable, without the moving mass of an effector-mounted extruder. About the only downside is that they look a bit weird.
Another option is the flex3drive, but that is quite an expensive solution that I haven't tried.
What nags me on every video i've watched is either the tilt that must impart some pull and potential tilt on the effector. I just can't get my head around how if the bowden tube is short enough in the 4 to 6 inch range that the mass of the extruder then becomes more than loosely coupled to the effector. This of course is a non issue for short infill work or continuous outline work but surely becomes an issue for fast moves around the bed?Quote
nebbian
The extruder itself doesn't really move when the effector does, it just sort of stays in the middle and tilts.
Re: First build - large Hex framed Delta - 3DR Mega style March 14, 2016 02:27AM |
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Re: First build - large Hex framed Delta - 3DR Mega style March 14, 2016 07:56AM |
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Re: First build - large Hex framed Delta - 3DR Mega style March 14, 2016 08:51AM |
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Re: First build - large Hex framed Delta - 3DR Mega style March 14, 2016 10:19AM |
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Re: First build - large Hex framed Delta - 3DR Mega style March 14, 2016 10:40AM |
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Re: First build - large Hex framed Delta - 3DR Mega style March 14, 2016 05:46PM |
Registered: 8 years ago Posts: 177 |
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PRZ
Ok, I made some exercise to see viability of system
first , one of the best online calculator for beam is here :
[skyciv.com]
two rods of 20mm have a bending inertia of 15700 mm4
an angle of 40x40x3, rotated 45, in its weakest orientation, does have an inertia of 14500 mm4, nearly the same of your two rods, at a fraction of the cost and weight.
But thats a bit too small for your machine, so I made calculation for 50x50x3 , which gives me 28800 mm4.
A bit surprised, I checked those number on old paper tables, and they are ok.
I have no data for rotated square tube, but you may have similar or better bending stiffness with a square tube 30x30x2 (delta pi is 20x20x2)
.
Re: First build - large Hex framed Delta - 3DR Mega style March 14, 2016 05:52PM |
Registered: 8 years ago Posts: 177 |
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GroupB
I have some original vslot and carriage and they really nice, but since you close to china .. I know robotdigg just get some vslot carriage, wheel and extrusion, I dont know about they quality but they are the exact copy of the american made one and so far robotdigg is a good china supplier with decent quality, you may want to try those, a least a sample to check the quality. Plus you can get your pulley and belts there and more (they have steel renforced or carbon gt2).
Re: First build - large Hex framed Delta - 3DR Mega style March 14, 2016 06:07PM |
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Re: First build - large Hex framed Delta - 3DR Mega style March 14, 2016 06:41PM |
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Re: First build - large Hex framed Delta - 3DR Mega style March 14, 2016 06:46PM |
Registered: 9 years ago Posts: 356 |
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aussiephil
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GroupB
I have some original vslot and carriage and they really nice, but since you close to china .. I know robotdigg just get some vslot carriage, wheel and extrusion, I dont know about they quality but they are the exact copy of the american made one and so far robotdigg is a good china supplier with decent quality, you may want to try those, a least a sample to check the quality. Plus you can get your pulley and belts there and more (they have steel renforced or carbon gt2).
My only concern about ordering lengths 1600 to 1800mm long direct from China is I've seen how parcels generally arrive from China (I buy a fair bit of other stuff) and I would be worried about bending and dents.
GT2 10mm Steel reinforced belt has been ordered and shipped just so I can get hands on it
Re: First build - large Hex framed Delta - 3DR Mega style March 14, 2016 06:53PM |
Registered: 9 years ago Posts: 475 |
Re: First build - large Hex framed Delta - 3DR Mega style March 14, 2016 07:00PM |
Registered: 8 years ago Posts: 177 |
Quote
GroupB
Quote
aussiephil
Quote
GroupB
I have some original vslot and carriage and they really nice, but since you close to china .. I know robotdigg just get some vslot carriage, wheel and extrusion, I dont know about they quality but they are the exact copy of the american made one and so far robotdigg is a good china supplier with decent quality, you may want to try those, a least a sample to check the quality. Plus you can get your pulley and belts there and more (they have steel renforced or carbon gt2).
My only concern about ordering lengths 1600 to 1800mm long direct from China is I've seen how parcels generally arrive from China (I buy a fair bit of other stuff) and I would be worried about bending and dents.
GT2 10mm Steel reinforced belt has been ordered and shipped just so I can get hands on it
They dont use china post, they use DHL, Fedex and similar service. You can also ask robotdigg to put the extrusion in a solid shipping tube I bet they could do that
Re: First build - large Hex framed Delta - 3DR Mega style March 14, 2016 07:05PM |
Registered: 8 years ago Posts: 177 |
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PRZ
AussiePhil, where did you get the GT2 10mm width (and pulleys) ?
Pierre
Re: First build - large Hex framed Delta - 3DR Mega style March 28, 2016 07:06AM |
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Re: First build - large Hex framed Delta - 3DR Mega style March 29, 2016 08:19AM |
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Re: First build - large Hex framed Delta - 3DR Mega style March 29, 2016 01:58PM |
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Re: First build - large Hex framed Delta - 3DR Mega style March 29, 2016 07:14PM |
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Re: First build - large Hex framed Delta - 3DR Mega style April 10, 2016 09:37AM |
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Re: First build - large Hex framed Delta - 3DR Mega style April 10, 2016 10:43AM |
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Re: First build - large Hex framed Delta - 3DR Mega style April 14, 2016 05:11AM |
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Re: First build - large Hex framed Delta - 3DR Mega style April 14, 2016 06:53AM |
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