Monday, 20 July 2009

HydraRaptor's second child

Back in March I had a visit from Marcin Jakubowski, the founder of Open Source Ecology. He was over here in Manchester presenting at a conference and asked if he could come and see HydraRaptor, as he wants to use RepRap machines on Factor e Farm. Like RepRap, his project also aims to change the world.

He asked lots of questions and made a couple of videos of my answers for his blog, which you can see here.

I volunteered to print a set of Darwin parts to help get Factor e Farm up and running with 3D printing. I was confident that I would have my Darwin running in time to churn out the parts. However, because I spent a lot of time experimenting with extruder designs in an attempt to get something more reliable, I ran out of time and had to print the parts on HydraRaptor.

Here they are, all 109 of them: -



All the parts were printed with 0.5mm filament at 16mm/s with 32mm/s moves. Most were sliced with Skeinforge set to 25% fill and larger objects have double outlines to maintain strength.

Here are some stats: -


Build time Plastic volume Quantity required Total build time Total plastic Weight Cost Percentage of total

Corner bracket @ 90%
02:44:44 29.1 cc 8 21:57:49 233.1 cc 291 g $5.83 29%
Diagonal tie bracket-chris

00:27:00 4.8 cc 20 09:00:06 96.4 cc 120 g $2.41 12%
Bed corner
01:32:06 15.5 cc 4 06:08:25 62.1 cc 78 g $1.55 8%
Z-motor-bracket-chris
01:23:12 14.6 cc 4 05:32:47 58.2 cc 73 g $1.46 7%
X motor bracket
03:56:35 37.2 cc 1 03:56:35 37.2 cc 46 g $0.93 5%
X-carriage

03:51:39 40.2 cc 1 03:51:39 40.2 cc 50 g $1.00 5%
Y housing
00:56:36 9.9 cc 3 02:49:47 29.8 cc 37 g $0.74 4%
Extruder drive block
02:30:44 26.5 cc 1 02:30:44 26.5 cc 33 g $0.66 3%
X idler bracket
02:28:06 25.4 cc 1 02:28:06 25.4 cc 32 g $0.64 3%
Y motor bracket
01:51:06 19.6 cc 1 01:51:06 19.6 cc 25 g $0.49 2%
Bed constraint
00:43:20 7.5 cc 2 01:26:39 15.1 cc 19 g $0.38 2%
Bed clamp
00:21:39 3.7 cc 4 01:26:36 14.7 cc 18 g $0.37 2%
Extruder base
01:13:19 13.1 cc 1 01:13:19 13.1 cc 16 g $0.33 2%
Z-coupler-airpax
00:14:21 2.6 cc 4 00:57:26 10.2 cc 13 g $0.26 1%
Opto bracket @ 50%
00:19:00 3.1 cc 3 00:56:59 9.4 cc 12 g $0.23 1%
X-belt-clamp
00:10:46 1.9 cc 5 00:53:50 9.5 cc 12 g $0.24 1%
Wiper-diagonal-bracket
00:43:50 7.6 cc 1 00:43:50 7.6 cc 9 g $0.19 1%
Wiper-brace
00:13:24 2.3 cc 3 00:40:11 6.9 cc 9 g $0.17 1%
X-constraint-bracket
00:38:10 6.6 cc 1 00:38:10 6.6 cc 8 g $0.17 1%
Pulley
00:12:35 2.2 cc 3 00:37:44 6.7 cc 8 g $0.17 1%
Bolt plug
00:04:36 0.8 cc 7 00:32:11 5.8 cc 7 g $0.14 1%
Tall foot
00:14:27 2.6 cc 2 00:28:54 5.3 cc 7 g $0.13 1%
Y motor coupling
00:25:02 4.5 cc 1 00:25:02 4.5 cc 6 g $0.11 1%
Z-adjuster-housing
00:24:12 4.1 cc 1 00:24:12 4.1 cc 5 g $0.10 1%
Short foot
00:11:21 2.1 cc 2 00:22:42 4.2 cc 5 g $0.10 1%
Fan base
00:22:29 4.0 cc 1 00:22:29 4.0 cc 5 g $0.10 1%
Y belt clamp
00:03:43 0.7 cc 4 00:14:50 2.6 cc 3 g $0.07 0%
Fan-leg
00:15:48 2.8 cc 1 00:15:48 2.8 cc 4 g $0.07 0%
X-motor washer
00:15:27 2.8 cc 1 00:15:27 2.8 cc 3 g $0.07 0%
Z-flag-slider
00:13:00 2.3 cc 1 00:13:00 2.3 cc 3 g $0.06 0%
Bearing 360 run
00:02:47 0.5 cc 4 00:11:09 2.0 cc 3 g $0.05 0% HDPE
Extruder PCB holder
00:09:45 1.7 cc 1 00:09:45 1.7 cc 2 g $0.04 0%
Z-opto-flag
00:08:45 1.6 cc 1 00:08:45 1.6 cc 2 g $0.04 0% Black ABS
X-carriage-bearing
00:08:39 1.1 cc 1 00:08:39 1.1 cc 1 g $0.03 0% HDPE
Y-opto-flag
00:07:43 1.4 cc 1 00:07:43 1.4 cc 2 g $0.03 0% Black ABS
Bearing 360 jam
00:02:49 0.5 cc 2 00:05:38 1.0 cc 1 g $0.03 0% Black ABS
X-opto-flag
00:04:43 0.8 cc 1 00:04:43 0.8 cc 1 g $0.02 0% Black ABS
Wiper-lever
00:04:26 0.7 cc 1 00:04:26 0.7 cc 1 g $0.02 0%
Z-flag-clamp
00:03:20 0.6 cc 1 00:03:20 0.6 cc 1 g $0.01 0%
Circlip
00:01:26 0.3 cc 2 00:02:53 0.5 cc 1 g $0.01 0%
Bearing 180-x
00:02:38 0.5 cc 1 00:02:38 0.5 cc 1 g $0.01 0% HDPE
Bearing 180-z
00:02:03 0.4 cc 1 00:02:03 0.4 cc 0 g $0.01 0% ABS




109 74:28:04 778 cc
973 g
$19.47 100.00%

The times and weights are calculated, and don't include the raft time, which is significant, or the time waiting for temperature changes and raft cooling. I weighed the parts on kitchen scales and they came out at 931g, so pretty close to the calculation. The cost shown is on the basis of ABS at $20 / Kg.

I save all the rafts for the day when we get recycling working. I weighed them in at ~ 200g, that is about 20% wastage and will bring the actual printing time up to about 100 hours.



I also wasted 150g in failed prints, for silly reasons, more on that later. It gives a measure of the reliability I am achieving at the moment, i.e. 8 parts failed out of 117 prints so 93% success rate. Of course the bigger the part is, the more chance something will go wrong, so by weight and time it is much worse .



I used plain ABS for most of the parts because it seems to bond better than coloured. I used black for the opto tabs. No guarantee that they will be opaque to IR, but I think black ABS usually is. The green parts are just ones I had left over from experiments.

I made some of the bearings in HDPE as that should be a better bearing material than ABS, lower friction and longer lasting. The black ones are "jam" bearings so I left them in ABS as they want maximum friction.



Some of the parts are my own design. Most significant are the z-axis parts described in the previous post. Here is a list of the other design tweaks, with links to the article describing them:- simplified diagonal tie brackets, X-motor washer, x-carriage bearing and the feet.

Some parts I had never printed before. The Pinch wheel extruder: -



The nozzle wiper assembly has appeared in the latest Darwin release but I can't find any assembly instructions. I leave it as a puzzle for Edward Miller, the guy who is actually going to build this machine.



Similarly the new adjustable z-opto flag assembly: -



I aimed to print these parts over the course of a week, three batches a day, but the machine had other plans and it actually took me two weeks. I will give more details tomorrow.

13 comments:

  1. Beautiful work. Thanks for the excellent documentation, as always. We can't wait to get this up and running at Factor e Farm, spreading RepRaps on this side of the big pond. How many RepRaps are there in the USA already?

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  2. Thanks very much NopHead, its great to see all the parts together in the first pic, and learning about the failure rate

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  3. Oh my god. Im out of words.

    Khiraly

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  4. Realy nice work !! A want one ! I want one !! :-)

    Congratulations from France (where nobody is realy interesting on Reprap I think)

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  5. Absolutely fantastic! Especially interesting is the exact weight of a reprap parts. I've been way overestimating in my calculation so far. Great work Nophead!

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  6. The Nozzle wiper assembly looks like an interesting set of parts.

    You show the cost of materials and time taken do you have any idea of what the cost of the power used would be?

    I have not seen the term double outlines used before how do you create a double outline?

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  7. You can see the nozzle wiper in action here.

    The power taken by the machine is only about 60W (40W if I disconnect the LEDs that illuminate it) and I can drive it from a laptop that only takes 20W, so that would be about 6kWh in 100 hours. That costs about 70p in the UK at the moment, so not much compared to the plastic.

    The biggest cost was actually shipping the ABS from the US and then sending the finished parts back the other way again.

    I get the double outline by setting "Extra Shells on Sparse Layers" to 1 on the very old version of Skeinforge that I use.

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  8. Hi Chris,

    Very good to have you back. Although I'm glad your holiday was nice :)

    I hear your Hydraraptor was down, so I was also printing out a set for OSE, because I'm a huge fan of what Marcin et al. are doing.

    I'm still having problems with warping of bigger objects. I just found out how cricital the raft is to reducing warping. Do you vary your raft settings for different object sizes? What are they? I'm still playing with the settings as I dare to produce bigger objects. (So far I have just 2 corner brackets)

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  9. Erik,
    See my latest post.

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  10. We have a Dimension Series Printer in my engineering class. Sure would be sweet to produce one of these. How much to share the .stl files?

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  11. Thanks very much for posting results.

    How much electricity does reprap consume?

    Aren't ABS tubes a lot less expensive than $20/kg? I don't know where to get "raw" ABS if that's not

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  12. Only about 40W, so the cost is negligible compared to the plastic.

    Not sure what you mean by tubes. We use 3mm ABS welding rod. It is a lot more expensive than raw ABS granules.

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