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Jolt & friends - Team Overkill - NSW
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Knightrous
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Joined: 15 Jun 2004
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Location: NSW


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quote:
Originally posted by haz:
Heavyweight Mangle! You know you want to Smile

Hobgoblin Razz
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Post Mon Mar 13, 2017 12:13 am 
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Nick
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Location: Sydney, NSW


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I don't really fancy building something I can't lift or fit in a suitcase - I do have an almost finished lightweight version though. Its meant for the US Robogames but between the registration being full and the new US travel policies, I probably won't go Sad.
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Post Mon Mar 13, 2017 12:23 am 
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Nick
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Project explosion:

The CNC enclosure is moving along; I measured the mill bases and worked out where to weld the support rails. The enclosure may look huge but there is little wasted space inside; the most I could shorten it by is 200mm.

More of the CNC mill came home from storage yesterday. The base of the mill is a big tub with just a few small holes in it - perfect for filling up with epoxy concrete. Its a slow & messy job but will kill vibration and (supposedly) produce smoother finishes.

Mangle 2:
... is definitely a thing Smile. I found the perfect sized piece of stock, so the cost for the new bot is $294 USD for material and a couple of hundred for the waterjetting. Everything else comes from the original Mangle or spare parts. Its a bit accounting trickery to call it a cheap project but its too good to pass up at this price.

3D printer:
I woke up with a crazy idea (not unusual but it normally involves bacon); I have a disused Printrbot that never worked properly and was superseded by the Wanhou. Since there is nothing to lose, I can try retrofitting it with some of the parts from the custom-built printer project. The feeder and hot end are an easy swap:



All that is needed is a 5 to 6mm aluminium adaptor plate between the printer and the head:



Next, the dodgy AF controller board gets replaced with the 32 bit Smoothie board. This adds better auto levelling, heated bed control and an LCD panel. Finally, adding a heated bed kit makes the printer compatible with all the interesting high temperature plastics like nylon and polycarbonate.

The printer only has a 200 x 200 x 150 print volume but will be perfect for antweight parts. I can't see any down side to this; if it works, then I have an extra printer and get experience with the new parts. If it doesn't work, I can just take the new parts off and use them elsewhere.

Mr T:
I had to pack up the sportsman to make room for the CNC enclosure build. The wiring and pneumatic installation is far enough along to tell that the frame doesn't need any changes, so its time for a quote and waterjetting.

Ant arena:
The CAD is all done and I will get a laser cutting quote at the same time a Mr T
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Post Mon Mar 13, 2017 10:25 am 
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Nick
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Out with the old (left) and in with the new. The original controller was easy to remove and that wiring loom isn't quite as messy as it looks:



The connectors on both boards are nearly identical but the pin-outs are different. They will all need to be disassembled and reconfigured to work but that's better than having to chop them off and crimp on completely new connectors.

There is room underneath the printer for the new controller but I am going to laser cut a new base to hold the power supply and the LCD display to make everything more user friendly
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Post Mon Mar 13, 2017 9:16 pm 
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Nick
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Mr Mangle 2

I cut out a first prototype of the frame today:



Compared to the original, the new frame is narrower and slightly taller. It has room for wider wheels and takes the narrower beater from Shiny. It has extra reinforcing under the weapon bearing blocks, but less than Shiny to save weight.

I reckon it will take a month to get it finished; 2 weeks shipping, 1 week for water jetting and 1 week for welding.
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Post Tue Mar 14, 2017 10:15 pm 
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Nick
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Mr Mangle 2

The frame has been shrunk in all three dimensions and somehow weighs almost 1,1Kg less, even though it still has 8 mm thick sides like the original. The weight reduction is a good thing as there are plenty of heavy new parts to soak up the spare weight.

One new idea I want to try is printed wheels using a polyurethane like Ninjaflex. The UK arena floor is none too flat and even when Mangle is balanced enough to drive straight on a smooth floor, it usually veers to one side or the other in the arena. If the wheels had 2 or 3mm of squish in them, the bot would be self-levelling and drive better. I figure that there is some combination of filament softness and infill density that will be just right.

Rather than print complete wheels for testing, I will use hard wheels and soft printed blocks like this:



It looks weird but will save a heap of filament and time. Once the blocks have about the right amount of give in them, I can fine tune with full printed wheel treads glued onto a nylon or HDPE hub.
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Post Wed Mar 15, 2017 11:38 pm 
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chunkulator



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Isn't the conventional wisdom that it's impossible to glue HDPE? Nylon sounds like a plan though.

Post Thu Mar 16, 2017 6:01 am 
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Valen
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If you want more squish if you put some holes through it it'll be more compliant. Stuff like this http://www.rense.com/1.imagesH/tiresdg.jpg
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Post Thu Mar 16, 2017 7:18 am 
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Nick
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@ Richard: True Polyethylene is a pain to glue to. I should try Nylon or polycarbonate (my fave hub material) first. For this experiment I will use urethane glue as it "should* stick to the urethane tread and 3M has a huge range of glue options to choose from.

@ Jake: that's a very fancy wheel, its probably not possible to go to that much detail in the small space I have. one easy option may be to tell Simplify 3D to omit the top & bottom layers and have the hexagonal infill pattern do the job. I found that once Jinjaflex was more than a few mm thick, it was surprisingly firm so the side walls are probably not needed.
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Post Thu Mar 16, 2017 7:50 am 
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Nick
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This Simplify 3D wheel model looks entirely plausible (assuming it will stick to the printer bed):



The honeycomb infill pattern is not radial like the Michelin tyre but maybe that doesn't matter so much - only testing will tell. The model has a 25% fill and four wall layers; so many parameters to play with!

Another option could be to print a really low infill / higher wall layer tyre and fill the whole thing with a really soft urethane to make a DIY run-flat tyre.
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Post Thu Mar 16, 2017 9:18 am 
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Nick
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Mr Mangle 2

The new design had a couple of roadblocks thrown at it today; The Thunderpower Lipo pack I picked and dimensioned the rear of the bot around is totally unavailable in Australia and Hobbyking was no help as they no longer ship lipo packs from Hong Kong. Glen came to the rescue by recommending Revolectrix packs - there are two possible replacements and one of them has specs so good they must be a mistake. If the specs are correct, Mr Mangle will be able to hit harder and run longer than ever before.

The other problems are my own stupid fault; so many small changes to the design crept in over the past few years and didn't get documented that now I have to weigh and measure every single component again to be sure its accurate in CAD and the weight spreadsheet. So far, just the screws weigh over 100 grams more than originally estimated Shocked. The bot is still under weight but some of the new ideas may not make it into the design.

Antweight

The nano receiver arrived to day and its very, very nano:



The best way to handle this is to package everything up in a single bundle and hope that nothing breaks Smile


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Post Thu Mar 16, 2017 8:03 pm 
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Nick
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3D printers:

I am upping my print game today; a high temperature upgrade for the Flexion extruder and a reel of PC-Max polycarbonate will make tougher antweight frames:



the extruder will still handle flexy filaments so this lets the Wanhou print a very wide range of materials.

The Printrbot refit is also progressing; its almost wired up enough for a power check and the heated bed will be here in about a week.
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Post Fri Mar 17, 2017 12:09 pm 
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Nick
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Progress:

Here is the latest prototype, Mr Manglwood Smile:





All the major parts are installed and fit well; the electronics module needs a little tweaking but that's it. All the parts came from Shiny or the spare parts box, so the original Mangle is still in running order.
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Post Sat Mar 18, 2017 8:20 pm 
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evil_steve



Joined: 06 Sep 2015
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How hot does the bed go on the i3? I tried printing some PC-Plus and found that at 110 it wasn't sticking to the bed that well, I've been meaning to try it again with a higher bed temp.

Post Sat Mar 18, 2017 9:45 pm 
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Nick
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Even after I insulated the underside of the bed, it only reaches 106 C. I didn't look up the specs for PC-Plus, but PC-Max needs an 80 C bed temp and the glass transition temp is 113 C, so 110 degrees is way too hot.

One thing I noticed with the Wanhou is that the build surface might look like Buildtak but it is nowhere as sticky. Most of my early prints needed a raft to be reliable and now with a real Buildtak surface, it takes real effort to get prints off the bed.

Looking at Polymaker's user guide, they recommend both Buildtak AND a raft, so that's the next thing I'd try.
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Post Sat Mar 18, 2017 10:10 pm 
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