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TBD - RedTip - NSW
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pilleya



Joined: 31 Mar 2016
Posts: 91
Location: Sydney


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TBD - RedTip - NSW

I thought that it was about time to start a Builders Report on the Sportsman that I am building for Vivid.

Over the last 12ish months, I have designed several different Sportsman and Feather robots. Roughly 5 different Feathers and 3 Sportsmans. While all of these have so far stayed in SolidWorks I hope to also build a Feather for Nationals.
Until about 3ish weeks ago, I was planning to build a Hammer Robot( named Thorium), but as time has dwindled on I lost interest in the design and began second guessing the ability of the Gears I had chosen to handle 3kw of Brushed Motor. With limited machining options and with my time quickly expiring I chose to change design.

I have finished the design of and are currently building a pushy/lifter/flipper style sportsman. I have selected and obtained all parts minus a battery capable of supplying the required current ( 150ishA@4S).

For drives I am running large Brushed motors at 4S with a 12-48 spur gear reduction and 4”/100mm Colsons. It is a 4WD robot with the front-rear wheels connected with #25 chain.

The lifter is a smaller sealed brushed motor in a planetary gearbox with transmission to the lifting forks via #35 chain.

Electronics is comprised of Talon SR motor controllers for the drive motor and a REV Spark controller for the lifter, the good thing about the Spark is that it has inbuilt limit switch inputs meaning that I can use an industrial switch at the top and bottom of the arm and when once the arm reaches that mount it will not go any further preventing problems/motor stall.

The frame of the robot as it is currently is designed to be laser-cut from 12mm MDF with a bent piece of 65x3mm Mild flat bar around the sides and rear. Top Armour is probably 3mm Al with probably 6mm of something like polycarbonate located over \

Post Tue May 23, 2017 9:22 pm 
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miles&Jules
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Joined: 19 May 2010
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Location: ipswich QLD


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Cool cant wait to see it👍
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Miles Blow - Julie Pitts
www.mulesfilm.com.au
www.wombokforest.com.au

-Pickasso- Vivid Sportsman champion 2015

Post Wed May 24, 2017 12:39 am 
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pilleya



Joined: 31 Mar 2016
Posts: 91
Location: Sydney


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Finalised the design, looking to have the parts laser-cut from 5mm Mild Steel( or hardox if I can get it so that I can use it as a Feather in the future).

Any recommendations on cheap laser places in Sydney? Plasma may work but I'm not sure how good the resolution would be on the slots.

I would really like the weapon parts to be made from Hardox.

I am getting the top and bottom panels/windows cut from 3mm 6061 and Polycarb on a CNC router over then next few days and will be making the small number of turned parts( axles and spacers)







Post Sat May 27, 2017 1:17 pm 
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evil_steve



Joined: 06 Sep 2015
Posts: 301
Location: Adelaide, SA


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That looks awesome! Can't wait to see it in steel

Post Sat May 27, 2017 3:32 pm 
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Nick
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Joined: 16 Jun 2004
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Location: Sydney, NSW


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I don't know about cheap laser, but DMG Engineering http://www.dmgengineering.com.au/index.php does very cheap water jetting - cheaper than that Aquacut place you used. With that frame design, you don't really need so many slots & tabs, they start to act like the perforations on a paper towel and they increase the cutting cost. I'd suggest about 1/3 as many from experience.

Is there a plan for welding the frame? From experience, it looks tricky unless I am missing something.
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Post Sat May 27, 2017 5:47 pm 
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miles&Jules
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Nice work👍
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Miles Blow - Julie Pitts
www.mulesfilm.com.au
www.wombokforest.com.au

-Pickasso- Vivid Sportsman champion 2015

Post Sat May 27, 2017 9:17 pm 
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pilleya



Joined: 31 Mar 2016
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Location: Sydney


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Thanks for the advice Nick, I will definitely reduce the number of slots/tabs. I am going to have to get it cut from 5mm rather than 6mm for weight reasons so I will be altering the design anyway.
When you have tab/slot parts cut do you enlarge/shrink the tabs at all or just have it the exact size?

I am going to go down and checkout a place called Lasermade on Monday which is close by, they do Jet and Laser but I have heard they are pretty pricey.

In regards to the welding most of the inner areas are accessible by a MIG gun and for the ones which aren't I am considering grinding an angle onto the tabs and then filling the gap in the slot up with weld before grinding smooth.

I am not going to weld all the way around like you do with your TIG and Ti, instead I'll probably just weld at key spots which should save time.

Post Sat May 27, 2017 9:51 pm 
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marto
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Given its your first bot, it's sportsman and the time why not just leave it as MDF?

Just armour the parts you (I) care about (BATTERY) ESCs Rx.?

Not best construction method but for a cheap and cheerful sportsman probably sufficient.
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Twisted Constructions
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Post Sat May 27, 2017 10:06 pm 
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Nick
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Joined: 16 Jun 2004
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Location: Sydney, NSW


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I used lasermade for waterjet cutting until recently; they used to do good work but screwed up a job in a major way last year (turned all round holes into larger octagons) Shocked When I asked for a quote on the last job, they quoted me over $3K when AquaCut was 1K and DMG was $650. I think this was partly as they have a charge for each hole on top of the actual cutting time, which would go badly for a design with lots of tabs & slots.

When your CAD file is imported into their cutting program, it automatically compensates for the width of the laser / waterjet so if you draw the parts with no clearance they will theoretically be a perfect fit. HOWEVER, this doesn't allow for the taper on the cut edge so you definitely want to add some clearance between parts. For waterjet cutting in 3 to 5mm material, I leave .2mm clearance all around slots & tabs and this ends up being a close fit. For laser cutting you might get away with less - its best to ask for advice from the place you get the quote.

I really like it when the parts are just tight enough to hold together but not so much that they have to be hammered apart. This makes setting up for welding really easy.

If you are going to weld the tops of the tabs to the surrounding panel (called plug welding) just make the hight of the tabs half the thickness of the panel. That way there is a handy recess to fill up with welding and there is plenty of weld left after you grind it flat. If that's the plan, make the tabs & slots a bit longer for more strength.
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Post Sat May 27, 2017 10:21 pm 
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pilleya



Joined: 31 Mar 2016
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Location: Sydney


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I have some 3S and 4S LiPos with XT60, that I am going to be running at Vivid, is anyone able to let me borrow a charger/help me charge batteries at the competition? My small one is alright for use at home but will take too long to charge batteries.

Also does anyone in Sydney have a T6A programming cable that I can borrow sometime next week( I figure it shouldn't take too long to program) as I forgot to order one.

Post Thu Jun 01, 2017 8:11 pm 
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chunkulator



Joined: 27 Jul 2016
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I can bring a T6A programming cable to Vivid. Don't have a spare charger though unfortunately.

Post Thu Jun 01, 2017 10:13 pm 
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chunkulator



Joined: 27 Jul 2016
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One thought on the charger. HobbyKing have these in stock in the NSW warehouse for a little over $40:
https://hobbyking.com/en_us/accuell-s60-ac-charger-au-plug.html

They are decent chargers for 3s and 4s and charge at up to 6A. I found one of these was more than adequate for one bot for the events I've done so far. If you order one today and choose Couriers Please as the shipping method it'll be in Sydney Tuesday or Wednesday.

Post Fri Jun 02, 2017 7:34 am 
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marto
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Should be plenty of chargers around.

Steve
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Post Fri Jun 09, 2017 9:49 pm 
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pilleya



Joined: 31 Mar 2016
Posts: 91
Location: Sydney


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Just finished building Tumbler( did everything yesterday). Although I need to properly setup the T6A I was able to get it driving in "tank" mode by messing around with the PWM channels. It is pretty manuverable and very fast, however the low weight(10kg with battery) means there is a lot of lost acceleration through wheel slip.


In regards to the lifter I am using a 200:1 planetary gearbox with a winch raising the arm, with surgical tubing to lower it( prevents it being like a wedge).

I am still using the same 6mm MDF frame( thanks for the suggestion Steve) but it is strengthened with 20mm Plywood on the sides 3-6mm 6061 on the top and 3mm Polycarb on the bottom, the fact that I can stand on it and drive it hopefully means that it should be up to the rigours of the competition Smile

Post Sat Jun 10, 2017 12:27 am 
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pilleya



Joined: 31 Mar 2016
Posts: 91
Location: Sydney


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Post Vivid Report on Sportsman Tumbler

Going into the event I didn't have big expectations for Tumbler the actual structure of which is made from 6mm MDF. I felt that the biggest risk to Tumbler would be taking a big hit(s) from one of the Pneumatic Flippers and having the frame crack on landing ( although I had plenty of spares). We ended up getting a good draw with first match up against Nibbler.

In the match against Nibbler, Tumbler was able to out manoeuvre Nibbler due to the fast/powerful drives( 670 watts per side)and low weight 10kg with battery however we ended up getting the lifter stuck in the gap between the arena kick plate and the MDF floor which caused loss of mobility( even though robot fully operational).

Second match up was against the walker Banana Bender, this seemed like a difficult matchup for Tumbler being only 10kg compared to the 20ish kg of Banana. We again used our speed to cause some big hits on Banana, however it was tricky because we would line up to do a rear/side hit and generally Banana was able to turn to have its scary lifter facing us by the time we approached. Banana bender picked up Tumbler twice overturning it, luckily it was invertible however the driving suffered while getting to grips with driving inverted( no driver practice in either orientation had occurred). Banana bender flipped us over again to which a "thankyou" was exchanged as we could now drive properly. We found that Banana Benders biggest weakness was that with the arm lifted up, it could be very easily pushed across the arena from the front.

It was a very enjoyable fight, and our first win.

Our last match was supposed to be against Chain Reaction, but was replaced with Glitch after it suffered in-repairable damage. We decided to drive inverted with the 3mm Polycarb on the bottom ( we had planned to drive 6061 on the top normally but the aluminium side had more ground clearance so we inverted it) we also added an extra 3mm 6061 plate over our electronics that we had previously taken off to increase ground clearance. Unfortunately Glitch’s Saw Outrunner had been smashed in a previous fight meaning that it didn’t really work properly (we wanted to see how our armour held up.

Being the two fastest robots around the box it was a very fast paced battle with many high speed collisions, one of which caused a section of our Plywood frame to crack and break off but it did not cause any problems. Our Aluminium box section lifter forks also suffered considerable damage against Glitch’s Wear Plate armour.
Overall a very enjoyable event, the Wooden frame held up very well, only breaking when a.) I drove at the arena wall at full speed to see if what happened during practice and b.) When I tried to lift up Deathroll during another practice time.

I was very happy with how the Drive system performed; the Talon SR controllers had no problem with the 190ish amps stall current on the drive motors in Tumbler. 4:1 with 4” wheels with those motors was a good combination of speed and acceleration (the fastest robot at the combination by a significant margin). I will certainly be using the same drive system until I want to commit the time and money to a brushless setup.

Now I just need to decide/design what I am going to bring to the national tournament in August.

Big thanks to Steve for running the event and helping/teaching me to program my T6A.

Also thanks to Don, Andrew and Richard for lending me tools( I could only bring as much as I could carry on the train). Also Glen for your awesome CNC plasma recommendations( hoping to build a Plasma to make parts for my next robot)

Post Mon Jun 12, 2017 3:49 pm 
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