Team Triforce Featherweight drum

[TechAUmNu]

Been designing and building a drumbot for the featherweight champs this year.

Battery: 12s lipo (2x Turnigy nano-tech 1550mah 6S 65~130C (450L Heli)
ESCs: 3x focbox (or something custom if we have time)
Weapon: ~5kG drum with 5060 380KV hub motor, hinged forks
Drive: 2x NTM-4248, 4 wheel drive, invertable
Armour: wrap around folded 4mm hardox 500, 2mm titanium top and bottom plates
Frame: 20mm aluminium


Some pics:
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[overkill]

How are you running the NTM-4248 on 12S? A 5S rated motor will melt pretty quickly on 12S, or are you just powering them from one 6S pack?

[TechAUmNu]

Using vescs so they are just rpm and current limited.

[Eidg]

Nice Drum how big is the Diameter?

[TechAUmNu]

The aluminium core is 110mm, tooth is 153mm.

[TechAUmNu]

Spent most of the day turning down the first bearing holder/mount for the drum. Then made the titanium shaft fit into it.
Got another one of these to make then I can test how the drum spins. Might need to limit the max speed a bit as I found the weapon motor is actually 380kv, so 19000RPM max at 12S (340MPH).

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[TechAUmNu]

Today I started boring out the inside of the drum for the hub motor, and took then ends off the motor can. Turned down the end of the titanium shaft to fit the bearing block and drilled the stator of the motor to fit on the shaft.

Unfortunately my lathe doesn't have enough torque to run the huge drill I am using so now need to wait on some boring bars before I can continue.

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[Andy]

Sweet! all sounds like it should be a beast, is there a reason you're using the propdrives over other 12s outrunners? especially for the drum itself.

[TechAUmNu]

Figured people would be interested to know where the parts are from...

I got a load of the NTM motors and the batteries in a hobbyking sale a few months back for about half price.
The focbox are from the first version of triforce before we switched to our own controllers.
The titanium bar is from a huge job lot of off cuts I got from a machine shop.
Hardox is cut and bent by kcut.
Aluminium plate and round stock from Aluminium Warehouse.
Shock mounts from polymax.
Wheel polyurethane casting rubber from MB fibreglass.
All bearings from simply bearings.
Belts from belting online.
Bolts from orbital fasteners.

[TechAUmNu]

We got accepted for Insomnia! So now the epic panic build begins. We called the bot 'Elevate'

Before we can even begin to make the aluminium frame we need to finish building our new cnc mill (which is rather massive) so I spent the whole day assembling it.

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We are using hiwin linear rails this time, of course the bolt heads don't quite fit. So had to machine 60 bolts to have very slightly thinner heads.
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Once the bolts were done I mounted the rails on the extrusion. This is really easy since it all self aligns to the rails (assuming they are actually straight!) This works for the X and Y axis.

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The Z axis will be mounted on a big plate of aluminium I have from the last mill. Need to get somewhere to put a bunch of holes in it!

[TechAUmNu]

Eventually got on to some bot parts, here are the four axles, just need to cut them apart on the chop saw.
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was originally going to do them in titanium but decided it was too heavy. Now just a bunch of pulleys to turn down after I make the wheels.

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Also decided to redesign the chassis to make it lighter. Some nice isogrid always helps! With a 1mm titanium plate to stop junk coming in. (This is behind the 4mm hardox so doesn't need to be very spinner proof)

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[TechAUmNu]

Some more work today making the chassis lighter... all the frame pieces are 20mm aluminium with 1mm titanium on both sides.

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[Andy]

Really nice work on the chassis design, love the cutouts!

[TechAUmNu]

Really nice work on the chassis design, love the cutouts!

Really hoping the armor keeps it protected, gonna be a mess if something like Neon hits it!

[TechAUmNu]

Lots more work on the bot, got the armor all worked out ready for kcut to cut and fold it, hopefully they can manage the shape.

Also had to order another 2 aluminium bars to redo the drum, as I mucked up the bearing pockets!

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As per usual it's turning into a manic rush to get everything done in time. With the CNC mill not going to be finished till late next week. At least I can get all the CAM, Lathe and electronics work done in the mean time.