First ever real build lews featherweight

Hi everyone!

Been lurking in the background a while now and im finally ready to start a build diary of my first ever build, ill try to keep this updated each week or so with the good and bad progress!

The plan was initially a swiss army bot and may still be ive kept the design a little vauge and moduler so i can be flexible as things progress.

ill start first with a spinner module as its fairley simple mechanically. all of this is work in progress but need to flesh some things out and explore the idea the center portion is completely reserved for weapon modules im aiming for a 50/50 weight between weapon and rest of bot ratio but 40/60 might be more realistic.

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Looks good, neat looking design ;)

Thanks Lucy :D

Ok so after struggling with the CAD for a few days and the sizing of components i think im pretty close.. i really just need to flesh things out wifes been a star and got me an early xmas present a 6040 CNC router with 4th axis!
im so happy to have a play with this, ive wanted one for so long! its taken me a few days to get it set up (thanks TeamSC ) im sure roboteernat is sick of all my questions but has been an amazing help in getting myself set up cheers if you see this!

I decided for my first test ill try a chassis prototype part in mdf and it came out great first try! over the next few days ill start chugging my way through some other parts (im making half the bot as its symetrical and all the parts easily fit the machine.

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Oh i forgot over the last few weeks i made a little progress on the wheels!

team SC batten boxes on some 65 shore 125mm castors that i have modified in my lill manual mill, i milled the faces flat and milled out the roller bearings this took a little getting right as i wanted to save as much meat as possible!

The hubs are held on the 12mm shaft portion with a keyway then the nut and finally the left hand thread screw with a nice anodised countersunk washer keeps the nut double snug!

In the last picture below you can see (not very clearly a ring between the hub and the wheel rim) i 3d printed a tight press fit ring that matches the hub and the wheel fillet this keeps my hub concentric while i drilled the mounts, im actually going to keep these fitted with epoxy and make them in a lairy colour or glow in the dark filiment!

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Ok so ive had some more good progress last night, ive popped out a few more mdf dummys on the cnc. its been usefull i can see i need to make pockets on the inner weapon plate im just awaiting a 5050 motor to test fit the pocket for the motor.

its given me a feel for the space avalible for the rest of the electronics i can now hopefully trim some dimensions down and save a little weight.
i still need to find a way to get the mill to chamfer the front frame on the ally version, if not ill prob do that on my manual mill.

Not sure why its upside down the source was correct way up ??
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Looks very compact, neat loooking (and upside down :P ) What is the overall dimensions of this going to be in the end do you reckon?

Hey Lucy! Ive never actually seen a featherweight before so im kind of making it up as i go but its ablout 380mm wide 110mm high 400mm long. The wooden model above is exactly half as the thing os symmetrical and the full bot wont fit my cnc.

Not sure how to flip that picture!

Looks great Lew, really neat idea to prototype in MDF! Look forward to seeing how it shapes up.

You just need a SRiMech for your camera!

Cheers Sam! Its been a learning curve!
Today i test fitted a front armour peice, it could do with being 2 mm or so higher, i also 3d prinded a motor mount these go top and botom normally but ive not yet got the hardware to test fit them properly.
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I think its back to the drawing board! I need to reduce the height by 5-10 mm to let it drive inverted doh! Thats with about 18mm ground clearance on the bottom. If i can reduce that by half it might be salvageable as it! Whats everyone's opinion on required clgtound clearance? Fronts scrapes the floor intentionally. Rear is lifted
(Edit ive managed to fudge the geometery 7mm withought drama so will try this)

I think we have 10-15mm of clearance on Ensign Wedgeley Crusher (125mm wheels with 100mm of chassis). There are some extra bits that stick out underneath that can get him beached, but 18mm is way more than you need at the wheels so you've plenty of room to play there. From memory I feel like some feathers run with not much more than 5mm all round.

Kinda depends on where the weight sits relative to the wheels and other contact points as well though, so YMMV...

Azriel is sightly bigger all around than your design and is raked with the front scraping along the floor and the rear raised. Sam is right in that there are some FWs that run really close to the floor (The Honey Badger was an example of this in its early iterations) but the floors in the arena are not level and you'll find this as you run in them.

Hi Sam and Lucy,
ok great makes sense mines also in 125mm wheels, raked with the front scraping i toyed with the idea of running a ball castor but they seme heavy, might put a nylon pad or simmiler, or just let it scrape.. ive now made it so i can adjust the height with spacers, the only down side was a larger wheel hole but that actually saved me a little wieght too!

I used to use ball castors in The Honey Badger and they never lasted. I find that off the shelf things like that tend not to in the arena.

Just let the front scrape. Not only will it make it easier to get under opponents and save weight, but it will also help dampen the steering/control slightly, as sometimes having a really free-running leading edge castor or BB unit can make oversteer an issue which just makes it more difficult to point the robot where you want it to go

agree, let the front edge scrape along the floor. You may even want to try determin the angle to cut the side wedges too so they run as close as to the floor as you can calculate - i tried tat but the calcs were off slihtly so had gc along the front side wedges

Ok re designed so the total height has been reduced 5mm to allow some inverted ground clearance, ive also just added 2 small nylon rubbing strips to scrape, unfortunately i couldent wrap my head arount the angles for front scraping but did add 2 wedglet things! Sorry unfortunately no pictures today but all id did was re mill the shorter chassis peices for test fit.

I think im pretty close to placing a laser order for the main chassis parts over xmas, i priced it up it was cheaper to get them cut then it was for me to buy the raw material and do them ! Wild ...

Over the next few days ill be looking for inspiration on the wepon modules... the spinners fairly useless for my most local matches and arenas.

Ok a quiet week but the cads coming along well! Ive also started playing with more mdf prototypes, space for the battery is a little worrying but i think it will be ok.... exciting news later this week hopefully! While i hunt for spinner motors, ive started the Hydraulic module! Really excited to play with that and get a feel for the weight its the heaviest module im working on.Attachment 9961
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Wonky pictures seem to have returned.... sorry!

Some exciting progress if a little frustraiting!

A little sneak peak at wepon module 2....

Ive finished putting together the hydraulics enough anyway to test , the motors come out a little long so im hoping to save some length on a brushless swap. Hoping a motor from lucy will suffice but i think really its begging for a 5050-5065.
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First attempt ever at milling carbon and the first part of the dampened electronics frames is done pretty happy with the results awaiting more CF and some specilised cutters.
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Looking very tasty - what thickness is the Carbon Fibre?

Thanks Lucy!

That battery protector plate is 3mm but i think ill do the esc brackets in 1.5mm there purely to support the components. You can see the intended X shaped esc brackets here with blue hdd rubbers onthe corner.
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Things have been a little tight over xmas so i started working on the box for the battery as i already had the materials.
The Battery enclosure is looking good just awaiting some foam to cnc a pocket into.
Theres a chance this wont be used but ive made it in a way it will also fit another bot i was planning next.
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Fancied trying somthing new today, so had a play with modeling the hydraulics! Little slow@12v hoping to swap that out with brushless 6s

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Looks very, very cool. How heavy is all the hydraulic gear?

Each ram and hose + oil is about 440g these are about 30mm too long really so im adding a little weight in the claw to cope with the longer than needed geometry.
The pump is a little heavier but i guess 70% of that weight is this big ol rs770-795 ish motor ( this or the spinner is what i plan for your motor to live ) should save weight and length!
I think for "a hydraulic" pincer the system should be very light in comparison to other steel rams and dc packs. But for a feather weight its still heavy and my armour will suffer. Awaiting new scales and ill get u a total module weight!

Hopefully yes, the motor should be ligher than a RS775 motor. I had to make this consideration for my Middleweight but if you are looking for modularity, design the weapon pod around the location of the motor as so to making dropping the pods in and out.

Hi Lucy,

Wondering if you can help me ID this motor i thought it was a RS775 but now im wondering if its larger maybe a 895! or larger if they go!
its 6.3mm shaft. body length 85mm body diameter 81.5 was in a 12v system.

more importantly im looking for a brushless that would match it in torque and a little more RPM (i will run 5 or 6 s) and of course a little lighter!

any thoughts?

That sounds like a Speed 900 to me. There were Tornado 850s (I think) but the size of the motor and the shaft suggests a Speed 900. They are fairly uncommon these days.

Thanks it lools a little closer! How does one translate brushed specs to brushless equivalent? Im guessing not so simple!

Hi everyone just checking in! the project is still alive and kicking ive just had some delays with another build,
im just wrapping my head around milling aluminium currently on the 6040 chinese CNC router. an update will follow soon once my batch of end mills arrive!

An update! Things are slowley moving! Not been so active here unfortunately fbook has been my dumping ground but wanted to give an update! Claws coming along nicely Attachment 10008

Looking very neat and tidy! Looks like 15mm Aluminium for the chassis?

Yep! 15mm main chassis, forks and lower pivot 10mm, top claw a sandwich of 8mm and 6mm spacers for 6mm hardox tooth.

Side armour PE1000 20mm honeycombed.
Front 20mm pe1000 some pocketing
Bottom 3mm ally top 3mm ally might swap to Ti or some ally carbon poly sandwich..

Pins are gr5 titanium

Its all started getting a bit posh :rofl:
Hope its enough!