First ever real build lews featherweight

[Supermotolew]

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.

CAD1.jpg

[Ocracoke]

Looks good, neat looking design

[Supermotolew]

Thanks Lucy

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.

CNC TEST.jpeg

[Supermotolew]

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!

WHEEL ON MACHINE.jpeg WHEELS MILLED TEST.jpeg MOTORHUB.jpeg WHEEL TEST.jpeg

[Supermotolew]

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 ??
MOCKUP.jpg

[Ocracoke]

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?

[Supermotolew]

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!

[McMullet]

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!

[Supermotolew]

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.
20211128_102747.jpg

[Supermotolew]

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)

[McMullet]

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...

[Ocracoke]

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.

[Supermotolew]

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!

[Ocracoke]

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.

[RogueTwoRobots]

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