@ Wazio: I measured one of the spur gears: It is 5mm thick by approx. 10mm diameter and has 15 teeth. Since most of the internal measurements of the gearbox seem to be metric, I'd guess the gear is module 0.5 and a 20 deg. pressure angle. I put the gear on a printed chart I have and it looked very close to .5 but I don't know any way to tell whether its an imperial pitch or something custom. Does anyone know of a way to calculate this?

Given that the gears we want are very small, it might be easier & cheaper to buy a length of 'gear rod' and cut off our gears to size in a lathe. I heard that's the way the gears for the Whyachi and Banebots products are made.
_________________
Australian 2015 Featherweight champion
UK 2016 Gladiator champion

Ahh, crap! I just found the formula for finding the module of a gear and the BB gears are either custom or imperial - it works out to 0.588.

Also worked out the diametrical pitch, which comes to 37.5 and doesn't sound like anything likely to be found in a catalogue
_________________
Australian 2015 Featherweight champion
UK 2016 Gladiator champion

Sounds like some pretty shit gearboxes if your going to these lengths just to get them to work... Sounds like the good ole $20 drills are 1UP'ing these things more and more

AndrewMOD's FTW!
_________________
https://www.halfdonethings.com/

Ok, so we are looking for some 15tooth, 5mm thick, 10mm Dia gears with a pitch of 37.5 and a module of .588, correct? I will send out a few mails to a few people and see what they can come back with... Everything is always somewhere... You just gotta find it!

The module size might not be totally accurate - I derived it from the formula M = D / (N = 2), where M is Modulo, D is outside diameter (10mm) and N is number of teeth. I got the measurements with a good digital caliper. but that doesnt let me measure the pressure angle and other small details.

If you find some place that looks promising, I'd see if they can measure up the gear to get a totally accurate match. I found Australia's only custom minature gear manufacturer and I will email them too. If we find the right place, I have some other ideas to make the gearboxes even better.

BTW: have you ever seen the insides of the TWR 18 Whyachi motor? It would be interesting to see if it had 3 or 4 gears in the second stage and what they were made of.
_________________
Australian 2015 Featherweight champion
UK 2016 Gladiator champion

@Andrew A (from the previous page): I don't have a lathe, so I made up a drilling jig like this:





This one fits two sized gears - I have had 100% success so far, but its probably easier in a lathe.
_________________
Australian 2015 Featherweight champion
UK 2016 Gladiator champion

Ya, I have 2 of them at the shop somewhere... I need to sell them actually, they are only taken up space on one of my tables. I will start the hunt today I do like the jig, however I think if I were to do this mod I would have to use a lathe... I have had bad luck at drilling out gears...

I will write up how the jig works for that 'how-to' article. After my first attempt with a plastic jig, every gear (about 20 so far) has been perfect. A lathe sure would be nice to have though...
_________________
Australian 2015 Featherweight champion
UK 2016 Gladiator champion

After Jolt was tossed about by a drumbot at the last event, I am in overdrive designing the frame for Scissorhands! I added many of the mounting holes for internal parts and corrected a major flaw in the Z dimension. The motor mounts had a work-over as well; I may go back to the 36mm motors after the excelent performance by the modded TWR15 units at the last event. That would allow for more armour weight and also save on battery power.

I plan to finish the 2D cad and then move the parts to Rhino to get an accurate weight for the frame - weight is tight and everything has to be accurate.

To get an idea of the performance, I might be able to change the test frame from using a tube spare to motor mounts made from flat panels like the final Ti version.

I piled up all the frame material today:




Astute readers will notice there is at least enough material for two complete bots here. Due to the stock sizes at Ti Joe's, I could get two frames built for hardly any more than one plus lots of scrap - I liked the first option better
_________________
Australian 2015 Featherweight champion
UK 2016 Gladiator champion

I finally finished the CAD for the frame - Rhino puts the weight at a fraction over 2.5kg without the welding. That's a little more than I wanted but really not too bad; I still have 1.3Kg left in the weight budget.

To check that everything fitted, I printed out all the frame panels on clear film and positioned the internal parts over them - that worked extremely well and just for once everything lined up first time. After weeks of adjustments, I can send the CAD off for a quote
_________________
Australian 2015 Featherweight champion
UK 2016 Gladiator champion

Waterjetting madness:

It started out when I needed some washers for the screws securing drive motor mounts to the frame. Making them from Ti seemed easy and saved a little weight. Next, I figured that washers are easy to lose; murphy's law dictates that a washer will always roll under to nearest immovable object or go down a drain . Several dozen bezier curves later, I present the Quad Washer (tm):




You can probably tell I was bored tonight...
_________________
Australian 2015 Featherweight champion
UK 2016 Gladiator champion

Progress:

I fabricated a sturdy connector block from UMHW and some M6 bolts today. Once that was done, the leads on the Lipo packs could be cut down and fitted:



To lower the chance of the leads melting, they are cut so short the packs only fit one way. I compared the cable to a piece of Dean's wet noodle cable and although the manufacturer specifies 14g cable on the packs, it is somewhere between 12 and 10g, which I am pretty happy about. Tomorrow may see a full spin-up test with the Lipos powering the Mag .

I changed the wheel mounting plates yet again; they are now quite curvaceous and made from two layers of 2.54mm Ti to save weight. The drive motors are back to the original TWR15 units, also to save weight. Here is a front view of Scissorhands to show the new motor mounts:



The transparent view also shows the hight adjustment; the blade can spin at floor level or about 30mm above it.
_________________
Australian 2015 Featherweight champion
UK 2016 Gladiator champion

Much better Nick

No more boring box for you
_________________
https://www.halfdonethings.com/

Alas, the side view is still a bit boxy - if there is any weight left, I was thinking of making some UMHW fins like the ones on Stainless Steel Rat.
_________________
Australian 2015 Featherweight champion
UK 2016 Gladiator champion

XD it looks like it's wearing fat pants.
Put some fluffy material on it!
BTW is it just the angle or does that blade look very small in that render?
_________________
( •_•)

( •_•)>⌐■-■

(⌐■_■)

YEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAH