Project Squirrel

[Outlaw]

I don't have any pictures, but I'll give you a word by word of what happened.

So, first time I tried driving, the nut was too loose on the axle itself, which meant that when the motor span, the wheel fell off, which was slightly comical but it shown that it had promise. So I tightened it up and tried again.

Second time, and this was the failure point. It ran around for a good 5-10 seconds, then I saw the axle spinning around in the wheel. The nut was still attached to the axle... but the epoxy resin connecting nut to wheel separated so neatly, that it was just spinning in the wheel itself.

So I'm pretty much back to square one. When I can, I'll get pictures of it, but holy Christ this is quite irritating... I think the only decent option here for me without pulling out my hair is to buy some wheels from someone.

[R9000]

Also consider these. They're longer so you'll have more support for your wheel on radial loads. Also if you're melting them into a hub, I like to take a grinder with a slitting disk and just cut some ridges onto the sides and corners of the nut. Gives more surface area for the material to grip onto, and means that even if it somehow comes 'unstuck' from the hub, it most likely still won't come out.

[Maxamuslead]

ok, i take it you don't have a blowtorch off any description? if not i can think of two possible possible ways.

1. cut out 2 new wheels and cutout the hex and use like that with washers on either side (when i get home i can show you a photo what i mean on my robot)

2. buy some banebot wheels with the required hub. (expensive Plus shipping and possible import tax)

if you have a blow torch you could do something similar what Ellis did in his video here

[Outlaw]

@R9000 Yeah, as much as I would like to do that, the wheels have a larger bore than the nuts in question, so there's a gap between nut and wheel. I filled the gap with as much epoxy resin as logical, and, like I said, the resin along with the nut just started to spin inside the bore.

@Maxamuslead I have no heating apparatus nor do I have any way to press the nut into a wheel. And I tried to cut wheels out from HDPE and they looked more like demented discuses.

So if there's any wheels that I can use... max I'd say'd be 5 inches diameter, with a bore that can take a 3/8 UNF nut, as said before, any advice would be a great help. Or if you can make them and such.

[Theo]

I have the exact same problem with mine, I just used some electrical tape but it didn't hold. You could try Banebots wheels or get some from Antazz if/when he does a second batch.

[Outlaw]

I'm looking at these wheels, Colson 5" wheels that could do the job (LINK) along with these press fit adaptors (LINK). Would these possibly work per chance? Or am I better off looking at something else?

[overkill]

The hubs have a smooth bore are designed to run on a 3/8" axle, not a drill motor. You need a hub with a thread in it - I'd get a local bot builder with a lathe to make you a set.

[Outlaw]

Oh yeah... forgot about the smooth bore part... well back to the drawing board.

[R9000]

Could always just buy a 3/8 UNF tap and tap it yourself.

[overkill]

The bore is already 3/8" - the tap will slide right through. The centre of those hubs is actually a plastic bushing so the bore diameter in the aluminium is more like 0.5". A 3/8-24 tap needs an 8.5mm hole, or preferably a slightly smaller 21/64" hole in aluminium for a stronger thread.

BTW: Many castor wheels including Colsons are made from polyethylene or polypropylene, which are 'low surface energy' plastics that are very hard to glue to - that's why your locknut hubs failed. There are special (and much more expensive!) epoxies designed to stick to PE and PP plastics but even they don't work that well. When I make Colson hubs, I make the diameter a little larger than the wheel bore and add barbs like that Banebots hub - AND then I add epoxy as well

[Maxamuslead]

Here is a suggestion. get some t81 wheels and get a 5/16 hub and tap it for 3/8 ( might need to double check that but the chart i looked at said that was the size of hole you needed to tap 3/8 tread into) and us t81 wheels. The big downside is that i cannot find them being sold in the UK so banebots is the only place to get them so cost can be a issue. Also if you don't have a tap and die set or not able to get someone to do it for you locally that is another cost.

[overkill]

Sorry, a 5/16" hole is too small. The tap will be cutting more than 100% of the thread depth, which is an excellent way to snap it. You are looking at the hole size for a UNC 3/8-16 thread.

[Maxamuslead]

derp nevermind didn't read it correctly.
http://www.carbidedepot.com/formulas-tap-standard.htm

Sorry, a 5/16" hole is too small. The tap will be cutting more than 100% of the thread depth, which is an excellent way to snap it. You are looking at the hole size for a UNC 3/8-16 thread.

Reading more into it wouldn't a m8/m9 size hole work

(my working. 3/8 unf requires a "Q" sized drilled hole which is 0.332 in which is 8.4328mm)

[overkill]

You are looking at the wrong thread; check the next line down for the 3/8-24 drill size. That chart says a Q sized drill which is right between 21/64" and 8.5mm

[RogueTwoRobots]

Forgive my ignorance, as I've not read through the whole thread, but are you basically after a 5" wheel with a 3/8" UNF nut attached to fit to a drill motor? If so, I've got a couple of homemade wheels from the previous incarnation of Drumroll still kicking about. They're 5" (give or take a smidge as they have bike tyre screwed on and it's worn a bit) and I welded a UNF nut onto a couple of pieces of steel which then bolt to the HDPE wheel. They're not pretty and they're not entirely concentric (so they wobble a little but nothing noticeable in the arena) but if they would be of use to you, let me know and I'll dig them out. Will be back in my workshop next week.

dr2_build (95).jpg