Build Log | Caractacus - Any Tips?

[willcaddy]

Love your videos Will, and the glitter!

Was the "spike" meant to look that rude?

Thanks for watching! Sorry about the slow reply!

Not intentionally but it did end up that way a little ha ha. The idea came out of sheer desperation because I wanted to compete in the event and couldn't get the axe on Caractacus finished in time lol so wanted the daftest idea I could find and that was it xD

[willcaddy]

Nah. If they are rated for 24v, the 22.2v LiPo and the 85A speed controller are more than enough. I've ran 4x of the Gimson motors on my middleweight robot Kaizen and that had enough grunt to work happily for a little while but couldn't take the pounding so often ended up blowing one or two after each event. Your arrangement is OK.

It may be worth checking your gearbox at the moment to see if any of the stages are plastic. An all metal affair will be more reliable when it comes to a pushing contest or flooring it. However, pinning the wheel to the shaft will be the same regardless of the gear material because the shaft will be made of metal.

Thanks a lot for the reply! Sorry for the long reply, been one of those weeks!

That's good to know In your opinion then is there a more reliable way of mounting wheels other than pinning straight to the gearbox? I'm looking for the most robust thing I can find at the minute being as my robot currently only has a spike ha ha

Thanks a lot!

[McMullet]

Thanks for watching! Sorry about the slow reply!

Not intentionally but it did end up that way a little ha ha. The idea came out of sheer desperation because I wanted to compete in the event and couldn't get the axe on Caractacus finished in time lol so wanted the daftest idea I could find and that was it xD

All the best ideas come from sheer desperation at the last minute!

I keep thinking about mounting wheels on separate bearings and driving them with a belt or chain, to minimise shocks and impacts getting to the gearbox bearings. That would seem like the best approach overall but it also feels like a lot of work compared to just bodging wheels straight onto the gearbox output shaft.

[Ocracoke]

In your opinion then is there a more reliable way of mounting wheels other than pinning straight to the gearbox?

Short of welding the wheel to the shaft with a metal plate, the "pin through the shaft" idea is the best method I can think of. However, you could also drill a small indentation, attach a wheel hub onto the shaft and then screw in a grub screw into the indentation on the shaft (remembering to thread lock it) and then mount the wheel to the wheel hub. That is the method I use to hold down the pinion gear on my Middleweight's axe and has yet to come off.

[willcaddy]

All the best ideas come from sheer desperation at the last minute!

I keep thinking about mounting wheels on separate bearings and driving them with a belt or chain, to minimise shocks and impacts getting to the gearbox bearings. That would seem like the best approach overall but it also feels like a lot of work compared to just bodging wheels straight onto the gearbox output shaft.

Yea xD It turned out well though!

That's exactly what I have been thinking of doing but again not sure if it's worth it. I had an idea about mounting a bearing into the shell of the bot and having that connected to the other side of the wheel and attach to the gearbox like it is currently. Maybe that will provide some extra strength without building a whole drive train? Any thoughts?

Short of welding the wheel to the shaft with a metal plate, the "pin through the shaft" idea is the best method I can think of. However, you could also drill a small indentation, attach a wheel hub onto the shaft and then screw in a grub screw into the indentation on the shaft (remembering to thread lock it) and then mount the wheel to the wheel hub. That is the method I use to hold down the pinion gear on my Middleweight's axe and has yet to come off.

Yea I think the pinning idea is the best one for me! What is your thoughts on a drivetrain? Worth it?

[Ocracoke]

Yea I think the pinning idea is the best one for me! What is your thoughts on a drivetrain? Worth it?

Technically the gearbox on your motors is a drivetrain. If you mean spur gears, I don't personally think it is worth it with the motors you have now. If you were running brushless or bigger motors, maybe.

[willcaddy]

Technically the gearbox on your motors is a drivetrain. If you mean spur gears, I don't personally think it is worth it with the motors you have now. If you were running brushless or bigger motors, maybe.

Yea, sorry I'm not very good with the terminology!

I mean just having the wheel separate from the gearbox maybe chain driven to take the strain of the gearbox itself from having the wheel directly attached. I'm just wary because the P60 gearboxs for example are pretty expensive and I don't want to break them every event lol motors are fairly cheap so I can buy loads of them.

Thanks again for being so patient and helpful!

[Ocracoke]

No worries, gotta learn somewhere!

Chain drive... Deathly Hallows did a chain drive for one of his Featherweights (and did a build diary here) which shows an implementation and I know at least Forge Master uses a chain for their axe. The trouble is that if you don't have the sprockets lined up right, the chain will come off.

I use spur gears in Kaizen's axe and for both Jibril's drive and axe simply because they are easier to get right than a chain. In the Featherweight category, Satanix uses a spur system that is pretty neat. However, this is all a bit of a muchness. I would personally stick with what you have for the moment and not worry too much about the gearbox.

[willcaddy]

No worries, gotta learn somewhere!

Chain drive... Deathly Hallows did a chain drive for one of his Featherweights (and did a build diary here) which shows an implementation and I know at least Forge Master uses a chain for their axe. The trouble is that if you don't have the sprockets lined up right, the chain will come off.

I use spur gears in Kaizen's axe and for both Jibril's drive and axe simply because they are easier to get right than a chain. In the Featherweight category, Satanix uses a spur system that is pretty neat. However, this is all a bit of a muchness. I would personally stick with what you have for the moment and not worry too much about the gearbox.

That's great thank you xD

I'll have to see exactly what failed on the cordless drill gearbox and if it's a plastic bit I'll see what I can do about a beefier metal one xD Either that or maybe look for some cordless drills cheap and nick the insides xD I'll give some build diary's a read too!

[Ocracoke]

Ah, I had forgotten one of your gearboxes has broke. I'd open it up and see what's going on in there first but for a replacement box, it might just be more economical to simply replace the gearbox and motor from another cordless drill, as you say.

[willcaddy]

Ah, I had forgotten one of your gearboxes has broke. I'd open it up and see what's going on in there first but for a replacement box, it might just be more economical to simply replace the gearbox and motor from another cordless drill, as you say.

Yea xD I shall try take a peak in the next couple of days and see!

I'm guessing it's harder to get the standard cordless drill gearboxes new? Because I haven't really found any online. I was thinking of looking around for cheap job lots lol

Thanks again xD

[Ocracoke]

The odd thing, I find, is that I can't get the gearbox on their own. I guess it's probably more economic to simply get the whole assembly premade than it is to have the parts shipped in separately. If you do end up replacing the gearbox though, you will want a like for like replacement as so to match the ratios on the other side.

However, if the gearbox is bust because of a nylon gear breaking, it makes longer term economic sense to get a pair of motors with planetary gearboxes on them which are all metal, like the Gimson range.

[willcaddy]

The odd thing, I find, is that I can't get the gearbox on their own. I guess it's probably more economic to simply get the whole assembly premade than it is to have the parts shipped in separately. If you do end up replacing the gearbox though, you will want a like for like replacement as so to match the ratios on the other side.

However, if the gearbox is bust because of a nylon gear breaking, it makes longer term economic sense to get a pair of motors with planetary gearboxes on them which are all metal, like the Gimson range.

IMG_20190215_122743.jpg

I'm no expert but I do believe that gearboxes are supposed to have teeth lol

It appears when the motor seized or during an impact it sheered a few teeth lol but the gearbox (apart from the outer casing) is all metal and it wasn't a plastic part that failed which leads me to believe getting an all metal one wouldn't help unless it is a hardened tool steel one or something. So currently shopping around for cheap job lots of single speed, non-hammer drills. Whats your favourite site to get this stuff from? I'm currently looking at eBay, Facebook and Gumtree lol

Thanks again!

[McMullet]

I've occasionally seen a joblot of "spares or repairs" drills (argos and others) appear on eBay. As Lucy says though, you need to make sure you have the same type all round or you'll go in circles.

If those are the three gears right after the motor that have broken, I would guess it's not down to the mounting. If it was the last set of gears before the output shaft that had died, or the output shaft bearing even, that would look like an impact on the wheel. I suppose maybe the motor slipped out of the gearbox (that happened to us several times at Robodojo), and then it span enough partially meshed to damage the gears?

[Ocracoke]

I've had this happen to me with Shu! where the end stage planet gears just got stripped. It wasn't that the motor was being overvolted (it was a 12V motor running on 9.9v), it was the load on the end of the lifting arm which then got stuck as the arm tried to continue moving. Torsion did the rest I should think. I seem to recall the gears being brass, which yours does too.