Here's the Ali Billet I was given. It was donated by a very kind man down the road from me who had it 'just lying around'. Given it's size it makes for a tempting drum spinner!
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Here's the Ali Billet I was given. It was donated by a very kind man down the road from me who had it 'just lying around'. Given it's size it makes for a tempting drum spinner!
The guy also has a large lathe and band saw which will be coming in handy!
Nice, when i first saw the picture it looked like a very large wood dowel!
Haha, it does rather look that way! Unsure why the forum uploader has put it on it's side though.
Haha, its funny what people have 'lying around'
Whats its dimensions? Any idea on weight?
It weighs a fair amount, my guess would be around 4kgs, but I'll stick on the scales in a bit.
That's an off cut too of what he had!
My plan is to bore out the middle to 20mm, make it a lot shorter and effectively use it as a stand to hold a 20mm Silver Steel shaft that will support the wheel.
The flat top will make a nice surface for a thrust bearing and it's size will means lots of mounting options.
Although looking at the build pics of Tetanus it may be a little overkill, very conscience of weight.
Too heavy for the kitchen scales, comes up as 4kgs on the bathroom scales. 100mm dia and 180mm tall. The internal height of the car wheel is 135mm (but that could be due to change if I can't find a better way to get the weight down).
Take away wheel clearance, thickness of the base, room for a thrust bearing and I'll likely need a 100mm tall block. That'll weigh 2kgs with the centre bored out. hhhhmmmm
What I need is one of these:
http://www.ebay.co.uk/itm/3707867405...84.m1438.l2649
Although one ideally not intended for an Aston.... Anyone any idea what I would search for to find one of these 'generally'?
does it have to be exactly the same
or would something like this do
http://www.ebay.co.uk/itm/Ford-Atlas...item1e79570089
You've not blown another prop shaft on your Aston have you?
I wish! I want me one of these:
http://preview.netcarshow.com/Aston_...977-800-01.jpg
@Plargen No, but that could be useful otherwise though!
So the single block of Ali plan was a no go, far too heavy.
So I had a plan to create 2 x 20mm thick braces separated by 4 x M10 bolts holding a 20mm Silver Steel shaft.
We're concerned that there will be too much flex and potential twist. Thoughts?
Attachment 3911
As long as you have good bearings there should be little twisting force between the two 'layers'. I imagine it should work as the main force acting on it is a sideways force from an impact. As I see it if you tried to push the shaft to one side it would put one of te bolts under tension, another under compression- the one under tension should be strong enough so should stop it be bending.
But obviously all this is just thinking out loud- there is no maths behind what I'm saying!
Alternative link positions on a FBS?
Other than out of the central stationary column? Ideally want it somewhere else to save weakening the shaft.
Ideas?
Put a hole in the shell, and when the bot stops spinning then you could reach the link through that????
Too dangerous I would fear.
That is totally against the concept of a safety link. You have to be able to get at the link even if the machine is out of control. If the weapon is spinning at all, that would make it impossible.Quote:
Originally Posted by Mega Masher
As for a solution, the only truly safe solution is the stationary central column if you are going for a design similar to LS4. I have seen links with long cable ties attached to them that stick out on the side but they can get cut or could be pulled out mid-fight.
Ok, I didn't know. Sorry peoples
Bit of a crazy solution but maybe you could take your steel shaft, cut it in half along the length (leaving two semicircular sections) then stick/bolt the two halfs back together with a thin layer of insulating plastic between them. The top of the axle is open at the top, you then have a circular magnet which you drop on the top of the shaft and acts as a conductor so connects the 2 halfs of the shaft. Inside the robot you have two "brushes" like on a brushed motor pressing against either side if the shaft, this acts as your link. To activate you put the magnet in place to deactivate you just pull it off.
That is crazy!
Anyone else have issues getting 3/8UNF studding connectors to wind onto their drill shafts? I get about 2 turns and then it locks.
Seems a waste to buy a 3/8UNF tap just to sort out 2 studding connectors!
Some use a tail sticking out from onder the machine.Quote:
Originally Posted by PJ-27
But that would be a weak spot with all those drums chewing up the floor.
I had some problems with some 3/8th UNF brass nuts a while back, not sure if they're quite the same, but a change of drill gearboxes sorted that. Not sure what the problem was though. The new ones have been fine ever since, so I'd assume it's either a bit of damage somewhere, or the shafts themselves have twisted slightly out of shape?
All brand new stuff, both connectors do it on both gearboxes. I'll try a different motor/gearbox and see if that changes then I'll know who the culprit is.
Sounds like they might be the wrong pitch. Imperial threads are written in the diameter of the screw in inches followed by the number of threads per inch. I believe drill shafts are 3/8-24. If you got something other than 24 (if someone can confirm that they are indeed 24tpi) then it won't thread on.
It threads on very nicely to start with, then just stops. Bought a 3/8UNF tap for £3.50 on eBay, figured it would be good enough just to sort this (although the tap cost more than the connectors.....)
Exactly, it will go on on for a few threads, which is just the slop you have between a fitting nut and bolt being taken up, then it will seize. Tapping it will either permanently wreck the threads as it attempts to tap it to a different TPI or do nothing as it'll be the same TPI as the nuts and just pass through. No reason for a brand new nut to not thread onto a clean drill shaft unless the threads don't match.
If you have a spare nut, cut it in half and hold up the exposed thread to the drill shaft. If it matches exactly but the nuts still don't go on you need to report a glitch to the man in the sky! :P
Disclaimer: if I am missing something stupid pls don't hurt me
I dunno, I just assumed 3/8UNF was 3/8UNF, no thread pitch listed on the connector stats. Replacing the nut will be a bugger.
If the seller specified that it is a 3/8UNF (that's 24tpi) then I'm at a loss! I don't understand how it can be too tight, especially if it winds on a little way, and still be the right thread. Hopefully they just have a bur from manufacture inside that tapping will clear. I suppose it's possible that they're somehow manufactured too tight but I don't see how really. Perhaps the seller incorrectly listed them as UNF, but even then if they were the other imperial standard pitches you'd have 8 threads too few or too many, which you'd think would be noticeable.
Anyway, hope you can fix it! Am fully prepared to eat my hat, seeing as I don't have one. ;)
Forcing in a 3/8UNF bolt makes some progress, I think it's just crappy manufacturing. Will sort it with the tap.
Anyone know a source for extra long left-handed thread bolts for the end of the drill shaft?
Made a little more progress, put the arms on to see what it looked like.
Attachment 4344
Attachment 4345
Going to be a pain fitting the actuator in!