Liftoff (FW) build diary

[Liftoff]

Re: Liftoff (FW) build diary

Right, its shopping time again!

Plans for the re-design in the final stages - mainly to do with weight reduction, believe me its not so simple eh!
I wouldn't like to order the wrong parts so my question : I'm downsizing the 5/2 valve from 1/2 to something smaller, will any size do? I'm looking at a 1/8 port size valve - like this
http://www.ebay.co.uk/itm/DC-12V-2-P...item53f148c741
Will it be suitable, I mean what else apart from taking longer to fill up the buffer tank should I expect?

[maddox10]

Re: Liftoff (FW) build diary

As long it doesn't get liquid CO2 , it should work fine for a while.

And I'm sorry, for that amound of £ that seller asks, I can't even ship you one of the dozen Festo's I have here.

[Liftoff]

Re: Liftoff (FW) build diary

Yeah I know...its dirt cheap! in fact I just bought it yesterday
The 1/2 one I have was of a similar make and similar pricing and it worked fine...up till now.
It's not worth spending too much money on something you might end up changing just after a season!

I also got my self a replacement QEV. The one I have installed is a 1/2 but quite bulky and heavy (I think its brass or steel) Found this on ebay, its smaller and lighter and still 1/2 - might need to modify the outlet though as it looks like its 3/8
http://www.ebay.co.uk/itm/160930294213

[Liftoff]

Re: Liftoff (FW) build diary

I have got the latest version of liftoff drawings in the final stages before the mods start taking place - parts started arriving as well, got the GR02's from Ewan, really compact compared the the Makitas I had before!

The basic design remains very similar, and I'm using the same platform - what's changing apart from the motors and pneumatic parts is the orientation or the ram. It will now be in a horizontal position rather than vertical. I've added a self-righting mechanism as I have moved the flipper hinge forward and I'm afraid it lost this ability it had before. I'm still a bit sceptic if the mechanism will work - if anyone could look into it from these pics and see something wrong or any place for improvement, I'm all ears!


General views : Front side.



Back side. Back cover I'm thinking about a polycarbonate panel, it would look really nice I think!



Top panels off - self righter linkage will be a nightmare I think



Flipper and self-righting mechanism in action...



Internal components layout

[Eventorizon]

Re: Liftoff (FW) build diary

I'm not an expert but I reckon that will work.

A few things I would change if it was me...

-Use a solid triangle for the ram to push against rather than the L shaped piece
-Give yourself 4WD by running a belt to the front, otherwise the weight out front will act like a massive pendulum making it difficult to steer
-Don't use the Sabertooth 50A [Unless you already have it] and go for TZ85A from Botbitz... Sabertooth's have a bad history in combat (But some people have never had an issue) Its hit and miss...

Besides that it looks superb! Its got this kind of cool angular look to it and has the guts to match!

[Liftoff]

Re: Liftoff (FW) build diary

Ah recognised the Sabertooth :wink: I got the 2x60 in there, I know its not highly recommended but we've used it with no issues last November... fingers crossed!!
Yes that L shaped piece is there because I got a piece of titanium in a roughly similar shape and thought I'd use it but triangular shape would be a better bet - will re design!

Drive is still a question mark, I had tracks on it and maneuverability was top notch, the down side was the added weight and less grip. I might go the 4WD way like you said or tracks again - both are possible in the available space.
Yes the wedge shape really looks like a stealth something - keeping it as low as possible - the highest point is just 160mm!

Thanks for the encouragement hope to make it to an event in the Uk next year

[maddox10]

Re: Liftoff (FW) build diary

Hammerhead II used that decoupled setup with reasonable succes, and I based the Gravity 2-3 setup on it.

[Liftoff]

Re: Liftoff (FW) build diary

Good to hear that Mario - I'll try to look up Hammerhead II to see how it's set up.
I tend to get a bit discouraged when I start complicating things...got to find some local waterjet cutting shop to do these little bits and pieces as most will be done from titanium and that's a nightmare to cut without proper tooling - I'll post a few close ups of the lever system - if there's anything wrong please point it out, thanks

[Liftoff]

Re: Liftoff (FW) build diary

Couldn't find any close up views of Hammerhead II internals... anyway here's my setup:

My concern here is that the links come almost in a straight position, and not sure if it will be too much of a mechanical disadvantage to overcome.



Flipper up

[maddox10]

Re: Liftoff (FW) build diary

Why not using bigger wheels or a Hard drivetrain and not needing a selfrighter?

[Eventorizon]

Re: Liftoff (FW) build diary

In theory I can see that it works but in reality... I wonder about the strength of the parts and the leverage you get.

Do you have accsess to something like MD Solids. You can used that to optimise the geometry of the mechanism my messing with the lengths of all the shaft and that kind of thing.

I am not sure what an alternative method might be but I don't think this will work reliably. Sorry...

[daliad100]

Re: Liftoff (FW) build diary

You could run a cable or two to pull it up and possibly down

[Ellis]

Re: Liftoff (FW) build diary

It looks like you have plenty of space to put in some friction driven wheels on top of the drive wheels, much like Crushtacean, seen at around 1:15 - http://www.youtube.com/watch?v=gEmRBaHRx7M - (I believe they worked like that, if not it serves to explain this)

Just trying to think sideways. This is a really nice robot!

[craig_anto]

Re: Liftoff (FW) build diary

fantastic work, loving the cad drawings too,

[Liftoff]

Re: Liftoff (FW) build diary

Thanks for the replies guys... For drawings I'm using Sketch up, got used to it now but some times its a real pita don't have MS solids Alex, will see if its downloadable and have a try there.
Material for the levers will be 4mm thick Gr5 Titanium - I think that will be suitable for the job, the problem is geting it into shape. There's no way I can form the levers in titanium using normal hand tools, the only solution is having them waterjet cut - I'm currently looking for some local shop which could do it for me without costing an eye :|
For sure I'll make a mock-up of the system using wood or acrylic just to see if the system works at all...hate surprises!!
Wheels on top might work to retain mobility upside down but I'd need to get the thing back in upright position to be able to fight!



Been thinking about cables Jordan, its possible to do it that way - got to refresh my memory on cables and pulleys (its been a while since I last worked on a 737!) Off to the drawing board!!
Thanks for the ideas!