Liftoff (FW) build diary

I've finally got most of the parts I need for the build so I thought I'll follow most of you and keep you updated on this build diary - at the same time any advice and comments are more than welcome as I'm no expert in this field!

So some details first - Liftoff shall be a LP flipper track driven by two motors. Details Below:

Drive type: Tracks
Motors: X2 Makita 6347D
Esc: Sabertooth 2x60
Armor: HDPE (plus steel if weight permits :roll: )
Weapon: LP flipper Co2 63mm bore cylinder

Pneumatic system parts mostly available and assembled, remaining is the cylinder which will be machined locally.
Will post some photos soonish.. :wink:

This is the pneumatic system, still missing the cylinder... Used 1/2'' fittings through out. Not yet fully tested as I got no Co2 available yet :cry: But monday I'll get an expired fire extinguisher and I'll have a go at refilling the bottles (I'm slightly concerned as this is my first fill! :roll: )

Partially tested the system at 6 bar this week and it worked fine, removed the regulator and supply tank and connected an airline to the 5 way valve inlet, energized the solenoid and bang - QEV opened and there was a large flow of air from the T-piece just behind the QEV.

The pressure gauge on the buffer tank is just a temporary thing - to compare the pressure to the regulator when I go to 11bar with Co2


http://i8.photobucket.com/albums/a49...z/P1060538.jpg

Another view, it will be quite a squeeze - 1/2 fittings don't come small nor light!

http://i8.photobucket.com/albums/a49...z/P1060539.jpg

All connected and ready to go - but just not yet, that extinguisher is still serviceable so I just checked every thing bolts on, Monday will borrow another one :D

http://i8.photobucket.com/albums/a49...z/P1060540.jpg

Where did you get the fitting to go from the co2 but to the ball valve?
Are those standard hydraulic ball valves?

off ebay, its a complete fill station for Co2 bottles, came complete with digital scales.

Ball valves look quite thick-walled heavy duty type, surely not normal compressed air or water type

Got it form here:

http://www.ebay.co.uk/itm/New-Deluxe-Du ... 668wt_1076

Got a question regarding HDPE, I'm using a 5mm thick HDPE baseplate for the build, but the material I got is warped and now I'm not sure if I want to use it any more. Is it normal for HDPE to be like that as even a couple of solid rods (30mm and 40mm dia) were bent?

I'm tempted to replace HDPE with an aluminium base plate but that will double the weight :cry:

5mmhdpe wont be that good base plate if your mounting stuff to it, it will bend quite a bit.

3mm ali is agood option, slightly heavier and a lot stronger, Battle axe only did a little dent to laser's base.

Hmmm :? thought Hdpe was quite stiff, similar to nylon.... that is, until I got the material this week :shock: , its quite bendy!

Will see if I can leave the 5mm hdpe base and reinforce it with alu - if not possible will have to opt for an all aluminium base plate.

The robot design should be quite sturdy, but in the end I will only know when its all assembled!

Depending on how you're building it the HDPE might be ok. If you're mounting stuff to it and trying to make it the part which holds the machine together than you've had it, but if you're using it as a baseplate and having bulkheads attached to it and other bulkheads thats where your strength can come in and it'll be fine. The latter is the way Cicatrix is built and it's pretty tough with a 6mm HDPE baseplate.

this is a basic idea of the robot layout, the back end will be quite rigid as there's a 70x70x5mm alu box section which will house the motors, that will be bolted to the base plate, the sides will be 10mm hdpe bulkheads containing the tracked drive. The front is my concern as there's nothing connecting the track housings to each other... I'm not sure about this but I believe that with the flipper arm retracted the whole thing should be pretty rigid, but flipper up I don't know!

http://i8.photobucket.com/albums/a49...uild/robot.jpg

This is the progress done so far. Its difficult to introduce a fwd bulkhead because the pneumatics are in the way!

http://i8.photobucket.com/albums/a49...d/P1060557.jpg

Could you have a low bulkhead between where your pneumatics stop and your flipper arm begins to lie the two forward facing bulkheads together? There must be a way somehow :)

Will have to find a way to fit it in I guess, there really is not much space as it will have to go round those fittings or the bottles, but I'll find a way, maybe I'll use aluminium or steel instead of hdpe to make it more compact, and then trim holes in it for the bottles and fittings to pass through... should work like that I think - off to the drawing board!

Got the fire extinguisher and went on filling the paintball bottles, but I have a small problem here. The bottles are 12oz ones and the extinguisher is 2kg - I only managed to fill the bottles to 10oz and 9.5oz. Before I filled the bottles I put them in the freezer as I had read somewhere that it should help, but still didn't manage to get 12oz. Is it anything to do with the extinguisher, maybe its too small at 2kg? :?

1. Fill the bottles to the correct weight. This is stamped on the bottles.
2. It will be difficult to get a full fill off of a small bottle
3. Don't worry if they are under filled

At 12oz its quite small, so every ounce counts! :wink:

I'm trying to fill it to its correct weight, but I cant... having another try at it - I've placed the bottle with 10oz co2 in it in the freezer, will try to top it up later on,in theory it should work - if not it'll stay as it is.

I connected the whole setup to the co2 tank to give it a couple of test fires and check if the regulator works. I can't manage to get enough pressure tho as it is leaking air from every fitting!! - Bloody thread tape wont work!
Now I found some threadlock and sealed all the fittings again - hope that works - off for testing!

Done testing and I'm happy :D but I did get the scare of my life as well!

One of the push fit fittings came apart - I mean literally came apart not just the pipe came off! Dont know if its just a defective part or it cant handle the pressure so until I get confirmation of how much pressure it can handle I'll have to lower the pressure.

http://i8.photobucket.com/albums/a49...z/P1060566.jpg

I was operating the system at 11bar when the fitting burst, I replaced it with a new one and got it going at 10bar without incident. Will post a video clip tomorrow.

I also manage to fill the co2 bottle up to 12oz - so freezing it worked :wink:

should be fine at 10bar, guess it was just a damaged one.

you're right, it should be good for up to 10bar, but have to say that to burst at 11bar they're designed to the limit!! :shock:
I had the safety valve set at 11bar, should I consider replacing it with a lower rated one or this was just a freak accident one off type?

I fear if you keep on working along the 10 bar line, you'll see this kind of failure a few more times.

On teflon tread tape. I don't use it anymore in connections I don't have to undo regulary.
I use 2K glue on those connections. Since I started doing that, leaks are very rare.

That's bad! :( I've been in contact with the shop where I bought them and I'm told they are rated at 10 bar max, so in theory they should be ok, but for how long I don't know! On a positive note, the lad at the shop told me they have others rated at 15bar so I'm going to get some of those to put my mind at rest.

yeah , thread tape - what a nightmare! specially the swivel push fittings which came with a pre-applied coating of teflon, bloody useless!
Used locitite 243 on all the leaking fittings and problem solved straight away. Pressurised the system and closed off the supply from the tank with no drop in pressure after 10min. Good enough for me

To bad, depends how you look at it. Those plastic push locks are strong enough for 10 bar.
But then the hose needs to go in perfectly straight, without any sideway force or pull on it.

At work we have problems in that respect. Packaging machines have in certain cases pistons that move along with the packaging material, even for meters.
If it is done well, it takes years before any hose or push lock fails, and then it's most of the time the result of degradadion by heat or UV light.
But some lazy people take a short cut when that happens. Not replacing the hose, but just cutting out the failed piece and by pulling and using up the slack reconnecting the 2 parts with a connector. And if that doesn't work, by rerouting the hose, not even bothering to see if it chafes or pulls at anything. Result. More problems.

Guess you're right maddox, the elbow fittings from the QEV to the 5way valve are a bit stressed - think I'll replace them with threaded 90' fittings, should come shorter than the current set-up and the fittings will be better aligned.

Here is a clip(Hope it works!) of the LP system test. Didn't bother connecting the solenoid, the valve has a manual deploy button :wink:
Looks like it's working ok, will have a better idea when the actuator is finished and tested

http://i8.photobucket.com/albums/a49...d/th_00000.jpg

Progress with the build of the chassis and motor housing is in good progress as well,

Started off with these motors

http://i8.photobucket.com/albums/a49...d/P1060541.jpg

Took them apart

http://i8.photobucket.com/albums/a49...d/P1060543.jpg

And put them on a diet :lol:

http://i8.photobucket.com/albums/a49...d/P1060544.jpg

After some sweat and a good slimming treatment with the belt sander they look like this:

http://i8.photobucket.com/albums/a49...d/P1060546.jpg

Now the motors can fit into this... the motor housing/retainer

http://i8.photobucket.com/albums/a49...d/P1060547.jpg

Motor housing bolted on to baseplate

http://i8.photobucket.com/albums/a49...d/P1060576.jpg

bottom view of baseplate

http://i8.photobucket.com/albums/a49...d/P1060575.jpg

And these are the parts competed so far

http://i8.photobucket.com/albums/a49...d/P1060577.jpg


I'm happy with the progress so far, not much problems till now apart from HDPE being a bit difficult to work with till you get used to it. Hope that by next week I'll get the actuator and wheels, I want to see it moving :D

That is a lot of rivnuts.

''That is a lot of rivnuts.'' well I had the team telling me the base was flimsy, my dad saying that normal wood screws will get pulled through the base - so I did something to prove them all wrong! :lol:
To be honest all those screws are an overkill, but that's where most of the power is concentrated, the motors and the hinge point for the flipper arm...so better safe than sorry :wink:

Very sensible, lots of fixings make a strong robot

Quote:

---

Originally Posted by Liftoff

Guess you're right maddox, the elbow fittings from the QEV to the 5way valve are a bit stressed - think I'll replace them with threaded 90' fittings, should come shorter than the current set-up and the fittings will be better aligned.

---

Could always go for smaller tubing for the retract (buffer fill). That would allow for a tighter bend radius.

That's true Kane - but I got no ''retract'' in this system, the tube which is out of alignment (the one from the 5 way valve to the QEV) is the main supply to the buffer tank. Retract will be by spring dampers or bungee chord.
Its still a good option to use smaller tubing though, lets see how the actuator goes and then proceed from there - I only need to lift 17kg, and if my calculations are right, using a 63mm dia actuator at 10bar should get a force of 300kg, should be enough I hope :roll: might also consider lowering the pressure to conserve Co2 and get less stress on the whole bot...

Looks really good. Don't forget your dump valve though.

''Don't forget your dump valve though'' Hmm...totally ignored that :?

I could place one on the regulator inlet, but that will be difficult to operate from outside (as per FRA regs.).
Having said that I probably wont need it as its not listed in these regulations where the competition will take place:
http://ieeesbmalta.org/index.php?option ... mitstart=1

Will try to think of how it could get incorporated into the system anyway - can someone please post a pic or link of a similar valve just to get an idea, thanks

this looks really good so far! :D

btw, you don't need large tubing on the buffer tank feed.

Thanks Jonny, doing my best :wink:

''btw, you don't need large tubing on the buffer tank feed.'' come to think of it its not really necessary, you're right - time for ordering parts and start modifying!

I've found this off ebay, looks good for a dump valve - its nice and compact, according to the description in the off position its exhausting. What do you think, is it any good?

Ops forgot the link -here it goes
http://www.ebay.com/itm/PT-3-8-16mm-Mal ... 372wt_1163

Looks like you'd have to hold your hand on it while it vents as I think there spring return (closed)... Meaning you'd be getting co2 vented into your hand... Most people here just use a ball valve... Like on a paintball filling station for example.... Put another T fitting before your PRV and stick it in there maybe?

i use http://www.ebay.com/itm/2pcs-6mm-to-6mm ... 337a4fb02f ones like that

Right I got it, thanks for the hint. Will replace the elbow with a Tee downstream of the regulator and place a small ball valve - shouldn't be a problem to make it accessible from outside.

Think its not a bad idea to build it to FRA regs just in case I come over one day :roll:

Apart from weight are there any restrictions regarding dimensions?

No restrictions on dimensions of the bot (excepting ant weights). You'll normally be limited by weight.

Good good, I'll keep an eye on the weight - thinking of it, the 5/2 way valve is too big, could have got one with smaller ports and retained the same effect.

More progress done today - most of the hdpe work done :D when you get used to it, its a good material to work with - only thing I hate about it is that it sticks to everything!

Here's a couple of pics with the progress so far:

http://i8.photobucket.com/albums/a49...d/P1060578.jpg

I've put the pneumatics in and after some trimming to the aft alu tube, got it a nice good fit.

http://i8.photobucket.com/albums/a49...d/P1060580.jpg

Weighed the thing and its already at 7kg - so it will be really difficult to keep with the 13.5kg limit, but for the competition it doesn't really matter as 17kg is my limit

http://i8.photobucket.com/albums/a49...d/P1060581.jpg

If you can build it inside 13.6kg it would be fantastic, that thing is beautiful so far!

Really nice work. Can't wait to see more progress!

Edit: could having the option to run it with wheels get it inside 13.6?

dont forget that extra 100g very useful :P

Thanks Ellis, trying to keep it as neat as possible, hope it will perform well also!

''Edit: could having the option to run it with wheels get it inside 13.6?'' I think we could put it on a diet to get it within the 13.5kg limit, the pneumatic system is heavy, I could do without most of the 1/2'' fittings and downsize, the valve as well, would still work with one half the size (that's weighing 450g alone!)
Wheels instead of tracks can be done as well, and that would loose quite a lot of weight as well considering the track system contains four wheels and two tensioners apart from the track itself.

But for this competition its better to keep to the 17kg limit, still need to add some removable steel armour at some areas, and the flipper arm will not come lightweight! Still not decided how to build the arm, steel or alu tube? Its the part which will receive the largest amount of abuse - so I think it will be steel...

''dont forget that extra 100g very useful '' didn't get it, remind me about that pls