Pneumatics for my axe

So,I need to sort out my axe.

Could someone please give me a list of every component needed for my axe to work.

My axe will work in the same way terrorhurtz and little hitters work with the rack and pinion,also,can anyone tell me where I can get a ram,rack and pinion for it.

Thanks.

HPC is the obvious choice, but they are very expensive especially for racks, I should know.

You need to work out how much travel you want your axe to have, what cylinder you are using, find a suitable rack to fit the cylinder. Then work out what size pinion you need to get the travel based on the MOD or TDI of the rack.

Take the stroke of the ram and work out what size pinion you need based on the stroke as a percentage of the circumference of the pinion. So if the stoke of 100mm and you want 120 deg travel (say mod1 for ease of calcs) you will need a 100* 3 as the circumferece (120 being a third of 360) so 300 /(2pi) = 47.7 for the rad of the pinion and 96 for the dia and teeth for mod 1. But it probably wont be mod 1 anyway.
But Im sure you knew all than nonsense anyway, plus i hope I got it right.

As far as pneumatics, bottle, reg, buffer, valve 5/2 or 5/3 valve(same as thz) then ram, plus fittings and pipe. All rated to the pressure you are running at, not forgetting a LP relief valve.

Thanks for the reply.Can you give some links to some of those parts please?Ive got a 600g co2 bottle is this big enough?Thanks again.

I have no idea where to start looking for a ram.

Yep thats what im using as do most people. Just dont copy the rest of my system or else, nah only kidding. I was lucky I had a ram so just had to find a rack to fit it. Mine is a 50 Bore 100 stroke, LH is about 80/80 I think.

Pneumatic stuff tends to be expensive new, start with ebay for valves, cylinders etc. Other things Technobots is as good as anywhere, unless you have your heart set on a particular manufacture, having said that Paul may have some contacts always worth giving him a ring.

Ok,thanks for the help Ed.

LH is 80 bore 50 stroke. Racks are expensive and heavy so both us and THz use the rams rod and cut teeth into it to save space, weight and complexity. All you then need is a cheap pinion gear. Only thing to note is how to keep the ram sealed if you use a double acting one.

Ok so how much money am I looking at spending on a rack?

The thing is I could get a ram at a similar size to yours Mark and make my robots chassis the right size to fit it,right?

So would any rams off this site be suitible?

http://secure.thorite.co.uk/8uwlhv226569/Pneumatic-cylinders-and-accessories/Norgren-Short-stroke-cylinders/c-1-389-629/http://secure.thorite.co.uk/8uwlhv22...ccessories/Nor gren-Short-stroke-cylinders/c-1-389-629/

Yes, once you get in the £150 pricerange.

A 50 or 63mm bore ram would accept a mod 2 round rack a 80mm bore ram would use a mod 2.5 round rack.

So, including machinist work to fit the piston to the rack, I think youre paying £250 for just the ram.
Then you need the -rather cheap- pinion, and the mounting to get everything together.

Hmmm...not cheap.Can you recommend any particular ram off that site please?And is there any performance difference between 2 and 2.5?

(Message edited by dan_boulton on July 22, 2008)

Nope, because I dont know what you wish to accomplish. Do you want THz in feather size?

And, I wont buy a LP ram, no need to.So I dont spend much time contemplating it.

But if really really asked nicely, I would say, a 63mm bore, 150mm stroke ram, with about all parts customized to accept better flow from the large valves, the round rack-rod and reinforced endcaps to accept the humongous forces.

Well,yeah THz in feather terms is what i have always wanted but....its going to be expensive.

Thanks for the help Mario.

Any ideas on how much a 63mm bore ram would weigh?

Roughly, 1.5kg, after all the modifications needed to make it a THz style ram/pivot.

Can anyone suggest a good metal for the arm of my axe?

A good quality aluminium or titanium are good suggestions. Also I recon on having spent about a grand on my feather axe when Ive finished.

A grand?!

Any pics?

Thanks for the help,what did you use for the arm?

mark- thzs rack is a HPC custom job... he sent me the technical drawing he sent to hpc :P

A very good grade of tool plate ali, not made it yet, infact not even got the material yet.

Ok,what kind of grade?

Ive never used ali so im not sure.

We use a rather large 60*25*950 solid sheet of 7075T6 ali for the axearm of Obsidian. I guess a 30*12 will do for a feather then.
My supplier for this stuff is Dejond, Wilrijk, Belgium. So P&P would make it rather expensive to get it from there.
For the gears, racks and simular stuff we buy at Stoffels, also in Belgium. Or go pure custom, but thats a very expensive option.

We use 2014T6 aluminium alloy for the axe shaft on THz.
The rack and pinion material is EN24 steel.

You could buy a length of round rack (not spur round rack) from HPC e.g. part 141-020-025 for £64 then drill and tap a hole in the end for a large bolt to hold the piston on.
see http://www.hpcgears.com/newpdf/round_racks_1_5mod.pdfhttp://www.hpcgears.com/newpdf/round_racks_1_5mod.pdf

The three most common strong aluminium alloys are:
1) 6082 - a weldable, medium strength alloy.
2) 2014 - high strength. Poor weldability. Not suitable for forming (bending).
3) 7075 - Strongest of the common alloys. Also not suitable for welding or forming. Tends not to be available in less than 1/2 thickness.

Generally you would go for the T6 tempers in the above alloys. This is the usual one most people supply.

All available from http://www.metalfast.co.uk/http://www.metalfast.co.uk/

Ed works in an aitcraft related business, so has access to alloys that us mere mortals can only dream about.

i found metalfast expensive compared to a ebay shop called alum-droitwich search for it they has a good stock of ali and can get what you want

eds on about a material called alumec, strong as hell, machines very nicely and its not too expensive.. minimum thickness is 20mm plate though.

Thanks for the help,I will look further in to this.

Do you think that an 8mm polycarb chassis could stand up to a fight?


(Message edited by dan_boulton on July 24, 2008)

Beat me to it Dave.

http://www.airtechnics.co.uk/catalogue/airtechnics_catalogue/pages/compact/isocompactcylinders.htmhttp://www.airtechnics.co.uk/catalog.../compact/isoco mpactcylinders.htm

Are these rams any good?

If you have the wallet for them, these are usable.

Compact but fairly heavy. They have a lot of excess material on the barrel.
Search on ebay for pneumatic cylinder.

I looked on ebay and all the bore sizes are to small...so what about these?

http://www.pneu-store.co.uk/acatalog/Pneu_Store_Webshop_CDG1_925.htmlhttp://www.pneu-store.co.uk/acatalog..._CDG1_925.html

CDG1BN80-150
Standard Type Double Acting, Single Rod

Price: £102.77 / Euro129.83 (Excluding: VAT at 17.5%)

Does that mean its 80mm bore and 150mm stroke?

I should expect so, but with those prices, and that brand it seems doubtfull.

SMC is good stuff.

Bore 80mm stroke 150mm that is correct. It says so in their documentation.

Thanks for the help.

I looked on ebay and all the bore sizes are to small

http://cgi.ebay.co.uk/Festo-Double-Acting-Compact-Cylinder-80mm-Bore-80mm-Stk_W0QQitemZ130181963557QQcmdZViewItem?hash=item1 30181963557&_trksid=p3286.m14.l1318http://cgi.ebay.co.uk/Festo-Double-A...re-80mm-Stk_W0 QQitemZ130181963557QQcmdZViewItem?hash=item1301819 63557&_trksid=p3286.m14.l1318

Leave it to the master.

Thanks for that one Woody.

Looking for more like 125-150mm stroke though.

Thanks anyway.

Dan,

Your building a feather not a middleweight.
I think your going to get into all sorts of probs with such a big ram.

Do some sums on co2 consumption and the energy your Axe mech could possibly use before sending you Bot over Axe Head.

http://www.roboticgladiator.com/tutorials/ax1.htmlhttp://www.roboticgladiator.com/tutorials/ax1.html

Perhaps John will step in with some guidance for you.... he posted a quick math guide for Axe acceleration and energy the RFL Forum.

Ok,Woody.

Do you mean weight problems?

Thanks for the link.

BTW i worked out on a pressure calculator that i would get 512 kg of force,is that good?

Cheers.

(Message edited by dan_boulton on July 25, 2008)

Weight of ram and axe mech ... CO2 Gas consumption = weight / mass of liquid co2 / size of required bottle etc ...all problems to be taken into account before buying things that will be no good to you.

The max velocity / accel of the head mass at a given distance is goverened by your rams force.

Once you get up to around 2 kJoules, a heavyweight robot would generally start jumping off the ground rather a lot.

Quick calc for your proposed ram.

Energy is force multiplied by distance in Newton Metres ...convert units
512kgs force = 5017 newtons
ram stroke 150mm
E = 5017 N * 0.15 m = 752.55 Nm or Joules