Pneumatic questions, sorry!

[Max]

Re: Pneumatic questions, sorry!

Can't you get smaller sheets of hardox (smaller than 6m x 2.5m)?

[maddox10]

Re: Pneumatic questions, sorry!

Can't you get smaller sheets of hardox (smaller than 6m x 2.5m)?

Yes, you can, but not in the 3.2mm thin plate we favor (and thinner isn't made by SSAB). Most steel-selling firms can deliver 4 or 5mm plate in 1 by 2 meter sheets. Weight is 7.85kg per dm³, so a 4mm thick 2m² plate is 64 kg , aboutish a £8 per kg, so, you know what to expect.
Also, asking a firm to cut up a standard plate will cost you. In most cases, the difference between buying a half plate or a full plate won't be enough to justify the half plate.

On welding hardox. There some things you need to take in account. Hardox becomes a low alloyed steel when heated over 250°C for a prolonged time. Unless you use the specified rods, you will get less strong welds, and a heat affected zone what is not as strong.

I weld my hardox with TIG, high amp setting for high speed welding, and use AISI 1.4571 rods (316 ti). That will lower the hardness in the weld affected zone, but the tensile strengts keeps up.

[jonny]

Re: Pneumatic questions, sorry!

you can get 3.2mm offcuts from a company called abba commercials for £50/sq metre minimum order quantity 1 sq m

[RogueTwoRobots]

Re: Pneumatic questions, sorry!

Abba commercial you say?
If you insist:

http://www.youtube.com/watch?v=OMXL62VVr2k

[jonny]

Re: Pneumatic questions, sorry!



here's a link to there website: http://www.abbacommercials.com/home.aspx

[maddox10]

Re: Pneumatic questions, sorry!

you can get 3.2mm offcuts from a company called abba commercials for £50/sq metre minimum order quantity 1 sq m

Handy, and £50 per 24 kg is damn cheap.

[Max]

Re: Pneumatic questions, sorry!

Thanks for finding that company, do you just call them/email them and ask for a sheet of Hardox?
And back onto pneumatics, why are rams always much longer than their strokes by at least 50mm? And is there a way to reduce the height without reducing the stroke?

[Kenny]

Re: Pneumatic questions, sorry!

the reason a 50mm stroke ram is longer than 50mm in height is because you have a wall at the bottom of the ram, the port height, piston width then the 50mm between the piston and the top cap ( thats why its called 50mm stroke because the piston can move 50mm in that gap) and then the width of the top cap

[maddox10]

Re: Pneumatic questions, sorry!

Most commercial pneumatic rams have several parts that increase total length of a ram compared to the stroke.

Some types of ram are ment to be as short as possible.
Others can be 100mm longer than their stroke because they got adjustable soft end-brakes , locking brake and so on.

Hydraulic rams are another matter, and these have wide pistons with a lot of sealing surface, and linear guides in the head to cope with the forces exherted on the rod.
Also, to contain 3000psi of pressure ,you need serious end caps and a very solid way to connect everything.

All good reasons why so many people with pneumatic machines use custom, or at least customized rams.

[jonny]

Re: Pneumatic questions, sorry!

they only sell offcuts they have though should be large enough for feather use. just email them asking what 3.2mm hardox offcuts they have lying around

[Max]

Re: Pneumatic questions, sorry!

why do you need a buffertank in an fp system because surley (due to the lack of a regulator) the pressure between the main tank and the buffertank would equalize meaning the co2 would condense in the buffer tank filling it up with liquid co2 and then it would just become a second main tank ? also, will the tank ice up/ freeze more or less in a fp system than a lp system and is there any way of reducing/stopping this?

[woody]

Re: Pneumatic questions, sorry!

You should not get much ...if any ..condensate from F.P. gas transfer.

[woody]

Re: Pneumatic questions, sorry!

The freezing is caused by the liquid co2 turning to gas.... it boils ...to do this it requires energy ...the energy to boil is taken either from the liquid itself ...making it colder and possibly even turning the liquid to ice ... and the surroundings such as the bottle and the atmosphere immediately around the bottle.

A fire extinguisher bottle doesn't freeze when used because a vast majority of the liquid expansion to gas occurs outside the bottle... the liquid is ejected and becomes gas / snow after exiting the nozzle and the atmosphere supplies all the heat energy for the liquid expansion to gas.

So it's heat transfer to the liquid...if you can improve it then you can derive some benefit.

[Max]

Re: Pneumatic questions, sorry!

Sorry but i still can't see the point in a buffertank in a hp system, I have a vague understanding of why you need one in a lp system (because it takes some time for the regulator to start and you want the ram to start extending instantly) but there is no regulator in a fp system so why bother with the buffertank?

[maddox10]

Re: Pneumatic questions, sorry!

Sorry but I still can't see the point in a buffertank in a hp system,

I do.

but there is no regulator in a fp system so why bother with the buffertank?

The valve in a paintball botle has a 2mm² hole, a Burkert valve has a hole of 126mm².

I have a vague understanding of why you need one in a lp system (because it takes some time for the regulator to start and you want the ram to start extending instantly)

A tiny wrong idea if you ask me. A regulator starts regulating from the moment the pressure drops below the set pressure.
But has a certain capacity in let trough. (CV)
A small regulator has small holes to let the gas flow, you just can't fit a 16mm hole in a 15mm diameter body.