Team MedBots

[jonny]

could be a flowrate issue

[Max]

I think the regulator was set a bit low so I'll get a pressure gauge and test.
Could you make a crude speed controller by having a circuit with a variable resister, a capacititor then one side of a relay and a small battery (3v) then to the other side of the relay attach the motor. Then use a servo to control the variable resistor and have a simular setup for reverse?
I know it wouldn't be the best but would it work?

[razerdave]

You could do. That is how some of the really old RC cars used to work, and also how th 4WD's worked before they made an interface for it (Look up Hypno-disc's build diaries)

[Max]

Right I am thinking of rebuilding my flipper with a fatter shorter ram.
I am thinking of a 100mm bore 80mm stoke running at 10bar.
To keep it as compact as possible I want to make it my self by using a piece of aluminium tube then having a piece of 20mm hdpe as end caps. I plan on drilling holes in the corners of the hdpe and using threaded bar to hold the end caps together with the tube in between.
Then make a aluminium plunger and then weld a peice of aluminium rod to the plunger.
Would this work? What thicknesses would I need? How would I get a good seal between the pipe and the end caps and between the plunger and tube?
Thanks,
Max

[psycho_fling]

first off i have no experience in this area but i would have a feeling that precision is very critical both for safty and to make the ram actually work. the best and easiest way to do so is using computer controlled machines with CAD models

like I say i might be wrong ....... dont let this stump your ambitions though

[Liftoff]

I'm doing something similar but to keep it simple I bought a cheap cylinder off ebay like this one:

http://www.ebay.co.uk/itm/Single-Rod-63 ... 569wt_1142

It can be disassembled easily, will use the same endcaps and piston and manufacture a new cylinder bore and piston shaft. The endcap I will fit a 1/2'' fitting to it for max flow.

[mightymouse]

Max

Buy a second hand low pressure ram and stick to the pressure ratings, it will be powerful enough for a feather.

100mm bore by 80 stroke is the same as the ram on Meggamouse so if you did build one properly it would be way overpowered, and use too much gas. I cannot recommend you build your own, if you have to ask the question, you will not have the skills.

Trevor

[Max]

I've found it hard to find a commercial ram with big enough ports (12mm) and ideally I want a smaller second port as well, commercial rams also seem to be very big and heavy considering the shortness of the stroke.

I also feel I lack the knowledge of how to build a ram, not necessarily the skills. Anyone can build anything with a good set of instructions and the right tools.

[psycho_fling]

i think the right tools is the pharse to think about

[Max]

Could you use a small botbitz controller (10amp) to an automotive relay so the relay turns on and off rapidly so you can vary the speed of a car fan motor cheaply? Could it also be used for a heavyweight motor (with a bigger relay)