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Author Topic: move rod 30 cm back and forward in a straight line  (Read 2769 times)
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So WTF is a "MacGuyver scenario"? The forum members are not mind readers, and and probably are rapidly tiring of the vague and evasive nature of this dicussion. This is a technical forum that expects some minimum level of technical knowledge and communication abilitys of the people asking questions.

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but using superglue can't be very durable.

Duh! Go to your local harware supply or walmart and get some slow setting J-B Weld epoxy.

Edit: a simple hot glue gun probably can fit your needs.
« Last Edit: July 24, 2011, 12:18:20 pm by zoomkat » Logged

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and for providing entertaining story lines
..and, as I remember, as a means of recycling footage shot for other movies and shows.
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I don't remember much of that. It was a major prime-time TV series with a budget of ~US$1000000 per episode.
Maybe we only got the pilots - it seemed fairly low-budget when I saw it.
I remember one episode that re-used footage from a (Ricardo Montelban?) movie - a bit like The Hulk episode that re-used footage from Spielbergs Duel.
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Well, help request of this type often tend to be part of "art projects" and such that the people working on them don't have much depth in the technical end of things. The typical request is "I have an arduino and need somebody to guide me in making a trombone playing robotic arm for my music class", or " I want to make a robot with an arm that can paint portrates of the people standing in front of it". Generally spending time "hanger flying" on secret projects quickly gets old and interest/support goes away.
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The general issue with vague requirements is that time and effort is spent to develop a solution that meets the vague requirements, only to have some previously undisclosed limiting requirement stated that makes the entire effort a waste. The instructibles threaded rod coupled with a stepper motor might be an easy fix, but it might have an overall height of 100cm, which might be unacceptable for the project. Who knows? I don't. 
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I tend to agree with the other comments made earlier.
This forum is for Arduino projects, not the mechanics weekly.

Linear actuation can be made by placing the rod in two bearings, and have the driving force push on the rod.
(think of the drive wheels on a steam train...I know the rod between the wheels changes height as well)
Another method could be to utilise a cogged belt and stepper motor from a printer (old dot matrix) to pull the rod along.
I've seen this very effectively used in a CNC machine, and can be relatively easily salvaged from an old printer mechanism (hence furfilling your MacGyver quest)

IMO if your questions started with "...guys I have two methods of moving this rod 300mm, and was wondering if it's easy to interface with a stepper motor..." it might be more acceptable.

Mark
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Hi. Please don't post hostile reactions. I think I have provided quite a few details by now. I'm sorry if my posts have not lived up to the standard you set for posts here but I hope you see that I've tried to be constructive and I haven't intentionally aimed to anger you. I'm puzzled by some of the irritation I have caused. I can't for certain reasons give all details on my project. That might be disappointing but that is how it is. But sometimes not every exact detail is required for others to nonetheless be able to give helpful advice. Please also keep in mind that I don't know all the terminology involved and I am not a native english speaker. I'm sorry for the MacGuyver reference. I thought that might be a bit funny but it might just have confused things.

Let me see if I can restate things I've said and add some more details. Maybe it will together be enough for some to give advice on.

I want a certain arduino controlled physical movement.
I want a rod to move out linearly 30 cm and touch something.
The needed pressure is very light. But more pressure is no problem either.
Arduino must be able to position the rod at any position between 0-30 cm but very exact positioning is not so important, it can be off with 1-2 centimeters without any problem.
If I can find a solution that can move out and with very light pressure push a button then that solution will definitely work for my specific use.
The dimensions of the rod are not important. It could be very thin because the pressure needed is so small. But a somewhat bigger rod is no problem either. I prefer smaller if that is more inexpensive and might require a less complex circuit for power feed (or perhaps be powered directly from the arduino card).
I want a DIY solution for cost reasons. I definitely can't afford a $80 actuator for this.
The project will be indoors. I have access to wall power and also a computer for USB power if that would work.
The rod must extend into air linearly. For the space of air between 0-30 cm there can be only the rod. So no wires or connecting rods can be secured to the part of the rod that extends.
Apart from that there are no space requirements. I have several meters of space on all other sides of the device.
It also doesn't matter how the device looks. I don't need to box it or anything like that. It can look like a big mess of wires, that doesn't matter.

I'm thankful for all suggestions I get. As I've said I'm particularly looking for details on prior arduino projects that implement something like this, the simpler the better. I also look for advice on product names for components that can connect a small motor with a threaded rod, as I think I can get a stepper motor working with arduino and threaded rod is easy to come by. Thanks.

@markB "This forum is for Arduino projects, not the mechanics weekly."
Ok, I might have misunderstood the forum section (and the forum in general) then. I thought mechanical topics when part of an arduino project was within bounds. Isn't it likely that many who are new to arduino also are pretty new to the mechanical issues?
« Last Edit: July 26, 2011, 05:22:35 am by roiny » Logged

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Well, you've had a bunch of recommendations already, not sure what else you need.  Reposting the initial question probably won't help much.

There are lots of ideas and examples on the internet.
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Hi,

I'm a newbie too and I've been thinking about your project. It sounds like one of those Mythbuster-type problems you see on the discovery channel, where they test McGyver episodes for realism etc...

If I wanted to build a cheap thing that moves a lightweight rod I would use a setup like in this attachment, I've seen the Mythbuster guys do this. You would need to play with the spacing of the free rolling wheels and maybe support the rod more. You might need thin tyres on the wheels to provide friction. I used some simple code from this site to play around with a toy motor:
http://ardx.org/CODE03. I'm not an expert but I think you can modify the code to have it gradually start up and gradually slow down. As someone said a stepper motor might be good but I don't know what to do with that.

 I also thought you could gear the motor so you can control things more easily or make the so called free-rolling wheels less free-rolling so they are semi-braked (technical term smiley)  a bit like driving with the parking brake half on, when you take your foot of the accelerator and put the clutch in,  you don't free-roll.

Anyway that's all I can think of right now. Hope it helps.



Good luck


* MoveRod1.jpg (39.92 KB, 465x282 - viewed 12 times.)
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Hi,

I'm a newbie too and I've been thinking about your project. It sounds like one of those Mythbuster-type problems you see on the discovery channel, where they test McGyver episodes for realism etc...

If I wanted to build a cheap thing that moves a lightweight rod I would use a setup like in this attachment, I've seen the Mythbuster guys do this. You would need to play with the spacing of the free rolling wheels and maybe support the rod more. You might need thin tyres on the wheels to provide friction. I used some simple code from this site to play around with a toy motor:
http://ardx.org/CODE03. I'm not an expert but I think you can modify the code to have it gradually start up and gradually slow down. As someone said a stepper motor might be good but I don't know what to do with that.

 I also thought you could gear the motor so you can control things more easily or make the so called free-rolling wheels less free-rolling so they are semi-braked (technical term smiley)  a bit like driving with the parking brake half on, when you take your foot of the accelerator and put the clutch in,  you don't free-roll.

Anyway that's all I can think of right now. Hope it helps.



Good luck

The problem with that simple solution is that the arduino would have no way of knowing where the starting rod position is when it starts up and therefore unable to decide how far it can move the rod in either direction. It needs some kind of position feedback, either continuous position feedback, or at least two end of travel indicators.

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Hi,

Would, say, a touch-activated switch at each end of the full travel to act as a stop signal work? This might give control at 0 and 30cm.

In addition, what if the toy wheel without the motor have pegs or paddles on them that can flick a rod which acts as a switch from 0 to 5v. There are two of them so you might be able to get the Arduino to count "clicks" forward and backwards, that way it could know approx where it is, with the end stops to reset the counting of clicks to 30 or 0. See attachment - it's a bad drawing. The pegs should be equally spaced and the spring looks like a bit of string, but it gives an idea of what I mean.


* WheelClickCounter.jpg (24.67 KB, 365x212 - viewed 9 times.)
« Last Edit: July 26, 2011, 07:31:22 am by trendski » Logged

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Hi Roiny,

A variation of a coilgun, normally propelling an iron bullet using electromagnetics, might work as well.
http://en.wikipedia.org/wiki/Coilgun
By controlling the coils slowly, a non metal rod with nut/bolt on the end should be moveable back and forth in a straight line.

Problem for others knowing little about your project is knowing thousands of ways to move an
rod. I guess most want to help and have enough imagination to get the job done.  If only 1% of their ideas really would be perfect for you though finding an answer to your project sort of becomes a guessing game though. It's a bit like asking you to help me with a job at a location at 3PM, but not telling
which location while there are thousands. Loads of people probably don't want to spend big amounts of energy answering your question that way and apparently rather make fun of instead.

Keep in mind, it's the nature of people wanting to solve problems to look what... the problem involves first,  certainly when problems are technical.







« Last Edit: July 26, 2011, 06:50:16 am by Simpson_Jr » Logged

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"Hi. Please don't post hostile reactions. I think I have provided quite a few details by now. I'm sorry if my posts have not lived up to the standard you set for posts here but I hope you see that I've tried to be constructive and I haven't intentionally aimed to anger you."

 "I'm puzzled by some of the irritation I have caused. I can't for certain reasons give all details on my project. That might be disappointing but that is how it is"

"I want a certain arduino controlled physical movement.
I want a rod to move out linearly 30 cm and touch something."
  

This is off topic with regards to your question, but I hope it will help you understand the reactions you get.

The internet, and especially a forum like this, is all about sharing information.
Information is valuable, and people will get very annoyed, if you ask them to spend their time to solve a problem for you, and you refuse to give anything in return.
The way you put it in your question implies, that either you want us to make your homework for you or you have some artistic or commercial adventure in mind ( and you can only reap the benefits of it, if you make it appear as if you are the genius).

A lot of those questions are seen at internet fora, and most of us have a little bell that starts ringing when people ask the way you do it.

If you want a useful answer, you must provide useful information.
Otherwise you should pay a professional to solve it for you.
It will be very costly, because knowledge is valuable. And a professional will also want all relevant information.

Please, please, please read this one: http://forum.arduino.cc/index.php/topic,148850.0.html
And a lot of your question regarding the reactions will be answered.







I really hope you are able to see, how little....
"I want a certain arduino controlled physical movement.
I want a rod to move out linearly 30 cm and touch something."
.....can be used for?

There is no free lunch, but if you behave, you will have lots of dinner invitations.
« Last Edit: July 16, 2013, 01:19:12 pm by Peter_I » Logged

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I like Trendski's idea. If one couldn't figure out (me) or can't afford rotary coding (me), I bet a series of cheap lever switches could be rigged up the distance of the rod every x centimeters to give decent feedback on where the rod was and was not.  
« Last Edit: July 16, 2013, 01:34:45 pm by bigred1212 » Logged

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