Author Topic: Hack your Servo V1.00: Make a linear actuator using a hobby servo pt2  (Read 5002 times)

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Offline AntonbTopic starter

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...continuing from Pt1 - - >



- Take the 5.8mm diameter brass tube pick one end and try to sand at least 5mm into the tube (on the inside). Mount the brass tubing on the vice without squishing it and apply a thin layer of solder on the inside.

- Ignite the flame torch, take the 4mm threaded tube (holding it by the screw) and move it on the soldered end of the 5.8mm diameter brass tube which should still be mounted on the vice. Using the flame torch heat-up both tubes and carefully insert the 4mm threaded tubing inside the 5.8mm tubing until is fully inside. Use a pair of pliers and insert the brass tube by holding the end of the screw that sticks out. Hold the threaded tube levelled inside the 5.8mm tube until the solder settles. If you do not have a flame torch use a candle, your soldering iron and your patience  ;D. Remove the screw. The end result will be the cylinder of your linear actuator.



- The cylinder length should be equal to: the actuator’s desired working length (stroke) + length of the 4mm threaded tube which is inside the 5.8mm tube + 10mm for the mounting hinge at the cylinder end.
  
- The thread length should be: the actuator’s desired working length (stroke) + length of threaded tube which is inside the 5.8mm tube + length of the thread which resides inside the servo casing, which is model-dependant.

- Take the non-threaded/non-soldered side of the cylinder and drill a 2.5mm hole through, 5mm from the tip.



- Cover the entire length of the cylinder with heat-shrinking tube and cut-off any excess bits. The 2.5mm through holes made earlier on the non-threaded side of the cylinder are now covered. Use the drill again to expose them and tap them through, using the M3 tap. Screw a 20mm long M3 studding or simply cut-off the head of a 20mm long M3 screw. This will act as your cylinder mounting hinge.

- Take the 4.8mm styrene tubing and M4 tap it 10mm deep. Cut a small ring 5mm in length and screw it in the M4 thread fully, from the side of the nut that was in contact with the washers (long side of the M4 thread). This will act as bushing between the thread and the servo’s case bottom cover. Ideally you should use nylon, copper or metal bushing.



- Secure the motor cables inside the servo casing using a glue-gun and use heat-shrinking tube to cover them. Assemble the servo including the thread, the styrene bushing and the washers.

- Screw-on the cylinder and you are good to go!

A video of the actuator:

Make a powerful linear actuator using a standard hobby servo


For those of you that have watched my video on the MTR Rover and read the post

http://174.120.175.50/~sor/robotforum/index.php?topic=9693.0
MTR the Multi-Tasking Rover


will understand where the idea of hacking the servo came from :)

Soon I will be posting assembly instructions, code and schematics on how to modify a standard servo to get full PID speed and position control with 10-bit resolution over 360 degrees – continuous ;)  

I look forward for your comments!



« Last Edit: January 13, 2010, 03:51:28 AM by Antonb »
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Offline madsci1016

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Re: Hack your Servo V1.00: Make a linear actuator using a hobby servo pt2
« Reply #1 on: January 12, 2010, 05:43:18 PM »
Why would you create a second thread for part 2? You should just reply to your first one with the contents of part 2, instead of using two threads.

Offline paulstreats

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Re: Hack your Servo V1.00: Make a linear actuator using a hobby servo pt2
« Reply #2 on: January 14, 2010, 08:16:22 AM »
Or better still, wait until the site is completely up and running again and apply for an account to make a "members tutorial".

they are on the main website www.societyofrobots.com   under "member pages"

Offline TrickyNekro

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Re: Hack your Servo V1.00: Make a linear actuator using a hobby servo pt2
« Reply #3 on: January 14, 2010, 09:15:41 PM »
I know this is kinda of topic, but you are Greek right? :-D

Greetings from Thessalonikh!!!!
Lefteris, Greece
For whom the interrupts toll...


P.S. I've been inactive for almost a year... Don't give promises but I'll try to complete my tutorials. I'll let you know when..

Cheers!

Offline AntonbTopic starter

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Re: Hack your Servo V1.00: Make a linear actuator using a hobby servo pt2
« Reply #4 on: January 15, 2010, 02:32:49 AM »
Hi everybody!

Apologies for posting multiple parts, thanks for the tip - I'm new around here and I didn't think of another way.
 
Greetings Lefteri!


hope you guys found the post useful.
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Offline hemanth

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Re: Hack your Servo V1.00: Make a linear actuator using a hobby servo pt2
« Reply #5 on: January 15, 2010, 04:32:09 AM »
The MTR rocks!  : 8) Waiting for assembly instructions! ;D ;D ;D ;D ;D

Offline AntonbTopic starter

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Re: Hack your Servo V1.00: Make a linear actuator using a hobby servo pt2
« Reply #6 on: January 15, 2010, 07:39:50 AM »
Soooon to come  ;)

part by part!

lets say this post makes a ref on the linear actuators that are being used to change the leg geometry.

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Offline hemanth

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Re: Hack your Servo V1.00: Make a linear actuator using a hobby servo pt2
« Reply #7 on: January 22, 2010, 12:24:41 AM »
are you going to enter this for the 5th SOR robot contest?

Offline AntonbTopic starter

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Re: Hack your Servo V1.00: Make a linear actuator using a hobby servo pt2
« Reply #8 on: January 27, 2010, 04:09:56 AM »
I haven't realised there is a contest. Could somebody point me to the right direction?
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Offline Joker94

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Re: Hack your Servo V1.00: Make a linear actuator using a hobby servo pt2
« Reply #9 on: January 27, 2010, 04:15:48 AM »
the decleration has passed and the due date is in about 10 days. you'll have to talk it over with admin.

http://www.societyofrobots.com/robotforum/index.php?topic=9224.0

Quote
January 1st, 2010 - This is the first due date. You must apply for a webspace account, as well as declare your entry with one or two pics/videos of your robot, by this date. Your robot doesnt need to be working yet, but I need to know who is competeting so I can set up your account and the voting structure. This is also a good way to keep you from procrastinating.

February 4th, 2010 - All submissions must be fully made by this date. I chose this date to give contestants all winter break to build their robot, yet not conflict with school/university. Make it the summer that changes your life (if making a robot would do such a thing).

February 5th, 2010 - Voting opens to the public!

March 10th, 2010 - Voting closes, and winners are announced. I will contact the winners for address info to mail them a prize.


Offline AntonbTopic starter

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Re: Hack your Servo V1.00: Make a linear actuator using a hobby servo pt2
« Reply #10 on: January 29, 2010, 12:19:28 PM »
Oh I didn't realise - I'm new around here and I have missed the announcement. Its a shame cause I was making a manipulator arm these days but I don't think its gonna be ready before the 4th.

Thanks for the info in any case

A.
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Offline hemanth

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Re: Hack your Servo V1.00: Make a linear actuator using a hobby servo pt2
« Reply #11 on: February 27, 2010, 02:45:28 AM »
Is it over yet?

Offline Joker94

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Re: Hack your Servo V1.00: Make a linear actuator using a hobby servo pt2
« Reply #12 on: February 27, 2010, 03:07:30 AM »
well the entries have closed but you can still vote.

just go to the MISC page and one of the top 5 threads is the thread in which you vote. "SoR 5th robotics contest"

Offline hemanth

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Re: Hack your Servo V1.00: Make a linear actuator using a hobby servo pt2
« Reply #13 on: March 16, 2010, 09:24:47 PM »
I was asking about the MTR not the contest!

Offline AntonbTopic starter

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Re: Hack your Servo V1.00: Make a linear actuator using a hobby servo pt2
« Reply #14 on: March 29, 2010, 05:50:17 PM »
I am afraid is work in progress. And I think It will always be. I have already started working on the second version.
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