Based on doing some web searches it looks like you can make your own sidewalk chalk. Perhaps you could experiment and find the perfect size and shape, as well as be able to vary the ingredients to adjust the strength? Perhaps you could make it inside of a tube of some sort and leave it in the tube while using it?
Making your own might be cheaper than buying it too?
Doing an "image" search for "sidewalk chalk holder" brings up all sorts of interesting gadgets out there. Things that hold multiple pieces, and even a thing that is supposed to connect to the back of a bicycle and hold chalk! You might find some inspiration there too.
............... Perhaps you could make it inside of a tube of some sort and leave it in the tube while using it?
I'm working exactly on this idea. However, the problem is very compicate........ I'm trying to manipulate the chalk like a pencil using some kind of sharpener...
While I’m waiting some accessories from e-bay in order to make the Artist’s painting mechanism, I decided to do some experiments for a potential replacement of the Motor Mount and Wheel Kit (#27971) with the NEW Motor Mount and Wheel Kit -AL(#28962) or MP(#28963) on Artist robot.
In this thread Matt released the Arlo’s 3D design files. So I took the NEW Motor Mount and Wheel Kit #28962 3D design files and I put them on Artist’s 3D design files.
Here is the result :
The NEW motors kit has a characteristic “curve” on its shape that leaves the back side of the motor under the Artist’s chassis .
So the Artist’s chassis must change.
The two potential changes are:
1) A second extension under the bearing block that will raise a little the motor kit or
2) A hole in to the chassis that will permit the motor’s assembly.
So I started the design of the painting mechanism. It will be something like this:
The mechanism has two servos. One mini servo that presses the chalk holder to leave the chalk out and a second standard servo that pushes up and down the entire chalk pen.
The chalk pen is prined by my 3d printer and has a spring in order to press slowly the chalk into the grownd. This spring acts like suspension that keep the chalk constantly into the grownd.
The manufacturing is difficult and I have to overcome a lot of challenges........
Hi Nikos
I like following threads that show mechanical design.
Is your stepper motor chalk pen lifter gear like fitting also a 3D printed part?
While your Artist robot is above my technical ability, I'm always learning new things.
Thanks for making frequent updates to your Artist thread.
Nikos
You understand correctly.
It was good thought using a rack and pinion from a broken toy.
I now better understand where you are going with this project.
I also use Sketchup for drawing and having my drawings 3D printed.
My experience with having round things 3D printed is that the print will always turn out
egg shaped. I think this has to do with the Stepper motor circle approximation in Makerbot printers.
Please don't let my comments here distract you from your project.
Thanks for answering my small question.
My experience with having round things 3D printed is that the print will always turn out
egg shaped. I think this has to do with the Stepper motor circle approximation in Makerbot printers.
In my case the 3D printer is not a problem. I have a creatr Leapfrog 3d printer, with dual extruder that prints very good and very accurate
But in order to print a gear, the printer needs and a second material PVA or PLa except from the ABS, and I don't have...
So I prefered the easier solution, to use an "end product" gear and rack....
Please don't let my comments here distract you from your project.
Any discussion is welcome,,,,,,,,
I'm in a very good way with the Chalk mechanism, and I think that the discusion here in this thread, has helped me in order to take the right decisions about that mechanical module.
The result that I have now is beyond my first expectation....
In the next posts I'll give more details and I'll also try to make a video.......
I decided to do the first test without the robot, using a small base from Plexiglas with the same high as the “Artist” robot (3,2cm from the ground).
For brain I used a propeller board and for power the Li-ion Power Pack Full Kit
The code I used was: the “StepperMotorTest.spin” for the stepper motor and the “standar_servo_propeller_demo.spin”
EDIT : the image above has an error. There isn't any Connection on pin P4, between ULN2003 driver Board and Parallax propeller. The right pins are four: P0,P1,P2 and P3.
So I prefered the easier solution, to use an "end product" gear and rack....
Just as well, you probably used an injection molded acetal or delrin gear & rack, which are stronger and more durable than anything you could have 3-D printed.
When do you anticipate testing the Artist on a sidewalk? Any chance before the New Year? I have found it can be a fun and motivating goal to to finish a robot before midnight on New Years Eve!
When do you anticipate testing the Artist on a sidewalk? Any chance before the New Year?
Why not erco?
If I transform the previous spin code that moves tthe machanism in to propeller C code (the Artist's programing language) the assembly of the mechanism wont be a problem.
I' ll open the Atrist and I'll adapt the mechanism into the right place.
Although the space is extremly limited (That was also a big challenge of this project), I think that will be all right because I have already take prevision the dimensions.
Of course I must create some code for the writings...
Except from the obvious Up and Down movement, the painting mechanism must have and other two features: the one is to release the chalk gradually as the robot writes because the chalk will be destroyed due to the ground friction, and the second is that the mechanism must constantly push smoothly the chalk holder in to the ground, in order to keep the touch with it, and simultaneously must absolve the shocks and vibrations like a suspension.
Here is a video with the painting mechanism in action.
[video=youtube_share;NF8Z1Sq7ibw]
You can see the triple function of the mechanism. It can move Up and Down, it can release the chalk and it can press the chalk in to the ground like a suspension using the spring.
Best wishes to all for these days!!!!!!!
.
I decided to give feedback feature on Atrists painting mechanism .
The feedback feature based on[url=http://learn.parallax.com/activitybot/build-whiskers[/url] ActivityBot Whiskers (touch sensor).[/url]
The idea is to use a similar circuit in order to know when the paining mechanism is in the upper or lower position.
In order to create that sensor used one from the two whiskers. I cut it in two pieces and I also used wire and 2 resistors 10k and 220 in order to make the circuit. I adapted the sensor in the back side of the painting mechanism. The one part of the whisker on the main body of the mechanism, and the second part of the whisker on the moving part of the mechanism.
Of course it is not a 100% feedback mechanism (like a potentiometer) because we havent any data for a random position of the mechanism. However we know when the paining mechanism is in the upper position and this is a perfect calibration method. The test I made was successful!
Today I installed the painting mechanism into the "Artist".
Inside the Robot the space is now completely full!
The result mechanically is very good.
I had in mind to add a push button with the appropriate circuit in order to change or install the chalk into the mechanism....
I realized that it wasn't necessary because I could use my finger in order to press easy and manually the chalk holder in order to change or install the chalk......
On the Top of the Robot I also added a3d printed part in order to hold the ULN2003 motor driver....
I agree with zappman, your robot is looking great!
You've got me thinking about adding some sort of drawing tool to my robot. As I just mentioned in another post, I originally planned to use a "T" shaped support in the center of my robot. After seeing your robot, I changed the design to keep the center of the robot clear for the possible addition of a hole and drawing utensil.
I'm also looking forward to seeing The Artist in action.
I agree with zappman, your robot is looking great!
You've got me thinking about adding some sort of drawing tool to my robot. As I just mentioned in another post, I originally planned to use a "T" shaped support in the center of my robot. After seeing your robot, I changed the design to keep the center of the robot clear for the possible addition of a hole and drawing utensil.
I'm also looking forward to seeing The Artist in action.
Duane,
In the next post, I'll also give and some interesting versions of my painting mechanism much more simpler, without chalk, but approriate for a common marker....
This version will be also perfect for the original Stingray Robot....
I think that zappmann also may find it very interesting for his FrankenBot
No, I don't have one. I don't know of anyone in the area who has one.
I'm hopeful I could rig something up once I decide to add a drawing utensil.
I'm still looking forward to seeing your continuing progress.
Edit: As I started thinking of ways to add a chalk holder to my robot, I realized it will be a while before I'll be able to test it. There's about 6 inches of snow outside and the sidewalks are in no condition for chalk art work. I have a feeling it will be a few months before I give writing with chalk a try.
Today in Patras was a very cold but sunny day. So I took the decision to make an outdoor test on Artists painting mechanism.
My first indoor robot test, on my houses moquette was successful.
However I wanted to see the result out on the rough streets surface.
The result wasnt the best. Unfavorably the chalks tracks were very indistinct, and the chalk broken (as you can see on 0:26) when the robot tried to push it a little bit more into the road .
Here is the video...
[video=youtube_share;LhMUyZYmVW0]
I have to admit that the road surface was rough enough! On the other hand the mechanism had a perfect function as I was giving commands using my remote and of course I had and a perfect response from robots vecho speaker.
The effort is continued ..
Tim is a stereotypical American male, who loves power tools, cars and sports (especially the local Detroit teams). He is a former salesman for the fictional Binford Tool company, and is very much a cocky, accident-prone know-it-all.
Comments
Making your own might be cheaper than buying it too?
Doing an "image" search for "sidewalk chalk holder" brings up all sorts of interesting gadgets out there. Things that hold multiple pieces, and even a thing that is supposed to connect to the back of a bicycle and hold chalk! You might find some inspiration there too.
Thank you for all your suggestions! You have gave me valuable Information!
I apology for the delay responce but I was very busy due to my work at school.
The truth is that I have stuck a litle bit with the painting mechanism......
I'm working exactly on this idea. However, the problem is very compicate........ I'm trying to manipulate the chalk like a pencil using some kind of sharpener...
In this thread Matt released the Arlo’s 3D design files. So I took the NEW Motor Mount and Wheel Kit #28962 3D design files and I put them on Artist’s 3D design files.
Here is the result :
The NEW motors kit has a characteristic “curve” on its shape that leaves the back side of the motor under the Artist’s chassis .
So the Artist’s chassis must change.
The two potential changes are:
1) A second extension under the bearing block that will raise a little the motor kit or
2) A hole in to the chassis that will permit the motor’s assembly.
So I started the design of the painting mechanism. It will be something like this:
The mechanism has two servos. One mini servo that presses the chalk holder to leave the chalk out and a second standard servo that pushes up and down the entire chalk pen.
The chalk pen is prined by my 3d printer and has a spring in order to press slowly the chalk into the grownd. This spring acts like suspension that keep the chalk constantly into the grownd.
The manufacturing is difficult and I have to overcome a lot of challenges........
Thanks Whit!
The design actually is looking good. However the materialization has some difficulties ....
For Instance, is difficult to find a spring in theese particular dimensions .....
Looking at this video I made a spring by my own....
Here is the chalk pen till now....
I repalaced the standard servo for Up & down with a 12v gear stepper motor and I also added two sliding bars.
Now I have a stronger and more accurate device.....
I like following threads that show mechanical design.
Is your stepper motor chalk pen lifter gear like fitting also a 3D printed part?
While your Artist robot is above my technical ability, I'm always learning new things.
Thanks for making frequent updates to your Artist thread.
If I understand correctly you ask about the rack that is moved by the stepper's gear?
Both rack and stepper's gear are not 3D printed parts (at the moment).
I don't know how to make gears and racks using sketchup and I also I'm not very sure about the quality of a 3D printed gear.
So I used a rack and a gear from an old broken toy .
You understand correctly.
It was good thought using a rack and pinion from a broken toy.
I now better understand where you are going with this project.
I also use Sketchup for drawing and having my drawings 3D printed.
My experience with having round things 3D printed is that the print will always turn out
egg shaped. I think this has to do with the Stepper motor circle approximation in Makerbot printers.
Please don't let my comments here distract you from your project.
Thanks for answering my small question.
Garyg
In my case the 3D printer is not a problem. I have a creatr Leapfrog 3d printer, with dual extruder that prints very good and very accurate
But in order to print a gear, the printer needs and a second material PVA or PLa except from the ABS, and I don't have...
So I prefered the easier solution, to use an "end product" gear and rack....
Any discussion is welcome,,,,,,,,
I'm in a very good way with the Chalk mechanism, and I think that the discusion here in this thread, has helped me in order to take the right decisions about that mechanical module.
The result that I have now is beyond my first expectation....
In the next posts I'll give more details and I'll also try to make a video.......
Here is an image with the final real model printed by my 3d printer, next to the 3d model made with ScethUP8.
Now is time to test the real function of the mechanism ...
For brain I used a propeller board and for power the Li-ion Power Pack Full Kit
The only I had to do was to connect the stepper motor and the mini servo to the appropriate PINS on the Propeller board, and power them with the appropriate voltage.
The stepper motor has also a ULN2003 driver board that is connected between the stepper motor and the propeller board. In this link, Erco has given a very useful video connecting this stepper motor and ULN2003 driverwith a Basic stamp Board.
Here is the wiring diagram of Artist painting mechanism:
The code I used was: the “StepperMotorTest.spin” for the stepper motor and the “standar_servo_propeller_demo.spin”
EDIT : the image above has an error. There isn't any Connection on pin P4, between ULN2003 driver Board and Parallax propeller. The right pins are four: P0,P1,P2 and P3.
Just as well, you probably used an injection molded acetal or delrin gear & rack, which are stronger and more durable than anything you could have 3-D printed.
When do you anticipate testing the Artist on a sidewalk? Any chance before the New Year? I have found it can be a fun and motivating goal to to finish a robot before midnight on New Years Eve!
https://www.youtube.com/watch?v=bya4uAdNXos
Why not erco?
If I transform the previous spin code that moves tthe machanism in to propeller C code (the Artist's programing language) the assembly of the mechanism wont be a problem.
I' ll open the Atrist and I'll adapt the mechanism into the right place.
Although the space is extremly limited (That was also a big challenge of this project), I think that will be all right because I have already take prevision the dimensions.
Of course I must create some code for the writings...
Here is a video with the painting mechanism in action.
[video=youtube_share;NF8Z1Sq7ibw]
You can see the triple function of the mechanism. It can move Up and Down, it can release the chalk and it can press the chalk in to the ground like a suspension using the spring.
For a possible improvement a feedback procedure will be ideal! (Something like Gareths (Chiprobot) feedback feature on his Linear Actuator)
.
I decided to give feedback feature on Atrists painting mechanism .
The feedback feature based on[url=http://learn.parallax.com/activitybot/build-whiskers[/url] ActivityBot Whiskers (touch sensor).[/url]
The idea is to use a similar circuit in order to know when the paining mechanism is in the upper or lower position.
In order to create that sensor used one from the two whiskers. I cut it in two pieces and I also used wire and 2 resistors 10k and 220 in order to make the circuit. I adapted the sensor in the back side of the painting mechanism. The one part of the whisker on the main body of the mechanism, and the second part of the whisker on the moving part of the mechanism.
Of course it is not a 100% feedback mechanism (like a potentiometer) because we havent any data for a random position of the mechanism. However we know when the paining mechanism is in the upper position and this is a perfect calibration method. The test I made was successful!
Inside the Robot the space is now completely full!
The result mechanically is very good.
I had in mind to add a push button with the appropriate circuit in order to change or install the chalk into the mechanism....
I realized that it wasn't necessary because I could use my finger in order to press easy and manually the chalk holder in order to change or install the chalk......
On the Top of the Robot I also added a3d printed part in order to hold the ULN2003 motor driver....
Thank you for sharing your design and build progress.
I can't wait to see the artwork you create with your robot.
You've got me thinking about adding some sort of drawing tool to my robot. As I just mentioned in another post, I originally planned to use a "T" shaped support in the center of my robot. After seeing your robot, I changed the design to keep the center of the robot clear for the possible addition of a hole and drawing utensil.
I'm also looking forward to seeing The Artist in action.
Duane,
In the next post, I'll also give and some interesting versions of my painting mechanism much more simpler, without chalk, but approriate for a common marker....
This version will be also perfect for the original Stingray Robot....
I think that zappmann also may find it very interesting for his FrankenBot
Have you a 3d printer? or can you find one?
No, I don't have one. I don't know of anyone in the area who has one.
I'm hopeful I could rig something up once I decide to add a drawing utensil.
I'm still looking forward to seeing your continuing progress.
Edit: As I started thinking of ways to add a chalk holder to my robot, I realized it will be a while before I'll be able to test it. There's about 6 inches of snow outside and the sidewalks are in no condition for chalk art work. I have a feeling it will be a few months before I give writing with chalk a try.
My first indoor robot test, on my houses moquette was successful.
However I wanted to see the result out on the rough streets surface.
The result wasnt the best. Unfavorably the chalks tracks were very indistinct, and the chalk broken (as you can see on 0:26) when the robot tried to push it a little bit more into the road .
Here is the video...
[video=youtube_share;LhMUyZYmVW0]
I have to admit that the road surface was rough enough! On the other hand the mechanism had a perfect function as I was giving commands using my remote and of course I had and a perfect response from robots vecho speaker.
The effort is continued ..
That is a rough road, I wonder if wet chalk or more weight would leave a darker line.
Excellent work.
That's a win in my book!
You didn't waste any time with erco's nudges.
I think we are witnessing the birth of the new Scribbler 4.
Or Stingray 2...
http://en.wikipedia.org/wiki/Home_Improvement_%28TV_series%29