Im making a tripod

So, Ive had this idea in my head for a while.
Its a tripod. But theres like 6 or so distinct pieces for the while thing.
I finally had some time to model some pieces out today.
I still need a couple of cross beams for support probably to stabilize it.

I worked out the formulas to run it. but dont have them with me atm.
They are really simple 3d Pythagorean theorem implementation.

But here are the blender files and a screenshot of the assembly. What does everyone here think?

It could also pretty easily be made out of MDF with a band saw and a drill press.

Ok, so i Put them up at the wiki.
[objects.reprap.org]
I need to format it better if anybody cares.

... read through my posts regarding tripods - my final setup is fully functional, but collects dust since then

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Yea, Ive seen your work and its really nice. I would love to get your input on my design. And if you made a control program for this I would like to take a peek if you're willing.

Your tripod seems really small. was it just a model or
I was trying to get one that has a decent printable area. this one should be about a 250mm triangle.

I forgot to mention i was going to see if these would work for the pivots instead of your magnet solution.
[h1072623.hobbyshopnow.com]

... i made it mainly as demonstration for the magentic-spheres-joints, but it would be fully functional for my normal building dimensions of some centimeters in size and until 10 microns accuracy.

Here is an even smaller tripod with solid-state-hinges and high accuracy (some nanometers) piezo-motors.

And a friend built a much bigger system similar to mine with linear motors from isel capable of 800 mm travelling range

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Viktor

Did you develop any arduino software for the Delta robot? Is it available anywhere? I am just beginning a delta design and would welcome any hints. I have the design about 90% complete in CAD an will soon be reprapping the parts.

I have worked out all the equations for transfering cartesian to delta coordinates, but if you have any C code that would be helpful.

Hi Martin,

... no, i haven't programmed the software - i planned to use EMC2, but then changed the priorities and delayed the tripod ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

I've been most successful with the search terms "Delta Inverse Kinematics". There is a java applet out there somewhere with published souce code I think, but I'm having trouble finding it.

[forums.trossenrobotics.com]

[letsmakerobots.com]

[www.cnczone.com]

[www.linuxcnc.org]

My design for a reprap stype delta robot is nearly complete. If you want to take a look follow the link for a CAD image of the design.

Any comments or suggestions would be welcome. I want to incorporate as much knowledge from here as possible before commiting to printing the parts.

Helium Frog Delta Robot

I forgot to mention, but I think the design looks brilliant. I have some of those ball joints you linked to. They will most likely get the job done, but their range of motion seems like a possible unnecessary restriction. I'm going to use mine for prototyping and switching to a spring, cup, and ball design ASAP.

How are you fabricating the plastic parts? Will you be uploading .stls?

I will upload everything If I get it working (under the GNU GPL licence). Even if I dont, I will probably upload the models anyhow as it might be a good start for someone else.

The ball joints (rose joints) are slightly restricted in movement, but I believe I have overcome this limitation in two ways.

1) position the joints in an orientation to use the ball rotation on the axis with the most movement. This is why the joints have been mounted horizontally.

2) Use a smaller centre screw. The rose joints are M8, but I am using a 6mm bolt with a 1mm thick sleeve. The main restriction to movement is caused by the head of the bolt, so this increases the movement to accomodate the 200mm diameter envelope I am going to have. By using a button head bolt you could probably increase this still further. The beauty of CAD is that I can position the mechanism to the furthest stroke and see the clearance.

By the way, there is a paper on how to calculate the angles for a delta robot here, and a small C program. Unfortunately its not the same design as it doesn't use linear slides.

Delta Robot Calculations

The calculations for the robot designs we are both developing are much easier. I am just putting the finishing touches to an excel program which calculates them. I'll then use this to check it against my model to see if it works ok before trying the code. This is some weeks off yet though!

Edited 2 time(s). Last edit at 05/13/2010 02:09PM by martinprice2004.

I Completed the excel spreadsheet. It may be of use to you when calculating the movement of the vertical axes. See link on left menu of page.

Excel Delta Robot Calculator

Did you succeed meanwhile or got stuck somewhere? Please, keep us informed. It is a cool project.

The german reprap group is going to continue Martin's project. First parts are printed already.

Does anybody know, why Martin abandoned it?

I did not abandon the project, but have a few other projects on the go at the moment (Baja Buggy and some animation software).

I have completed the frame and now need to finish the central carriage. I notice that the German forum has made some parts similar to mine which is good news and at least shows that I was heading in the right direction with my design. I hope they get further than I have at the moment.

I will try to get the models of my design translated to .stl format and post them on my site if I have time so that anyone without CAD facilities has a good head start with the models.

@ Viktor
If you get time perhaps you could relate this to the German forum as like most British I only speak English!

Edited 1 time(s). Last edit at 10/20/2010 07:46AM by martinprice2004.

... i'll try to synchronize - there is a plan to setup a Wiki-page, first German, then English too ...

Maybe this will be of interest for you too - [forums.reprap.org] - here i posted some simplified calculations for converting XYZ-coordinates to the positions ABC of the linear drives ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Thanks Viktor

I think your equations are more arduino friendly than mine!

I shall work on the Helium Frog website over the next few days to try to make it a little more useful for people who are interested in the design and post all that I achieved so far.

The designs are in Catia V5 format so If anyone uses this I can include the assembly file as well which may be of use for lengths of the rods., but I will also do the individual models in .stl.

I did a little translation of the German forum and noticed that there was a discussion as to the maximum angle of the rotary joints. I spent some time working on this and the M8 "Rose Joints" I used in my design have sufficient movement for a 200mm diameter working envelope. It is just a case of orientating the joints so the neutral point of the joint is in the correct position so you can use the full movement. You can also use a M6 bolt and cylindrical spacer to give extra movement of the joint. I really liked the idea of the reprapped joints and I think a fatigue resistant hinge (Living Hinge) idea would also work well.

The assembly I built was a little unsteady at first, but I have added a little more bracing and I think will work quite well.

The only thing I really haven't done yet is the centre moving tool platform. My design is a little large to reprap on a makerbot (Would be OK on a Reprap though), so I would like to change this.

Has there been any progress on the software yet? I would be nice to see your little delta robot dusted off and working!

... i'm actually busy with some other urgent tasks, so can't reactivate the tripod in near future

For reprapped (or milled) hinges i was thinking to make some semi-cartesian hinges with miniature ball-bearings i have lying around (10mm outer diam. 3mm hole) - simply a rod centered in two bearings with two axial oriented bearings at the ends, where the struts(?) are fixed in the holes and can perform any angle you can have in the setup without limitation.

You need it 6 times, but the parts are really easy to print or mill ... it's only the count of 24 bearings, what's not so optimal ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Hi Martin,

wakeer is asking ifyou can give us some specs of your setup - possible angles, length of the struts and maybe the construction data.

With Reinoud's firmware (in the other thread) we should have most of the puzzles of a delta/tripod, so this can go much faster in teamwork

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Viktor

I have been working tonight on the helium frog website and uploaded most of the main .stl models. There is also a .stl file of the complete assembly which you can have a look at. It should give you enough information to work out most of the dimensions and bearing sizes etc. Let me know if there is anything the team urgently needs and I will get on to it tomorrow night. I have models of the motors, joints base plate etc. which I could upload.

The frame is quite strong, but I am going add the front triangular brace on the other two sides. This would make the frame very stiff. I also changed the motor mounts. They are now simpler to make as they are less tall, but it does mean you need motors with threads on the bottom.

I think we may be on to a popular design if we can get it to work as the rapid prototype part count is very low and could be reproduced much quicker that the reprap. I hope the team posts more details of their progress soon.

Here is the link to the Heliumfrosch-Deltaroboter!

Helium Frog Delta Robot

Edited 2 time(s). Last edit at 10/20/2010 03:59PM by martinprice2004.