Quote tells us about a neat actuator concept that’s as old as dirt. It’s capable of lifting 7kg when powered by a pager motor, and the only real component is a piece of string. The concept behind the twisted string actuator, as it’s known to academia, is as simple as putting a motor on one end of a piece of string, tying the other end off to a load, and putting a few twists in the string. It’s aby mofosyne - Mechanics
Just found your vid. Its pretty cool! Love it! Btw I noticed you have motors on the arm itself, don't you want to keep the weight of the arms down, by relocating the motor elsewhere? On a previous thread, I was talking about printing twice the size of the printer using a forklift mechanism. I wonder if your design has any potential to be modified to print twice its size. (e.g. maybe a sissorby mofosyne - Delta Machines
I written a general idea on forklift arms in However I thought a specfic idea similar to above could apply to deta robots. Notice how some forklifts could lift twice it's height? Well what if we replace the sides with a forklift mechanism, such that the delta robot could print twice its height (Or triple the height, with the right mechaism) Pros: More compact form for delta robot, prints twiby mofosyne - Delta Machines
If anybody is thinking of designing some new concept 3d printer, I would like to ask you to consider if this is practical. Have you considered implementing a "forklift" mechanism? I mean specifically the type used in tall warehouses, that can extend twice the forklift's height? This will allow you to extend the printing size of your 3d printer to 'twice' its size. In the future, if we get realby mofosyne - Mechanics
Acumen, It sounds rather interesting of a concept to have a telescopic arm design, especially with Annirak's link above on lego linear actuators. The biggest concerns I could think of, is 'accuracy' of the gearing (especially if you are printing these arms yourself), and also printing speed. Secondary concerns is, how 'far' can it contract and extend. If the telescopic arms can only move two timeby mofosyne - Delta Machines
thanks Idolcrasher, at this stage I don't have the required skills to tackle this soon, but I like the idea of non-orthodox platforms (such as the rostock delta robots). You make a good point about the benefit of a stationary platform. In that case I think Martinprice bot is a good idea. I got a few ideas to further extend his bot concept. For martinprice wall mounted robot, I was worried abouby mofosyne - Delta Machines
Good work! It looks pretty big. I wonder how a motorized platform would fare with this device, when we want a larger length wise(as well as height) prints.by mofosyne - Delta Machines
Annirak: what happens if instead of '3 arms', we use 4 arms instead? Would such design be kinimatically possible? And would it have any benifits compared to the 3 arm standard delta configeration?by mofosyne - Delta Machines
The precision of Rack and Pinion might be an issue. I wonder if its possible to using linear actualtors to replace the arms, while also leaving in the stepper motors. Essentally the system will now have 6 motors instead of 3. The 'extendable arms' can be either motorized, or pnumatic, but motorized seems cheaper. Something like Correct me if I'm wrong, but the properties of "linear actulatorby mofosyne - Delta Machines
yea thats the problem I see with this kind of design. For every length increase in the extruder arm... there is a twice increase in the height of the parallel delta robot. Surely there is a way to solve this?by mofosyne - Delta Machines
There is quite a lot of place wasted near the top of this delta bot. Is there anything that can be done to reduce this? or at least make good use of it (e.g. by filling it with the eletronics. Or placing a raspberry pi on it, etc...)? edit: Perhaps the filament spool can be placed in that 'extra arm space'by mofosyne - Delta Machines
I thought about that too, however I wonder if its really suitable for reprap, as it is quite big lengthwise, and a bit top heavy looking. By the way, I think you can keep the 'extrusion probe' from twisting if you add extra arms 'parallel' to the original arms, but connected directly to the extruder instead. I can draw that out if you don't get what I mean. (don't worry about this idea if twistby mofosyne - Delta Machines
Well cables are way more cheaper than belts, you can get cables from any art stores. To deal with slips there is perhaps two ways to deal with that, for the stepper motor you would just wind the cable multiple times (and perhaps cover the motor with rubberbands for better grip). Second method perhaps is to add high tension springs to the end of each cable as it is attached to the moving platform,by mofosyne - General
No probs. But it wouldn't hurt to at least shoot an email to thingverse and other 3d file repository about if they have any API that you can tap into in the future? Just ask if they have an API, and if not, if they can develop and publish it? Once you got the info, post it here! I'm sure a few budding coders would be more than happy to make an app for all platforms, not just the raspberry pi.by mofosyne - Developers
Okay I decided to quickly sketch my concept out. First image: simplifed rostock delta style Second image: simplified traditional delta arm, but inverted (just thought of it today) Personally I like the first image, as it has the most similarity with the original mendel, and it would be easier to modify existing mendel design to use this instead. However I can imagine the second image havingby mofosyne - Delta Machines
Good point. Going to need a strong motor to overcome the tensioning system. Also the extrusion nozzle can't be too heavy that it overcomes the tensioning system. Since the tensioning arm is not active, I wonder if vibration is going to be an issue.by mofosyne - Delta Machines
How would fishermen wire work for this? Would it be any better?by mofosyne - General
Pardon for bumpting this old idea, but I think its a really cool thing you are doing. Have you considered this? Instead of using a system of 'arms' why not replace the arms with 'pullys', and configer it as a delta robot [ something like this ]. edit: This video shows the potential of parallel cable robots . Obviously with pulleys you can't be as fast and as accurate, but you can scale thisby mofosyne - General
Looking back at the spingband idea again. I think the design in is actually not that bad of an idea for reprap, as long as the platform itself can move up and down. It seems the design in the picture above, only allows for movement in the xy plain, but it could still be very stable due to tension on 4 sides. My only problem with implementing the springband form, is that it would require 4 motorsby mofosyne - Delta Machines
Have you guys considered, once you manage to get this system to work, to make a 'dedicated' distro with a 'market app'? For example browsing, choosing, downloading, and printing off ThingVerse? With just a direct connection to the web, it would be like browsing android or iOS markets for apps. Hell it could even be done like a vending machine, put coins in, choose an object, and out comes your itby mofosyne - Developers
Oh also I think this design would do well with a 'cable drive' instead of a timing belt. Easier to find such material. E.g. FoamCore drive cables . Very simple to do, and appears just as stable (not sure about speed of movement however).by mofosyne - Delta Machines
I had a look at rostock delta robot, and I like how fast and stable it appeared to me: I also had a look at the design of the mendel reprap, and liked the idea of a motorized platform to reduce probe shake. The problem I can see with rostock delta robot, is the platform size appears small, and making the platform bigger would require the arms to grow even larger. While I can't totally imagineby mofosyne - Delta Machines
Interesting, however again, I think penumatics is out of the questions for reprap (as i doubt we want it to use fluids. As for the springband idea, its getting there, but I think theirs are more for 'pick and place' in a 2d platform. Anyway have you guys seen FESTO's new delta design? . Frankly I think it looks pretty good, only problem I can imagine for their design, is that it is restricted iby mofosyne - Delta Machines
Is it possible to "contract" and "extend" the length of the arms of the delta robot with a linear motor, as opposed to changing the angle using a servomotor? This would surely make the robot a little more compact. Just remember to add 'moveable joints' so the 'arms' can still bend around. Two inital thoughts on implement this: 1. Pnumantic style like . Sounds messy, and expensive to aquire theby mofosyne - Delta Machines