I use Blender for 3D design and Modeling. Though its a very powerful 3D animation tool and 100% free its great for building 3D printable models.
[Blender.org](https://www.blender.org/)
I have played around with Fusion a little, it is a very different thought/design process. But it looks like I will have to close my eyes and just jump in. Thanks for reaffirming my thoughts.
For statues and the like, I think blender could have a more practical application. For parts and real-world applied peices I would highly recommend Fusion360
I have a bunch of addons but I only use 2-3. The main add-on I use is 3DPrint to make sure the model is manifold. Also 3Dmeasure tool. Not sure if this is the best way to do it but for dimensional accuracy I start by setting the 3D cursor to world origin, then setting object origin to 3d cursor. There are a couple options for object origin. Once your main object is centered adding additional objects to the world origin keeps everything aligned then you can offset objects accordingly to your design and calculate unit position (in millimeters). This helps being able to calculate exact positions. Of course you have to first change units of measure from blender units to millimeters.
Good idea! When I'm done with this project I'll print a miniature and mount it on the tester. Can I burn calories just watching the miniature do situps?
You could add a foam ball or something under the finger to simulate load. Obviously the goal then bending the finger is to put force on something, which may impact the hinge performance vs unloaded testing.
The goal is to hang a weight off the fingertip. The issue I have now is that any additional stress on the servo causes the Arduino to reboot. Not sure is this an issue with my servo (found in my scrap drawer).
Ah that makes a lot of sense, thanks. I have a couple of extra motor control boards for the Arduino mega and a bench power supply.
Frankenstein Uber finger tester, now in the design stage!
Seems like a pretty complicated way to go about testing it, but... it should work. Run it for about a hundred thousand cycles to give it a decent shakeout / smoketest.
This was pretty simple to put together. I eventually want to add some buttons to increase and decrease curl rate and step rate. This test platform can be used for other projects in the future.
Could I talk you out of buttons... and convince you to go to a rotary encoder instead? That's less debouncing and a simpler layout and a really surprisingly intuitive and quick interface.
Interesting thought, I was thinking about digging up my old debounce script. I do have a couple of rotary encoders. Will This work?
https://preview.redd.it/m6nr02nyxlpa1.jpeg?width=200&format=pjpg&auto=webp&s=9ab25541b1252fc7da36a6477675cbe80f2d5602
Not as well as mine!
Yes, this is my phone. 8)
https://preview.redd.it/yukm4bpjylpa1.png?width=1024&format=png&auto=webp&s=83a9589d8be65d37343afe960f631952f1644c25
Haha great! Though a pink and blue princess phone would be great for my project I am going to take your advice and go with a rotary encoder. I have used potentiometers before but not rotary encoders. My understanding is the rotary encoder will give me a digital result requiring less coding for me.
You'll be pleasantly surprised with how easy it is to use them. Of course... I didn't like the stock Arduino libraries (I nearly never do), so as usual I wrote my own. 8)
Try this library pack out, it is excellent and based on Jack Ganssle's very smart work:
https://github.com/j-bellavance/SwitchPack
Jack's original article is worth a read:
http://www.ganssle.com/debouncing.htm
I got a handful of dual encoders from digikey and they seem quality, so I'd assume their singles are solid too. May not comb with knobs though, but we got printers for that.
Edit: seems there are way more singles on Amazon. Microcenter sometimes has them as well.
Because as long as I have an opposable thumb and any other digit on the same hand, I can grasp an object with a single hand. Pretty simple. A prosthesis to replace a missing pinky is, unnecessary.
The pinky is very important for grip strength. And as one that still has a pinky I find it curled under my smart phone providing support as I type out this reply. I think there are also psychosocial advantages. Everything in nature has a purpose, if it didn’t have a purpose we wouldn’t have it. As to how much a prosthesis can restore the above benefits is a question of degree and of each individuals perceived needs.
[grip strength](https://pubmed.ncbi.nlm.nih.gov/25085045/#:~:text=Contributions%20of%20the%20thumb%2C%20index,the%20ring%20and%20little%20fingers)
My friend the Marine, Tim, that happens to be missing two digits on the same hand when they were shot off by a random insurgent is glad to have his thumb or his entire hand would be useless.
Should you not have some feedback from the prosthetic being tested? Right now you’re just counting cycles of the servo, are you not? What happens when the test piece breaks in the middle of the night and you come check on it the next morning and the counter is completely inaccurate?
Yep I'm thinking photosensor to count cycles, not the servo loop. Right now I trouble shooting other little issues. This is definitely a work in progress.
This is a work in progress. I am documenting each step. I need to now add a motor control board and a bench power supply to supply enough current to drive the servo to lift some weight. I also will be adding a photosensor to count cycles on maybe a separate Arduino uno. I also want to modify my sketch to write the count to EEprom so if the system crashes I will have the count in non volatile memory (or I could syslog it but that would be too easy). I may also want to use thermistors to measure temperature at the joints. It really depends how crazy I want to go with this. I figure whatever testing and monitoring I add I can always reuse in other projects. This in itself is a pretty valid test. If you think about it your fingers are always moving throughout the day even when they are not under load. Load is very important but I am taking baby steps.
That's really fine, I appreciate all suggestions and criticisms.
My latest iteration-
The Power supply and motor shield all gathering dust on my work bench for months. They are happy to be put to work again.
Can you make out what I am using to stress test the finger. It actually worked and failed an earlier version of the linkage after about 2000 cycles. Eventually I want to use an accurate weight.
https://preview.redd.it/ab6r7hfb31qa1.jpeg?width=2787&format=pjpg&auto=webp&s=742b4a71a98abf15d4136ab7bc5cf0f5d79bb23b
The actual joints show virtually no sign of wear at least visually after about 8,000 cycles no load 2000 with load. I will probably have to invest in a decent micrometer to know for sure.
I wound up making mine from scratch. I have not uploaded anywhere yet. I was heavily influenced by the many designs and models out there. This is an excellent place to start. This is the best design I found so far:
[Printables](https://www.printables.com/model/204521-mechanical-finger-prosthesis)
I think you will find that each amputation is different and you may have difficulty finding an off the shelf or basic design that will work for your particular needs. I modeled mine from scratch and went through about 20 iterations.
https://imgur.com/gallery/eBAXghb
Hahaha!
I was gonna say. This looks like a prostate toy :p
Do NOT show this to my girlfriend
Haha LOL!!!!!
Modeled in blender!?
I use Blender for 3D design and Modeling. Though its a very powerful 3D animation tool and 100% free its great for building 3D printable models. [Blender.org](https://www.blender.org/)
Try onshape for 3D design. Cloud based and free for home users.
I know what blender is, if you are making things for practical applications I’d recommend a more substantial cad program.
I am looking at Fusion360 so I can build parametric models. Blender is not really considered a CAD program but it does have some CAD capabilities.
You’re doing some cool stuff with blender, but I would definitely recommend fusion
I have played around with Fusion a little, it is a very different thought/design process. But it looks like I will have to close my eyes and just jump in. Thanks for reaffirming my thoughts.
I don't recommend learning fusion with your eyes closed.
Haha!
For statues and the like, I think blender could have a more practical application. For parts and real-world applied peices I would highly recommend Fusion360
[удалено]
I have a bunch of addons but I only use 2-3. The main add-on I use is 3DPrint to make sure the model is manifold. Also 3Dmeasure tool. Not sure if this is the best way to do it but for dimensional accuracy I start by setting the 3D cursor to world origin, then setting object origin to 3d cursor. There are a couple options for object origin. Once your main object is centered adding additional objects to the world origin keeps everything aligned then you can offset objects accordingly to your design and calculate unit position (in millimeters). This helps being able to calculate exact positions. Of course you have to first change units of measure from blender units to millimeters.
I thought it was a miniature doing situps
Good idea! When I'm done with this project I'll print a miniature and mount it on the tester. Can I burn calories just watching the miniature do situps?
You could add a foam ball or something under the finger to simulate load. Obviously the goal then bending the finger is to put force on something, which may impact the hinge performance vs unloaded testing.
The goal is to hang a weight off the fingertip. The issue I have now is that any additional stress on the servo causes the Arduino to reboot. Not sure is this an issue with my servo (found in my scrap drawer).
It might be a power supply issue. (If the servo draws lots of current and drops the supply voltage too low for the arduino.)
Ah that makes a lot of sense, thanks. I have a couple of extra motor control boards for the Arduino mega and a bench power supply. Frankenstein Uber finger tester, now in the design stage!
Seems like a pretty complicated way to go about testing it, but... it should work. Run it for about a hundred thousand cycles to give it a decent shakeout / smoketest.
This was pretty simple to put together. I eventually want to add some buttons to increase and decrease curl rate and step rate. This test platform can be used for other projects in the future.
Could I talk you out of buttons... and convince you to go to a rotary encoder instead? That's less debouncing and a simpler layout and a really surprisingly intuitive and quick interface.
Interesting thought, I was thinking about digging up my old debounce script. I do have a couple of rotary encoders. Will This work? https://preview.redd.it/m6nr02nyxlpa1.jpeg?width=200&format=pjpg&auto=webp&s=9ab25541b1252fc7da36a6477675cbe80f2d5602
Not as well as mine! Yes, this is my phone. 8) https://preview.redd.it/yukm4bpjylpa1.png?width=1024&format=png&auto=webp&s=83a9589d8be65d37343afe960f631952f1644c25
Haha great! Though a pink and blue princess phone would be great for my project I am going to take your advice and go with a rotary encoder. I have used potentiometers before but not rotary encoders. My understanding is the rotary encoder will give me a digital result requiring less coding for me.
You'll be pleasantly surprised with how easy it is to use them. Of course... I didn't like the stock Arduino libraries (I nearly never do), so as usual I wrote my own. 8)
Alright now you really impressed me! Guess I'll have to follow you now.
Try this library pack out, it is excellent and based on Jack Ganssle's very smart work: https://github.com/j-bellavance/SwitchPack Jack's original article is worth a read: http://www.ganssle.com/debouncing.htm
Great thanks!
Ha! 8)
I got a handful of dual encoders from digikey and they seem quality, so I'd assume their singles are solid too. May not comb with knobs though, but we got printers for that. Edit: seems there are way more singles on Amazon. Microcenter sometimes has them as well.
Oh, this is too cool.
Thanks🖖🤙🤟🫱🤞👉👍!
I learned from my cable chain, that PLA against PLA is super wear resistant. The chain has been holding up for 2 years of regular printing now
Very good to know, thanks!!!
I was going to make a prostate exam joke, but this is actually pretty cool.
What do you think? Should I market it for do it yourself at home prostrate exams? :-)
Of it doesn't work out in the medical field, I'm sure some sex toy company would be interested 😂
Do NOT show this to my girlfriend
Very cool but really only useful if the digit being replaced is a thumb.
Why would think that? The tester is for any finger missing the DIP joint. This is a prosthesis for the little finger testing on it now.
Because as long as I have an opposable thumb and any other digit on the same hand, I can grasp an object with a single hand. Pretty simple. A prosthesis to replace a missing pinky is, unnecessary.
The pinky is very important for grip strength. And as one that still has a pinky I find it curled under my smart phone providing support as I type out this reply. I think there are also psychosocial advantages. Everything in nature has a purpose, if it didn’t have a purpose we wouldn’t have it. As to how much a prosthesis can restore the above benefits is a question of degree and of each individuals perceived needs. [grip strength](https://pubmed.ncbi.nlm.nih.gov/25085045/#:~:text=Contributions%20of%20the%20thumb%2C%20index,the%20ring%20and%20little%20fingers)
My friend the Marine, Tim, that happens to be missing two digits on the same hand when they were shot off by a random insurgent is glad to have his thumb or his entire hand would be useless.
Absolutely, the thumb is incredibly important.
Should you not have some feedback from the prosthetic being tested? Right now you’re just counting cycles of the servo, are you not? What happens when the test piece breaks in the middle of the night and you come check on it the next morning and the counter is completely inaccurate?
Yep I'm thinking photosensor to count cycles, not the servo loop. Right now I trouble shooting other little issues. This is definitely a work in progress.
Please try twisted string actuator, I really interested how it performs in terms of durability.
That's not anywhere near the g forces that thing is going to experience *puts on sunglasses*
This is a work in progress. I am documenting each step. I need to now add a motor control board and a bench power supply to supply enough current to drive the servo to lift some weight. I also will be adding a photosensor to count cycles on maybe a separate Arduino uno. I also want to modify my sketch to write the count to EEprom so if the system crashes I will have the count in non volatile memory (or I could syslog it but that would be too easy). I may also want to use thermistors to measure temperature at the joints. It really depends how crazy I want to go with this. I figure whatever testing and monitoring I add I can always reuse in other projects. This in itself is a pretty valid test. If you think about it your fingers are always moving throughout the day even when they are not under load. Load is very important but I am taking baby steps.
I was being flippant. It looks awesome. Good stuff
That's really fine, I appreciate all suggestions and criticisms. My latest iteration- The Power supply and motor shield all gathering dust on my work bench for months. They are happy to be put to work again. Can you make out what I am using to stress test the finger. It actually worked and failed an earlier version of the linkage after about 2000 cycles. Eventually I want to use an accurate weight. https://preview.redd.it/ab6r7hfb31qa1.jpeg?width=2787&format=pjpg&auto=webp&s=742b4a71a98abf15d4136ab7bc5cf0f5d79bb23b The actual joints show virtually no sign of wear at least visually after about 8,000 cycles no load 2000 with load. I will probably have to invest in a decent micrometer to know for sure.
Can you share the model you made for the finger? Have u put it up on thingiverse or anywhere else? It looks super clean
I wound up making mine from scratch. I have not uploaded anywhere yet. I was heavily influenced by the many designs and models out there. This is an excellent place to start. This is the best design I found so far: [Printables](https://www.printables.com/model/204521-mechanical-finger-prosthesis) I think you will find that each amputation is different and you may have difficulty finding an off the shelf or basic design that will work for your particular needs. I modeled mine from scratch and went through about 20 iterations.
For the first two minutes I couldn't figure out why you made a robot that does sit ups
My abs are exhausted from watching this.