3D Measurement: Low Cost, High Accuracy

[@josholiver7873]

I always appreciate how far down the rabbit hole you go on working on your projects.

[@ScottRumschlag]

Thanks, I ran down it pretty far on this project.

[@bkoholliston]

I know this is an older video but it just showed up on Hackaday and I have to say that you deserve a lot of respect for this project. It is just really excellent engineering work!

[@pfroud1]

Definitely would like a second video covering the encoders. Awesome work

[@ScottRumschlag]

I might hit a few topics in a followup, thanks.

[@gersoncastro3710]

would love to see more about how you built this system.

[@dankasprick1801]

As a fellow engineer and nerd I appreciate all the effort and thought you put into this! Well done!

[@ScottRumschlag]

Figuring out the final gravity direction issue was a minor life event, I can tell you the date and approximate time, ha ha.

[@DanielSMatthews]

It would be interesting to see if it could be combined with a 4K projector and FreeCAD such that you were able to see the lines and faces that you have defined as you are measuring up a surface, and at the end everything is in a CAD file for you.

[@solidacid1337]

I thoroughly enjoyed that. First time I saw one of these machines was a commercial one, some guy at my job uses it and ever since I saw it I've been thinking about how to achieve that kind if accuracy. Thanks for explaining it so in depth!

[@tonysfun]

WOW! I love your table project - and other videos! You are a very talented young man and I like to thank you for sharing your work here!

[@JonPrevost]

If that cable is stranded then it will change it's length based on twist. Best to keep the cable twist to a minimum in the way in which you would need is to have a floating greased ball bearing at the tip to handle connection. Give it a slight twist and see if that is what is causing your errors. The wood absorbing moisture seems like another potential problem but maybe not if you calibrate it before usage. I wonder how well multifilament fishing line would work since it reduces a bunch of error amplitudes. Please post the plans. I think I'd like to try and make one.

[@felixdietzCGN]

this is very interesting! I like the way you unwrap the development process and all the problems along the way!

[@ScottRumschlag]

Thanks, it takes more effort than you might think to plan and edit these videos, so it's nice to hear they're appreciated.

[@31gane]

Thanks for making this document. Not many who do have privilege or time to create a document of learning. Thanks again. I really appreciate how much labour and thought have gone through in creating a measuring device. Given the rich history of meteorology, i personally will consider this transparent process of making one making it eligible in the hall of commons. This is a neat example and illustration on the ability of how much humans can think balancing a need of measuring, without compromising quality, affordability and preserving its knowledge of making to inspire other makers who have similar needs. I can see a rich relationship between the mind, the hand, the work and the need. Basically it questions the authority of making things unaffordable and its relationship with the quality. Probably your work might attract someone from humanities to research the very process of making tools and instruments in the modern era given the ubiquitous noise of digital gadgets and smart proprietary devices. I also must appreciate on how much FOSS, FOSH ecosystem tools and softwares you are using even for the demonstration. Thanks again for that..... Please continue doing what you are doing. Always remember there are people like you who can both plan, act which are also a deserving contribution for the strength of commons both in knowledge and practice perspective.

[@Steve_Just_Steve]

Great video and channel! Glad I found you! That is one of coolest things I've ever seen someone build in their garage. You built a DIY FARO arm with awesome range for $400? That's absolutely incredible! Great work, looking forward to going threw your previous vids and can't wait for ones to come. Thanks for sharing!

[@ErosNicolau]

Superb going through the thought and problem solving process! You are giving as an example the precision at 2 meters away. Have you considered using a weighed pulley instead of a spring? The force would be much more consistent, and this would also eliminate the elongated hypotenuse error. Having the end of the string attached to a fixed point, then around a weighed pulley, maybe even inside a tube, for isolation, then back up, would allow you a 2m useful travel for a 1m pulley travel. Or, with two pulleys, 4m for 1. Just a thought...

[@ScottRumschlag]

Yes, it's a good option for fixed location devices but I wanted this to be portable so size and ease of transport are high priority.

[@minecrafter0505]

Highly interesting project and video. I'd love to see a more polished, less prototyp-y version of this (if you are still working on this stuff). I find it fascinating that this kind of accuracy is not something we have for granted these days without extremely expensive equipment. One more thing: Could you make a video where you go more into detail on what prevents the Vive's lighthouse system for this? Especially if you were to build your own lighthouse with fewer location updates per second (since that would decrease the timing problems).

[@TheMadMagician87]

I would be interested in plans if you chose to go for it, I think this is an amazing project!! Really well done, thanks!

[@Andyinater]

Absolutely amazing video - I had a recent inspiration to try and create the same instrument, and lets just say I'm glad I can learn from your 500+hours before committing my own.

[@intjonmiller]

I love the way you approach problems in a ruthlessly thorough manner. The use case that most interests me is measuring wear in machine tools, as well as setting them up with minimal bed warp (far more accurate at least on a good size lathe than a machinist's level, isn't it?). Definitely interested in plans and code.

[@davidriley7659]

re spring tension, would a pulley and weight would provide a constant tension? i.e. 6:1 block and tackle. If you're worried about the cable slipping around the drum 9:53 , perhaps wrapping it around once or twice, would create some friction. just thinking out loud here.

[@ScottRumschlag]

I considered those options, weights create excellent, smooth tension but are bulky. I forget the exact figure but slippage was quite low even with a partial wrap, multiples have the issue of wanted to rub against the next wrap or require guides to maintain alignment. It needs to spool on a drum anyway so I figured why not thread it, spool it under tension the entire way, and be positive it cannot slip or lay inconsistently.

[@justavian]

Do you have a patreon account? I don't immediately see it. Even if i don't see myself wanting plans for this kind of project, as an engineering nerd i'd still be happy to support your work.

[@ScottRumschlag]

Thanks, no account yet but it's definitely good to know there's interest.

[@TheMadMagician87]

@@ScottRumschlag I second this, fascinating stuff!

[@felixdietzCGN]

I guess you already thought about other possible use cases or workflows and I'd love to hear more about that - like a closed-loop-positioning on a CNC-machine or automatically generating plans for furniture, drywall or flooring by feeding the data into a parametric CAD-software - and so on :)

[@WobblycogsUk]

Very impressive project, the level of detail you've gone into is astonishing. Measuring that accurately for home improvement made me chuckle though, you'd be better off with a tape measure and a couple of tubes of caulking.

[@cdd7672]

I am just curious, if you weee to slowly spin the machine clock wise and slow down as you approach to fib numbers clockwise and counter clock And point 3 laser making triangle on the floor. Now you compare the perfect triangles of fib to those points. Your accuracy should be little higher. No? Like 200 times each way

[@Bigman74066]

Very interesting video. Reminds me of the 'applied science' channel which is also an excellent channel. I would have liked a walk-around video, I can't see how it's put together (not even roughly).

[@jamesscott8962]

That's what NASA must be thinking every launch. The accuracy is literally astronomic. I like the way you think. I don't want to bother you with my expedition into inventing, but I can say they all end up costing a ton of money and huge amounts of time. Best wishes.

[@paulsimpson6290]

What a truly fascinating video and such a cool project. I would love to see a longer video showing the detail of the bearings, the encoders and so on. You mention that this is a prototype. I assume that means a "production" version? (Even if you only build one!) If so, PLEASE video the whole build. I could watch this stuff for hours! Of course, that assumes you aren't going to start selling them - something like this for under $1000 would make a killing, I think! Alternatively, a set of plans (and suggested sources for components) would sell well, I think! Now, I did have some thoughts / questions... 1. You mentioned various sources of error, including your own weight deflecting the floor. I was wondering if your own pulse may also cause a slight oscillation that affects accuracy? Not sure how you would compensate (other than perhaps wear a pulse meter and have it auto-correct for the oscillations!) Am I over-thinking this? 2. Would it be possible to have it map a path, rather than a point? My use-case would be scribing in a cabinet to a wall. If you were to drag the sensor along the path of where the cabinet meets the wall, you should be able to transfer the data to a CNC machine and have the cabinet arrive on site with an edge that perfectly matches the wall!! 3. I noticed the probe appeared to have the wire attached slightly down from the end. As you move around, that would make the angle you hold the probe at make the measurements change (if the end is on the point to be measured, moving the handle of the probe away from the device would increase the distance slightly.) Not much, but with the accuracy you have achieved, significant! How did you address this? Once again, thank you!

[@wnxeagle2]

Super interesting and a huge source of knowledge in all your videos.

[@mfx1]

Does it have an accelerometer? That could help with errors due to it being out of level or shifting on a flexible floor, I notice it has a bullseye bubble so an accelerometer could remove the need for that and improve accuracy even further.

[@Tehknein]

Any consumer option similar to this exist? This would be perfect. I build race cars and this would make templating for laser cutting extremely easy for sheet metal floors an firewall.

[@onorton88]

Proliner by Prodim, it is exactly this, must be where he got the idea.

[@MrNickBarker]

I’m not a mechanical engineer or have any training in metrology, but here is an idea based on some logical extrapolation. I’m probably missing something important. I wanted to see what you think, since I don’t have enough time/resources/knowledge to test this idea out any time soon. Theory behind my idea: You talking about the optical encoder resolution, and having to be an order of magnitude better, got me thinking. The closer you measure to the center of a circle the harder it is to get a high resolution. The further out you measure the easier it gets, since the center of rotation is still the same but the dividers can be bigger. The same would apply to 3d space i.e. a sphere. Using an object of fixed length, with one fixed point (the point we are trying to measure) we could form a sphere of a known radius. Measuring the locations of the free end of the object, gives us points on the sphere. Given that we are measuring at a distance we don’t need a super high resolution and we know that we are dealing with a “perfect” sphere, so we can use the points to find the center precisely. With enough points, you could probably average out any errors. Practical example: Attach an awl of a known length to a Vive controller. Stick the awl into the point you want to measure. Move the the Vive controller around while the awl point remains in the same position, thus forming a (partial) sphere. Use the Vive lighthouses to capture sphere points. Even regular movement (shaking) of the users hand while holding the controller can be used to get points. As I said at the start, I’m probably missing something, but I needed to get this idea out so I can focus on other things. Please let me know what you think :)

[@ScottRumschlag]

The concept is sound, in fact it's used to measure "around corners" by commercially available cable measurement systems.

[@MrNickBarker]

Is there any downside compared to your system (excluding the cost of components)?

[@ScottRumschlag]

This can be used as a sort of "add on" to the cable strategy, so it's not exclusive. A fixed length rigid piece is also pretty cheap, it's mainly math and the ability to hold that point on exactly the same spot while rotating. (the latter being more difficult than the math).

[@tvathome562]

Wow I want one of these to encode 3d objects for 3dd printing , please sell me the plans

[@doodoodoodadadadoo]

Thoroughly enjoyed your video, keep up the great work!

[@lionafrody6183]

Where are you going? Why not clip. I am waiting for you

[@tomed73]

Nice work Scott. Congrats

[@politicalagnostic]

I really enjoy the way you take us through the process. You've mentioned that your motivation is enabling off-site remodeling. It could (in a particularly distant future) allow a completely automated workshop. I'm thinking 3D printing accuracy and speed but with real wood, operated entirely by robotics. One of the thoughts I had is that the process wouldn't work with any air movement or circulation affecting the thread. While briefly puzzling over that I wondered if you considered separating the thread spooling from the boom? That would allow for the boom's angular calculations to be indepedently precise, and future adaptations to the distance mechanism can be developed and experimented separately. It would likely require the distance mechanism to mount to an outer frame so it doesn't affect the boom. Perhaps at some point a caliper-like device could be made that wouldn't suffer from gravity. (Telescoping caliper? Reaching, I know...) Anyway, please continue these videos.

[@ScottRumschlag]

The boom follows the cable to indicate direction, even a telescoping mechanical system would sag and require correction, in addition to being far more expensive. The cable is 40 lb stainless steel fishing wire, so it has some mass and shouldn't be affected by modest air movement indoors. Boom effects on the cable could be minimized by increasing cable tension, but this gets problematic if it bends the frame or causes it to lean in any way.

[@cnc-ua]

Very inspiring video. Appreciate your effort of putting it together.

[@Tsthai1]

I would to like import for commercial goods, how I take it.

[@wirekat]

Thanks Scott, I really enjoy your insights.

[@milimeter9]

amazing. How can I contact you please?

[@therealspixycat]

Very interesting! Thanks for sharing! And may I ask which optical encoder you have used?

[@primetimeseim]

When can someone buy one of these?

[@twinsjg1]

I visited your site and I saw that you selling some of your plans ,are you planning to add this project plans for sale ? Thanks M

[@ScottRumschlag]

Not enough interest, thanks for the enthusiasm though.

[@twinsjg1]

@@ScottRumschlag any chance that you can share with more details about project I found few similar projects but most of them are up to 30cm . Thanks

[@ethedona]

What a fascinating machine.

[@alastairchestnutt6416]

Very informative. Certainly not easy. Well done.

[@bdavis0718]

I would like to have a discussion about this system further. Could you please contact me?

[@ScottRumschlag]

Send me an email: [e-mail]

[@eliocassano5389]

can i buy your meter? 

[@orousloth]

ProDIM already make a measuring device like this. But yeh it's quite expensive.

[@davidriley7659]

fantastic! it's basically a manual theodolite :)

[@aion2177]

Damn! Can't wait looking up your other videos. Subscribed :D

[@aserta]

A simple solution to any potential sticking of the mechanical part of this device would be procedural. IE, you pull the wire by a little more than you need and operate the measurement on retraction. Tension would sort point A B (tube and chassis orientation) to C perfectly. But i'm just rambling, it's a very nice device. Frankly, you shouldn't put this online, and you should sell it. This is a device that would be very useful in measuring monument houses (europe), structures, or even emplacements for machines, equipment that requires that sub-mm spacing to be on the dot. Example: you need to lay a precision slab of granite for laser measurements, usual process is to deal with it onsite and have a lot of "slack" in your structure, but, what if you didn't need that. You could provide exact room specs to the manufacturer and deal out of the expenses. Just my 2 cents. Again, really nice device, a lot of work went in to it, and it's evident.

[@serdarbas8016]

If you sold this item commercially you would be rich. Prodim Proliner costs over 20k for very same thing.

[@Rob_65]

"I can build this for about 400 dollars" - yes, the materials will cost you that much. But don't forget that making 1 prototype is different from producing series of this with the required accuracy. Also don't forget the 500 hours you spent on developing the prototype. This would have cost you over 50,000 Euro (~ 60,000 USD) when thid would have been executed by an engineering company. But this still is a very nice project and it shows that "hobby level" does not mean you can't acquire professional quality. For remodeling and other purposes I think I'd still prefer the laser measurement equipment. I have seen too many times that we have to go back to a customer's site to remeasure because we forgot that one measurement or we have to go back because the customer called to ask if we can also do that other thing in his kitchen or bathroom. Yes, laser measurement will get you this 99.9994% of extra data you don't need but if this means that I don't have to spend a few extra hours driving and measuring this pays off quickly. But laser measurements are not always possible: glass, mirrors, shiny tiles or fluffy carpet are just a few things that will affect the accuracy or even completely mess up the measurements.

[@aloysiussnailchaser272]

Very admirable work and well presented. However it’s stretching things somewhat to say it cost $400. Maybe the materials cost that, but what about the 500 hours of work? The US minimum wage is $7.25 per hour, so that takes the total cost to slightly over $4,000. A gentleman as skilled as this probably earns some what more than that, so let’s make it $20 per hour. That would make it $10,400 in total. I apologise if they’re Canadian dollars. I couldn’t quite get the accent, and the mix of units used didn’t help.

[@mikenetherlin1209]

Very cool.👍

[@darkomenz666]

Hello Scott, This is a cool project. What model encoder did you use? Regards, Brennen

[@garagemonkeysan]

Wow this is amazing! : )

[@mike-synthetica]

Supercool!

[@SSukljian]

Beast

[@abdulaiabdurahmani2913]

GREETINGS from Kosova