What kind of engineer
 

can build me what is essentially a laser guided CNC machine?

If something is mounted to a table, I need a laser guided arm to "read" the object and then modify it (sand) to a certain spec. Even though hundreds of the "same" piece will be mounted, one by one, each one is unique.

Who would create this kind of thing?

I'd ask a cue factory who engineered their cnc work. McDermott cues has many different cues with varying inlay patterns. Here's a factory video on how they make cues. It only touches on the CNC work, but should give you an idea...

https://www.youtube.com/watch?v=Kj-jkVcYPpw

Try looking on Pinterest. ;)

Shaun, it sounds like you would plan to procure a commercially available laser-guided CNC milling machine and are trying to figure out who you would hire to "program" it for your use case right? What I am disambiguating here is that you are not talking about finding someone who will build you a custom CNC mill.

Grant, I think using and off the shelf robotic arm would be cheaper and more effective than a CNC machine actually. It would be best to replicate a human arm and hand, I think. Talking with an inventor/engineer would help finalize the design.

The key element to this device is the laser tells the arm where it is and how it should be sanded or otherwise acted upon.

CNC machines have Renishaw probes that can probe the surfaces in every plane and then determine the amount of material to remove.

3 axis or 5 axis??

That is great news, thanks. My sense is 3 axis would be fine.

A laser would be helpful in that it (just thinking outloud) may be more precise. For example, say you have a piece of aluminum and it has a pit here and there. The pit may .2mm in diameter and .5mm deep. The sanding head will need to sand either all of the material away to remove the pit or create a blend to a non-pitted surrounding surface.

What you are describing is a full scan to map the surface of the object that would then be acted on intelligently by an algorithm to drive selected remedial corrections which "should" give a corrected result. However, constantly modifying the "map" real time would be intensive. Resolution of the scan is a determinant factor.

It's a bit different than programming to take off material overall to a certain depth.

How does it know the pit is not supposed to be there?

That question is specifically meant to get you thinking.

You could try Haas but the way their F1 team is doing that may not be the best idea. ;)

Look up Coordinate measuring machine, so using one of these to scan and a reg CNC mill to finish, the software to get the program to talk would be another thing.

I have never tried sanding using a CNC mill though.

I used some small HAAS toolroom mills TM2, they were good machines.

Very good points here.

What might work as a v1.0 is the operator can determine a depth of material removal overall. That in itself would be a big help. For example, if there are 5 pits and a deep scratch, the deepest pit is 1 mm and the scratch is .05mm deep with .2mm deep pits here and there, having the entire piece sanded down .5mm would be very helpful.

In my thinking, the laser is used for:

Determining the entire scope and shape of the piece

Determining depth of flaws to be removed by sanding

That latter may be a fixed amount (operator controlled) based on the initial entire piece scan.

Perhaps I am not understanding the issue, but if you have the part geometries predefined, it doesn't really matter how near or how far the unmodified part is to the finished geometry. A CNC machine will cut it to the geometry that is predefined via the CAD/CAM program. The measurement probe, be it small point contact or laser scan, could provide verification of the finished item.

A similar methodology is used in the manufacture of orthopedic prostheses (e.g. knee and him implants) which are somewhat customized to patient-specific dimensions.

If I am misunderstanding the question, please let me know. I do have close to 40 years of experience in the design and manufacturing of prototype precision parts for aerospace and biomedical applications, much of this via CNC and CAD/CAM, and perhaps I can provide some other suggestions.

You know that thinking is not my strong suit. :)

I think that would be operator set. Point the laser at a known perfect surface and that is the standard. Any surface farther away would be defined as a pit or scratch.

Will add this to my research, thanks.

I'm probably not being clear in how I define the original parts to be sanded. They are parts that are 50 years old. They were originally manufactured to be identical but were created and modified by hand, slightly, when new, to all fit together. And they have been in use for 50 years subject to all kinds of stresses which means that two of the same pieces can be pretty far off in terms of overall dimensions.

So any machine acting on them needs to know the exact shape and dimensions of that piece vs. another "identical" one next to it.

Does that make sense?

How big are the parts? Small, like Porsche letter emblems?
Is this a one time deal?

long and thin and some are bent and creased in complex shapes. This a many time deal. I wouldn't even blink if I put $30K into the project. I hope that doesn't sound like a naively small amount. I have no idea what something like this would actually cost.

I was thinking if the parts were small (like porsche lettering or smaller), and it was a one time deal, befriending a dentist and using their digital scanners, and then find a machine that could read the files and mill it out. I think the files are stl.

I don't know how these scanners would read longer objects, but I don't really know.

Older equipment can be found cheaper, probably not what you want, but, more just thinking out loud. Good luck.

edit- now youve got me googling the accuracy of the dental scanners- Values ranged from 16.3 [2.8] µm (CO) up to 89.8 [26.1] µm (OC4) for in vitro trueness, and from 10.6 [3.8] µm (CO) up to 58.6 [38.4] µm (iT) for in vitro precision for the complete-arch methods. They seem to handle small stuff really well.

edit two- that might be a good thing to research on the milling end also- what it the ability of different machines to cut to the specific tolerances you need.

This is a tougher thing to automate than it probably seems. It is multidicipline for mechanics, machine learning, and metrology

There are a lot of ways for a machine to physically measure a part, Photogrammetry, Laser scanning, direct probe. Hopefully the basis for the sanding or machining of the parts already exists for adaptation or it could get VERY expensive to develop.

I don't have any great useful advice and I don't understand the requirements well obviously but my experience is that this sort of thing is very expensive to do well, but the only way it can be economically feasible is if existing machine platforms can be adapted.

Another thought is that if you have a desired final shape a machine can be used with open loop tool passes programed to the right geometry, maybe on the low material condition side of the tolerance. That way you can knock down high spots to an acceptable geometry.

If a machine needs to recognize qualitatively unsightly defects and make decisions on how to blend them into the rest of the part, it could be quite an ambitious project.

Couple of things.

You are not DIY'ng this.

The tolerances you are looking for are tight.

A $30K Artec Leo which is a pretty nice device won't pick up that .05mm because it's accuracy, under perfect conditions is, 0.1mm.

Accuracy of these devices is dependent on a variety of conditions including the materials reflective properties and how much energy they reflect back, the influence of surface reflectivity.

They run the gamut of Diffuse, think concrete, tends to scatter the energy and less comes back to the sensor.

Specular, shiny, metal, mirror, makes nice tight return energy groupings but can miss the sensor completely.

Reflexive, sends back the most energy, stuff like road signs and road paints that light up at night.

I just don't see a way to build or even buy what you are looking for that will generate the efficiency required to pay for itself.

Machine learning.

He'll blow more than $30k just training the models and we haven't even gotten to hardware yet.

I'm not in the biz - only barely biz-adjacent but I think there's something called "on tool metrology" that actively measures dimensions while work's being done. With some cleverness you could "sneak up" on a surface and work from there.

I think that you're not even in "a house in a decent neighborhood" pricing though. More like "a house with servants quarters". We're doing that in our very expensive corner of the defense industry because, duh, other-people's-money.

I'm doing CT radiography now and there could be some cool ways to use that, but you're again talking hundreds of kilobucks just for the looking, before you ever get to the interpretation or the actual doing. Done right however you get precision into single-digit micrometers. Would be a brilliant way to get exact copies of something.

(national labs are not the real world)

What I've learned of some modern white-light interfereometry tech absolutely broke my mind until I actually understood it. Like "does not follow the laws of physics/imaging as I was taught them" but it's amazing stuff.

Barely even cutting edge anymore. I think there's a Keyence system that's pretty affordable (for a research lab) that can do z-axis into the nanometers, on a countertop, in the air in a normal lab space. No SEMs, vacuum chambers or levitating/magic/unobtanium tables necessary. I'm sure Zeiss and their peers have something similar.

If I am reading this right you are trying to take imperfections out of items that are now-nonstandard. To do this with automatic machines I would think you need to add a bunch of zeros to your number above. There is a reason hand finishing is used and that is you can hire a lot of hands for what it would cost to begin to engineer what you are looking for.
Machines are great for repetitive processes where you want many of the exact same, not so good for one offs with lots of variables. Man is still the go to for that.

Use image recognition instead of a laser. Mark the areas with black sharpie, and the machine massages those spots.

If a 'lego computer' can solve a rubik's cube or sort legos, your device should be able to sand marked spots.

100% NOT a civil engineer.

my eyes glazed over reading the original post. :)

I talked with my friend who has done a lot of programming work using lasers to find things and like many here said it really can't be done easily. Thanks everyone for the interesting ideas and reality check.

If nothing else some recent machinery purchases have made the entire restoration process significantly easier and faster.

Did do a little thought experiment on the math. At $45K, it would break even in one year.

I would think utilizing a GOM or FARO style laser scanner somehow communicating with a CNC machining center is what you are talking about. Laser scanners are extremely accurate, we actually have 2 here and they scan to the micron level. The key would be taking the point cloud that these produce and somehow making a machining center understand this by converting to some sort of surface recognized by the CNC machine.
Is this possible....maybe....but you are looking at a huge investment.
We scan part surfaces all the time here and for tooling repair work, we can download this file into a CAD software and create the surfaces we need to duplicate the shape. So really this technology exists. How to actually use the scanner to teach the CNC machine....thats next level.

If you can do that, it should be relatively easy to tell the CNC to remove .5mm over the entire surface which would work well for my needs. You would have to create an algorithm to define the surface but that is just removing points in the cloud (points that define pits) to create a perfect surface.

Actually not that straight forward.

The reference model and the piece that needs work would need to be 100% identical, no variations.

At that point you might as well scrap the idea of the reference model all together and scan every work piece.

But the time and effort for that would most likely not offset the savings of hand working the piece.

There are plenty of existing robots that can be programmed for finish work.

But they don't really care where they are starting from and are working to a known consistent end product.

It seems your starting point is critical to getting the correct end product and since it's variable it's tricky.

This

Things are getting there very quickly. Ten years ago we could get CT scans of irregular (i.e. real) parts and piece them together into solid models for further work, physics simulations in our case, but it sometimes took many hundreds of nerd-hours to process each one.

Nowadays we can do it in minutes (OK maybe a nerd-hour). I've led projects using that tech to eventually make $10M disappear in less than 1/1000th of a second. Super cool to wrap the whole world around and actually use our supercomputers to deal with reality rather than idealized models.

I might have lost the focus here - as much fun as it's been.

Dude with a buffing wheel? How far short of the goal is that?

;)

(edit to echo Tobra/jrj3rd...)

The piece that needs work is the reference model. They are one in the same. That's what is scanned. Every piece of work will be scanned because each one is unique.

You clearly have not hand worked the piece(s). :) Seriously. That's where ALL of the time saving is: having a "robot" do all initial prep and surfacing.

Robots can't do the finish work. That requires hand work and a trained eye. You have it reversed. Roughing out a surface is what a robot is good for. Creating a perfect final surface is what humans are good for.

In a v1.0, the end product is very simple. Remove .XXmm of material across an entire surface that has been scanned.

The accuracy and quality of the model the robot will work from is only as good as the scan which will without a doubt require manual clean up and that clean up can yield a model that no longer accurately reflects the object that needs rough work.

Trust me, the skill set required to clean that scan is going to cost you more than what it costs to do the rough work by hand.

It's every bit as much an art as the hand finishing plus you have the science of it all to contend with.

If you were working with an organic material like wood or stone it would be easier but you are working with metal which introduces all manner of complications.

There is a considerable amount of man hours that will go into it per piece at a much higher hourly pay rate because of the skill set required.

Remember, we built a company around the science of this and I would not consider what you want to do for more than 30 seconds, at least not with what's available today.

I see what you are saying but in my particular application, the surface (metal and cast Mg) is irrelevant. It is on any surface that will ultimately be modified or sacrificed.

What's the best color/type of surface to be scanned? Matte black? If shiny metal is the worst, matte black is probably the best. That's literally 10 seconds to apply a coat of matte black spray paint to create a perfect scanning surface.

Cleaning a scan will be done programatically, automatically. The best thing about software is you write it once, pay for it once and keep selling it or using it over and over and over.

I'm going back on what I said earlier. In its simplest form, scanning an object, creating a reference surface and then telling a CNC to remove .5mm of material over the scanned surface can't be that difficult.

<iframe width="600" height="350" src="https://www.youtube.com/embed/-6QxUEt5mlA" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

Great example of over engineering a simple task for no gain.

You'd get the same result in the same or less time if you simply took a hi res pic with scale bars and brought into a vector based editor like Illustrator to generate the file to feed to the CNC.

If it's a one off part it would be quicker to print it out on paper and spray mount that to the gasket material and cut by hand.

If it's a repeatable part where you need hundreds you make a die and stamp it out like a cookie cutter.