3D Model CNC Machining STL
Many shops are reluctant to machine parts using STL CAD models. Shops that embrace STL have an advantage over those that don't.
I recently surveyed a number of contract manufacturers with CNC machining capabilities. Only one shop responded positively. And they didn't say that they could or did machine from STL, but that they thought they could. I provided them with an STL file of part of an avocado to see if they could tool path it. They sent me a picture of the partial avocado machined from foam. I thought that was a pretty impressive response given that all the other shops either just said "no" or didn't respond.
Why is it important to be able to machine using STL files?
Most additive type rapid prototyping methods (SLA, SLS, FDM, EBM, 3DP, etc.) rely on CAD models in STL format. When going from prototype to production, I think there's an advantage to using the same file for both.
Many 3D laser scanners and X-ray CT scanners output STL files. If the purpose of scanning is to be able to machine a replacement part for a +20 year old aircraft, legacy tooling, patterns, etc, why add the burden of creating solid models from the STL output by the scanners? Why not just machine the STL? The concept is already established in rapid prototyping as "scan to print". If modifications are needed, software like Rapidform's XOR Redesign have tools for modeling with STL.
For more advantages to STL, see Tom Beard's Modern Machine Shop article.
Sunday, March 27, 2011
Tuesday, February 22, 2011
3D Model of a Hand
3D Model of a Hand
Smooth_On's 'Life Casting Starter Kit' is easy to use and a bit of fun.
Most of the things I replicate are inanimate, like engine head ports or coins (Redesign on a Dime). For things like that, I've used slow setting low shrinkage silicone rubber. For living things you need something a bit quicker and safer. Just to try it out, I purchased a kit from Reynolds Advanced Materials and made a plaster reproduction of my hand. It was pretty straight forward - once I read ALL of the directions. The first attempt didn't work because the materials were too warm and set up before I could get my hand in. The folks at Reynolds were very understanding and helpful.
The second attempt went better, but I had a few air bubbles in the plaster. I scanned the plaster replica with my ZScanner 800 and the voids were easily fixed using Rapidform XOR. You can download a free copy of the STL file, just click on the hand and select download.
I expect my next attempt to give much better results.
Smooth_On's 'Life Casting Starter Kit' is easy to use and a bit of fun.
Most of the things I replicate are inanimate, like engine head ports or coins (Redesign on a Dime). For things like that, I've used slow setting low shrinkage silicone rubber. For living things you need something a bit quicker and safer. Just to try it out, I purchased a kit from Reynolds Advanced Materials and made a plaster reproduction of my hand. It was pretty straight forward - once I read ALL of the directions. The first attempt didn't work because the materials were too warm and set up before I could get my hand in. The folks at Reynolds were very understanding and helpful.
The second attempt went better, but I had a few air bubbles in the plaster. I scanned the plaster replica with my ZScanner 800 and the voids were easily fixed using Rapidform XOR. You can download a free copy of the STL file, just click on the hand and select download.
I expect my next attempt to give much better results.
Friday, February 11, 2011
3D Model Replicator
3D Model Replicator
Unlike the Replicator in the fictional Star Trek universe, today’s Additive Manufacturing (AM) machines can’t produce foods, drinks or electronic gizmos. But some of today’s machines can produce parts out of plastics, resins and even metals with little more than the press of a button.
Conventional manufacturing processes are typically subtractive and start with a piece of material that’s bigger than the desired part and then remove the excess to reveal the finished part. The waste, the bits and pieces removed, can often be recycled, but at some expense. AM processes start with nothing and build the finished part with little or no waste.
AM encompasses a number of manufacturing processes including:
* Fused deposition modeling (FDM)
* Electron beam melting (EBM)
* Selective laser sintering (SLS)
* Stereolithograpghy (SL)
* 3D printing (3DP)
As some of the names imply, some of the processes require expensive high tech equipment and highly trained technicians. But some of the processes, like 3D printing, are becoming simple enough to be used in high school classrooms. Relatively inexpensive kits are available that allow building a personal 3D printer today much like kits of the 1970’s allowed building personal computers.
To print a part, two things are required; a 3D printer and a computer 3D model of the part to be printed, usually in STL format. The STL file is loaded into the printer’s software, the software ‘cuts’ the 3D model into thin slices and directs the print head to deposit each slice in sequence. Just like Star Trek, the user pushes a button and a part appears, albeit much more slowly than in the movies. With ever continuing advances in AM technology, the time may not, in fact, be too far distant when, rather than go to a store to buy a widget, we simply download a 3D model file for a widget and print it on our version of a Replicator.
Unlike the Replicator in the fictional Star Trek universe, today’s Additive Manufacturing (AM) machines can’t produce foods, drinks or electronic gizmos. But some of today’s machines can produce parts out of plastics, resins and even metals with little more than the press of a button.
Conventional manufacturing processes are typically subtractive and start with a piece of material that’s bigger than the desired part and then remove the excess to reveal the finished part. The waste, the bits and pieces removed, can often be recycled, but at some expense. AM processes start with nothing and build the finished part with little or no waste.
AM encompasses a number of manufacturing processes including:
* Fused deposition modeling (FDM)
* Electron beam melting (EBM)
* Selective laser sintering (SLS)
* Stereolithograpghy (SL)
* 3D printing (3DP)
As some of the names imply, some of the processes require expensive high tech equipment and highly trained technicians. But some of the processes, like 3D printing, are becoming simple enough to be used in high school classrooms. Relatively inexpensive kits are available that allow building a personal 3D printer today much like kits of the 1970’s allowed building personal computers.
To print a part, two things are required; a 3D printer and a computer 3D model of the part to be printed, usually in STL format. The STL file is loaded into the printer’s software, the software ‘cuts’ the 3D model into thin slices and directs the print head to deposit each slice in sequence. Just like Star Trek, the user pushes a button and a part appears, albeit much more slowly than in the movies. With ever continuing advances in AM technology, the time may not, in fact, be too far distant when, rather than go to a store to buy a widget, we simply download a 3D model file for a widget and print it on our version of a Replicator.
Monday, January 10, 2011
3D Model Redesign on a Dime
3D Model Redesign on a Dime
The X-ray Computed Tomography (CT) project is pretty much complete. The STL files and the larger than life coins look pretty good. Click here to download a brief project description. Click here to purchase high resolution STL files of the coin (Dime) at 1X magnification.
The X-ray Computed Tomography (CT) project is pretty much complete. The STL files and the larger than life coins look pretty good. Click here to download a brief project description. Click here to purchase high resolution STL files of the coin (Dime) at 1X magnification.
Monday, December 13, 2010
3D Model of a Dime, Update
3D Model of a Dime, Update
Although Zeiss' CT scan data is exceptional, the 3D model is still a work in progress.
Zeiss provided multiple excellent scans of two plastic replicas of a Dime. The average resolution of the scans is .032mm (.0013"). While all the details are clearly visible (even John Sinnock's initials below Roosevelt's bust), the surface is a little noisy as if the Dime was made of fine sandpaper.
Using Rapidform XOR software, I've created a pretty smooth version of the dime, but have lost some details. You can still see the "JS", but not clearly. I've submitted a request for assistance to Rapidform. Hopefully, they'll be able to show me how to do a better job of smoothing the data to create a nicer 3D model of a Dime...
Although Zeiss' CT scan data is exceptional, the 3D model is still a work in progress.
Zeiss provided multiple excellent scans of two plastic replicas of a Dime. The average resolution of the scans is .032mm (.0013"). While all the details are clearly visible (even John Sinnock's initials below Roosevelt's bust), the surface is a little noisy as if the Dime was made of fine sandpaper.
Using Rapidform XOR software, I've created a pretty smooth version of the dime, but have lost some details. You can still see the "JS", but not clearly. I've submitted a request for assistance to Rapidform. Hopefully, they'll be able to show me how to do a better job of smoothing the data to create a nicer 3D model of a Dime...
Sunday, December 5, 2010
3D Model of a Coin
3D Model of a Coin
Using Zeiss' X-Ray Computed Tomography (CT) scanning service to create high resolution CAD model of a Dime (10 cent piece).
Normally, a Dime would not be a good subject for CT scanning; coins are relatively small with intricate detail and are made of dense metals. To get around the density issue, I used very low shrinkage silicone rubber to create molds of both sides of a Dime. I then cast urethane plastic replicas and sent the replicas to Zeiss for scanning. Careful vacuum degassing of the silicone and urethane was critical to capturing the intricate details.
Zeiss' Metrotom 800 CT scanner is able to capture very small details, as small as .01mm in some cases. It is also accurate to +/-.0045mm. The high resolution and accuracy coupled with the carefully crafted replicas should produce exceptional CAD models...
Using Zeiss' X-Ray Computed Tomography (CT) scanning service to create high resolution CAD model of a Dime (10 cent piece).
Normally, a Dime would not be a good subject for CT scanning; coins are relatively small with intricate detail and are made of dense metals. To get around the density issue, I used very low shrinkage silicone rubber to create molds of both sides of a Dime. I then cast urethane plastic replicas and sent the replicas to Zeiss for scanning. Careful vacuum degassing of the silicone and urethane was critical to capturing the intricate details.
Zeiss' Metrotom 800 CT scanner is able to capture very small details, as small as .01mm in some cases. It is also accurate to +/-.0045mm. The high resolution and accuracy coupled with the carefully crafted replicas should produce exceptional CAD models...
Monday, November 1, 2010
3D Model of Aircraft Longeron
3D Model of Aircraft Longeron
Reverse Engineered cracked longeron, designed doubler (splice) and provided adaptive machining 3D model using ZScanner 800, Rapidform XOR software and Solid Edge CAD software.
Client provided: 1. four foot long cracked section of longeron removed from aircraft 2. two foot long plaster cast of inside surface of remaining section of longeron (mating surface for doubler) 3.six foot long pre-machined blank for replacement longeron with integral doubler.
All 3 components were scanned using ZScanner and then modeled (minus crack) using Rapidform to create Parasolid 3D models. Solid Edge was used to 'assemble' 3D models and to design replacement longeron with inegral doubler inside pre-machined blank to insure 100% cleanup and to equalize material removal. Client was pleased with results.
Reverse Engineered cracked longeron, designed doubler (splice) and provided adaptive machining 3D model using ZScanner 800, Rapidform XOR software and Solid Edge CAD software.
Client provided: 1. four foot long cracked section of longeron removed from aircraft 2. two foot long plaster cast of inside surface of remaining section of longeron (mating surface for doubler) 3.six foot long pre-machined blank for replacement longeron with integral doubler.
All 3 components were scanned using ZScanner and then modeled (minus crack) using Rapidform to create Parasolid 3D models. Solid Edge was used to 'assemble' 3D models and to design replacement longeron with inegral doubler inside pre-machined blank to insure 100% cleanup and to equalize material removal. Client was pleased with results.
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