Reverse Modeling an Impeller Made Easy with Geomagic Design X

Reverse Modeling an Francus Runner with Geomagic Design X

When small business owner Matthew Percival of  3DRevEng was contracted by  Dependable  Industries, a pattern and tooling shop in Vancouver, British Columbia, to assist in the reverse modeling of a power generation Francis Runner casting, the full power of Rapidform XOR was put to the test.

Percival had a very finite, one-day window of time to 3D scan the part.  There was no drawing to confirm against, so he had to be able to work quickly and accurately. The working runner that was being reversed engineered was on its last repair cycle and needed to have a replacement casting ready in one year. The scan data was acquired in about four hours using a hand held scanner.

The deep narrow pockets of the hydraulic passages limited the scanner’s range and made complete data acquisition impossible. With about 85% of the part scanned, Percival knew he had enough to make a complete CAD model using Rapidform XOR.

3D Scanning a Francis Turbine

3D Scanning a Francis Turbine



“For me, XOR is the obvious software choice. The ability to generate solid models directly on the scan data is priceless.”  – Matthew Percival of 3DRevEng

Using the data live on site, Percival was able to create sketches and smooth lofted surfaces between the two sides of the acquired data and conform it to the casting using hands on methods in XOR.  Doing this revealed a number of interesting details to the customer:

●     The center axis of the impeller was no longer square to the vanes which results in an unbalanced and inefficient part

●     The cast surfaces were badly worn and out of typical tolerance

●     The volume of each cavity was inconsistent XOR easily overcame these issues.  Percival was able to generate sketches on the blade, as well as an accurate smooth surface that he could revolve around the extracted revolution axis. The surface was then trimmed to match the profile and revolved to obtain the proper count of blades.  Comparing this data live with color deviation maps to the scan data, Percival was able to

ensure that accuracy was within the client’s requirements.

Matthew Percival is the owner and operator of 3DRevEng. Percival is a problem solving specialist with over a decade of experience in CNC Composite mold design for the automotive and transport industry.While working on the periphery of a few projects utilizing 3D scan data and reverse engineering, Percival realized there was great business potential and a good match between his current skill set and the need for large amounts of raw scan data post processing.  The lack of 3D scanning services in the Vancouver area made for a risky but potentially high-growth business plan. Percival realized the majority of the time was spent not on the actual scanning, but largely on the post processing of the raw scan data.  A proper software suite was required to work with the data provided by the scanners, so he tested all the well known reverse engineering software products. Rapidform XOR soon became the clear choice because of the ease of use and powerful suite of tools.

“Jobs which had taken days to process were now complete in hours, giving new life to sample projects I had deemed not cost effective, due to the enormous amount of time required to produce usable data.” – Matthew Percival

deviation map of scan vs cad

XOR’s Accuracy Analyzer displays the deviation between the newly created CAD model and scan of the turbine

XOR’s Accuracy Analyzer displays the deviation between the newly created CAD model and scan.

The problem of the part not being on the center axis was easily fixed, since XOR allowed Percival to redesign with design intent.  He was able to model the part by extracting the profile, generating a sketch and adjusting the revolution axis to the proper design intent. Lastly, he merged the model and

extracted the radii from the scan data, applying it to every blade. Once the model was complete in XOR, he used XOR’s LiveTransfer technology to send the entire feature-based solid model into Solidworks and saved it as a native sldprt file for the client.

Using the CAD suite in XOR and the product knowledge provided by the customer, Percival was able to recreate the entire runner as a solid model true to design intent.

Using the CAD suite in XOR and the product knowledge provided by the customer, Percival was able to recreate the entire runner as a solid model true to design intent.

in the hydraulic passages of pumps and power generation runners. The fully integrated CAD package in

XOR saved multiple headaches and allowed for on-the-fly scan to CAD data comparisons.

Cost Savings and Breakdown of Project

  • Cost savings in decreased downtime of hydro power generation plant
$ 20,000 per day*
  • Average cost to traditionally reverse engineer a runner
$ 3,800 and 4 days
  • 3DRevEng cost
$ 2,500 and 2 days
  • Cost to manually produce foundry tooling from traditional reverse engineering data
$ 35,000 and 5 weeks
  • Cost to CNC cut foundry tooling from CAD data made in Rapidform XOR
$22,000 and 3 weeks
  • Cost savings in finish machining and balancing of a casting made from CNC tooling
  • Cost savings and power generation efficiency resulting from highly-accurate hydraulic passages and balancing


*Estimated cost savings


The successful completion of the Francis Runner project has opened the door for other impeller projects for Percival and 3DRevEng.  These projects include aquaculture impellers, mining impeller blades and Pelton wheels.  Rapidform XOR allows Percival to quickly use complex shapes and surfaces to produce models within hours, which would otherwise have taken weeks.