Restoring a broken Capitel

01/03/2013 Posted by Claus

Engineer Argo Luus from Reval Stone explains:  “A customer turned to Reval Stone to have a number of capitals produced based on a broken, old capital. It was a bit damaged, only one side was untouched and original. The original side was scanned in and mirrored to form a square capital in CARSO 5X CAD/CAM….”

The damaged original

1/4 of the capitel is enough to create a perfect symmetrical capitel in seconds

The new capitels was made in Kaarma stone, a soft and porous limestone, very easy to machine. A number of blocks each of 425 x 425 x  700 mm was prepared and mounted in the vertical lathe of the CMS/Brembane Speed 236 CNC machine.

The instructions for the machine (G-code) was made in CarsoLathe CAD/CAM and prepared by Joonas Tiido, CAD/CAM expert and CNC operator at Reval Stone. Supports were added in both ends to strengthen the capitel during machining. The stone is soft and natural cracks can appear and cause the stone to break during processing.

3 different cutting tools was applied:

  • A tool path using a saw-blade with a step so big that ribs can be removed using a hammer. A very efficient way to remove material fast.
  • A bigger Bull-nose shaped cutter was applied for the semi-finishing.
  • Finally a conical Widia tool with a nose radius of 3 mm was used to finish the capitel

 


Raw block of material

 


Rib sawing is fast

 


For every depth layer the machine stops, so the operator can break the ribs with a hammer

 

 


Semi finishing

 


Finishing pass

 


All done in less than 4 hours

 

 

Total machining was 4 hours including setup and manual removal of ribs. Excess material on top and bottom was cut of on a bridge saw machine.

 

Reval Stone is one of the oldest enterprises quarring and processing Estonian dolomite limestone in Estonia. Reval Stone has several 3- and 5-axis CNC machines and are experts in 3D Scanning, machining and hand finishing.

www.revalstone.com

 

 

 

 

 

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