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Issue link: https://mms.epubxp.com/i/313389
mmsonline.com June 2014 MMS 103 feature Mr. Rosenthal developed a strategy to simplify setups using expanding dowels installed in a Corian sub- plate. The dowels are used not only to locate the part on the table, but also to secure it for machining. He can also easily remove, flip and re-install the part to access its bottom surface. loaded on a dedicated PC near the machine. He can also install the touch-trigger probe into the machine's spindle and use the control's coordinate system rotation function to determine a par t's edge alignment when installed on a table. This establishes not only where the part is located on the table, but how it's oriented. That way, it isn't necessary to dial-in a part to ensure it is set up parallel to the machine axes. In fact, Mr. Rosenthal uses part probing capa- bility as part of a standardized workholding method he developed using a Corian locator plate drilled with a grid of holes to accept DexLoc expanding dowels from Jergens. Shops commonly use these dowels simply to locate vises on a subplate, but the dowels serve as both locating and workhold- ing devices in this application. With a drilled Corian subplate installed on the table, the machine takes light facing cuts across the entire sur face of the subplate. This leaves behind a subplate surface that's normal to the machine's Z axis, compensating for any variance in table levelness while creating a reference plane in the Z axis after the surface is probed. Next, a sawn blank, such as the one shown on page 102, is probed to determine its X-Y center point, and then holes are drilled at the correct spacing to match two or more hole locations in the subplate. To secure the blank, Mr. Rosenthal inserts expanding dowels into the proper hole locations in the subplate. The top and bottom of the se dowe ls ex pand se parate ly, so he f irst uses a hand tool to expand the bottom of each installed dowel to lock it into the subplate. Next, the stock is dropped onto the dowels and the top of each dowel is expanded to secure the par t for machining. This workholding method provides adequate gripping force because the cutting loads are light for much of the work Mr. Rosenthal performs. Plu s, it of fe r s ac c e s s to f i ve s id e s of a pa r t during machining, which wouldn't be possible using conventional clamps. This enables him to ac curate l y squa re s aw n sto ck a nd mac hine a part from the middle of the stock (between the dowels). He can also easily remove, f lip and re -i nsta l l a wo r k p i e c e to ac c e s s i ts b ot to m surface. If holes for dowels have no impact on part design, Mr. Rosenthal can profile around the dowels, too. What's Next? Between the CNC mill and air compressor on his side of the garage, Mr. Rosenthal has limited remaining floor space. However, he'd like to add a CNC turning center at some point. He also plans to add a four-axis machining module to his CAM package when he starts encountering parts that might be a good fit for machining using the rotary table he purchased. That said, Mr. Rosenthal is still unsure where all this will ultimately lead. It may be that he'll take on more work for his existing customer or add customers. My hope, though, is that he'll strike a nice balance between performing work for others and himself, so machining remains less of a job and more of an enjoyable experience. S&W; Engineering, call 541-388-1001 or visit incrediblemachine.com. SolidCAM, call 866-975-1115 or visit solidcam.com. 0614_MMS_retired.indd 103 5/14/2014 8:44:29 AM