posted 06-12-2001 08:34 AM            

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Other than hanging them off a bridge in the hot sun .Any and all secrets, tricks and advise would be appreciated.

[This message has been edited by ssmith (edited 06-12-2001).]

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posted 06-12-2001 08:43 PM               

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Unfortunately, you are out of luck on those cloudy days...for relatively small diameters (say 90mm or less), the only resort is to grip them close to where they are stuck in a strong and stable bench vise with appropriate soft jaws so as not to damage the elements. One element at a time is then heated using an acetylene torch or heat gun, preferably at the screw roots, along the entire length of the element (alternative is to put the end of the screw which is stuck into the extruder barrel, heat to temps high enough to melt polymer). Then use "gentle persuasion" with a heavy mallet with soft head (i.e. rawhide mallet works best), or use a heavy mallet against a piece of wood (2x4) which is placed against the flanks of the element or kneading block. Several good blows with the mallet should do the trick. Use the heat to do the work, make sure the element is good and hot. I have personally gone through several good sized trees to disassemble one set of shafts...Other approach for larger diameters is to send to your supplier who will use this same concept on a fixture with pneumatic hammer drills, worst case requires brass drifts. DO NOT HIT SCREW ELEMENTS WITH ANY METAL, ONLY WOOD, PLASTIC, ETC. (I do not favor using aluminum or brass). There is one company who makes such a machine if you are doing this on a regular basis. If you assemble the screws correctly (i.e. meticulously clean and inspect all screw element mating surfaces for damage before assembly) then they should come off as easily as they go on. Please email me if you need further details.

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