Film-Tech Forum ARCHIVE: the making of the "starwheel, cam and pin"

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Posted by Erkan Umut (Member # 330) on 11-21-2005, 03:43 PM:

I am wondering the manufacturing of the "starwheel, cam and pin" in brief.

Could you tell me the phases from the beginning till end:

*What kind of materials (such as steel...) are used?

*What kind of processes (such as hardening...) are used?

*What are the manufacturing equipment (such as milling-grinding-lapping machine...)?

Thank you very much for all...

Posted by Mark Gulbrandsen (Member # 72) on 11-21-2005, 08:57 PM:

Sure, I've been through the LaVEzzi plant many times with Al LaVezzi. I was fortunate to live just a short distance from their plant for a large part of my life.

Raw material is gnerally stainless steel for stars and cams although I don't know the actual alloy they use. Theor raw stock room is actually highly controled and only a few factory people have access to it. Photos were never allowed to be taken on past visits.

Roughing out of stars and cams is done by a bank of auto feed CNC lathes. This part of the operation has always fascinated me because the roughed out part is just a few thousandths oversize of the finished product. Extremely heavy cuts are taken and these lathes and according to Al LaVezzi these lathes have been known to birst into flames on occasion from the heat generated during these heavy cuts. Smoke pours from these machines attesting to the heat thats being generated! This heavy cutting is necessary to keep the costs of making the parts down by minimizing the number of passes made on a given part and hence a shorter time involved in making them.

Roughed out parts then go though various stages including heat treating if necessary, and then usually back into a CNC machine of some sort to arrive at the exact finished size. LaVezzi does alot of the work by CNC and some machines are dedicated to doing just one job.

The other very interesting procedure there is the final grind on both the star wheel radius and the slot. This is done on a Studer air bearing grinder(they have two of these)which runs almost noisless. The final grind is so slight that sometimes it can't even be heard, but ususlly the operator hears a slight tik when the wheel passes over the part. Amounts as small as one micron are removed this way.

All finished parts then to through a NIST tracable temperature controled quality control room and are checked with a video comparator against the designed dimensions for proper tolerances. Any that don't meet tolerance are rejected and destroyed. There are not many reject parts there... those guys are really pretty amazing to watch and many of their employees are life long and have worked on making these same parts for many years.

Hope this gives you some vague idea......

Anyone else thats been thorugh there please add to this....

Mark

Posted by John Pytlak (Member # 331) on 11-22-2005, 08:41 AM:

The manufacturers generally would consider their procedures (alloys used, machining and finishing methods, heat treating, QC, etc.) proprietary, and not something they want shared with potential competitors.