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Building Tips and technical articles. => Building techniques => Topic started by: Paul Smith on November 29, 2009, 08:49:03 PM
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I'm looking for the nomenclature and source of the fibre material used for 4" stunt bellcranks.
I need to make a few specific ones form myself, not utilize the off-the-shelf designs.
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I suspect what you refer to is the Linen-based Phenolic as supplied by Tom Morris (and Jim Snelson). I get mine from Aircraft Spruce. A 1' x 1' piece (1/8" or 3/16" thick, depending) will make a LOT of bellcranks!
I've found that there are two ways to cut this stuff. First (my way) is with a #5 reverse-tooth blade in a scrollsaw. I think Tom and Jim make then with routers, using a template and a piloted cutter. Be sure to center-punch all holes prior to drilling. This stuff has a very hard, slick surface, and bits tend to "walk".
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http://www.aircraftspruce.com/catalog/mepages/phenolic.php
Thanks for the advice. Is the above link to Westinghouse Grade L Mircata what you had in mind? I guess 3/16" would be OK for the .35 to .51 range?
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That's the stuff!
Actually, Tom says the 1/8" L-Phenolic is adequate for anything you can hold on to. The 3/16" material can offer a little less "wobble" on the shaft, but isn't really necessary.
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I was planning to go thick to give the pivot more support, then reduce mass by enlarging the lightening holes.
But maybe I could accomplish the same thing with 1/8" stock and a pair of doublers glued to the center section.
However, by the time my next project is ready for a bellecrank, those Canadian power steering systems will have come down in price.
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"Micarta" is the British name, "Phenolic" is what it's called in the USA. It can also be had with paper laminations instead of linen. I've been told that it's one of the oldest types of "plastic", and it still is used often today. I made some parts last month from Linen Phenolic...nasty yellow dust is a problem. I had a shop vac running all the time, but it only helped "somewhat". I still see small deposits of the yellow crud on my milling machine, floor, etc. Like all plastic machining, you'll find dust or chips for weeks or months.
Parts made from the stuff tend to look kinda fuzzy, but that can be fixed. Sharp tools really help, but burnishing with paste floor wax can make a world of difference. y1 Steve
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Also available from McMaster Carr. They have a large selection.
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<SNIP>
Parts made from the stuff tend to look kinda fuzzy, but that can be fixed. Sharp tools really help, but burnishing with paste floor wax can make a world of difference. y1 Steve
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Yeah, I wax my bellcranks too. It helps with the appearance points I get! LL~ LL~
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<SNIP>
Parts made from the stuff tend to look kinda fuzzy, but that can be fixed. Sharp tools really help, but burnishing with paste floor wax can make a world of difference. y1 Steve
Yeah, I wax my bellcranks too. It helps with the appearance points I get! LL~ LL~
Along with your legs----pilot appearance points count too! y1
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I also polish my pushrods!
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"Micarta" is the British name, "Phenolic" is what it's called in the USA. It can also be had with paper laminations instead of linen. I've been told that it's one of the oldest types of "plastic", and it still is used often today. I made some parts last month from Linen Phenolic...nasty yellow dust is a problem. I had a shop vac running all the time, but it only helped "somewhat". I still see small deposits of the yellow crud on my milling machine, floor, etc. Like all plastic machining, you'll find dust or chips for weeks or months.
Parts made from the stuff tend to look kinda fuzzy, but that can be fixed. Sharp tools really help, but burnishing with paste floor wax can make a world of difference. y1 Steve
I use this stuff at work (Airline/ Overhaul). Boeing uses it quite a bit on their aircraft for spacers, non-structural shims, etc. Cable pulleys and guides are also made from Phenolic.
A word of caution about sanding - the fumes are BAD health-wise so use ventilation and it will clog alum-oxide sandpaper quickly. Makes good scrapers also!