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| slowcoach:
Cheers Guys, A sharp tool and plenty of WD40, worked a treat :thumbup: I ended up with a really nice finish :D Thanks Rob |
| andyf:
--- Quote from: cidrontmg on October 20, 2010, 12:53:39 PM --- --- Quote from: andyf on October 20, 2010, 11:42:00 AM --- Also, avoid running Tufnol against Tufnol - for example, a Tufnol gear should be meshed with a metal one, not another one made of Tufnol. Andy --- End quote --- A good advice, but both Myford (ML7, S7) tumbler gears are Tufnol, running against each other, all the time... My first pair ran for >40 years, then I replaced them.... --- End quote --- Hi citrontmg, I've found the bit about gears on the Tufnol website: The pinion, or the wheel with the higher speed should normally be made from TUFNOL laminates and the mating wheel from metal. The metal gear should preferably be made of hardened steel but, failing this, a machine cut cast iron wheel usually gives good results. It should have machine-cut teeth because non-metallic gears will not mesh truly with a tooth having either a cast or machine-moulded finish. Due to the comparatively low modulus of elasticity, the teeth of a TUFNOL gear adapt themselves quickly to suit the profiles of the metal mating gear. Any slight inaccuracies in tooth form and spacing are soon accommodated. TUFNOL to TUFNOL drives are not generally recommended as no additional benefits are achieved, except in a few special cases. Such instances may occur, for example, in corrosive conditions or where electrical insulation is required. My memory was at fault :doh: . Though it talks about mating Tufnol gears to metal ones and says Tufnol to Tufnol isn't recommended, it doesn't actually say that this might cause problems, merely that there are "no additional benefits". Andy why, or |
| Lew_Merrick_PE:
All, I believe that "Tufnol" is a brand name of a cloth-phenolic composite material. I have the (US) MilSpec on phenolic materials should someone need strength properties. The thing about machining phenolic is that (A) you use a vacuum to keep the dust out of your lungs; (B) use only sharp cutters; (C) lubricate it -- we used to use a 5% solution of glycerin and water back when I did such things for my living; and (D) keep it cool either by limiting the time in the cut or applying an air blast to it (aimed into the vacuum collector). The theory is that the resin is complete cured in the resulting material. The problem with this is that catalyst/resin systems are like glass -- they approach that state asymptotically. Running phenolic on phenolic can give you both wear and sticktion problems -- and they can mutually bond if you stop them after they have been within a couple degrees of their critical temperature. The last factor is quite rare, but it does happen. Does this help? |
| cidrontmg:
--- Quote from: andyf on October 21, 2010, 06:37:45 AM ---My memory was at fault :doh: . Though it talks about mating Tufnol gears to metal ones and says Tufnol to Tufnol isn't recommended, it doesn't actually say that this might cause problems, merely that there are "no additional benefits". Andy why, or --- End quote --- Hi Andy, that makes perfect sense, about the additional benefits. I have great faith in Myford engineers, they seem to know their business about long-lasting equipment. If they mate two Tufnol gears together, it canīt be an awful sin to do so... :beer: :wave: |
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