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| slowcoach:
Anyone had any experience milling Tufnol? I have a upcoming project that requires me to machine some :dremel:. Cheers Rob :thumbup: |
| John Swift:
Hi Rob I've not used tufnol but if its like srbp circuit board ( synthetic resin bonded paper) I would take care not to breath in any dust produce I'm not sure how easy it will be to machine it may delaminate if your not careful John |
| andyf:
I've done it, Rob, but only for one small part. Someone asked the same question on another forum, and a chap who seemed to know what he was talking gave a lengthy reply relating to phenolic resins such as Tufnol, which is paraphrased below: Phenolic resins are thermosetting resins which get hard with heat and cannot be remolded any further past this point. d If you really overheat phenolic it will start to char and then it just falls apart. Usually what limits it max temp are the additives. If the filler is a cloth fiber the cloth starts to suffer at a lower temp than the resin. The trick to machining phenolic, especially with fiber fillers, is to use an extremely sharp tool. As the filled phenolics can be somewhat abrasive you wind up having to resharpen quite frequently. Also as someone else suggested, cut across the grain of the filler if possible. If you have some unwanted fuzziness on your cut surface, you will have to apply some sort of grinding cloth or paper to finish it up, preferably with a lubricant. Most applications however do not require a very fine finish so extra polishing stages are more cosmetic than anything. To get the type of finish you require will depend on the grade of phenolic you're using and will need a certain degree of fiddling around to get the result you want. When we needed a fairly fine or polished surface we resorted to hard carbide or diamond laps and lots of lubricant, but that was for very specialized applications so I don't think most folks will need to go to that extreme. I think that the references to abrasive fillers refers to glass fibre and suchlike, rather than the more usuual cloth and paper fillers. It might be worth mentioning that water is a good lubricant for Tufnol; hence its use in the marine environment. Also, avoid running Tufnol against Tufnol - for example, a Tufnol gear should be meshed with a metal one, not another one made of Tufnol. Hope this helps a bit. Andy |
| picclock:
I've only milled the cloth type. Definitely gives a better finish in one direction. Found best finish was with WD40 (lots of it). Other lubes including water still gave fuzziness. I supect the wd40 wicks into the fibre, sticking the fuzzy bits together, making it cut more cleanly. Water may work if you use soap or similar to reduce surface tension (never tried water with soap). This was all by trial and error (mainly error), so best result may be to see what is acceptable to you. Best Regards picclock |
| cidrontmg:
--- 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. An excellent material, Tufnol. Wear a mask when milling. It doesn´t smell very attractive anyway. Do the same if you grind it. Use the sharpest cutters you have. If you can, keep it wet (water). Also helps to keep the dust at bay. :wave: |
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