#1
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Polyamide (Nylon) Rack - will it work?
Any thoughts on a Plastic rack? Should give a very smooth motion and low wear with reduced strength compared to steel, but maybe still viable?
Francis |
#2
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Things to consider:
Will grit embed into it? Will it attract electrostatic loaded waste? Will d/sided tape stick to it? Will the metal pinion strip off the rack teeth if a car hits an obstacle? Will d-sided tape hold it in place with fluctuations in humidity? (Polyamide is notoriously unstable when moisture is involved) But, it might just work. However, I can't see any major benefit over the steel rack. Already we have quite a smooth ride and low wear. We don't have noise and corrosion problems for which "plastic" racks are typically the cure. |
#3
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From http://www.plasticsmachining.com/mag...702/nylon.html
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#4
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...wow, a whole heap of considerations Gerald.
My concern initially is with Roughness of movement and energy losses due to a dirty rack. I intend to "mow" PU and EPS foam and it will be sh&&t loads of the stuff... I mean to the point where the machine will have to be fully enclosed while cutting is happening. As for electrostatic loaded waste, I know that the EPS waste will have a lot of that, and a plastic rack might be very troublesome there. I am trying to imagine as well if a rack with a modulus of 1.5 would deal better with dust or not, since there seems to be more area for the bits of dust to spread to. But, we'll see, I might give it a go. |
#5
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Well, the guys who are using modified ShopBots for surfboard shaping don't seem to be saying they have issues with the metal racks & pinions. (nor with the V-rails)
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#6
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Yeah, but usually most guys use the standard flute mills (coated with carbide abrasive... SSG, MCM or even plain grit abrasive coatings) and that makes a pretty manageable waste and you can add a DMS (dust management system)
I want to use a large disk, this little guy makes havoc. and it's too awkward to make something effective for sucking dust, plus it would take out the advantages of using a disk. And also I'd like to make a machine that is able to perform plenty of work and that doesn't have to be groomed too much. |
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