Thread: Finish on soft plastics
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07-05-2017 #21
What we're trying to highlight, is that that finish is down to cutter/work piece deflection. The fact it's only noticeable in certain materials, doesn't make it a problem with the material.
If you zoom in on that last pic, the problem is still there, it's just not as obvious.
Different cutters and materials will create different cutting forces and resonances, so what can be barely noticeable with one material and cutter combination, can become glaringly obvious by just changing either the material or cutter. And if you have any flex/backlash in the system, any issue can get amplified.Avoiding the rubbish customer service from AluminiumWarehouse since July '13.
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07-05-2017 #22
The material is so soft that it's what you're doing with it and not the material causing the problem, have you tried disposable HSS 2 flute endmills (Carbide isn't as sharp unless you grind it razor sharp yourself and then it's a crap-shoot on anything but plastic so you have to reserve the tools for plastics), with lots of air from several directions to shift the chips and adequately cool the tool and material in all cutting directions?
Another alternative is the above plus a shallower cut using a ramped profile path.
Something as simple as ambient temperature differences can change what happens when you're cutting temperature sensitive materials and your basic set up isn't adequately controlling all the required environmental variables.
This stuff quite literally is Rocket Science ;-)
- NickLast edited by magicniner; 07-05-2017 at 06:20 PM.
You think that's too expensive? You're not a Model Engineer are you? :D
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07-05-2017 #23
These are the cutters I buy for cutting plastics, not tried or even thought about HSS tbh.
http://www.cutwel.co.uk/routing/rout...-63-850-series
Limited to 1 nozzle for air blast but can get another from work, will try that next time.
Cheers for the help and suggestions
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07-05-2017 #24
If the surface defect is imperceptible to the touch have you considered flame polishing?
I use a waft of the old blowtorch flame on clear acrylic surfaces to improve finish and render machining marks almost invisible.You think that's too expensive? You're not a Model Engineer are you? :D
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07-05-2017 #25
Not that I have had experience with nylon but I did read somewhere that some people but the nylon in a fridge or freezer to cool it then machine it. Just saying
..Clive
The more you know, The better you know, How little you know
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07-05-2017 #26You think that's too expensive? You're not a Model Engineer are you? :D
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07-05-2017 #27
I bought a buffer to polish clear and solid coloured acrylics when needed, can't use the buffer on nylon though I tried
Yeah I've red that cool the plastic before cutting it
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08-05-2017 #28
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08-05-2017 #29
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08-05-2017 #30
Yes, more parts but also greater risk for tool deflection if you are using 2mm cutters.
But we are discussing soft material here... aren't we?
Also, the full pass cleaning I normally make is just shaving off about 0.1mm. That gives very good results, even if the cutter is not brand new.
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