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| everymatic
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Thu Feb 05, 2009 9:04 pm Plastic knob |
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Hi, I am trying to design (indeed copy) a plastic knob for a guitar amp I own, but I'm running into major hurdles with machine shop software.
Below is the basic structure of the knob, which should be Injection Moulded, but the only way I can figure out ot make this shape is by lathe.
The problem is, the knob should have an "S" shaped raised spline in the middle of that concave section at the top. But I cannot figure out how the hell I can do that.
| Description: |
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Download |
| Filename: |
knob by lathe lathed hole full structure top bevel.ems |
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4.66 KB |
| Downloaded: |
22 Time(s) |
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| everymatic
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Thu Feb 05, 2009 9:13 pm |
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Just to help out, here's a pic of the amp knobs in close up that I'm trying to copy. One is missing, and I need to replace it.
The diameter of the knob is 47mm, and the cross section of the "s" shape, long ways, is an arc 47mm wide and 7mm high.
| Description: |
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| Filesize: |
26.94 KB |
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184 Time(s) |
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| everymatic
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Thu Feb 05, 2009 9:55 pm |
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I managed to get over the initial lathe problem by switching to Rapid Prototyping and using the Revolve command. Yippee. One step closer. But that raised and convex "S" spline has me stumped.
| Description: |
| With "S" spline on top view |
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Download |
| Filename: |
Knob Rapid Prototype with s spline.ems |
| Filesize: |
6.25 KB |
| Downloaded: |
22 Time(s) |
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| Tech2
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Fri Feb 06, 2009 4:34 am |
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Is this closer to what you want? I also changed from rapid prototype to lathe and mill. I added some edge rounding but it gets deactivated due to sharp inside corners - you can resolve that if you wish.
| Description: |
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Download |
| Filename: |
Knob forum.ems |
| Filesize: |
6.04 KB |
| Downloaded: |
22 Time(s) |
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| everymatic
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Fri Feb 06, 2009 8:06 am |
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oooh!
I cant open that ems file. I get an error message saying it was created with a newer version of the software. I have v1.55 which is the version currently available on the download page.
Am I missing a download link somewhere?
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| Tech2
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Fri Feb 06, 2009 9:11 am |
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Sorry about that - please try this one.
| Description: |
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Download |
| Filename: |
knob.ems |
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15.4 KB |
| Downloaded: |
22 Time(s) |
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| everymatic
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Fri Feb 06, 2009 9:23 am |
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That's very close indeed.
I ran off another one this morning which is even closer to the original. I was inspired by your last post about switching from RP to Lathe and Mill.
As you can see, it looks great, but I cant get the profile right between the splin and the edge. It should be curved rather than straight.
I've played around with the radius setting on the mill, but it doesn't seem to be making that much dofference in 3D, even though it's much closer to what I want when I view from the front.
| Description: |
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Download |
| Filename: |
Knob lathe and mill spline.ems |
| Filesize: |
5.92 KB |
| Downloaded: |
24 Time(s) |
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| Tech2
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Fri Feb 06, 2009 11:50 am |
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There is a bug in the 3D view for far edge rounding in this design however it would be machined. You can add a Comment To Machinist to point this out.
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| everymatic
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Fri Feb 06, 2009 11:54 am |
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That's fantastic . Thank you so much for your guidance and help. I'm obviously a complete beginner at this with no knowledge whatsoever of CAD, but this app made things a little easier for me. Every other package I've tried has been a disaster.
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