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-   -   'proper' CAD drawing & inaccurate scanspeak datasheet? (http://www.diyaudio.com/forums/construction-tips/193057-proper-cad-drawing-inaccurate-scanspeak-datasheet.html)

cersepn 22nd July 2011 01:14 PM

'proper' CAD drawing & inaccurate scanspeak datasheet?
 
hey guys, i plan to get my front baffle CNCed by a local shop. But because i don't know any CAD at all, i had to learn from scratch. The shop takes dxf files and this is the sort of template they need (not mine but another DIYer's files).
Required template:
InfoFile.jpg
SampleFile.dxf

I'm not sure what kind of CNC router they're using, but if i understand the lady correctly, it seems like the dxf has all the measurements and dimensions already embedded inside?

Well, i didn't get the sample template at first and i didn't know what was needed so i ended up doing a 3d dxf, which the lady told me was utterly useless (yea i'm a total noob at this).

I'm using solidworks. I'm wondering if i can simply "Make drawing from part", and then the resulting 2D dxf will have all the required measurements already embedded, or are there more steps to be done, such as in this way?

The other problem i have is with regards to the alignment of the screw holes. The d3004/6600 datasheet lists the pitch diameter as 90mm. From the drawing, it seems like 90mm is the distance between the centre of the screw holes.

But I measured the unit i have and it seems more like the distance between the outer screw head edges. Am i measuring the wrong thing and what is the proper way of dialing in the distance?

The tweeter comes with an in-built gasket. The depth of the flange is 6mm, gasket included. If i have a 6mm depth routed out, after i screw in the tweeter, wouldn't it be too shallow? How much compensation is necessary to get a perfect flush fit?

As for the tweeter's outer diameter, if my unit measures 104mm, how much larger should the routed hole be? 104.5mm?

Finally, is it okay to use #8-32 screws with #8-32 hurricane/t-nuts for mounting both the tweeter and woofer? Or would it be better to get bigger screws for the woofer?

I hope you made it this far. Thanks for bearing with me! It's my first diy project so i'm trying to do everything to the best of my ability. :)

Steve Eddy 22nd July 2011 02:01 PM

Looks to me like they're wanting a JPG of a dimensioned drawing, and a DXF of a "clean" two view drawing without any titleblock or dimensioning text.

I can help you out with the DXF if you'd like.

As for the pitch diameter, as per their drawing, it should be the center upon which the screw holes are set. Since it uses an even number of screw holes, you've got pairs of screw holes directly across from each other. So if their drawing is correct, then the distance between the centers of a pair of those holes should be 90mm or about 3.54 inches.

As for the depth, if the flange and gasket total 6mm, then if you make the depth of your counterbore 6mm, then the flange should end up flush with the face.

As for the tweeter diameter, I'd bump it up to 106mm to give you a 1mm gap between the flange and the counterbore.

As for the t-nuts, I've a question.

In your drawing, I see a 45 degree chamfer on the inside surface. I'm not seeing how you'd be able to get the t-nuts inserted as the screw holes are going through the chamfer.

se

cersepn 22nd July 2011 02:30 PM

Steve, thank you so much for offering to help, that is really kind of you! I might have to take you up on that one :D

Since the gasket is compressible, wouldn't the depth be less than 6mm after i tighten the screws, and then it'll end up not being flush?

Yea, about the chamfer, i'm not too sure how to insert the t-nuts. While doing some research, i saw some cabinets with chamfers only at the areas where there are no screw holes. But i obviously have no clue how to model that out so.. yea.

And i have a feeling the CNC shop is going to charge me a lot more for such complexity. Might you have any better suggestions for me? I really appreciate all the help i can get. Thanks a million!

Steve Eddy 22nd July 2011 02:53 PM

What's the gasket made of? Unless it's a foam or something, it's not likely to compress by any significant amount.

And I doubt it would really cost any more to do a "skip" chamfer. It's not really going to result in additional machine time which is what determines cost after the setup charges and whatnot.

Have you checked the center-center spacing of the screw holes yet to determine of the Scan Speak drawing is incorrect?

What woofer are you using by the way?

se


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