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NFX Design Notes are Here (Read 27794 times)
John in CR
Ex Member



Re: NFX Design Notes are Here
Reply #15 - 07/26/06 at 02:31:37
 
The plans are kind of tricky to find.  There's a link at the bottom of Steve's design notes linked in his first post of the thread.

Before cutting wood, we need to get a clarification.  As drawn, the  A brace won't fit at the joints of the rear panel with rear left and and rear right panels.  It looks like the A brace will need an additional 45 degree angle cut along the outer portion of its rear end.

I'll also make the adjustment to make the joint of the 3 rear panels a simple butt joint.  The increased surface area of the angled joint should make it plenty strong without adding a complex joint.


Lastly, what exactly are "poly foam spheres"?  Are we talking about rough surface or smooth surface styrofoam type balls available at hobby stores or are we talking about some type of foam rubber?  If we're talking about polystyrene balls, which aren't very absorbent, then rounded chunks of foam rubber may be the first cab tweak.
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« Last Edit: 07/26/06 at 02:41:28 by John in CR »  
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SoundOfMusic
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Re: NFX Design Notes are Here
Reply #16 - 07/26/06 at 11:12:59
 
cannot find the width of the front baffle on the plans!?

please help

SOM
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John in CR
Ex Member



Re: NFX Design Notes are Here
Reply #17 - 07/26/06 at 14:05:40
 
[quote author=SoundOfMusic  link=1153620804/15#16 date=1153908779]cannot find the width of the front baffle on the plans!?

please help

SOM [/quote]

Just add up the rear dimensions shown.  Steve likes to make people think sometimes.
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rmt
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Re: NFX Design Notes are Here
Reply #18 - 07/26/06 at 16:19:29
 
[quote author=John in CR  link=1153620804/15#15 date=1153877497]
Before cutting wood, we need to get a clarification.  As drawn, the  A brace won't fit at the joints of the rear panel with rear left and and rear right panels.  It looks like the A brace will need an additional 45 degree angle cut along the outer portion of its rear end.

Lastly, what exactly are "poly foam spheres"?  Are we talking about rough surface or smooth surface styrofoam type balls available at hobby stores or are we talking about some type of foam rubber?  If we're talking about polystyrene balls, which aren't very absorbent, then rounded chunks of foam rubber may be the first cab tweak. [/quote]

I interpret brace A as drawn in the callout, without a 45 degree angle at the rear, as correct.  I think the 45 degree line you are viewing is the backside of braces B which are at different elevations than braces A.  I see brace A as setting flat end grain (8 degree crosscut) against the back panel.

The ball surface texture question is one I have too.
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« Last Edit: 07/26/06 at 16:20:11 by rmt »  
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John in CR
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Re: NFX Design Notes are Here
Reply #19 - 07/26/06 at 22:55:48
 
RMT,

I see what you mean, but that leaves too little surface area for my tastes in the joint of the rear panel and P3's.  I'd rather cut the 45 out of the end of the A brace or chisel out a space on the P3's for the A brace.  Either way I will join the A brace to both the rear panel and the P3 on its side.  Also, I don't care about the end grain of the rear panel being exposed, so I'll definitely make it wider and join with more surface area to the P3.

Lastly, I'm going to have to think about the 8 degree rake long and hard.  I can see that it's going to be a real construction pain and more than likely, I'll just construct it square with some extra length at both ends of the full length panels.  Then cut the rake angle off the top and bottom when I'm finished.  The only possible detriment I see is that the B braces won't be perfectly horizontal or flush with the top and bottom.  Maybe do only the B braces at the 8 degree angle?  I don't see how anyone is possibly going to get a perfect fit on those P2 and P3 panels (you need an 8 degree angle on something at a 45 degree angle, so you have an odd shallow angle in 2 dimensions for those panels.  I'd have to revisit the math involved to even figure out the angles, much less cut them).
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Chris K
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Re: NFX Design Notes are Here
Reply #20 - 07/27/06 at 03:59:05
 
[quote author=rmt  link=1153620804/15#18 date=1153927169]
The ball surface texture question is one I have too. [/quote]

Think "NERF" ball, you know the soft foam kiddie play balls about 6 or 7 inches in diameter?
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rmt
Ex Member



Re: NFX Design Notes are Here
Reply #21 - 07/27/06 at 04:56:27
 
[quote author=John in CR  link=1153620804/15#19 date=1153950948]
 I don't see how anyone is possibly going to get a perfect fit on those P2 and P3 panels (you need an 8 degree angle on something at a 45 degree angle, so you have an odd shallow angle in 2 dimensions for those panels.  I'd have to revisit the math involved to even figure out the angles, much less cut them). [/quote]

John,

The applied math here is using compound angle formulas.  Imagine trying to build a four sided box that is narrower at the base than the top like a decorative flower pots.  If you know the angle going up and how many sides you have,  a compound angle formula will tell you the correct bevels and miters for cutting.  I found the formulas browsing woodworking sites as many have fabrication tips and the compound angle question is a popular one.  I will say that one must still be careful about when and how to apply the formulas.

As a check I went through the plans and sketched each piece in two dimensions.  I then created a third view of the true angle of the bevels which also happens to be a view that is an end view showing the true width of the piece.  I used basic trig to transfer the projections onto the 3rd view and the angles just jump out at you.  I really need to buy some CAD software, but old habits die hard.
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John in CR
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Re: NFX Design Notes are Here
Reply #22 - 07/27/06 at 06:19:09
 
My off the cuff guess would be 8 degrees divided by the square root of 2, but correct or not, I have no interest in trying to cut it.  I'll take the easy route.
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Manowar
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Re: NFX Design Notes are Here
Reply #23 - 07/27/06 at 13:52:23
 
On the rear corners of the base it looks like round protrusions, can anybody clarify this? And these 6" poly balls, are they just resting on each other? where would I get these?

Manowar  ???
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« Last Edit: 07/27/06 at 13:52:56 by Manowar »  
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rmt
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Re: NFX Design Notes are Here
Reply #24 - 07/29/06 at 21:44:13
 
Well I completed a good part of my scale model. I made it full sized.  I am quite pleased with the results as all the pieces fit together nicely.   I used some scrap MDF from a home entertainment center I had been saving for a project.  It was not too difficult to cut the bevels and miters after studying the plans.  I checked my math with projection drawings so I was real sure the parts would fit.  They did.  This is not to say I cut the parts correctly each time. I want to emphasize here that the miscuts were the variety where I put the piece in the crosscut saw backwards or upside down from the correct way.  Very easy to do if you get complacent.  I initially cut the tricky ones much longer than needed and then cut them down to size after a first cut to check fit against the other part.  I then could use the same saw setup for the opposite end.  I cut the PL-xs from a four foot section and just worked it down from there.  This method works well for getting a length of stock that has a good cross section from the long rips.  The beginning and ending of a long rip sometimes lose constant cross section so if you cut a longer piece you will have a better chance of getting a good part to cross cut.

Also use the front as a template to set the length of the side pieces. Otherwise you will not have a flat top.

I would have finished the model but it was just too darn hot out there. I had to cut and assemble outside because of the MDF dust.  That stuff is nasty. Tough on your saw blades too. I have had a mask on since yesterday in this heat.  Yuck!  All my tools are on rollers so I move them outside for cutting and welding.  Did I mention already it is really hot outside.

My next step is to get some birch plywood to build a set to use. I will use the model pieces as a template for saw setups and as a guide to keep the cutting R/L pieces organized.  Fun build.  I have decided to go with real solid maple or cherry instead.  btw, I will not use MDF again.  My wife was not pleased with the dust.  Wood chips she does not mind but MDF dust - NO!
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« Last Edit: 07/31/06 at 00:21:25 by rmt »  
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John in CR
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Re: NFX Design Notes are Here
Reply #25 - 07/29/06 at 22:28:26
 
RMT,

How much to do an extra pair while you're at it? Cheesy
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Manowar
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Re: NFX Design Notes are Here
Reply #26 - 07/30/06 at 18:16:13
 
Has anyone figured out what the baffle width is?

Also when looking at the top of the plan, are the side ports open between P2-R on the right side and and the back verticle panel R and same as the left side P2-L and R?

No dimensions given for pedestal and top and bottom boards! will these be available later or do we just have to try and build it with the info we have?

Manowar ???
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rmt
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Re: NFX Design Notes are Here
Reply #27 - 07/30/06 at 22:13:24
 
[quote author=Manowar  link=1153620804/15#26 date=1154279773]Has anyone figured out what the baffle width is?

Also when looking at the top of the plan, are the side ports open between P2-R on the right side and and the back verticle panel R and same as the left side P2-L and R?

No dimensions given for pedestal and top and bottom boards! will these be available later or do we just have to try and build it with the info we have?

Manowar ??? [/quote]

What piece are you referring to as the baffle?

The opening in the back is along braces B between p2 and p3.

The dimensions are all there.  Look again.  

However, the rear spikes are drawn in a different location in the front view than the plan view.  Front view shows rear spikes outside the speaker width and the spikes are clearly inside the 4.3 inch square in the rear.  No big deal it just illlustrates you can put them where you want.
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Steve Deckert
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If the 1st watt
sucks why continue?

Posts: 2441
Re: NFX Design Notes are Here
Reply #28 - 07/30/06 at 23:01:47
 
The poly foam balls are what we grew up knowing as NERF balls.  Now available by the name POOF balls.  I got them from Walmart, but have also found them online.

Steve
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Manowar
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Re: NFX Design Notes are Here
Reply #29 - 07/30/06 at 23:27:50
 
[quote author=rmt  link=1154300940/15#27 date=1154294004]

What piece are you referring to as the baffle?

The dimensions are all there.  Look again.  
[/quote]

I was referring to the baffle the speaker mounts too!...OK you have to add the dim. of R which is 3.75 plus the 4.3 x2 for the dashed square for a total of 12.35"


Cry
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