Building the Nathan 10

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pjpoes said:

I worked at a summer detailing Superformance kit cars. The shop did final assembly, installation of engines and drive trains, and sold these. These were 60-100,000 dollar kits. With no pre-assembly but including all needed parts you were generally looking at around 50-60 grand, and thats a lot of money. While they were supposed to be wonderful kit cars with very well engineered and well built chassis and parts, they often required a lot of work from the assembler. Superformance, as many of you may know, is considered one of the best kit companies on the market, and there is no doubt that you get an amazingly good performing car for the money, with good thorough engineering. It's just that the nature of DIY is that a lot of final assembly is often required, things rarely just bolt together.

I live very near Roush and have done some things with them. I saw a kit Ford GT there that looked far better made than the real Ford GT. They said it was made in South Africa. It was gorgeous. As an ex-car engineer (I did a lot with engine tuning) I can tell you that the kit was a better car.
 
Yes the South African Factory and Roush relationship would imply its Superformance to me. Once finished, they really are great cars and very well engineered. What you said about it being better is exactly what the shop owner said to me. They are a classic car dealer, restorer, etc, as well as building race cars (Mostly Radicals), and then did this as well. They said they had worked on numerous Ford GT40's and had two Ford GT's, and this kit was a better car. I've been around Watkins Glen in the Daytona Coupe at speed, and it was an amazing experience. The same factory also makes the Nobles, which are an amazing value. I wish I had the money for a toy like that. I drove an M12 around Watkins myself and was in love. I didn't want to get out when I was done, I just wanted to stay attached to that sports car as long as I could. My best time in my WRX is 2 minutes 8 seconds on the long course (mind you thats only 5 seconds slower than a dodge Viper can run the course and ~40 seconds slower than an Indy car can run the course. I ran just under 2 minutes in the Noble having no practice with it and having not driven the course in a few months. To me at least, thats telling a lot about how well engineered a car is (To be that easy to drive).
 
1mm? That's pushing it in my opinion. That might be possible in a fully automated process but for relatively low volume kits I doubt it would be economically viable.

I think I'm pretty thorough in terms of measurement and accuracy in the setup of my cuts, but I still make 1mm+ errors with regularity. I keep wood filler, bondo, epoxy, etc., and a ton of sandpaper on hand in my shop because it's easier for me just to handle the imperfections later rather than cut new pieces or invest in more accurate equipment.
 
We noted response variations when the driver was dispaced from the waveguide - not concentric - of about .5 mm, maybe a little more but probably less than 1 mm. (Remember that this is all done "by eye".) When I "smooth" the throat with clay, I would "estimate" that I am getting to within about .1 mm, but that may be optimistic. The driver has a >1 mm gap all the way arround the phase plug. This has to be filled.

I have noticed how quotes of these tollerances have gotten ever smaller and smaller over time. Kind of like how we remember our first love.

Non-concentricty would be a worst case because this will create a non-axi-symmetric mode. Non-axisymmetric modes are the lowest cut-in frequency of all modes. A mismatch which is perfectly circular would not be as serious since its effect would occur at a higher frequency. Clearly a "perfectly smooth" transition is optimal, but this is not realistic. There will always be errors.
 
hehe, Bondo and sand paper is much cheaper than a good Bosch or Dewalt sliding miter saw and quality table saw. Cheap Delta Table Saws and basic chop saws are all I can really afford right now.

I think one of the problems with holding tight tolerances with MDF is that, besides the softness of the material, it absorbs water like a sponge. This means unlike normal wood, which still sweels and shrinks quite a bit, this stuff really swells and shrinks. It's not a dimensionally stable product at all.

Dr. Geddes, you have mentioned clay a few times, and I'm curious, do you mean modeling clay?
 
Ex-Moderator R.I.P.
Joined 2005
Well, I learned allready in my young years that when cutting with a handsaw half the pencil line should be removed...its not about how accurate you cut, but how accurate you make the marking line :confused:

When using a tablesaw you usually attempt to cut all items with the same measurements in one and the same process

Are you using a handheld circular saw...well, thats bloddy awkward
 
I don' t use lines anywhere, I couldn't see them anyways. I use templates for everything, but getting the templates right takes a little time. Once they are there, then things go pretty smoothly.

I do use modeling clay. It works very well. It seals the gaps and smooths the small variations quite nicely and doesn't harden. If you know that you are not going to change the driver then something more permanent might be better - like silicone or filler putty, but I am never that confident - so I use clay. It takes only a very small amount - less that a finger tip. As I said, the gap in the driver makes this a necessity, but it also fills any other voids and deviations that could be a problem. Fingers are very sensitive to small deviations. You can feel a flaw in a surface that you cannot see.
 
Customs

gedlee said:

I am finding serious issues with shipments out of the country as customs seems to want to open them up, but not repack them correctly. I'm not sure how to resolve this. Any ideas? There is no way that I can insure that they will repack the boxes correctly. And I don't understand why they opened them. I mean its not like wood looks dangerous on an X-ray.

Based on recent experience shipping a lot of technical equipment transatlantic, good accompanying documentation helps very much. Minimum would be a packing list that includes photographs of the parts and a statement that these are a kit of parts that go to form a loudspeaker - along with a photograph of the finished item. Basically, the more information provided about the contents, in a form that a customs officer can qucikly check against x-rays at a glance, the less chance that they'll feel compelled to open the package. A couple of photos taken during packing can be advantageous.

Of course the document does not have to be made anew every time. A generic document with embedded photos of the various items and typical packing (assuming you do it reasonably consistently), and a check list of items actually present in a given shipment should suffice. At least that is what we do, and we've had zero problems (going into USA). The quality of the photos/printing/photocopying does not need to be very high.

Ken

ps. I'm happy now that I missed the Thai waveguides: the newer options look much closer suited to my construction skills. Eventually I'll decide what to buy.
 
Originally posted by gedlee The fact is that the DIY community is a "Beta" test and whats wrong with that? ... Be fully assured that the prices will go up as the bugs are fixed - if you haven't noticed they already have.

Earl, I didn't know that this is a beta test and I'm hoping the prices for the final kit will go up very high because otherwise your statement is a slap in the beta testers faces. I did a lot of software beta testing and all those tests had one thing in common: I didn't had to pay anything.


Originally posted by tomcat9 Earl, do you know why so Markus and other potential buyers are not happy? It is one simple word.

Expectation.

Tom, you're absolutely right but you also have to asks why were those expectation so high? There are several (good) reasons for this that led e.g. Brett to expect this

An externally hosted image should be here but it was not working when we last tested it.


... and not that

An externally hosted image should be here but it was not working when we last tested it.


Next question would be: "Who's fault is it?". The vendor not delivering a detailed description of his product or the customer not asking for the details?

Best, Markus
 
hidden agenda

markus76 said:


Earl, I didn't know that this is a beta test and I'm hoping the prices for the final kit will go up very high because otherwise your statement is a slap in the beta testers faces. I did a lot of software beta testing and all those tests had one thing in common: I didn't had to pay anything.


Next question would be: "Who's fault is it?". The vendor not delivering a detailed description of his product or the customer not asking for the details?

Best, Markus

fault lies with the vendor. All posts revolving around the ip constantly stressed the need for HIGH PRECISION in the design and fabrication of these speakers. The apologists comments are sad, as if anecdotal evidence of poor mfg. in other venues somehow justifies what is occurring here.

Nowhere was any mention of "Beta Testing" at DIY Audio mentioned prior to this thread, much less the "entrance fee" to be enrolled in such a test. This "Beta Test" scenario being spoken of now by the vendor seems insulting to this forum, especially in light of the total lack of precision in the delivered goods.

If this is the result of using templates, maybe the method of mfg. should revert to using lines, eh?

Interesting how the condescension continues... earl just doesn't get it...

As with Shin, I don't have a horse in this race, earl seems to dislike my perspective, so I'll leave those wishing to pursue this to their foibles. Good luck...I hope EG gets with the program, and collaborates to advantage with J. Janowitz, to deliver what could be a superior product. Please drop the attittude, it's highly unprofessional.

John L.
 
I really think that the expectations are unreasonable. For Dr. Geddes to have made horns like the RCF, but to his specification, would have drastically increased the price, or again, stuck Earl in a situation where he could end up losing a lot of his own money. He would have to contact a company that can cast horns like that. They would have to tool up for this one particular horn, which would likely cost in the 20,000 dollar range (and we haven't even made a horn yet). That means that if Earl made 10 horns, each would have to cost 2000 dollars, plus the cost of materials, shipping, and any profit margins. Every time the tooling wears out, he would have to do that again. And those prices are still more typical of Chinese manufacturing than they are of American.

Compare his horns to the wooden horns some companies sell. Clearly designed with a different mounting purpose, yes, they are better finished. However an unfinished basic wood horn with precision machined adapter plate costs roughly 600 dollars each from most vendors I have contacted. Dr. Geddes horns require that you mount them yourself using an adhesive of some kind. Because the way you mount them could vary quite a bit, he leaves the excess flange on for the end user to trim (Which I understand is only true of the fiberglass horns). When you buy an R/C car the body comes the exact same way. This is not an unreasonable or uncommon way of doing things.
 
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