Your welcome.
---------
Note:
Buying your colour paint from a specialist ensures that Your cans all have the same 'code' / come from the same mix 😉
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Note:
Buying your colour paint from a specialist ensures that Your cans all have the same 'code' / come from the same mix 😉
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First one fiberglass sanded and did a small test with P38 body filler.This one is really easy to sand. and leaves very smooth finish even after 120 grit sand paper.Works best at 150rpm on a lathe.Not much heat,dust keeps going down.GREAT!
Next second enclosure to fiberglass.
Danny
Next second enclosure to fiberglass.
Danny
Attachments
Looking good barackuda 🙂
I'd hit it again as theres still some resin 'high spots' - will help keep the bondo layer thin as you have to put enough on to have some remaining over the 'peaks' when you sand / have sanded.
Also helps keep the diameter of the 'finished' piece closer to spec.
I'd hit it again as theres still some resin 'high spots' - will help keep the bondo layer thin as you have to put enough on to have some remaining over the 'peaks' when you sand / have sanded.
Also helps keep the diameter of the 'finished' piece closer to spec.
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I was thinking about it to put another layer of FG over it.The finishing one. Not sure on that though. If not I will sand it some more.The high spots are actually not that high, you can feel it with a finger, but its really shallow.
What is the usual thickness of bondo you use? Or what is max that I should avoid?
Danny
What is the usual thickness of bondo you use? Or what is max that I should avoid?
Danny
Personally.... I would not put finishing tissue over the top as:
1) It might make it no better than it is now and just add another step.
2) It might make the finish worse (higher highs and lower lows)..... more pain in correcting.
Hmmm, it's really hard to say as I cant lay my hands on it to feel how irregular it is........ if the hollows are no more than say 0.3mm - 0.4mm you'll be fine.
Hehe, also another 'hard to answer' question!
Have you watched any show's like 'Boyd Coddington's Garage'?
When a metal panels been beaten to shape, it's full of dimples n ripples - only very slight but they are there.
How the body shop guys deal with this is simple - they 'skim' on a layer of bondo, let it cure out then sand the c**p out of it.
The high spots are raw metal, the lows are the colour of the bondo - the bondo 'lows' are 'flat spots', this stage it all looks a bit 'mottled'...
So they do a second skim and sand again, rinse repeat till the panel is correct in its contours and a single even colour.
It's hard to say how thick this layer should be, my best guess would be 1.5mm - given that panels flex a fair bit even on 'Big ol' Yank Tanks' with their thick metal hides and driven in a 'Florida Granny' manner.... or trailered to the point of destination 😀😀
I'd follow the same scheme for your teardrops - skim on bondo with a 'stiffish' applicator (wifes credit card 😉 ), mount it your lathe and sand till the highs show.
Apply a second thicker layer and sand till its smooth, no highs or lows showing.
DONT PANIC if you sand through this layer - say in a band - keep the workpiece in the lathe, mix some more bondo and apply while rotating slowly.... leave to harden, sand again 🙂
Now, only You can be the judge as to the required thickness, it will take a bit of 'getting the feel' and trust in your abilities / senses as you work through the 'grits' towards priming.
Jeez, just typing this has given me the itchies.
Which reminds me - if your getting itchies from glass:
DO NOT WASH IN HOT WATER - This will Open your skins pores and allow the glass to migrate further in.
Rinse dust of thoroughly under Cold water - cold water Closes your pores - and pat dry 😉
I'll add this to your train of thought...
Do not underestimate the power of the ply layers coming trough... You have experienced the powers that the ply forces on itself leaving you with a cracked enclosure. Even after covering the enclosure with cloth and whatever resin you choose.... the ply won't stop entirely from moving about with changes in humidity. A thicker layer of bondo won't let that ply movement shine trough. You want a gloss finish, if you create that with the glass layer you have on there now, look at it 2 months from this point on and it will change on you. You can slow down the process of the change in the birch ply with humidity, but I'm pretty sure you won't ever stop it. Best you can do is hide it, that takes a coat that can handle that. Hope this makes sense....
Do not underestimate the power of the ply layers coming trough... You have experienced the powers that the ply forces on itself leaving you with a cracked enclosure. Even after covering the enclosure with cloth and whatever resin you choose.... the ply won't stop entirely from moving about with changes in humidity. A thicker layer of bondo won't let that ply movement shine trough. You want a gloss finish, if you create that with the glass layer you have on there now, look at it 2 months from this point on and it will change on you. You can slow down the process of the change in the birch ply with humidity, but I'm pretty sure you won't ever stop it. Best you can do is hide it, that takes a coat that can handle that. Hope this makes sense....
For small scratches and such, you can use glazing putty. you just smear a tiny bit into the scratch, let it harden, and sand away the excess. Fast and easy and takes paint well. This is the stuff I've used:
3M? Acryl-Red Glazing Putty, 14.5 ounce tube, 05098 - Putty - Body Filler, Glaze and Related - Products
3M? Acryl-Red Glazing Putty, 14.5 ounce tube, 05098 - Putty - Body Filler, Glaze and Related - Products
True.
1mm or 100mm - if the base structure shifts to 'that' degree, the bondo will crack no matter what...... 1 month or 1 year down the line.
Bondo takes longer to cure out the thicker it is.
Bondo SHRINKS no matter the thickness, in fact, the thicker it is, the more it shrinks...... this is 'no $h1T', it's why body shop guys use as Little bondo as possible.
Its even possible for thick bondo to 'shrink off' what it's attached to.....
Dont believe me - go ask a bodyshop 😉
I think (with my near 21 years of experience of putting composit on substrates that Have to move / flex (or not in the case of racing propellers bolted to 4.5bhp 10cc race engines)) that barackuda will be just fiiiine with the steps I have written.
OR If barackuda fancies it:
He can box them up, pay for shipping (to me and back) and materials, I'll stabilise them in a laminating room and finish them for him right down to Taupo gloss (a finish worth £22 per foot on a board).
For free - no charge for time.
I could make a mold from them while I'm at it..... 😀
Once you have your shape, use it as a buck to create a GRP mould.
Then make as many GRP copies as you need and maybe sell some to admiring friends.
Then make as many GRP copies as you need and maybe sell some to admiring friends.
Not forgetting that if one did this, one would only need a single teardrop (less postage) and to send a pair to the designer / owner f.o.c.
Sippy:
I knew good people still exists on this world 🙂
I will try to finish them of my self, if I'm struggling with the bondo or the finish, I will take up on your offer....very very very generous offer!!!!
Of course, you can make a mold if you wish.I will be happy to provide the enclosures for copy, no copy law here 🙂 And it would be interesting to see different drivers put into them and have it closed or ported (the back provides this option).....
I am speechless to know how you willing to help. This does not happen often.Thank you kind sir !
For now I will use your extensive experience on this technique and if I mess it up, will be your turn 🙂
P.S. If you want to make a mold anyway, I could send one to you when they primed (before painting).
Danny
I knew good people still exists on this world 🙂
I will try to finish them of my self, if I'm struggling with the bondo or the finish, I will take up on your offer....very very very generous offer!!!!
Of course, you can make a mold if you wish.I will be happy to provide the enclosures for copy, no copy law here 🙂 And it would be interesting to see different drivers put into them and have it closed or ported (the back provides this option).....
I am speechless to know how you willing to help. This does not happen often.Thank you kind sir !
For now I will use your extensive experience on this technique and if I mess it up, will be your turn 🙂
P.S. If you want to make a mold anyway, I could send one to you when they primed (before painting).
Danny
Danny,
There a Loads of 'good people' existing, they are usually out-spoken and thus keep their light under a bushel....... watch out for the ones flying the 'Saltire'!
(Happy Saint Andrews Day AndrewT (and all other Scotsmen))
I'd rather you persevere and have the satisfaction of saying 'I did it myself' - I have faith in you getting the job done, as you are a 'smarter cookie' than you let on 😉
What you could do is send me your drawings and I could work from those, make a plug, make a mold.....
I ran all this past my gf and she pointed out the 'economic' side of things, smart lass she is!
I think we should talk via pm to keep this thread on track.
There a Loads of 'good people' existing, they are usually out-spoken and thus keep their light under a bushel....... watch out for the ones flying the 'Saltire'!
(Happy Saint Andrews Day AndrewT (and all other Scotsmen))
I'd rather you persevere and have the satisfaction of saying 'I did it myself' - I have faith in you getting the job done, as you are a 'smarter cookie' than you let on 😉
What you could do is send me your drawings and I could work from those, make a plug, make a mold.....
I ran all this past my gf and she pointed out the 'economic' side of things, smart lass she is!
I think we should talk via pm to keep this thread on track.
Perhaps a look at how the Overkill Audio 'fibreglass units' were built would be worth a good look - it's not as easy as it looks (what is!) and you can add significant performance with variable wall thickness, mass loading, baffle/diffusers, flexible mounting, etc,
That Nautilus design isn't the 'last word' on mid chamber design - plenty of other work done over the years.
That Nautilus design isn't the 'last word' on mid chamber design - plenty of other work done over the years.
I've looked a few times for more in depth info on Overkill Audio's work, found nothing to really feed my brain with.
What I've read and 'seen' of inside the Nautilus is nothing more than market speak and purdy graphix.
KEF make (or have made) a big 'Egg' mid enclosure as well, I have had dealings with their eng dept as I intended to put one of their UniQ's in a 'Tear Drop' - I got side tracked by multiple bereavements (3 in the space of 10 days) and just about everything got put to one side this year, including a 2 day tour of KEF UK's site.
This thread gave me the idea in the first place and almost a year later it gives me the inspiration to get going again 🙂
Sippy I am actually playing with a thought to ditch the Sigmas (although dont really want to) and use Tannoys 6inch dual concentrics ( nice pair for sale on fleabay). But their not new drivers so you dont know....
I bought some Kef 75mm Uni-Q drivers for very cheap and have an idea for pc Mini monitors a'la Boenicke W5 type.
But I think Ill go for the Sigmas in my "eggs" 🙂
Anyway, whoever is interested in Sketchup drawings of my teardrops, Im happy to provide the files.
Danny
I bought some Kef 75mm Uni-Q drivers for very cheap and have an idea for pc Mini monitors a'la Boenicke W5 type.
But I think Ill go for the Sigmas in my "eggs" 🙂
Anyway, whoever is interested in Sketchup drawings of my teardrops, Im happy to provide the files.
Danny
Well just a few comments about designing the shape/parameters of the "Teardrop" that may be of interest, including the idea that most of us don't have access to sophisticated test equipment but can use some sense in reducing the guesswork quite a lot from the start and going back to the work done on these sorts of cabinets from years gone by.
The first is the required internal volume for the chosen driver - this is quite specific and no guesswork involved - included in this is the ratio between the F3 of the design and the effects on radiated response/limitations of the external shape, including the 'front surface' curvature (spherical, parabolic, etc) and complicated by the way the driver is mounted (flush mounting often involves assembly of driver from inside the chamber that then involves an technique for final chamber assembly, etc - and the list of practical problems/solutions for this sort of mounting goes on quite a bit.
Then there's the balance between the damping factor and freq response, transient response, etc, and the addition of standing wave/reflected peak pressure wave diffusers deflectors as separate from just adding extra damping material (that is also mixed/matched for the 'proper' damping characteristics
The list of things that have to be considered and compromised with for any speaker driver/chamber design goes on, and on and a "teardrop" shape isn't any different but has the potential to reduce/eliminate some of the problems that plague traditional type speaker box designs and most/much of the work has already been done over the years
The first is the required internal volume for the chosen driver - this is quite specific and no guesswork involved - included in this is the ratio between the F3 of the design and the effects on radiated response/limitations of the external shape, including the 'front surface' curvature (spherical, parabolic, etc) and complicated by the way the driver is mounted (flush mounting often involves assembly of driver from inside the chamber that then involves an technique for final chamber assembly, etc - and the list of practical problems/solutions for this sort of mounting goes on quite a bit.
Then there's the balance between the damping factor and freq response, transient response, etc, and the addition of standing wave/reflected peak pressure wave diffusers deflectors as separate from just adding extra damping material (that is also mixed/matched for the 'proper' damping characteristics
The list of things that have to be considered and compromised with for any speaker driver/chamber design goes on, and on and a "teardrop" shape isn't any different but has the potential to reduce/eliminate some of the problems that plague traditional type speaker box designs and most/much of the work has already been done over the years
Hi James.
I am nit planing to comercialize my speakers.Not now nor later. I did not use any sophysticated software or anything else.I put the Sigmas in a 7L closed box and listened to them.Also run it in WinIsd to see the response and SPL and power handling with excursion.
As Ill be using helper woofers I dont need them to do 20-20k....
I had a listen in my teardrops and I liked it.That is why Im building them up.When done I will do the measurement.
For my ears they sound very very pleasant...Even if the measurement shows horrible response...I dont care.As long as I like the sound why should I?
This is a trial and error build as stated at the beggining of the thread.No science here hehhee except human ears.
Danny
I am nit planing to comercialize my speakers.Not now nor later. I did not use any sophysticated software or anything else.I put the Sigmas in a 7L closed box and listened to them.Also run it in WinIsd to see the response and SPL and power handling with excursion.
As Ill be using helper woofers I dont need them to do 20-20k....
I had a listen in my teardrops and I liked it.That is why Im building them up.When done I will do the measurement.
For my ears they sound very very pleasant...Even if the measurement shows horrible response...I dont care.As long as I like the sound why should I?
This is a trial and error build as stated at the beggining of the thread.No science here hehhee except human ears.
Danny
Nothing wrong with the 'human ears' for a design tool!
Actually Danny I do it the same way but when changed to a different driver using the same chamber, got wildly different results and eventually got around to sorting out a couple of the basic parameters to reduce the 'tuning time' - I think as you play with the shape and everything, you develop a similar 'feel' for the sound by just 'doing it'..
One thing that did drive me crazy was the way these shapes totally change the way the speaker relates to a room and the way you can get a much more precise image and depth that's unobtainable with the same driver in a conventional box
My current chambers under design (Xovers 125Hz to Bass driver) are going thru much of what I mentioned above altho I've used the 'tapered resistant' rear chamber similar to the Nautilus midranger - it's proving to be a real PIA even with access to the BBC, Epsilon, etc design papers!
I had a good look at the Overkill midrange chamber and I can see where the rather high price tag comes from - jeez, nothing left to chance there.
All the best - it's a fascinating way to build speakers.
Actually Danny I do it the same way but when changed to a different driver using the same chamber, got wildly different results and eventually got around to sorting out a couple of the basic parameters to reduce the 'tuning time' - I think as you play with the shape and everything, you develop a similar 'feel' for the sound by just 'doing it'..
One thing that did drive me crazy was the way these shapes totally change the way the speaker relates to a room and the way you can get a much more precise image and depth that's unobtainable with the same driver in a conventional box
My current chambers under design (Xovers 125Hz to Bass driver) are going thru much of what I mentioned above altho I've used the 'tapered resistant' rear chamber similar to the Nautilus midranger - it's proving to be a real PIA even with access to the BBC, Epsilon, etc design papers!
I had a good look at the Overkill midrange chamber and I can see where the rather high price tag comes from - jeez, nothing left to chance there.
All the best - it's a fascinating way to build speakers.
Try the Nataloss chamber for the midrange - works very well. No coloration at all and is similar to infinite baffle.
http://www.diyaudio.com/forums/full-range/247598-nautaloss-ref-monitor.html
Or even the Hypercube with some stuffing for a rear chamber works nicely too. Very open sound.
http://www.diyaudio.com/forums/full-range/265053-hypercube-loudspeakers.html
Both are easy to make.
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