Phil Starr Posted July 2, 2015 Author Share Posted July 2, 2015 Yep the bracing is simple enough. With the aim of simplicity I reckoned to stick to only straight cuts and to use ply offcuts to keep the costs down. I rejected the idea of complex interlocking internal bracing like the Barefaced model as being too complex with the tools available to most people. Then the question was how to brace, across the cab to opposite panels to stop the cab bowing in and out with the pressure changes created by the cone movement or to stiffen the individual panels by sticking plywood 'vanes' onto them effectively creating a series of T beams across the panels. In the end I glued the vanes on and linked the opposite panels by screwing some cross braces in, so doing a little of both and making the job very straightforward. Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted July 2, 2015 Author Share Posted July 2, 2015 Oh, someone asked the weight of the cab. It is 14.2 kg. Quote Link to comment Share on other sites More sharing options...
Chienmortbb Posted July 2, 2015 Share Posted July 2, 2015 [quote name='Phil Starr' timestamp='1435832015' post='2812787'] Oh, someone asked the weight of the cab. It is 14.2 kg. [/quote] That is a good weight for a cabinet. Iwill you make up the 18mm cab before you publish the cutting plans? Quote Link to comment Share on other sites More sharing options...
stevie Posted July 2, 2015 Share Posted July 2, 2015 I'd estimate the weight of the 18mm birch ply option at around 18kg, or slightly less than the Bergantino HD112 (at 20kg but with a tweeter), which is manageable but not what I would call lightweight. The poplar ply version would probably be around 12-13kg. Quote Link to comment Share on other sites More sharing options...
Passinwind Posted July 2, 2015 Share Posted July 2, 2015 [quote name='Phil Starr' timestamp='1435832015' post='2812787'] Oh, someone asked the weight of the cab. It is 14.2 kg. [/quote] Nice. My Thunderchild 112AF is 15 kg (w/ two tweeters no less), makes for an easy one hand grab. Quote Link to comment Share on other sites More sharing options...
Ghost_Bass Posted July 3, 2015 Share Posted July 3, 2015 One more idea, could you release the plans with measurements in milimeters also? Would be great for EU builders Quote Link to comment Share on other sites More sharing options...
LukeFRC Posted July 3, 2015 Share Posted July 3, 2015 surely the designers are old enough that they aren't using the metric system! The 12mm, 15mm or 18mm chat makes me helpful its going to be in nice simple metric! Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted July 5, 2015 Author Share Posted July 5, 2015 The designers are old, but I'm a science graduate so I can just stretch to cm. Quote Link to comment Share on other sites More sharing options...
tauzero Posted July 5, 2015 Share Posted July 5, 2015 The UK has been metric since 1973 so it shouldn't be an issue. The fact that there are numerous people who have proved unable to cope with a system based on the number 10 and prefer systems based on a mixture of bases 3, 8, 12, 14, 16, 20, and 22 shows only how popular care in the community is. 1 Quote Link to comment Share on other sites More sharing options...
stevie Posted July 5, 2015 Share Posted July 5, 2015 It's interesting (well at least I think it is) that our European neighbours still refer to loudspeaker sizes in inches as well as cms. Quote Link to comment Share on other sites More sharing options...
Chienmortbb Posted July 6, 2015 Share Posted July 6, 2015 From memory, the SI (Systeme International) is the real name for the metric system. It has been used in the UK Engineering industry since the 1960s. I started college in 1968 and we never used the Imperial System. In engineering, mm is the preferred unit of measurement or metres for bigger items. I cannot remember seeing cm on a engineering drawing. However as I am old and of failing mental faculties (think plywood debacle) this may all be rubbish. Quote Link to comment Share on other sites More sharing options...
mrtcat Posted July 6, 2015 Share Posted July 6, 2015 (edited) Anyone looking for a plywood supplier in the Oxfordshire area should definitely try WG Powell on the cowley rd in Oxford. They have a good stock of Baltic Birch Ply and have always been able to source Poplar Ply in low volume for me too. If you ask really nicley they may offer trade price which makes the Birch Ply less than Wickes / TP / B&Q etc charge for really poor quality far eastern ply. I've always found the quality very good and the a 12mm sheet usually has 7 even plys (no 1mm veneer or any of that nonsense). They also take good care when cutting for you so you get good clean, accurate square cuts. Edited July 6, 2015 by mrtcat Quote Link to comment Share on other sites More sharing options...
Ghost_Bass Posted July 6, 2015 Share Posted July 6, 2015 Well, i still read comments with people refering to inches (and lbs) on the web so that post was just to be safe. Quote Link to comment Share on other sites More sharing options...
Marvin Posted July 6, 2015 Share Posted July 6, 2015 Building and builders merchants are fantastic for mixing it ALL up. 12mm ply in an 8'x4' sheet please. I need a piece of 2"x4" that's 3m long and so on Quote Link to comment Share on other sites More sharing options...
Ghost_Bass Posted July 6, 2015 Share Posted July 6, 2015 Correct me if i'm wrong but you still have you speed limit signs in MPH over there in UK, isn't it? So there's still a mix of metric and imperial systems. Quote Link to comment Share on other sites More sharing options...
tauzero Posted July 6, 2015 Share Posted July 6, 2015 Yes, we keep some imperial units to keep the simple-minded happy (Americans, of course, use them all the time). Quote Link to comment Share on other sites More sharing options...
Ghost_Bass Posted July 6, 2015 Share Posted July 6, 2015 Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted July 6, 2015 Author Share Posted July 6, 2015 Please, please stop the units thing, plans will all be in metric units. Except the speaker size. Otherwise I'm going to resort to bushels and cubits 1 Quote Link to comment Share on other sites More sharing options...
stevie Posted July 6, 2015 Share Posted July 6, 2015 I thought we were using a 30cm speaker...... Quote Link to comment Share on other sites More sharing options...
Chienmortbb Posted July 6, 2015 Share Posted July 6, 2015 To think this used to be a pint sized thread😜 Quote Link to comment Share on other sites More sharing options...
Chienmortbb Posted July 6, 2015 Share Posted July 6, 2015 (edited) To make things worse some UK manufacturers make 10" speakers that are much larger than 255mm. Edited July 6, 2015 by Chienmortbb Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted July 8, 2015 Author Share Posted July 8, 2015 (edited) OK a couple of shots of the interior first one shows what i mean by vane bracing, this is the back of the cab http://i743.photobucket.com/albums/xx71/Phil_Starr/1x12%20prototypes%20vane%20brace_zpsfauvbstr.jpg?1436341953488&1436341955868 incidentally you can see one of the voids in the external ply, a dead knot that has fallen out. Second one shows the internal bracing http://i743.photobucket.com/albums/xx71/Phil_Starr/1x12%20prototypes%20internal%20bracing_zps9y14tdo5.jpg With a bit more detail, this shot also shows the reinforced butt joints I use, a 25mm sq batten screwed and glued along all the joints. Strong and easy to make. http://i743.photobucket.com/albums/xx71/Phil_Starr/1x12%20prototypes%20brace%20detail_zpshldb6lcs.jpg If anyone wants to redo this so the pics display directly then that would be great. Edited July 8, 2015 by Phil Starr Quote Link to comment Share on other sites More sharing options...
GrahamT Posted July 8, 2015 Share Posted July 8, 2015 Phil, It is most probably me being thick, but I cannot open the link to Photobucket. Maybe there is a hole in my bucket? ....Sorry.. BTW, I have a few rehearsals coming up at Churchinford in preparation for a gig in Bridgwater on 24th July. Can I have a go with your cab please? I have a couple of Genz Benz Reflex 112's to do a direct comparison. Please call me on 07802 967649 to discuss. Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted July 8, 2015 Author Share Posted July 8, 2015 If anyone wants to start a build before I've had time to write this up and get drawings done it shouldn't be too difficult. The external dimensions are 360x424x530mm the baffle front is set back 30mm from the front of the cab so internally the depth is 306mm. The four ports are made of standard guttering downpipe 190mm for a 50Hz tuning, and 260mm for a 40hz tuning. All this information is elsewhere in the thread but it's probably hard to find. Stevie wants a 3/4" cab with a slot port so as soon as I get time I'll build it and take some shots of the build so you can follow that. I'll make the plans for both the 12mm braced version and the slot ported version available to people so you can decide which you want. Just to remind you the driver we used is the Beyma SM212. The cab would work with the Eminence Beta12A-2 and the Eminence Kappalite 3012HO though the Betas lacks the xmax and the Kappalite is a lot more expensive. We haven't tried either speaker either so I'm not recommending them, just pointing out possibilities we might try the Celestion at some point. Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted July 8, 2015 Author Share Posted July 8, 2015 [quote name='GrahamT' timestamp='1436342239' post='2817172'] Phil, It is most probably me being thick, but I cannot open the link to Photobucket. Maybe there is a hole in my bucket? ....Sorry.. BTW, I have a few rehearsals coming up at Churchinford in preparation for a gig in Bridgwater on 24th July. Can I have a go with your cab please? I have a couple of Genz Benz Reflex 112's to do a direct comparison. Please call me on 07802 967649 to discuss. [/quote] Hi Graham, I'll pm you later, I need to get some work done I've changed the links, hope they work now, let me know and I'll try again later if there is still a problem. Must work, must work. Quote Link to comment Share on other sites More sharing options...
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