acg Posted April 30, 2015 Author Share Posted April 30, 2015 Talking about the colour coats, while turning this last horn I put a couple of strips of two different black paints on a scrap piece of MDF that had been primed: the matte black enamel; hammerite textured metal paint. Both paints were crudely brushed on so not exactly representative of what they would look like sprayed on, but I just wanted to get a feel for how they compare. So in various lights and various states of dustiness I have been looking at these two test strips to try to figure out which I prefer. The hammerite paint is a little "sparkly" compared to the dull matte black, but when you put a camera flash against them they both seem to behave reasonably similarly (see the photo below). The sales guys told me that to get the least lustrous finish that the matte black paint should be sprayed on from a distance, which I have not done here of course. Just to look at on a piece of board, I do like the textured finish of the metal paint, and it also does seem to manage dust better than the matte black, but it is a tiny bit bronzed and reflective in brighter lights. The textured paint does have the advantages of me not having to mess around with an additive to get the textured finish that I want inside the horns mouths and that I should be able to dispense with the spray gun idea completely and perhaps swap the hammered paint on with a sponge. It is easy...it looks good to me...plus it should be quite easy to patch up dings and scratches down the track and the dusting interval can be extended. 1 Link to comment Share on other sites More sharing options...
Guest Posted April 30, 2015 Share Posted April 30, 2015 Wow, wow, wow and wow. :blink: We need an OMG button next to the LIKE button. :lol: Link to comment Share on other sites More sharing options...
acg Posted April 30, 2015 Author Share Posted April 30, 2015 Wow, wow, wow and wow. :blink: We need an OMG button next to the LIKE button. :lol: My wife thinks I am nuts. She had one of her friends over the other day who also has an audiophile husband (she said this to me like I have leprosy or perhaps even ebola, not a love of music) and to commiserate they both went and had a look in my shed as if to say "well my husband is more whacky than your husband love"... 1 Link to comment Share on other sites More sharing options...
Guest Posted April 30, 2015 Share Posted April 30, 2015 (edited) I kinda understand how the duplicator works.... The white guide is for the shape, obviously. But where and how is the base of the duplicator attached to the table? Does it slide back and forth, with the point closest to the lathe chuck following the white guide? Top job on constructing the whole thing and indeed turning the horns. Edited April 30, 2015 by Dirty_vinylpusher Link to comment Share on other sites More sharing options...
acg Posted April 30, 2015 Author Share Posted April 30, 2015 But where and how is the base of the duplicator attached to the table? Does it slide back and forth, with the point closest to the lathe chuck following the white guide? The duplicator is not connected to the table...think of it as just another hand-tool...but one that sits on its 100mm wide and about 300mm long steel base on the outboard table...when I am not using it I pick it up and put it on a piece of carpet under the lathe so it is out of the way...it weighs maybe 8kg+ so I have to be very deliberate and gentle when the lathe is spinning and I just chew away at the MDF until the tracer hits up against the white profile bolted to the table. When that happens I have cut to the required shape...easy...and repeatable. Link to comment Share on other sites More sharing options...
Guest Posted April 30, 2015 Share Posted April 30, 2015 Cool. Very clever. I suppose when turning MDF it's less likely to "grab" as it might do with timber... Link to comment Share on other sites More sharing options...
acg Posted April 30, 2015 Author Share Posted April 30, 2015 Cool. Very clever. I suppose when turning MDF it's less likely to "grab" as it might do with timber... You have to be careful with MDF because where they are glued together is very hard compared to what is in the middle of each sheet or ring...so it can and does grab when going from soft to hard, especially if the section of horn you are cutting is not yet perfectly round and there is an element of "grab" already there when the cutting edge engages the wood again. I rough out the outside of the horns with a normal hand held tool (with the duplicator tool acting as the tool rest) until the horn is perfectly round and then I use the duplicator tool to finish it off and cut to the required shape. Link to comment Share on other sites More sharing options...
Guest Posted April 30, 2015 Share Posted April 30, 2015 You have to be careful with MDF because where they are glued together is very hard compared to what is in the middle of each sheet or ring...so it can and does grab when going from soft to hard, especially if the section of horn you are cutting is not yet perfectly round and there is an element of "grab" already there when the cutting edge engages the wood again. I rough out the outside of the horns with a normal hand held tool (with the duplicator tool acting as the tool rest) until the horn is perfectly round and then I use the duplicator tool to finish it off and cut to the required shape. Right...ok. Well, be careful then. Link to comment Share on other sites More sharing options...
aertex Posted April 30, 2015 Share Posted April 30, 2015 (edited) great stuff Anthony. You're getting so bloody good with it, next you'll be doing this for a day job . Stuff those moo's of yours. Is this channels horn profile and dimensions the same as that of the favoured feline we all know (and love ) Alan Edited April 30, 2015 by aertex Link to comment Share on other sites More sharing options...
acg Posted April 30, 2015 Author Share Posted April 30, 2015 great stuff Anthony. You're getting so bloody good with it, next you'll be doing this for a day job . Stuff those moo's of yours. Is this channels horn profile and dimensions the same as that of the favoured feline we all know (and love ) Alan Yep, this is the horn that he has sitting right at the very top of his stack. Operationally, it should be exactly the the same as the one I am turning, except mine is heavier. Link to comment Share on other sites More sharing options...
hochopeper Posted April 30, 2015 Share Posted April 30, 2015 (edited) Operationally, it should be exactly the the same as the one I am turning, except mine is heavier. Edited April 30, 2015 by hochopeper Link to comment Share on other sites More sharing options...
davewantsmoore Posted May 1, 2015 Share Posted May 1, 2015 (edited) Is that (pics in post 275) how much thickness you're going to leave in the horn? (or do they need to trim down further?) Edited May 1, 2015 by davewantsmoore Link to comment Share on other sites More sharing options...
acg Posted May 1, 2015 Author Share Posted May 1, 2015 That's the thickness Dave. It varies along the length from thicker at the throat to thinner toward the mouth. The primary idea was to do with the angle that the outer profile of the lower horns presents to higher horns as a reflecting surface...I wanted less being reflected back into the mouths of higher horns so I endeavoured to keep the outer profiles as flat as possible within reason. Side benefit is increased weight and hopefully fewer vibrations. Link to comment Share on other sites More sharing options...
davewantsmoore Posted May 1, 2015 Share Posted May 1, 2015 So what's the dimensions of the mouth hole, vs the outside (468mm?) dimension of the circular baffle? Did you model it's effect on the response? Link to comment Share on other sites More sharing options...
acg Posted May 2, 2015 Author Share Posted May 2, 2015 Throat is 38mm and mouth is 468mm. The profile is exactly the tractrix exported from Hornresp but I have made sure the mouth terminates at exactly 90 degrees and then rolls away quickly from there. Is this what you were asking Dave? Link to comment Share on other sites More sharing options...
acg Posted May 2, 2015 Author Share Posted May 2, 2015 Reading again Dave, I think you mean how thick is the wall at the mouth... the answer is quite thin...maybe an inch extra diameter past the 90 degree termination point of the tractrix curve. No idea how I would model this... Link to comment Share on other sites More sharing options...
Guest Posted May 2, 2015 Share Posted May 2, 2015 I'm confused too now... Is the width of the "rim" as seen in this pic, finished size? Or are you going to make hole bigger/OD smaller? Link to comment Share on other sites More sharing options...
acg Posted May 2, 2015 Author Share Posted May 2, 2015 That is about halfway along the horn...another 8x32mm rings to glue to th owe pictured. Link to comment Share on other sites More sharing options...
Guest Posted May 2, 2015 Share Posted May 2, 2015 (edited) That is about halfway along the horn...another 8x32mm rings to glue to th owe pictured.Ah ok makes sense.Will you need to support the horn on rollers or something when it's at full length? (You may have mentioned this earlier in the thread...) Edited May 2, 2015 by Dirty_vinylpusher Link to comment Share on other sites More sharing options...
acg Posted May 2, 2015 Author Share Posted May 2, 2015 I should be able to turn out to about half a metre length without support but I will definately need rollers by the time I get to a metre length. Link to comment Share on other sites More sharing options...
davewantsmoore Posted May 2, 2015 Share Posted May 2, 2015 Reading again Dave, I think you mean how thick is the wall at the mouth... the answer is quite thin...maybe an inch extra diameter past the 90 degree termination point of the tractrix curve. No idea how I would model this... Right. An inch is fine... I should have realised the pic I was referring to was only half way down the horn. Derp. You can model it really easy in hornresp... but 1" is insignificant for 1khz. Link to comment Share on other sites More sharing options...
Nada Posted May 2, 2015 Share Posted May 2, 2015 My wife thinks I am nuts... There's a fine line between genius and eccentricity. Unfortunately the common folk have no means of discrimination. Best to just smile inanely. ...the duplicator tool at full reach into the...the. ..Horn. ....I prefer .turning the inside..And a shot down the barrel. .... hmm, maybe your wife is actually jealous of the loving your putting into these thiny veiled sax toys 1 Link to comment Share on other sites More sharing options...
acg Posted May 2, 2015 Author Share Posted May 2, 2015 You have an active mind yourself there Hugh! Link to comment Share on other sites More sharing options...
acg Posted May 7, 2015 Author Share Posted May 7, 2015 Took 10 minutes to glue the raw second stage of the Fundamentals Horns to the turned first section. I will turn this to shape and then glue on the third and final stage of three 32mm rings. 1 Link to comment Share on other sites More sharing options...
Tony ray Posted May 7, 2015 Share Posted May 7, 2015 Cannot believe how the base plate supports the weight. They must be getting heavy The thickness is huge. So the sound has no where else to go but out. Doing the knuckle test would be like knocking on a tree. Link to comment Share on other sites More sharing options...
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