Modifiction to HD15 Flare |
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HighLift
Registered User Joined: 01 October 2008 Status: Offline Points: 76 |
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Posted: 19 November 2009 at 10:06pm |
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Does the HD15 flare need to be curved?
I've noticed quite a few around with 5 or 6 straight sections making up the flare but why not less say 3 sections. For example: if the chamber volume is the same as the original curved flare what adverse effects could this have? edit:spelling Edited by HighLift - 19 November 2009 at 10:27pm |
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fat_brstd
Old Croc Joined: 23 August 2008 Location: Melbourne, OZ Status: Offline Points: 2126 |
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general concensus is that 5 straight sections is the closest and easiest way to get very close to the original shape of the curved section. I believe Heathrow B Line did a pdf file which shows you how to cut the wood to get use 5 straight bits of wood instead of the curve. I cant remember the length of each one but the angle was an 81 degree mitre on both ends of each of the 5 panels. If you search in this section you should find i.
edit: found it - http://www.bl-online.org/users/lasse.lukkari/hd215/HD215.pdf its 124.7mm outside edge and an 81 deg mitre on both ends for the 5. I dont know if anyone has done a 3 sectioned one before but i doubt it. Have you calculated the change in chamber volumes and horn flair rate?certainly be interested if you have. Edited by fat_brstd - 20 November 2009 at 12:41am |
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cravings
Old Croc Joined: 30 January 2007 Location: Ireland Status: Offline Points: 7442 |
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i think someone did one where they cut (can't remember how much tbh) about 12mm through a single piece of wood in 4 places and folded it slightly on the cuts.. to get the 5 piece sectional curve.. can't remember who... mykey may have been in the thread, or he may have even suggested it...
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HighLift
Registered User Joined: 01 October 2008 Status: Offline Points: 76 |
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Cheers FB: This'll be a plan B
Well the chamber volumes wouldn't be a problem to calculate so they're the same as the original HD15, but the horn flare rate is what I'm worried about. I was planning on just dividing the (roughly) quarter circle into three, so that the joints on the straight parts are equidistant. I'll get some drawings up of a design proposal, but to be honest I don't have a clue what considerations need to be made concerning the flare rate. Any advice in this department would be much appreciated.
Hi Cravings: I tried that but birch ply snaps pretty easily and I'm not really up for MDF. I have access to a good table saw that can cut angles well so I don't have a problem cutting the individual parts and gluing them with PU glue. |
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HighLift
Registered User Joined: 01 October 2008 Status: Offline Points: 76 |
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Here's the draft:
You can just make out the outer face line (R395mm) of the original curved flare in red. The 3 parts are 212mm on the longest face and each part has 75° angles both ends. A bit has been chopped of at the throat area to keep consistency with the original design. There's a chamber volume difference from the original curved design of +20cm3. These cm3s will be taken up by handles ;-) Now the question remains... Could there be any adverse effects of this design modification??? Anyone done an AB test of the curved design against the 5 sided one from HBL??? If so, any noticable difference?? Should I just go for it???? Edited by HighLift - 20 November 2009 at 3:21pm |
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schiller
New Member Joined: 30 November 2007 Location: Greece Status: Offline Points: 8 |
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None. even if you build it with 3 straight sections |
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HighLift
Registered User Joined: 01 October 2008 Status: Offline Points: 76 |
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Done them with 3 sections.
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backlash
Old Croc Joined: 11 November 2008 Location: Devon Status: Offline Points: 3532 |
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WOW that looks impressive!
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Jake_Fielder
Old Croc Joined: 08 October 2007 Status: Offline Points: 4231 |
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The three section thing would be fine, i really like the look of it also
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backlash
Old Croc Joined: 11 November 2008 Location: Devon Status: Offline Points: 3532 |
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I think a 2 section would look cool, much more like a funktion one style band pass just got to make sure the driver fits and the internal volume of the rear chamber stays the same!
<or 1 section might be nice > |
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djyves
Young Croc Joined: 06 April 2009 Location: the Netherlands Status: Offline Points: 564 |
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yea 1 section 1 curved section
Edited by djyves - 30 December 2009 at 9:40pm |
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"If brute force doesn't work, you're just not using enough!"
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backlash
Old Croc Joined: 11 November 2008 Location: Devon Status: Offline Points: 3532 |
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