John - there's certainly a lot of very ingenious methods for clamping flat panels, but the vacuum bag rig does come in very handy in a commercial shop when building curved plywood/ veneered reception walls or valances.
Several layers of "rubber ply" bending plywood and overnight with 2 part resin or even yellow glue and you've got something more than structural enough for speaker enclosures. Building the jig is what takes the time.
BTW, gorgeous job of finishing on your 3way project posted elsewhere
http://www.diyaudio.com/forums/showthread.php?s=&threadid=102180
Several layers of "rubber ply" bending plywood and overnight with 2 part resin or even yellow glue and you've got something more than structural enough for speaker enclosures. Building the jig is what takes the time.
BTW, gorgeous job of finishing on your 3way project posted elsewhere
http://www.diyaudio.com/forums/showthread.php?s=&threadid=102180
psychocow21 said:
Totally wrong! If you subscribe to the true meaning of High Fidelity, this means that that you are aiming for the smallest possible added resonances (which are responsible for 'coloration'). High Fidelity means that the original input signal is amplified and reproduced WITHOUT added impurities along the way. Resonances added by the speaker enclosures or any form of signal distortion in the amplifying chain means you will no longer have High Fidelity.
I would suggest that you try using HD3 (high density) MDF which is extremely heavy and non resonant. Usually you won't find it on the shelves of your MDF stockist and you have to order it in (18mm raw only). It is commonly used to build toilet room partitioning because it is impervious to water absorption.
See http://www.thelaminexgroup.com.au/partitioningsystems/index.asp#top
and
http://www.thelaminexgroup.com.au/downloads/trade_essentials/Availability_Guide.pdf
You are right. When I was reviewing what I had written I suddenly realised I had got it wrong but I hit the submit button anyway. Stupid I know.
I tried to edit the post before it was seen but do you think I could find an edit button anywhere? No! even though I have permission to edit/delete my own posts and the f.a.q. says that I can do so by hitting the EDIT button, I can't find one.
Anyway, while on the HD3, Laminex have changed their website and the links I posted are now superseded. Even so, there is even less info on HD3 on their new website than the old one. Here is what Lenehan Loudspeakers has to say on MDF, HD3. ( I agree with him).
I tried to edit the post before it was seen but do you think I could find an edit button anywhere? No! even though I have permission to edit/delete my own posts and the f.a.q. says that I can do so by hitting the EDIT button, I can't find one.
Anyway, while on the HD3, Laminex have changed their website and the links I posted are now superseded. Even so, there is even less info on HD3 on their new website than the old one. Here is what Lenehan Loudspeakers has to say on MDF, HD3. ( I agree with him).
I checked the f.a.q. and it doesn't say there is any time limit for editing or deleting your own posts. I did shoot a query off to the moderator abot 15 minutes ago but haven't received a reply yet. I wonder if there was some admin reason and this facility had been removed until I sent my email just now?
I don't think it's mentioned in the FAQ. If you click on 'edit' for your last post, stick a space at the end of it (or whatever minor change that won't affect the meaning of it), go & do something else for 30 minutes, & then come back & try to save the changes, you'll get a box come up saying you can only edit within 30 minutres of posting (I paraphrase, but you get the idea).
The restrictions here are very effective generally & the 30 minute idea is a good one IMO, curse myself on occasion though I do if I make a mistake.
A few amusing things can occur through the forum software's rare mistakes though. For example, one of my interests is the defunct martial art 'Bartitsu', taught around the turn of the 19th - 20th century by E. W. Barton-Wright (& mis-spelled by Conan-Doyle in his Sherlock Holmes story The Empty House as 'Baritsu') but the 4-7th letters are starred out when I mention it as a personal interest in my profile, I assume because of the electronic assumption that I'm refering to the, ahem, upper chest of a lady.
Edit -I see it's starred out here too. I'm not complaining at all -the software is very effective 99.999% of the time, & the fact that the forum is kept clean is a very good thing indeed. It just gives me a bit of a chuckle when I see these rare errors.
The restrictions here are very effective generally & the 30 minute idea is a good one IMO, curse myself on occasion though I do if I make a mistake.
A few amusing things can occur through the forum software's rare mistakes though. For example, one of my interests is the defunct martial art 'Bartitsu', taught around the turn of the 19th - 20th century by E. W. Barton-Wright (& mis-spelled by Conan-Doyle in his Sherlock Holmes story The Empty House as 'Baritsu') but the 4-7th letters are starred out when I mention it as a personal interest in my profile, I assume because of the electronic assumption that I'm refering to the, ahem, upper chest of a lady.
Edit -I see it's starred out here too. I'm not complaining at all -the software is very effective 99.999% of the time, & the fact that the forum is kept clean is a very good thing indeed. It just gives me a bit of a chuckle when I see these rare errors.
Yes, I tried something similar on one of my earlier posts and I was able to edit it about 30 mins afterwards. However, right now on refreshing the page I see that the EDIT button has been removed from that post.
Also I am sure the reason why I couldn't edit my first post (ugh - silly me) was because I had not properly set my time zone in my profile. When I was searching around for how I could edit that post I discovered the time zone error and corrected it. That is probably why my subsequent posts did have the EDIT button.
Also I am sure the reason why I couldn't edit my first post (ugh - silly me) was because I had not properly set my time zone in my profile. When I was searching around for how I could edit that post I discovered the time zone error and corrected it. That is probably why my subsequent posts did have the EDIT button.
Scottmoose said:I
A few amusing things can occur through the forum software's rare mistakes though. For example, one of my interests is the defunct martial art 'Bartitsu', taught around the turn of the 19th - 20th century by E. W. Barton-Wright (& mis-spelled by Conan-Doyle in his Sherlock Holmes story The Empty House as 'Baritsu') but the 4-7th letters are starred out when I mention it as a personal interest in my profile, I assume because of the electronic assumption that I'm refering to the, ahem, upper chest of a lady.
I see what you mean. Of course there should be no reason why your profile, which includes the correct name for the Martial Art of Bartitsu, should be subject to censorship. Maybe the censor needs to be educated
rherber1 said:
I used to use exclusively HDF (called medite here)... a piece of 1/2" has about the same mass as a piece of 3/4" MDF. It is far better than MDF, but i still choose BB over it.
All materials resonate. HDF just has a higher resonant frequency (because it is stiffer) with a higher Q (ie headed in the direction of plywood)
dave
rherber1 said:
Just reading that... they say HDF is ~7x as expensive as MDF. You guys in Oz are sure hammered on the good building materials. Here a sheet of Medite is typically about 30-35% more than MDF (ie is a sheet of MDF is $15 then a sheet of Medite is $20-22 (i liked using 1/2" laminated both sides with formica)), For that kind of differential i don't see why they don't just go for proper plywood. Everwhere they write HDF, you could put BB... there would be an even greater differential.
It is interesting that they have some fancy names for some stuff i call standard practise
dave
At least we can get some stuff over here, though there's little variety. Birch ply (not void-free) has just increased again at the local B&Q to £41 (~81 Canadian dollars) for an 8'x4' sheet. MDF has hit an all-time high too. I'm casting around for different suppliers. Problem is, I'm in the North of England (they can't fly helicopters up here in case we natives start worshipping it as a God) and all the good timber merchants follow the usual UK proceedure and are located down south.
I just have known that the local equivalent of Home Depot carries pine ply. That they call it "Premium quality Pine phenolic compensated planks" and they ask "mere" ~14 USD per sq.meter (8' x 4' sheets).
As they carry it in their "construction yard" area, I expect "premium" means "not too much damaged". I'm planning to check it in the next two weeks to finally build my very own FE166E BIBs, so I'll be able to report back soon.
Any feedback / suggestion on Pine Ply ?
Gastón
As they carry it in their "construction yard" area, I expect "premium" means "not too much damaged". I'm planning to check it in the next two weeks to finally build my very own FE166E BIBs, so I'll be able to report back soon.
Any feedback / suggestion on Pine Ply ?
Gastón
ghpicard said:
The Fir ply up here is made from Douglas Fir which is actually a pine tree... performance is relative to the number of plys... the more plys the better. 5 ply 3/4" here is common vrs the 13 plys for 18mm BB. I'm of the mind that number of plys is actually more important than the species.
davew
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