Just discovered, much to my surprise, that the local independent art/craft shop does 30"x40" 5mm boards for £6.50 🙂 Might well source my foamboard from there as I'll be able to select the best boards rather than trust the postal system to deliver intact boards 🙄.
I wonder if that is the deluxe product meant for displays. It has a rather heavy facer and might be hard to work with. The FC we have here is simply for behind paintings and pictures when you frame them. $1.25 CAD
Hi Cal,
Unfortunately the only foam board that I've come across is the 'deluxe' type with the heavier smoother/plasticky facing 🙁
The only other option would be Depron, which is XPS foam used for RC model building.
Unfortunately the only foam board that I've come across is the 'deluxe' type with the heavier smoother/plasticky facing 🙁
The only other option would be Depron, which is XPS foam used for RC model building.
post1320 thanks for the answer xrk971. in order to achieve a 1" throat I will have to remove the first 2" of the spiral. this will enlarge the chamber and shorten the length of spiral. Do not think this will effect much but I am no pro. what do you think?
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No, you do not have to have a 1 inch throat - that was just my back of the envelope estimate of what the throat width is. As I recall, the full scale Cornu (27.6 in) has a throat of 1.2 in and scaled x 22/27.6=0.96 in. If you can get the driver to fit in the chamber then build it as is, no trimming of spiral needed.
The thicker faced paper can work just fine. I have used it and it just requires more pressure with a knife when scoring the lines for the bends. It makes a very sturdy baffle though - feels much more solid than the cheap dollar store stuff. Go for it! 🙂
xrk971 Maybe my blow up is off. I think i have the one done by planet10 due to the sqaure corners. throat measures 3/4" . what harm would it do to cut out some inner spiral
A couple of inches won't hurt but you don't need to worry about the throat gap - it is not critical. As long as your driver fits - which it should if you scaled it to 22 in wide.
The TC9FD's are on the way from Germany 😀
Now I just need to source a glue gun and get the foam board.
Out of interest how many glue sticks did it take you guys to build your spirals?
Now I just need to source a glue gun and get the foam board.
Out of interest how many glue sticks did it take you guys to build your spirals?
Toolstation do 100 sticks for £4.50.. a REALLY nice glue gun for £22 http://www.toolstation.com/shop/Professional+Glue+Gun/p29000
and a craft knife hobby kit for £11 🙂 51 pieces ..
http://www.toolstation.com/shop/Hobby+Knife+Set/p58235
.. I'm in Chelmsford .. Hobbycraft do 3 A1 sheets for £8 too..
They also do this glue gun http://www.toolstation.com/shop/Hot+Melt+Glue+Gun/p24076
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Thanks for the info, I've sourced a gun and glue courtesy of Amazon. Much as the tool station gun is nice I can't justify £22 on a tool for a budget build. Maybe if the foam core addiction kicks off I'll upgrade 😀
As I mentioned earlier the local art shop does ~A0 sheets of foam core for £6.50. So I'm going to source it there as I can pick and choose the sheets to get the best edges and it saves on delivery charges or a car journey to the nearest Hobbycraft.
I've also sourced a local printing company who can print out the 20" spiral templates for a few quid to save me having to stitch several print outs together.
Speaking of the templates, my next question is how was everyone transferring the design to their foam board? I think I saw it mentioned earlier in the thread that Cal was using a pin to put marks on the board from his template.
I was thinking of gluing the printed templates directly to the board and then working on top of them.
I just printet the scaled pdf in 1:1, tapet it in position and ran a knife along the spirals, this scored a easily traceable line on the surface 🙂
Thanks for the reply. You've given me an idea of using a serrated tracing wheel to transfer my spiral to the foam board.
An externally hosted image should be here but it was not working when we last tested it.
If you have some carbon paper, you will be golden. It's useful to have a seamstress around to borrow sewing tools eh? 🙂
The TC9FD's arrived today 😀
Got the templates printed and trimmed to size. The foam board is in the spare room. Just waiting impatiently for the glue gun and glue to arrive, it's taken Amazon 4 days to dispatch items that were in stock 🙁
Looking at the driver dimensions and the template, I was wondering do you need to remove some of the first part of the inner spirals to allow room for the driver?
Got the templates printed and trimmed to size. The foam board is in the spare room. Just waiting impatiently for the glue gun and glue to arrive, it's taken Amazon 4 days to dispatch items that were in stock 🙁
Looking at the driver dimensions and the template, I was wondering do you need to remove some of the first part of the inner spirals to allow room for the driver?
No, it should fit just fine in a 20 in Cornu with the stock plan scaled to size. If you find that it is tight, trimming a few cm's off the passage is not a big deal - you will lose bass extension proportional to distance reduced.
Ok, thanks for reply. Hopefully my scaling and printing have been accurate and everything fits 🙂
A quick question and apologies if it has been answered already but how do you hot glue the back board? The glue dries so quickly it seems impossible to cover one curve edge let alone all four are people using a different glue for the second side?