routeing of shelf on diy rack??

Ive got all the metal work for the tnt flexi rack and off to buy some mdf today.
Im probably going to get 20mm thick mdf.
ive read somewhere about people haveing spiral grooves routed in the underside of the shelf, what the advantage of this over damping material?

A chippy friend if going to drill the holes in the shelves for me and also shape the edges for visual niceness, just wondering if i should ask him to route the underside aswell.

haveing difficulty tracking down neoprene washers, any ideas?

if anyone is interested i got the steel work from woodbury chillcot bristol although i think they have depot's in different area's

3 x 1M cut to length stainless steel 20mm threaded bar
24 x 2mm thick 20mm i/d stainless washers
24 x 20mm stainless nuts

all for £32 includeing delivery

 

Intrigued, I had a look, and here it is:

http://www.clearlight-audio.com/Seiten/start_e.html

- photo at 10 o'clock.

On Hi-Fi Cables's website it's described as a "helical spiral" (which is garbage - helical = 3 dimensions, spiral = 2 dimensions), and it is stated to improve damping. Any type of groove cut in MDF would make it inherently more flexible, but I don't know why a spiral would operate any better than, say, concentric circular "bullseye" grooves. Or indeed why it would operate at all. But then, given my experiences with Mana, perhaps I'm not the person to comment.

 

thanks for the link

sounds possibly like a touch of snake oil then, maybe ill stick with some damping material

 

might be worth copying the qs ref racks and cut a large hole out of the middle of the shelf . just make sure your kit can straddle the hole .hope you can see the picci ok.

 

Ya I was thinking of doing this to the rack I'm designing, but then its a lot of extra hassle, probably best to line/spray it with damping stuff, sorted.

Ya I'm having problems with getting rubber washers too, I'm sure someone gave me a link on the old GH site but I've lost it. Failing that I think the Madhippy suggested cork.

I'd like to know if you find that 20mm thick rod is stable enough I was going to go for 28mm but if 20mm is fine then that saves me a few mm which would work better for me.

I'm going going to build anything yet was we may move house so I'm holding off till we get settled cos I'll have to measure up again.

 

tbh the 20mm in SS is well solid, i cant imagine much would make it distort

 

There are a few things you can do That i've mentioned in posts before, for instance floating another shelf over the fixed one [works very well for me]. The neoprene washers I could not find but if you go to a wet suite maker and get there off cuts [for free] you can make the washers. I opted for Nylon over sized washers to spread the load a bit as MDF is fairly soft.

If you router the edges this will help in wave dispersion. A self by Ruark the speaker maker from a few years back had a v notch cut in the edge of the shelf that was to act as a wave guide. I had mine rounded, both to remove the corners as you look from the top [appox 50mm radius] and the edges as you look from the sides. I also laqured the shelves with polyeurathane varnish [well local spray shop did] about 4 - 6 coats gives adeep mirror finish in a warm honey colour.

 

Although MDF seems to be the universally most used material for this type of job , i also think that 18-20mm Brazillian Ply is a nice strong material to make shelfs from. It is easy to work with and is really quite good from from a structural point of view as you have the various different layers in the composite itself , ie wood and glue/resin, this should help to break up or disperse any feedback waves. Also the wood is usually placed with opposing grain directions so this will aid stiffness. Just an idea. I used a 7 ply version of this material to quite good effect when i made my Turntable wall shelf for my LP12, it is easy to work with and if you can find a decent peice with a good grain structure it polishes up quite nicely too.

If you have SKY/Cable there is a program called 'New Yankee Workshop'. I can watch this program for hours at a time, Norm is a great master craftsman and uses Plywood (usually cherry) in his creations on a regular basis.

Just another idea/angle.

 

Norm is god :notworthy , I miss Sky and I hate DIY.

 

obviously you aint been in scotland long enough s+c :JPS: :duck: after all a 4 x 8 sheet of 3/4 mdf is olny a tenner in b+q

 

Hmm, OK i can see that Mr Hippy , but i suppose it depends how many shelves you are making. I think my Piece of Ply was about £7 and big enough for two full sized shelfs. I've now got a full polished one for normal use and a 'bog seat' for fine tuning the '12 from underneath. Although I won't be using that one for a while now.
All I'm really saying is, It's a great material and if you are popping into B&Q anyway you might as well look at all the options , they may have a special offer on or something.

 

I'm not going to disagree with you sid ....but

don'tyou really hate it when someone says that.

MDF has very consistant properties, is well damped and is easily worked. The ply may and I stress may be strong but it will have a springyness inherent in its construction, all those long fibers aligned in layers.

I can see the ply in a combination shelf with other compimentary materials, say like aluminium and/or perspex.