goskers

I have tried to do some searching here and on google with regards to HDF, it's properties and the best places to source it. I have come up with some interesting answers that need some clarification.

From what I have read, HDF also shares it's name with hardboard which was orignally developed by a gentleman named Masonite. Density of HDF has a broad varience just like MDF.

The MDF that I have always used usually has a lighter tan color. Hardboard/Masonite has always had a darker brown color and comes from either a cold or hot process depending on the double sided finish. Is the stuff called hardboard the same as HDF or am I missing the boat?

Thanks

JonMarsh

I'm not familiar with the specifics of the manufacturing process of the two. I used to use masonite at time in the past; it usually had a grid tecture on one side, smooth on the other, and was a rather dark brown color as you note.

Elsewhere on the forum has been posted material comparisons of typical MDF, HDF, ply. The HDF I'm using is light tan, smooth on both sides, denser and stronger than MDF, but not too different in weight. I'd guess differences in the glue binders.

I'm still pondering whether I should just junk the HDF approach to the Isiris baffle and bite the bullet for phenolic, which is like the X material that Wilson Audio uses. OTOH, I wanted the project to be somewhat realizable by others without "Xtreme" measures.

__________________
the AudioWorx
_______________________________

Modula MT
M8ta
Modula Neo D CC
Ardent
Modula MT XE
Modula Xtreme


still coming in 2010....

Ardent Cxi (updated design, new woofers)
Ardent CCX (Compact Center Xtreme)

mmoeller

What type of phenolic? I've seen some very different types w/ all types of materials;
paper, cotton weave, and more.

JonW

Yeah, whenever you mention HDF, I've wondered what it might be. Around these parts (midwest) you can buy panels of what's called "hard board" (or maybe it's "hardboard"). It's much like Masonite but smooth on both sides. Typically 1/8" thick I think. Very cheap. I used it to mount my crossovers. The best way I would describe it is 'peg board without all the holes.' Maybe that's the same thing as HDF?

---k---

http://www.keidel.com/design/select...atl-eng.htm#HDF

I think there are two differnt things out there being called HDF. One is a super duty MDF, and the other is like Masonite.

__________________
-Ryan
The Sietecerocero Project! ND140/BC25SC06 MTM & TM
My CJD Khanspires - A Dayton RS28/RS150/RS225 WMTMW
My CJD Khancenter - A Dayton RS28/RS150/RS180 WTMW Center
My CJD In-Khan-Neatos - A Dayton RS180/RS150/RS28 In/On Wall MTW

goskers

This would confirm the different process types which would produce a one vs two side smoothness.

Phenolics would be great but I am sure it would be more difficult for everyone to get their hands on. Since the driver cost alone would be quite steep I am not sure that the Isiris is going to be a low cost project to begin with. What's another couple hundred when you just dropped 2k in drivers!!

jdybnis

My biggest grief with corian (other than the price) is the appearance. I don't like the glassy plastic look. There are some other materials that look better and might do the job as well.

http://www.ecodesignresources.com/e...ountertops.html
http://www.ecodesignresources.com/e...rison_Chart.pdf

This place is the bay area sells a bunch of alternative counter-top materials. My favorites are the ones made by Paperstone and Squak Mountain that look like slate. The pdf link has a comparison chart.

__________________
-Josh

bob barkto

Processing and density are the keys.

The processes...

Wet process panels are a mixture of expanded wood fibers and water. The slurry is pressed under high heat and pressure to bind the fibers using the lignin in the fibers as the "glue".
A clue to a wet process board is the screened appearance on one side. But it is not a reliable indicator as some wet process panels are available smooth on both sides.
Wet process panels have very low moisture resistance and are prone to splits resembling delamination.

Dry process panels are expanded wood fibers mixed with synthetic resins/glues and pressed under heat and pressure. These are superior to the wet process panels in several key characteristics. The fibers bind in a more 3 dimensional matrix and when combined with the superior qualities of the resin binders yields an inherently stronger panel. The resins also increase moisture resistance substantialy compared to wet process panels.

The names...

Hardboard is the densest/heaviest of these types of panels. It is the only panel comonly made using the wet process, but can be made using dry process methods. 70-80+ lbscuft. Usualy only available in thin sheets, 1/4" or less.

Tempered hardboard is hardboard that is treated with various resind/oils to improve performance in certain applications. Typicaly it provides a panel that needs no further finishing and increases moisture resistance.

Masonite is the trade name for hardboard manufactured by the Masonite corporation. The originator of hardboard.

HDF is next with a density of 60-70+ lbscuft. Normaly sold in thin panels like hardboard but occasionaly available in 1/2"-5/8" for special applications. A dry process panel.

MDF and lighter panels range from 60 lbscuft at the heavy end down to 40 or so for the super light panels. MDF and relatives are dry processed.

Color is not a reliable indicator for ordinary hardboard, HDF or MDF.
Some HDF is dark, some light. Same for MDF.
Although, hardboard and HDF are most commonly found as a light tan color.

MDF varies most in color from light tan to as dark as tempered hardboard.

Weight and process are the only true indicators used to distinguish these products. Manufacturers are free to call a panel anything they want but the above are industry accepted standards.

Hope this is helpful.

goskers

Thanks so much for the information and clarification Bob.

So it would seem that the hardboard would be what we would want to source for lamenating purposes.

BrianJD

Lots of sources for phenolic, but not sure what grade is needed?

Also look for toilet partitions (solid phenolic) at surplus building supply and
local nonprofit building material recyclers.

acculam.com
usplastics.com
k-mac-plastics.net
portplastics.com
phenolic-sheets-rods-tubes.com
sdplastics.com
calsakplastics.com
professionalplastics.com
modernplastics.com
plasticdistribution.net

ThomasW

Probably slightly more than just a "couple hundred" for the sheets of Phenolic needed for this design.

Also machining phenolic is nasty, nasty business.

__________________

IB subwoofer FAQ page

ThomasW: curmudgeon in training, putting the no in innovation

BrianJD

Well, yes for new but no for recycled.
As I said above, you can find large sheets of phenolic at surplus building supply outlets and recyclers. My brother has 4 sheets in his garage that cost $50 each, 3/4" thick; approx. 5.5' x 5' , solid black color, no laminate.

We used some of it to make a copy of my JessEm router table top, which is phenolic. Then used my Bridgeport for the lift plate opening. It machined up quite nicely.
The same thing can be done with a router, just make sure to use a spiral carbide bit not straight sided ones. You could also use bits made for plastics, but its not really necessary. The nasty part of machining phenolics are the fumes.

ThomasW

That and the 'saw-dust' is what I was referring to..

__________________

IB subwoofer FAQ page

ThomasW: curmudgeon in training, putting the no in innovation

jquin

FYI

This is some more HDF info.
I am still trying to decide if the masonite with the checker one side will be OK for the M8ta.


http://www.panel.com/pdffiles/whati...e7a765e57e2803c

JoshK

Anyone considered the bamboo ply? It should be quite stiff, but what is it resonant character?

mmoeller

Yes... It tastes great by has very little nutritional value.

noah katz

Originally Posted by JonMarsh
I'm still pondering whether I should just junk the HDF approach to the Isiris baffle and bite the bullet for phenolic, which is like the X material that Wilson Audio uses. OTOH, I wanted the project to be somewhat realizable by others without "Xtreme" measures.

Cheap but labor intensive, but one could bond three 1/4" hardboard panels into 3/4" panels, then bonding two of those together with Green Glue to get a heavy, stiff, well-damped baffle.

__________________
------------------------------
Noah

kvardas

There is a manufacturer that makes a material that is essentially a fiber/phenolic board. I forgot the name company though.

JohnL

I think you're speaking of Garolite

kvardas

speedle

At $250 bucks a case, I wonder how much Green Glue that would take? Not much, I would venture, if you could buy it in less than case quantities.

noah katz

I bought some by the tube, $14 ea IIRC, and no, it wouldn't take a lot.

__________________
------------------------------
Noah