# Metal or MDF speaker rings for doors?



## ErinH (Feb 14, 2007)

There's a machine shop downstairs and I've considered asking the machinist (who's a super nice guy) if he would mind cutting me some speaker rings for my doors when he gets some time.

Takes on metal material vs. MDF for rings?

Looking to go thin and thinking that thin metal is better than thin MDF. Probably 1/4 or 1/2" at most.


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## dogstar (Jan 31, 2007)

Plastic cutting boards FTW.

Metal could work, but if it isn't perfect it's difficult for most people to correct. Plus it would rust if not properly sealed.

You could go aluminum and have some REALLY nice, incredibly overbuilt but still light weight rings. 
No rust, although it does oxidize like a some beach.
Plus with some patience and a file any small problems could be touched up.

If you do go with metal of any kind, make sure and use lots of foam to insulate it from the door.


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## ErinH (Feb 14, 2007)

We have some aluminum out here...

I was actually about to ask about "Great Stuff" foam spray to seal up the door.


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## Thumper26 (Sep 23, 2005)

x2 on the cutting board. It's what I'm using in my next install.


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## ErinH (Feb 14, 2007)

wth is a cutting board?


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## MidnightCE (Mar 5, 2007)

bikinpunk said:


> wth is a cutting board?


its for kitchens, you cut **** on it so you dont **** up your countertops.


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## ErinH (Feb 14, 2007)

MidnightCE said:


> its for kitchens, you cut **** on it so you dont **** up your countertops.


lol. Thanks for putting that so elegantly.  

I got it now...I was thinking a cutting board was some special machine. lol


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## Weightless (May 5, 2005)

It's usually a white material. Go to bed bath and beyond and you can buy some there...even though there are cheaper places.


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## dogstar (Jan 31, 2007)

It's high density plastic, usually anywhere from 1/8" to 1" thick.

Walmart usually has em pretty cheap.


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## ErinH (Feb 14, 2007)

What did you use to cut the ring with? A regular router bit?


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## syzygy9 (Jun 28, 2007)

typically cutting boards are polyethylene and that should work fine

you can use a regular router bit, but it needs to be sharp to make a clean cut because PE is kind of "gummy" (that's the best word that comes to mind).


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## ///Audience (Jan 31, 2007)

im liking this cutting board ideas but what are the pros/cons to regular MDF? weight?


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## ErinH (Feb 14, 2007)

You wouldn't have to worry about the elements.


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## fastev (May 28, 2007)

You can have your machinist friend cut you some nice plastic ones...

HDPE works well, and it can be cut to any shape you want on a mill.

*edit* This would probably be plenty for a few rings.


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## dogstar (Jan 31, 2007)

I cut it with a jigsaw.

Benefits = many.
It holds screws better.
Waterproof.
Stiffer than MDF on thin rings.
Comes in pretty colors.


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## ErinH (Feb 14, 2007)

I just might give that a go.

Sure it's about the same price as a small sheet of MDF.


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## Thumper26 (Sep 23, 2005)

that website is nifty, but look aroudn walmart, target, kmart, etc. you might even find something at a dollar store, which would be the jackpot.


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## khail19 (Oct 27, 2006)

I bought some scrap HDPE at a local plastic store in 0.5" and 0.75" thicknesses. I've used it for baffles in my car and my wife's as well. The stuff works great, and moisture has no effect on it at all. I just used a jigsaw with a medium tooth blade to cut it.


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## Rudeboy (Oct 16, 2005)

All that is well and good and what I will use next time, but I have seen some high end/competitor/fanatic types use machined steel and brass.


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## Thumper26 (Sep 23, 2005)

Rudeboy said:


> All that is well and good and what I will use next time, but I have seen some high end/competitor/fanatic types use machined steel and brass.


lol, yeah when i have JL/Alpine/Kenwood/Eclipse/Zapco, etc paying for the install, i'll have platinum plated speaker grills.


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## JayBee (Oct 6, 2006)

i've never thought of using plastic cutting board before but i like the idea.


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## Robert_R (Jun 18, 2007)

Totally love the cutting board idea........my wife is going to kill me know when she realizes the cutting boards are missing from the kitchen.


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## khail19 (Oct 27, 2006)

[email protected] said:


> Totally love the cutting board idea........my wife is going to kill me know when she realizes the cutting boards are missing from the kitchen.


My wife came in the garage one day and saw a cutting board with 2 holes cut out of it and started freaking out. I had already bought a new one and put it in the kitchen, but I let her steam for a while before I told her.


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## Robert_R (Jun 18, 2007)

khail19 said:


> My wife came in the garage one day and saw a cutting board with 2 holes cut out of it and started freaking out. I had already bought a new one and put it in the kitchen, but I let her steam for a while before I told her.


Love it!!! Totally going to do that. Love getting the Wife all pissed.


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## Rudeboy (Oct 16, 2005)

[email protected] said:


> Love it!!! Totally going to do that. Love getting the Wife all pissed.


At least we'll know what happened when you stop posting to this board


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## azngotskills (Feb 24, 2006)

What about the affect of heat on the plastics? No warping? I live in Texas and thats a big concern.


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## invecs (Jul 30, 2005)

I'm using plexiglass spacer for my brother's car...it works great. Should have thought about the cutting board.


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## DonovanM (Nov 1, 2006)

azngotskills said:


> What about the affect of heat on the plastics? No warping? I live in Texas and thats a big concern.


They won't be exposed to direct sunlight, I highly doubt it.


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## azngotskills (Feb 24, 2006)

DonovanM said:


> They won't be exposed to direct sunlight, I highly doubt it.


It doesnt matter because heat will still get to the plastics. Im wonder how the heat will affect the plastics though.


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## Rudeboy (Oct 16, 2005)

azngotskills said:


> It doesnt matter because heat will still get to the plastics. Im wonder how the heat will affect the plastics though.


Pretty sure these things are meant to go through a dishwasher. That should be somewhere in the range of maximum heat inside a door.

Yup, faste's link says dishwasher safe.


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## azngotskills (Feb 24, 2006)

OK then...i guess cutting board might be a go for the new install  FWIW this has been mentioned long ago by B-squad in his build thread IIRC


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## drocpsu (May 3, 2005)

wow, where do you guys find .75" thick plastic cutting boards? I feel like all the ones I've ever seen were like .25 thick.


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## theothermike (Dec 20, 2006)

i believe the material is delrin...


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## Thumper26 (Sep 23, 2005)

theothermike said:


> i believe the material is delrin...


that's what my guitar pics are made of.

i think it's slightly different.


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## khail19 (Oct 27, 2006)

drocpsu said:


> wow, where do you guys find .75" thick plastic cutting boards? I feel like all the ones I've ever seen were like .25 thick.


I've never seen a cutting board that thick. You could either make multiple rings and stack them, or find a plastic shop that sells HDPE (high density polyethylene) in various thicknesses. I got a scrap piece of 3/4" that was big enough for 3-4 spacers for about $10.


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## khail19 (Oct 27, 2006)

theothermike said:


> i believe the material is delrin...


From what I understand, Delrin is much harder and denser than HDPE. It would be more difficult to cut and shape, I've read that it machines much like softer metals. I've seen Delrin used a lot for automotive suspension bushings, and even shift knobs.


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## azngotskills (Feb 24, 2006)

fastev said:


> *edit* This would probably be plenty for a few rings.


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## xcoldricex (Apr 28, 2007)

these videos may help people when using plastics!

http://www.diymobileaudio.com/forum/showthread.php?t=17941


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## dogstar (Jan 31, 2007)

azngotskills said:


> OK then...i guess cutting board might be a go for the new install  FWIW this has been mentioned long ago by B-squad in his build thread IIRC


I was going to give credit, but damned if I could remember who suggested it. 

Delrin would work, but it can crack easily when cutting.

Heat won't bother a cutting board, most of them are stable well over the boiling point of water.


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## Abmolech (Nov 2, 2006)

> All that is well and good and what I will use next time, but I have seen some high end/competitor/fanatic types use machined steel and brass.


Hoped they used "bell" bronze 

Seriously guys plastic is fine, but cutting boards are not thick enough to stop warping (the door etc is not flat)
I would suggest something in the region of 30 mm plus thick.


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## ThisWasAndy (Nov 10, 2006)

Anyone have any pics of cutting boards used as baffles?


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## Ge0 (Jul 23, 2007)

khail19 said:


> From what I understand, Delrin is much harder and denser than HDPE. It would be more difficult to cut and shape, I've read that it machines much like softer metals. I've seen Delrin used a lot for automotive suspension bushings, and even shift knobs.


Have a lot of fixtures mae to hold electronic assemblies in my occupation. 9 times out of 10 they are machined out of Delrin. I doubt this would be a fabricators 1st choice if it was that difficult to work with.

Ge0


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## khail19 (Oct 27, 2006)

Ge0 said:


> Have a lot of fixtures mae to hold electronic assemblies in my occupation. 9 times out of 10 they are machined out of Delrin. I doubt this would be a fabricators 1st choice if it was that difficult to work with.
> 
> Ge0


I think Delrin is easily machinable, especially with proper lathes and cutters and such. It seems that if you only had a jigsaw though, HDPE would be easier to work with. I've never tried cutting Delrin myself, so I could be wrong. I just think that something commonly used to replace metal components would be harder to cut than something that scores easily with even a dull kitchen knife.


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## azngotskills (Feb 24, 2006)

ThisWasAndy said:


> Anyone have any pics of cutting boards used as baffles?


http://www.diymobileaudio.com/forum/showpost.php?p=60325&postcount=13


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## fastev (May 28, 2007)

The problem with delrin is that it can swell. I've made some paintball gun parts from it and it works great as it is light and strong, but get a little oil on it and you have another story. I've machined some delrin parts at work as well, and have run into the same problem. I switched to HDPE and been fine since. That link I posted a few pages back has thicknesses up to an inch, so it shouldn't be a problem to make any size ring you'd need. It will cut with a router too, just be sure to take small cuts as it will get hot in a hurry. 

Tap sells all kinds of plastics, HDPE is in my opinion the best material for non-wood rings. (aside from metal if you want to go that route) I've bought nearly all my fiberglassing materials from them as well, good prices, and great products. They have sheet carbon fiber and carbon fiber cloth too if you have a really crazy project in mind...


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## khail19 (Oct 27, 2006)

fastev said:


> The problem with delrin is that it can swell. I've made some paintball gun parts from it and it works great as it is light and strong, but get a little oil on it and you have another story. I've machined some delrin parts at work as well, and have run into the same problem.


It's funny you mention swelling, because the Wiki article I was just reading says that Delrin is used in many paintball markers because it is very resistant to swelling.  



Wikipedia.com said:


> It is also used extensively in paintball markers, where it is used to make bolts, pump handles and many other parts. Its low cost, adequate strength, light weight and self lubricating properties make it ideal for markers. The other material commonly used for markers, Nylatron, while slightly lighter, is more prone to swelling. A swelled part can make the mechanism impossible to operate and sometimes even damages the marker. Nylon-based products such as Nylatron have better wear-resistance than Delrin, but do not have good moisture-resistance, and are therefore not suitable to high-humidity or underwater applications.
> 
> Delrin's resistance to liquids and low coefficient of friction have also made it useful as a bearing-replacement in casters and wheels, to be selected in cases where corrosive environments make a traditional roller or ball bearing impractical.


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## FoxPro5 (Feb 14, 2006)

HDPE is cheap, easy to work with and easy to find. Pretty colors and left over garlic flavor is an added bonus. 

I've also used PP plastic which is just as dense and rigid. On my current baffles, I went door panel-->1/2" PP-->3/4" MDF soaked in resin and double coated in Spectrum--> 3/8" HDPE-->driver. Just a pic of the overal construction. The white stuff is a bondo-glass milkshake I made to back fill the gap. What's not pictured is 1 lb of non-hardening modeling clay used on the inside and outside of the plastic parts of the baffle. 

My actuall baffle right now is a little different then in the pic because I've since removed an MDF layer an put HDPE on the mounting surface instead. I have 18w Scan's on them exactly as you see in the pic and I get very little, if any resonance in my doors. You can't argue with resuts.









Best tip I ever got in baffle building was from thadman. The kid's a genius, I say...just read his posts. He mentioned the best way to mantain rigidity, yet prevent mechanical energy from the driver to the door was to use different materials at varying thicknesses in the baffle construction and NOT to use screws, but 3M bonding tape to hold it all together. Makes sense to me since the energy will be transmitted right though the screw to the door where you DON'T want it to go.

Now if I could just find some lead sheeting, I'd certainly throw that in the sandwich as well. Dream on.......


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## Abmolech (Nov 2, 2006)

Decoupling is a good idea, as you gain less panel resonance.
Downside?
That is precious energy lost in the form of heat.
(A driver is less than 5 % efficient, so any extra loss is painful indeed)
Ideally driver should have a rigid mount, preferably the motor magnet, with a decoupled basket mount.
(not for the faint hearted)


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## dogstar (Jan 31, 2007)

You can find it... just gotta bite the bullet on price


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## FoxPro5 (Feb 14, 2006)

dogstar said:


> You can find it... just gotta bite the bullet on price


Right, a nice heavy lead bullet right in the ass!  Pb prices went up 58% this year. If you know something I don't, please share.


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## dogstar (Jan 31, 2007)

Its only money 

My local guys must have missed the memo... 
I hadn't bought much lead for years, but had to pick some up a few weeks ago and it was $0.64/lb.
Don't think it was much cheaper than that last time I bought any, it was definitely over $0.50.

Try to find some wheel weights and melt them down, then pour into a cookie sheet to make your own lead sheeting.
Theres a lot of crap in wheel weights... probably wouldn't be my first or even second choice, but they're cheap in the junkyard.


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## HawaiianBassHead (Sep 18, 2007)

I have dive weights, they're cheap, I was gonna suggest melting them, my dad melts weights for fishing, or at least he used to, he still has the melting pot, it's just a cast iron bowl with a propane torch/cook top under it, doesn't take long at all and he melts ALOT more than you'd need to make sheets... BIG DOWNSIDE, you CANNOT breathe that ****, I think being around him melting that **** as a kid (for his own hobby purposes so not even alot) are partially to blame for my bad lungs  ... but I also used to smoke loads of pot back in high school lmao.. but yeah, diving and fishing weights are cheap, a propane torch and a cast iron pot from a friggen salvation army or something would work... I've seen the white plastic cutting board rings for speakers on ebay before a while back never really considered making them though too lazy, but thrift stores have cutting boards to guys  it's kinda like recycling, you may even get lucky and find like an old trumpet down there to use as a horn :lol: diving weights go cheap on ebay and thrift shops to ftw 

I happen to have 10 pounds of lead weight just sitting and this is just what's right here LOL


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## Luke352 (Jul 24, 2006)

I have just under 1/4 thick aluminium for my door baffles and it work well, it's attached to my inner door panel which is actually a composite plastic with aircraft fuel tank sealant.


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## havok20222 (Sep 5, 2007)

Cutting board is basically the same stuff as Marine Board...or pretty close. Same stuff they use for cabinets and such in a lot of newer boats.

http://www.sdplastics.com/marine_board.html
http://www.deltainsulation.com/PDF/LITi_DMB_03.pdf


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## Genxx (Mar 18, 2007)

HPDE is being used by many of the top installers now. Thats where I found out about it 8 months ago. I thought everyone new about this already. Tapplastics which someone already linked is one place just search HDPE and you will find a bunch of places to order it.

Here are a few other links of places I have looked.
http://www.professionalplastics.com
http://k-mac-plastics.com/hdpe-sheet.htm

As far as heat goes all of the installers I have talk to using the stuff in some high end expensive ass installs are having no issues with them warping. The thinnest anyone has told me they used is 3/4 and if you want to get real crazy use 1". This stuff is not cheap though if buying new sheets. This is what will be used in all my vehicles no more wood baffles for me.


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## OldOneEye (Jun 16, 2005)

dogstar said:


> Plastic cutting boards FTW.
> You could go aluminum and have some REALLY nice, incredibly overbuilt but still light weight rings.
> No rust, although it does oxidize like a some beach.
> Plus with some patience and a file any small problems could be touched up.


Bare aluminum oxidizes pretty easily. On the other hand, once oxidized, that layer is pretty impenetrable (aluminum oxide). It isn't like Iron oxidizing to rust. The aluminum oxide creates a pretty strong barrier that prevents any further oxidation.

If worried about it, prep and prime it and your done. 

As mentioned by GEO, Delrin is popular. In some cases they might make something in Delrin first because its cheap, and easy on equipment before making the real part out of billet or whatever else. Worked as a fabricators assistant a long time ago in a plastic shop so I got to see some stuff when I went to go make pickups for supplies. An additional property of Delrin is that is slippery. Not that you would need that in a door, but you could get away with a few pieces when you motorized instead of a regular drawer slider.

Juan


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## Babs (Jul 6, 2007)

So why not just seal plain old MDF really well (by some means, resin, paint, other) so it's protected from moisture?


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## syzygy9 (Jun 28, 2007)

i'm not sure how the subject of Delrin made it's way into this thread, but let me say that almost every statement i've read in this thread about Delrin is false.

In a previous career as a mech. eng. in product design i designed a lot of parts from Delrin and also machined many of the prototypes on a CNC mill.

Delrin machine great, but it can stress relieve itself and warp if proper care is not taken to not remove too much material from one side too quickly. It does not swell....it is specifically used in industries where it will contact gasoline or propane or various oils because of this trait. It is extremely tough and does not crack. One interesting thing is that nothing sticks to it...there is no solvent that can effectively bond it and no tape or glue that can truly stick to it with much sucess. Also, it's really expensive compared to HDPE or even ABS.


I'm sure nobody really cares about all this, but i feel better now


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## Rudeboy (Oct 16, 2005)

Babs said:


> So why not just seal plain old MDF really well (by some means, resin, paint, other) so it's protected from moisture?


That's probably the most common approach. The problem is that it gets a little complicated when you have to seal bolt holes and the like. Nothing can breach the waterproofing or the MDF will swell.


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## dogstar (Jan 31, 2007)

Babs said:


> So why not just seal plain old MDF really well (by some means, resin, paint, other) so it's protected from moisture?


Moreover, WHY use MDF?

Firstly, while cutting it you are going to get sawdust all over, then messing around with paint and sealant, letting it cure, retouching spots you missed...
Then when you decide to remove/replace the speakers and accidentally strip a screw hole you get to remove the baffle, drill new holes, seal them and reinstall.

Get cutting board, trace pattern, cut and mount. Done.


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## chuyler1 (Apr 10, 2006)

What do you guys use to properly seal the cutting board? MDF has a flat surface and creates a very good seal with the driver without using any fillers. Most cutting boards have a rough surface to them so I would expect you'd have to use a layer of something to produce a proper seal.


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## khail19 (Oct 27, 2006)

chuyler1 said:


> What do you guys use to properly seal the cutting board? MDF has a flat surface and creates a very good seal with the driver without using any fillers. Most cutting boards have a rough surface to them so I would expect you'd have to use a layer of something to produce a proper seal.


HPDE is naturally very smooth if you buy it from a plastic store. The cutting boards are textured so they don't slide around easily. I just used some foam gasketing tape to seal the speaker, and both foam tape and clay to seal the spacer to the door.


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## Jack Watts (Sep 26, 2007)

I'm sure that HDPE will work well--and it's certainly more water resistant than MDF. Still, if you try to shape it with a router, there's a good bit of tear-out, and most cutting boards are pretty thin (1/2" or less). Plus, the screw holes will probably have tear-out as well.

I'd suggest looking for some Corian scraps from your local architectural salvage place (Restore or the like in the Pac NW). It has all of the properties for a baffle: doesn't warp, heat resistant, dense, machines easily, and cheap! You can get scraps of this stuff for free or almost free, and it machines better than MDF, no warping, no worry about heat, comes in cool colors, etc. Plus, when you drill for the screw hole, the ID will actually match that of your drill bit! I made some temporary MDF baffles, but they're soon to be replaced with these. MDF baffles in Seattle seems like a really bad idea.

One word of warning: you won't be cutting this stuff with a jig saw.

For you North Carolina folks, there's a lifetime supply of free speaker baffles right here!: http://raleigh.craigslist.org/zip/434163893.html


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## GlasSman (Nov 14, 2006)

dogstar said:


> Moreover, WHY use MDF?
> 
> Firstly, while cutting it you are going to get sawdust all over, then messing around with paint and sealant, letting it cure, retouching spots you missed...
> Then when you decide to remove/replace the speakers and accidentally strip a screw hole you get to remove the baffle, drill new holes, seal them and reinstall.
> ...


I agree with you 100%. And I sell a ton of MDF rings. But it's whats expected by the majority. 

HDPE is a MUCH better material.

Outlet stores like TJ MAx and stores like Christmas tree Shop has cutting boards for a fair peice.


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## FoxPro5 (Feb 14, 2006)

Try Ikea for your smaller drivers, they're like one whole dollar for the baby ones. 

The 3/8" one I found was at Kohls IIRC. You know it's going to be on sale if it's at Kohls.


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## OldOneEye (Jun 16, 2005)

One of the reason I would use plastic is sort of different than others. When they made the car, outside of the spare tire well, and maybe some cosmetic dash trim, not too much wood in there. Why? Lots of plastic, vinyl, and metal, but no wood.

So I'd rather not use it if possilbe.

Juan


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## fastev (May 28, 2007)

syzygy9 said:


> Delrin... does not swell....it is specifically used in industries where it will contact gasoline or propane or various oils because of this trait.


Interesting to note, perhaps the material I had was Nylatrol and not Delrin; it swelled up a few thousandths when it came in contact with some air tool oil; just enough that it would no longer work where I needed it...


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## Rudeboy (Oct 16, 2005)

syzygy9 said:


> ... I'm sure nobody really cares about all this, but i feel better now


You must be lost and thinking you are on a different board if you think there is a detail too small for us not just to care about, but to debate for weeks to come


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## Fixtion (Aug 25, 2006)

I have access to a laser cutter.  It can cut plastics. Uses acad drawings for measurements. Who wants to sign up. 

-Fixtion


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## dogstar (Jan 31, 2007)

Been there, done that. 
3 years on Mazak 1500 watt and 2500 watt 6 axis machines.

You don't want to cut hdpe with a laser, lol.  It makes a MESS. Plexi is bad enough.
And yes, plexi would work, but it's rather pricy when you get into 3/4".

A laser does nice work, but total overkill for plastic speaker rings... although it'd be perfect for some aluminum rings.


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## birdie2000 (Jan 27, 2007)

Fixtion said:


> I have access to a laser cutter.  It can cut plastics. Uses acad drawings for measurements. Who wants to sign up.
> 
> -Fixtion


Damn, that's awesome! Oddly enough I even drew up a concept adapter ring in AutoCAD so I could print out paper templates for test fitting. If you're serious about that I may take you up on your offer one day.


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## Ge0 (Jul 23, 2007)

OldOneEye said:


> Bare aluminum oxidizes pretty easily. On the other hand, once oxidized, that layer is pretty impenetrable (aluminum oxide). It isn't like Iron oxidizing to rust. The aluminum oxide creates a pretty strong barrier that prevents any further oxidation.
> 
> If worried about it, prep and prime it and your done.
> 
> ...


Nice to see you again Juan. I remember you from almost 10 years ago on rec.audio.car

The only reason I mentioned Delrin is becuase I have 1st hand experience saying it is easliy machinable. It is somewhat resistant to heat. I do know it does not like 250C. I warped a test fixture made of Delrin in an environmental chamber the other day . However, The cabin of a vehilce (where the door is located) rarely exceeds 80C even in the warmest climates. Delrin can survive this no problem.

Ge0

Ge0


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## ErinH (Feb 14, 2007)

Revival.


I went downstairs and asked our machinist about cutting plastic. After a few minutes of explaining what I'm wanting to do he said he has 1/2" & 1/4" plexi that I could use. Just get him the OD & ID and hole pattern and he'll make 'em for me sometime this week.

So, my question. I'm having fit issues with the way things are right now (1/2" mdf). Is 1/4" that much weaker than 1/2"? The only issue I'm worried about is cracking. 

Takes?


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## caohyde (Sep 27, 2005)

bikinpunk said:


> Revival.
> 
> So, my question. I'm having fit issues with the way things are right now (1/2" mdf). Is 1/4" that much weaker than 1/2"? The only issue I'm worried about is cracking.
> 
> Takes?


i envy you for having access to a machine shop with a machinist. all the things that you can do with a lathe and probably some other things. 

about the question, yeah, 1/4" plexi is a bit too brittle. especially if you're at the point of tightening things up (screwing the plexiglass to metal and speaker to plexiglass.


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## caohyde (Sep 27, 2005)

btw, i used plastic chopping boards for my friend's car, it worked great.


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## birdie2000 (Jan 27, 2007)

I would think 1/4" would crack or warp as well, but I'm no expert.

Especially since you'd have to make sure the screw/bolt heads are sunk into the plexi when securing to the door so the driver can sit flush and seal properly. I know this was the problem with using cutting boards in my truck. I countersunk the holes enough to allow the bolt head to be flush with the surface and the weak point in the ring from this caused the ring to warp when fastened to the door.


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## 02bluesuperroo (Oct 31, 2006)

Bought my HDPE from ebay. 3/4" thick and about 18 x 24 for $22 shipped. Worked great.

Post #40
http://www.diymobileaudio.com/forum/showthread.php?t=19513

This stuff was great to cut although it made a mess. When you screw into it you can take the screws in and out over and over and the threads stay nice. This is far superior to wood and isn't much more expensive and is just as easy to work with.


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## ErinH (Feb 14, 2007)

02bluesuperroo said:


> This stuff was great to cut although it made a mess. When you screw into it you can take the screws in and out over and over and the threads stay nice. This is far superior to wood and isn't much more expensive and is just as easy to work with.


So, how did you cut it? Router or jigsaw? 

I was worried a router would melt the material which is what got me started asking our machinist. 

I wish he was into car audio. It would be much simpler to explain what I want done. But, he's there nonetheless.


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## ///Audience (Jan 31, 2007)

My cutting boards just got routed out for my Seas yesterday! two 1/2" cutting boards for a buck at wall mart.. and they had neon green! Enough room on em for an 8" outter diameter and some rings for my large formats.


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## ErinH (Feb 14, 2007)

Do you guys have variable speed routers, or does this stuff not melt as you cut it?

Last time I tried to cut plexi I had to go slow; with my router I have no ability to change speeds so I'm stuck with "HELLA FAST".


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## birdie2000 (Jan 27, 2007)

I used my router with an up-cut spiral bit on it. Made a mess, but IMO less so than MDF and it's much easier to clean up because it's large pieces of plastic instead of a very fine dust. It didn't melt the piece I was cutting at all, however the shavings were warm and somewhat melted.

Frankly it worked really nice, I'm definitely doing it in the future.

I have a variable speed, but I seem to remember having it on a faster setting. If I remember correctly I think it worked better (cleaner cuts) the faster you went, both with the blade and the speed you're turning the piece/router.


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## ErinH (Feb 14, 2007)

Good to know.

I was about to go ask the machinist to cut them for me right now; but I've still got to figure out what shape I want the outer part in. I think I'm going to _not_ have a perfect circle this time.


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## FoxPro5 (Feb 14, 2006)

I just have a cheap Craftsman one speed jigsaw and a generic blade for cutting wood (I think.) The teeth on the blade are more rough/rugged then they are fine. I just hold the thing wide open and blasted right through it. The blade effectively "chips" the plastic at high speed. It worked great for me...no melting. The downside is that plastic goes everywhere!

I've tried my Dremel on plastic (HDPE, PP, PC) and at the highest RPM it will melt it very easily. But I suppose it depends on the nature and tolerance of the exact plastic you're using.


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## ErinH (Feb 14, 2007)

Thanks.

Hey...got a question for you (b-squad). Where did you purchase your scan 12m's (4.5 revs)? I'm looking into those but didn't see them on madisound.


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## syzygy9 (Jun 28, 2007)

I would not use Plexi if you're mounting to an irregular (i.e. not perfectly flat) surface as it will crack easily. Plexiglass is touted as being flexible, but that's only in comparison to it chief rival for most apps...real glass.

Here's a site that carries HDPE in sheets....it's approx. $18 for a 12"x12"x3/4". http://www.mcmaster.com

Just type HDPE or UHMW in the search box. This isn't the cheapest place, but it's quick, simple, and informative. For comparison, an equivalent size piece of ABS at this site is $33 and Delrin is $52.

Your machininst should be able to do the same thing with HDPE/UHMW that he can do with Plexi, but he will want to use a new/very sharp tool to make a clean cut. I'm lazy and will probably make mine out of ABS or Delrin because I can mill them nice and clean without having to fuss with the parts afterwards and there is a plastics supply place a couple miles from my office that offers much cheaper pricing.


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## s10scooter (Feb 5, 2007)

I tried the cutting board to make a ring to have something sturdy to mount my tweeter to. (I have the cal27, so I have to drill into something)....

I think it worked out very well.

I cut out the ring, expoxied the ring to the door panel and used a machine screw and nut to fasten the tweeter to the door panel. Nice and strong, I'd say....plus it glues to plastic okay.


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## OldOneEye (Jun 16, 2005)

syzygy9 said:


> I would not use Plexi if you're mounting to an irregular (i.e. not perfectly flat) surface as it will crack easily. Plexiglass is touted as being flexible, but that's only in comparison to it chief rival for most apps...real glass.


Yup. Plexi is quite fragile. Lexan on the other hand is way more flexible. It absorbs energy from a bullet and spreads it out (so it resonates instead of breaking). Bad for baffles though if you think about it. 

Juan


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## birdie2000 (Jan 27, 2007)

That's the one thing about HDPE, nothing really sticks to it. You can make a bond, but it'll come apart pretty easily. 3M makes some crazy expensive stuff that can bond it, but it's hardly worth it.


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## s10scooter (Feb 5, 2007)

birdie2000 said:


> That's the one thing about HDPE, nothing really sticks to it. You can make a bond, but it'll come apart pretty easily. 3M makes some crazy expensive stuff that can bond it, but it's hardly worth it.


That epoxy seemed to stick to it pretty well. If it doesn't the nut behind it will keep it secure...interesting nonetheless.


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## FoxPro5 (Feb 14, 2006)

bikinpunk said:


> Thanks.
> 
> Hey...got a question for you (b-squad). Where did you purchase your scan 12m's (4.5 revs)? I'm looking into those but didn't see them on madisound.


Bought them used from a forum member.

http://www.madisound.com/catalog/pr...d=917&osCsid=7691a13deaadae7937f98a0941e22740

Dylan at Timber Audio can help you too, I think

As far as plastics go, look for a surplus supply store in your area. I'm lucky because there's one about a mile down the road form me. The guy gets the coolest **** and sells it for pennies on the dollar. I bought an 8 sq ft sheet of 1/2" white polycarbonate plastic for like $7-8 or so. Same stuff they make Mac laptop computers out of. The man has saved me some serious cash with my install goodies. 

I've also seen cheap cutting boards at Big Lots (which makes Wal Mart look like Sax 5th Ave).


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## 02bluesuperroo (Oct 31, 2006)

No melting and I had my router and jig saw full bore. In case you didn't look at my pics, here they are:

I used a piece of 3/4" HDPE I bought on ebay for $25 for my speaker baffles. I couldn't have been happier with the material









It sure makes a mess though...









Completed baffle









Dos baffelibros









Good thing this stuff didn't itch









I use non-hardening modeling clay to seal up the baffle to the door


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