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View Full Version : patching holes in mdf?



Lil Poot
01-16-2009, 09:32 AM
so i drilled holes in my last 2 boxes to mount to the chassis of my truck. they're really nice boxes, so i'd rather not just throw them away. whats the best way to patch up a good sized (1/2 inch diameter) hole in some mdf?

PaulThompson229
01-16-2009, 09:34 AM
Mix up sawdust and glue and fill the hole with that, put a peice of tape on the bottom side of the hole to hold the mixture in place until it hardens.

Lil Poot
01-16-2009, 09:34 AM
Mix up sawdust and glue and fill the hole with that, put a peice of tape on the bottom side of the hole to hold the mixture in place until it hardens.

is this better than wood filler putty?

PaulThompson229
01-16-2009, 09:40 AM
is this better than wood filler putty?


I would assume so seeing as the glue joints are supposed to be the strongest parts on the box, so I think the same would be true for a sawdust/titebond plug, this is the way I have always done it. The putty doesn't bond to the mdf and soak in like the glue does so it seems to me that high enough pressure on a putty plug could blow it out of the hole, I have never used putty before though so I can't say from personal experience.

Lil Poot
01-16-2009, 09:41 AM
how do you gauge how to mix it, just eyeball it, look for a certain consistancy, measure?

PaulThompson229
01-16-2009, 09:44 AM
No specific measurements, just make it thick and lumpy, kind of like the consistancy of cookie dough, then pack it into the hole as tight as you can, after that put a few extra drops of glue onto the top of the plug so it can soak down into the mixture and the surrounding surface wood.

dman4486
01-16-2009, 09:45 AM
how do you gauge how to mix it, just eyeball it, look for a certain consistancy, measure?

just by consistency......mdf is made of is sawdust and glue:fyi:.....so you are just creating more mdf:p:

mlstrass
01-16-2009, 11:33 AM
why not just glue a small piece of scrap MDF over the hole...

Trey803
01-16-2009, 11:34 AM
Caulk?

fatboyracing
01-16-2009, 11:36 AM
put a peice of mdf inside the box covering the hole

I Like Waffle
01-16-2009, 12:14 PM
liquid nails :)

PaulThompson229
01-16-2009, 12:17 PM
why not just glue a small piece of scrap MDF over the hole...

He wants it to look good


Caulk?

Doesn't bond to the wood


put a peice of mdf inside the box covering the hole

Wouldn't cover the hole on the outside, again he wants it to look good


liquid nails :)

You fail, liquid nails *****

chase007
01-16-2009, 12:22 PM
use e-poxy it can hold 5,000 poud per sq inch but it cost like 35$ a tube i i have 4 tubes on my shelfs there so handy in box building for thoughs fck ups

PaulThompson229
01-16-2009, 12:24 PM
use e-poxy it can hold 5,000 poud per sq inch but it cost like 35$ a tube i i have 4 tubes on my shelfs there so handy in box building for thoughs fck ups


Interesting, never heard of it, got a link?

chase007
01-16-2009, 12:28 PM
Interesting, never heard of it, got a link?

local hardware store has them..at my resturant we poured epoxy on the bar so it had this clear finish coat on it like a big thick layer of sealer....sec i'l get u a nice link but ur local stores always have this ...even walmart http://www.aplusbputty.com/applications.htm


e-poxy>all glues

--Navi--
01-16-2009, 12:30 PM
bondo

PaulThompson229
01-16-2009, 12:30 PM
local hardware store has them..at my resturant we poured epoxy on the bar so it had this clear finish coat on it like a big thick layer of sealer....sec i'l get u a nice link but ur local stores always have this ...even walmart http://www.aplusbputty.com/applications.htm


e-poxy>all glues


Oh, lol I fail, I know what epoxy is, I thought the way you wrote it (e-poxy) you were talking about a specific kind

Loctite epoxy is nice, its what I use for my recones

chase007
01-16-2009, 12:42 PM
yeah man just use epoxy its very nice and works well and plus if u got extra left over u can always use it for something elce...I win epoxy win's this thread A+

PaulThompson229
01-16-2009, 12:45 PM
^^ umm no? Even though I agree that epoxy is extremely useful, it still doesn't bond to the wood. MDF paste is the best option.

bjfish11
01-16-2009, 01:05 PM
With a hole that size, I would not use sawdust and glue mix. Instead, get a dowel pin the same size diameter as the hole, cover it in glue, shove it in. When the glue is dried, trim off the excess of the dowel. Best way to do it IMO.

PaulThompson229
01-16-2009, 01:06 PM
With a hole that size, I would not use sawdust and glue mix. Instead, get a dowel pin the same size diameter as the hole, cover it in glue, shove it in. When the glue is dried, trim off the excess of the dowel. Best way to do it IMO.



Very good idea, I never would have thought of that, +1 for joo :D

I Like Waffle
01-16-2009, 01:09 PM
Why does liquid nails ****? i read good things about it on here before and i used it to seal up my first box i built :(

Louisiana_CRX
01-16-2009, 01:09 PM
gorilla glue

dman4486
01-16-2009, 01:10 PM
Why does liquid nails ****? i read good things about it on here before and i used it to seal up my first box i built :(

I know it is good for bonding 2 things together, but I don't know how well it would work for filling a hole.

PaulThompson229
01-16-2009, 01:12 PM
Why does liquid nails ****? i read good things about it on here before and i used it to seal up my first box i built :(


For sealing seams it is fine, for any type of adhisive/patching purposed it doesn't work well. It does not soak into the wood and create a chemical bond like wood glue does, only a surface coating. I made the mistake of building my first box with liquid nails back when I didn't know jack **** about car audio and the box blew apart on 800rms.

snb778
01-16-2009, 01:15 PM
bondo

x2 on that..... and I even put some resin and or fiberglass on top of that... I had 3x 4" holes for some aeros on my box I covered using this method.

I Like Waffle
01-16-2009, 01:35 PM
im running about 1200rms, and i also used a shitload of screws in the box too. I used gorilla glue in the seams and went along the inside edges with the liquid nails. Ill see how it holds up i suppose

dman4486
01-16-2009, 01:38 PM
im running about 1200rms, and i also used a shitload of screws in the box too. I used gorilla glue in the seams and went along the inside edges with the liquid nails. Ill see how it holds up i suppose

gorilla should be fine especially with screws, but I don't believe it has the bonding abilities of wood glue.

could be wrong

IDSkoT
01-16-2009, 01:45 PM
put a peice of mdf inside the box covering the hole

This, or cut a circle roughly the same size, wood glue it up and wood filler it up.
Bam.

Vermithrax
01-16-2009, 03:04 PM
With a hole that size, I would not use sawdust and glue mix. Instead, get a dowel pin the same size diameter as the hole, cover it in glue, shove it in. When the glue is dried, trim off the excess of the dowel. Best way to do it IMO.

I have to agree with BJ on this. If you don't have dowels you could countersink a 1/2 or 3/4" screw in the hole and putty over it.

scoob8000
01-16-2009, 11:58 PM
half an inch is a little big for any kind of glue or putty.

Grab a 1/2" wood dowel from Home Depot or Lowes, cut a couple pieces .75 thick (or whatever thickness MDF you used) and glue them in the holes..

[edit]


With a hole that size, I would not use sawdust and glue mix. Instead, get a dowel pin the same size diameter as the hole, cover it in glue, shove it in. When the glue is dried, trim off the excess of the dowel. Best way to do it IMO.

You beat me to it! :)

93dakota
01-17-2009, 12:20 AM
x2

Lakota
01-17-2009, 12:29 AM
I was going to say fiberglass, but cutting out a circle and sticking it in there is easier...

jco1385
01-17-2009, 12:30 AM
dowel rod seems legit

Lil Poot
01-17-2009, 02:26 AM
can i expect a 1/2 inch dowel to go into a 1/2 inch hole, or will i need to take it a 1/64 or 1/32 or something bigger? just wanting to make one trip out to lowes as cold as it is right now, and i don't have drill bits that big other than my 1/2 inch.

19992wdtaco
01-17-2009, 02:58 AM
I filled holes with just a basic two part 5 minute epoxy. Most are good on wood, metal, etc. Cover the hole from the inside to keep the epoxy in the hole so it doesn't leak down while it cures.

scoob8000
01-17-2009, 11:16 AM
can i expect a 1/2 inch dowel to go into a 1/2 inch hole, or will i need to take it a 1/64 or 1/32 or something bigger? just wanting to make one trip out to lowes as cold as it is right now, and i don't have drill bits that big other than my 1/2 inch.

lay a piece of paper over the hole and rub it with a crayon or pencil, take the tracing with you.

Maybe a short bolt/washer/nut could be another (temproary) option..

iamamp3pimp
01-17-2009, 12:17 PM
local hardware store has them..at my resturant we poured epoxy on the bar so it had this clear finish coat on it like a big thick layer of sealer....sec i'l get u a nice link but ur local stores always have this ...even walmart http://www.aplusbputty.com/applications.htm


e-poxy>all glues

Overkill


mdf/sawdust or LN will work fine

is it sealed or ported?>???

Lil Poot
01-18-2009, 09:12 PM
they're all ported. here's some pics of my new box, for your viewing pleasure. tommyk90 designed it, bj fisher built it. it should make some noise ;)

http://i39.tinypic.com/sx0kmg.jpg

http://i44.tinypic.com/ipnno4.jpg

iamamp3pimp
01-18-2009, 11:14 PM
nice.

Lil Poot
01-19-2009, 08:07 AM
i'm a sucker for bare mdf and rounded edges :D

edzy
01-19-2009, 11:15 AM
^^^ X4 Dowel.

even if you have an old broom stick lying around, just cut/sand it to fit and wood glue it in.

You could also use a nut and bolt with some rubber washers, like a toilet tank to bowl kit.
Kinda ghetto way about it, but its an option.

wgsj_fortvalley
01-19-2009, 11:34 AM
He wants it to look good



Doesn't bond to the wood



Wouldn't cover the hole on the outside, again he wants it to look good



You fail, liquid nails *****

right:)

wgsj_fortvalley
01-19-2009, 11:43 AM
they're all ported. here's some pics of my new box, for your viewing pleasure. tommyk90 designed it, bj fisher built it. it should make some noise ;)

http://i39.tinypic.com/sx0kmg.jpg

http://i44.tinypic.com/ipnno4.jpg

that is a really nice boc. i like the way u did the double baffle. my next box will probably be like that. but just do like the other guy said and mx the sawdust and glue together and fill the hole. ive never thought of it.

Lil Poot
01-19-2009, 12:22 PM
i'm using the dowells and blue to plug the holes. not in this box, but my last 2 that were mounted using the same holes as this one has.