Jump to content

Welcome to SMD Forum
Register now to gain access to all of our features. Once registered and logged in, you will be able to create topics, post replies to existing threads, give reputation to your fellow members, get your own private messenger, post status updates, manage your profile and so much more. If you already have an account, login here - otherwise create an account for free today!
Photo

Kerfing 101 - How to Kerf Bend MDF wood - VIDEO


36 replies to this topic

#1
mklett33

mklett33

    System of the Month October 2013

  • Members

  • 690 posts
  • Gender:Male
Kerfing 101- UNDER CONSTRUCTION

What is Kerfing?
“Kerf” by definition means “width of a saw cut”. This is the width of the actual saw tooth itself as opposed to the width of the blade as a saw tooth flares out and away from a blade. “Kerfing” is a term that many woodworkers have adopted to define the process of making several cuts within a piece of wood to achieve the removal of material. Often this removal of material will allow one to then bend the wood stock making a nice professional and appealing curve that can be incorporated into the project.

Kerfing and Car Audio:
What can Kerfing do for you in your quest of car audio domination? Well first of all it is important to note that in any ported subwoofer box hard corners are the devil. They do not allow efficient air flow which can result in less output and more port noise. Kerfing your port will allow you to maximize efficiency and create the most non-turbulent flow for the air moving in and out of the enclosure.

Secondly Kerfing can be used to make an enclosure or other part of your build more appealing to the eye. You could use it for corners of an amp rack, or to make a custom arm rest more smooth. Kerfing is a process you need to learn to take your builds to the next level.

What you need:
This is outlined in the video but you will need the following (* means you don’t HAVE to have it but it is recommended):
  • Circular Saw (Or table saw but the process will differ from the video) Disclaimer: My Saw blade is 1/8” wide. I recommend the same width!
  • T-Square (Or table saw fence)
  • MDF
  • Wood Glue
  • Safety Glasses
  • Tape Measure
  • Marker/Pencil
  • Clamps
  • Fiberglass Resin*
  • Fiberglass Chop Mat*
  • Body Filler*
  • Sand Paper*
The steps:
http://www.youtube.com/watch?v=GbEjGdu5dfw&feature=g-upl&context=G2117d99AUAAAAAAAAAA

http://youtu.be/bqeOiT1tE7I

Watch the video! Once the kerfed section is made load it up with wood glue and clamp it in place. Finish with fiberglass resin and chop mat and for that added professional touch apply body filler to the area and sand!

The Math:
I go through the math in the video but in case you are having a hard time understanding this should help. Please note this is used for slot porting applications so when I reference “diameter” I am NOT talking about a circular port, I am talking about the curve of the kerf if you were to look at it along its cross section. See the photo below:

Posted Image

Step 1: Determine the diameter of your curve. Note I said “Diameter NOT radius” if you have your radius just multiply it by 2 and you now have your diameter).

Step 2: Find the circumference of a circle using this diameter. The equation is:

Posted Image

Step 3: You should now have a value for your circumference. Take this value and divide by 4 for a 90 degree turn or 2 for a 180 degree turn, this will give you the “length of kerf”.

Posted Image

Step 4: Record your value for the length of the kerf. This is how much material along your mdf “linearly” must be used to make your curved kerfed section. This is the value you want to “mark off’ for your kerf on the mdf. (Note that this method can also be used to find the “length” of this part of your port so that you can build your port to the target tuning length. Instead of using the diameter of your kerf arc, use the diameter of the arc that is the centerline of the port).

Step 5: Now that you have marked off where your kerf will be on the mdf you are going to take your “length of kerf value” and divide it by 12. This will give you your length between cuts.

Posted Image

Now in the video I show a trick for making these divisions perfect. That way if your value is something like .6384 you don’t have to guess on a tape measure. My method is also much faster as it doesn’t require this steps math. Once you have marked out all the distances between cuts you can proceed with cutting and making your kerfs!

Other notes: These are other notes that have been brought up on other forums and I feel are helpful.
  • I made the mistake of wearing gloves in the video. Never wear gloves with rotary tools!
  • It is not recommended to apply screws in the kerfed section of the mdf, it will likely split, instead use clamps (or heavy objects) and wood glue.
  • If you are blade in not 1/8 you will need to do some math to determine how many cuts to make. I generally remove an inch and a half of material, so if your blade is smaller, more cuts, wider, less cuts. Note that fewer cuts will lead to a rougher curve and more a smoother curve but with less strength.
Pictures:

Design of an enclosure using a Kerfed Port:
Posted Image

Box with Kerfed Port:
(Picture to come)

Box with kerfed port and kerfed exit of port:
(Picture to come)

Edited by mklett33, 11 February 2012 - 03:50 PM.

-Mark @caraudiofab

 

Check out my tutorial on Kerfing your subwoofer port!

http://www.stevemead...mdf-wood-video/


#2
30Hz.wav

30Hz.wav

    145db

  • 18+ All Access!
  • 1,139 posts
  • Gender:Male
Nice video. Just watched the whole thing. Lot's of useful information. Your definitely good at this shit!

#3
stevog

stevog

    140db

  • Members

  • 782 posts
  • Gender:Male
nice video im definitely going to give this a try on my next box build. :good:

#4
Trigg

Trigg

    BRONZE SUPPORTING MEMBER

  • SMD Bronze Member
  • 166 posts
  • Gender:Male
  • Location:Z-Hills, FL
Garage View Garage
:good:

there is some VERY hard headed people out there. Anyone who says a DD-1 isnt necessary is also saying an O-scope isnt necessary. Anyone who says an O-scope IN THE MINIMUM isnt necessary, is a noob. Forget the DD-1 for a minute, any reputable installer will at LEAST use an O-scope. Those guys in that thread are clowns. Hard headed clowns.


#5
fecupe2001

fecupe2001

    Drunk SPL

  • Members

  • 5,577 posts
  • Gender:Male
  • Location:Panama City, Panama
  • Interests:Car audio and hookers :D
Watching it right now, thanks!!

I´m the SPL Gains topic creator!! wanna get louder?? check this: SPL Gains. Panamenian 2009 & 2010 Bass Race 149.9 Champ First Venezuelan Bass Race competitor and champion!! Loudforce Distributor for Latin America.

 

2 Loudforce 15" subs and a 2K wired at 1 ohm,  http://www.stevemead...ideo-on-page-3/

 

8 loudforce 15" subs and small power, http://www.stevemead...-bandpass-wall/


#6
mklett33

mklett33

    System of the Month October 2013

  • Members

  • 690 posts
  • Gender:Male
Thanks fellas please just remember to subscribe if you have a YouTube account. It encourages me to make more videos

-Mark @caraudiofab

 

Check out my tutorial on Kerfing your subwoofer port!

http://www.stevemead...mdf-wood-video/


#7
jokerklown

jokerklown

    130db

  • Members
  • 328 posts
  • Gender:Male
  • Location:Minnesota
Awesome video man

#8
fecupe2001

fecupe2001

    Drunk SPL

  • Members

  • 5,577 posts
  • Gender:Male
  • Location:Panama City, Panama
  • Interests:Car audio and hookers :D
Iīve never build a kerf port before, it actually doesnīt look that difficult, iīve worked A LOT with fiberglass and mdf lol, my biggest concern is the maths, i still donīt understand how do i figure where i have to start the kerf, i know you explain it but man oh man, my english suck ass big time lol

I´m the SPL Gains topic creator!! wanna get louder?? check this: SPL Gains. Panamenian 2009 & 2010 Bass Race 149.9 Champ First Venezuelan Bass Race competitor and champion!! Loudforce Distributor for Latin America.

 

2 Loudforce 15" subs and a 2K wired at 1 ohm,  http://www.stevemead...ideo-on-page-3/

 

8 loudforce 15" subs and small power, http://www.stevemead...-bandpass-wall/


#9
P-rez

P-rez

    130db

  • Members

  • 426 posts
  • Gender:Male
  • Location:Los Angeles, CA
Nice vis...just finished watching it...I will definitely will b trying this on my future box...
Its All Good!!! Build on hold...

#10
teardrop

teardrop

    145db

  • Members

  • 1,108 posts
  • Gender:Male
  • Location:kentucky
realy good vid thank you
Posted Image

#11
650rcode

650rcode

    125db

  • Members
  • 101 posts
  • Gender:Male
  • Location:Menlo Park, CA
Sick vid man. Thanks for the helpful tips, i might have to borrow your saw guide idea, seems more efficient than mine
Posted Image


2003 Mach 1 Build


HU: Alpine CDA-9857
Sub: Fi Bl 4"VC fully loaded
Sub Amp: RF 1500-1bdcp
Highs Amp: Kicker KX650.4
Highs: Polk Audio db 6.5 comps
Epicenter

#12
Blue

Blue

    Official Chug King

  • 18+ All Access!
  • 2,208 posts
  • Gender:Male
  • Location:San Jaghetto
Watched the whole thing also. I use just a circular saw, level and clamps. But I think I'm going to have to copy your t-square set up though cuase that is ingenious and didn't think about making something like that.
formerly known as Blue86f150

its a 4th order just because its tuned in the 40z doesnt mean it wont reach down and jiggle your balls at sub 30 hz frequencies.

Regardless if they were dipped platinum and were stuffed in Beyonce's twat.....way too fucking exspensive

this sux camel dicks


#13
lapaynem4

lapaynem4

    125db

  • Members
  • 146 posts
  • Gender:Male
  • Location:Tn.
  • Interests:Car audio, Shooting sports.
Pretty cool vid. :good:
2004 Chevy Trailblazer LS
DC Power Alternator
Kenwood KDC-448U
Kicker ZX650.4
Kicker ZX1500.1
4 Polk Audio DB6501's
4 Kicker CVR 10's
5.25ft^3 box with 33hz tune (Ram Designs)
XS Power S3400 (front)
Kinetik Hc2400 (rear)
Knukonceptz Kolossus Flex 1/0
Stinger ANL Fuses and Holders

X-overs set with SMD CC-1
Gains set with SMD DD-1 (-5db)



Future Upgrades:
4 Dc lvl 4 12s
Dc 5k amp
XS Power D3100's

#14
mklett33

mklett33

    System of the Month October 2013

  • Members

  • 690 posts
  • Gender:Male
Thanks everyone. do you guys think its sticky worthy?

-Mark @caraudiofab

 

Check out my tutorial on Kerfing your subwoofer port!

http://www.stevemead...mdf-wood-video/


#15
fecupe2001

fecupe2001

    Drunk SPL

  • Members

  • 5,577 posts
  • Gender:Male
  • Location:Panama City, Panama
  • Interests:Car audio and hookers :D
yes it is,but you never know, my 31.000 visit spl gains topic never got sticky hahaha

I´m the SPL Gains topic creator!! wanna get louder?? check this: SPL Gains. Panamenian 2009 & 2010 Bass Race 149.9 Champ First Venezuelan Bass Race competitor and champion!! Loudforce Distributor for Latin America.

 

2 Loudforce 15" subs and a 2K wired at 1 ohm,  http://www.stevemead...ideo-on-page-3/

 

8 loudforce 15" subs and small power, http://www.stevemead...-bandpass-wall/


#16
mklett33

mklett33

    System of the Month October 2013

  • Members

  • 690 posts
  • Gender:Male
Math

Posted Image

-Mark @caraudiofab

 

Check out my tutorial on Kerfing your subwoofer port!

http://www.stevemead...mdf-wood-video/


#17
fmedina

fmedina

    150db

  • 18+ All Access!
  • 1,825 posts
  • Gender:Male
  • Location:vacaville, ca
  • Interests:i love audio!!
very useful info. gj man. i will deff try kerfing on my next enclosures. but what i dont get is how do you get the diameter for the length of the kerf? math has left my brain lol
1996 chevy blazer 4door
Posted Image

#18
lowsound10

lowsound10

    130db

  • Members

  • 393 posts
  • Gender:Male
  • Location:Florida
i just dont understand is the kerf part of the port or do you have to had more length? great job on vid!! might have to try it out
Vehicle: 2008 Mustang V6 Exterior: Blacked Out Taillights, Turn Signals, Side Markers-Black 18x8 Enkei ls5-6000k HID's Interior: Blue LED Strips with Module for Music-Hardwired Beltronics RX65 with Blue LED and remote button Sub: 2 10 inch custom subs Amp: Hifonics BRz 2600 Wire: Knu 0 gauge Headunit: Kenwood kiv-bt901 Damplifier: Fatmat Rattletrap Electrical: Stock Alt/Stock Battery/Big 3

#19
baaudio

baaudio

    System of the Month December 2013

  • Members


  • 2,043 posts
  • Gender:Male
  • Location:Seattle
  • Interests:car audio!
Garage View Garage
very useful info man! keep up the great work, i sub'd the channel too :drinks:

Team NWSPL

baaudio Build Log
97 Explorer Sport/Mechman 370 & 270/NEW SHIT COMING!!!

157.1 @ 30hz SEALED 159.7 OUTLAW MUSICALLY

 


#20
mklett33

mklett33

    System of the Month October 2013

  • Members

  • 690 posts
  • Gender:Male

i just dont understand is the kerf part of the port or do you have to had more length? great job on vid!! might have to try it out


Consider it as part of the port length.

-Mark @caraudiofab

 

Check out my tutorial on Kerfing your subwoofer port!

http://www.stevemead...mdf-wood-video/




Reply to this topic



  


0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users