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mklett33
12-23-2011, 11:02 AM
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

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:

http://i268.photobucket.com/albums/jj26/mklett33/Kerf2.jpg

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:

http://i268.photobucket.com/albums/jj26/mklett33/1.png

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”.

http://i268.photobucket.com/albums/jj26/mklett33/2.png

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.

http://i268.photobucket.com/albums/jj26/mklett33/3-1.png

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:
http://i268.photobucket.com/albums/jj26/mklett33/Kerf1.jpg

Box with Kerfed Port:
(Picture to come)

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

35thStangGT
12-23-2011, 11:25 AM
Very nice video!

bubbagumper6
12-23-2011, 12:37 PM
Very nice, would like to see this stickied.

I like your trick for spacing the cuts, seems like a great time saver. My only question is about the number of cuts, I would think for larger diameter kerfs you might want more cuts to provide a smoother curve, no?

06goat
12-23-2011, 01:23 PM
Great video. This woulda been a lotta help when I was trying to figure out the best way to do my kerfs lol

Whereabouts in Michigan do you live?

slim2fattycake
12-23-2011, 01:39 PM
Very nice, would like to see this stickied.

I like your trick for spacing the cuts, seems like a great time saver. My only question is about the number of cuts, I would think for larger diameter kerfs you might want more cuts to provide a smoother curve, no?

Yes. More cuts for a smoother curve but its harder to not mess up.

psychoacoustics
12-23-2011, 01:50 PM
nice tricks good video !

mylows10
12-23-2011, 01:55 PM
very good job.yes this needs to be stickied

Nut Hair Trick
12-23-2011, 01:57 PM
Yes, very nice video and the only one I have ever seen that was this detailed. It seems as if folks were scared to share their secrets before. Thanks

pro-rabbit
12-23-2011, 02:12 PM
Yes, very nice video and the only one I have ever seen that was this detailed. It seems as if folks were scared to share their secrets before. Thanks

Never scared ( I don't use them a lot anyway), more like there are several ways to do it. This is a similar method to what I use though.


Very nice video, seen it over on SSA the other day. Looks great and well thought out.

Imtjnotu
12-23-2011, 02:28 PM
Great video. This woulda been a lotta help when I was trying to figure out the best way to do my kerfs lol

Whereabouts in Michigan do you live?

i cant take u serious with ur avatar hahahahahahahahaha dat lama

Bggd_GMC
12-23-2011, 02:41 PM
nice vid


isnt it easier to do it with router?

pro-rabbit
12-23-2011, 02:46 PM
table saw is easier I think

06goat
12-23-2011, 02:48 PM
i cant take u serious with ur avatar hahahahahahahahaha dat lama

dat lama srsbznz

Nut Hair Trick
12-23-2011, 04:05 PM
Never scared ( I don't use them a lot anyway), more like there are several ways to do it. This is a similar method to what I use though.


Very nice video, seen it over on SSA the other day. Looks great and well thought out.

I wasnt even thinking of you when I made that statement. I've seen builders when asked about Kerfs say something like "well ya know, I have a certain equation I use", then they dont go any further into it. So, to me, the math of it all was the best part because it was so simple. But you're right, there are other ways to do it, and I'm sure I could have very well figured it out on my own. This video really made it simple for people using circular saws that don't have access to a tablesaw.

pro-rabbit
12-23-2011, 04:15 PM
I wasnt even thinking of you when I made that statement. I've seen builders when asked about Kerfs say something like "well ya know, I have a certain equation I use", then they dont go any further into it. So, to me, the math of it all was the best part because it was so simple. But you're right, there are other ways to do it, and I'm sure I could have very well figured it out on my own. This video really made it simple for people using circular saws that don't have access to a tablesaw.

Very true, and I didn't take it personal at all. Just figured I would offer my input into it.


I agree though is is a very good video to learn from. I wish I had something like this when I was doing trial and error stuff years ago lol.

Tek18
12-23-2011, 05:14 PM
VERY VERY VERY VERY nice video.

stickied? please?

ItsAJeepThing
12-23-2011, 05:54 PM
Nice video man. I am going to do this in the near future.

mklett33
12-24-2011, 05:41 PM
Thanks for all the kind words guys, I am glad you found this helpful. I will be sure to post more How-To Videos in the near future, mainly things I have always wondered and had to learn myself. Might as well share the wealth, to many people protect how things are done.

Thank you to whoever stickied this!

kramer_212
12-24-2011, 05:47 PM
nice vid

KTMrida4life
12-24-2011, 06:27 PM
Nice video, I really like the trick about spacing out the cuts.. would've never thought of that.

Nice american eagle "hat".. and Im really diggin the motocross gloves. haha

I use mine too for working on stuff sometimes.. but most of the time I actually use them for what their intended for :]

Falcons
12-24-2011, 06:44 PM
Can you put up a link? Usin my iPhone right now

DonH
12-24-2011, 07:02 PM
nice vid bro! great job, I use my table saw to do this as its MUCH faster but your way works great. can i make ONE note...

DO NOT WEAR GLOVES MAN! WORST thing you can possibly do is wear gloves on your hands when operating any sort of machinery that rotates. What is going to happen when the rotating blade snags a piece of your glove by chance? your hand will be ****** into the turning object, in this case your blade. BAD news man! you will loose your hand. Ive seen it happen on a drill press. totally nasty stuff. guy was wearing gloves, fabric got caught 1/2" bit grabbed on, ripped his **** index finger clear off. seriously.

now +1 for your video. great job.

DonH
12-24-2011, 07:03 PM
vid link

Kerfing 101 - How to Kerf MDF for your subwoofer enclosure - FULL Detail - YouTube (http://www.youtube.com/watch?feature=player_embedded&v=GbEjGdu5dfw)

Team TH (Donny)
12-24-2011, 07:26 PM
Excellent, quick, and simple way of showing how to Kerf. This will be great for those who seek info on "how to's" in box building, so they can better their knowledge in the skill. Keep up the good work!

sacsking916
12-24-2011, 07:29 PM
awesome A++++++ thank you

wenn_du_weinst
12-24-2011, 07:34 PM
I have known how to kerf for a while but I was still entertained. pretty good video.

KTMrida4life
12-24-2011, 07:35 PM
nice vid bro! great job, I use my table saw to do this as its MUCH faster but your way works great. can i make ONE note...

DO NOT WEAR GLOVES MAN! WORST thing you can possibly do is wear gloves on your hands when operating any sort of machinery that rotates. What is going to happen when the rotating blade snags a piece of your glove by chance? your hand will be ****** into the turning object, in this case your blade. BAD news man! you will loose your hand. Ive seen it happen on a drill press. totally nasty stuff. guy was wearing gloves, fabric got caught 1/2" bit grabbed on, ripped his **** index finger clear off. seriously.

now +1 for your video. great job.

I saw that happen on the TV show American Chopper a few years back.. and for anyone who has seen the show, it happened to Rick.. whose like a robot when it comes to working with metal. It grabbed his glove and literally turned his hand into what looked like hamburger meat, they couldn't even show it on TV.

I agree in this case, when working with stuff that spins/rotates.. gloves aren't your best bet safety wise. In any other situation I would wear them.

wenn_du_weinst
12-24-2011, 07:45 PM
yeah I know 2 guys who rolled their fingers because they insist on wearing gloves at work.

duanebro
12-24-2011, 07:57 PM
Thanks for the video. And thanks for the tip on the gloves guys.

I use a thin kerf blade on all my saws, will that work? or do I need to change to a wider blade? (I know I would need to make more cuts.)

mklett33
12-25-2011, 10:49 AM
I use a thin kerf blade on all my saws, will that work? or do I need to change to a wider blade? (I know I would need to make more cuts.)

Technically more cuts, with and 1/8" blade I do 12 cuts which would be 1.5" of material removed. So if your blade is smaller take 1.5 and divide by your blade thickness to get how many cuts you need.



DO NOT WEAR GLOVES MAN!


Actually I am usually good about this rule. Never use them on a drill or grinder. Wasn't even thinking about it while I was doing this video but thank you for pointing that out!

~M

hispls
12-25-2011, 11:04 AM
You're like the Bob Villa of box building now. Well done, but why the motorcycle gloves?

J31Rob
12-25-2011, 11:10 AM
Nice video. I'm glad I don't have to do any of that though. Being in the lumber industry you tend to find some mega hookups. I've got a panel guy that can do everything within 0.001" accuracy. All cuts, kerf cuts included. CNC FTW.

35thStangGT
12-26-2011, 03:52 PM
How would you put a screw into the kerf'd piece? Can you? Lol.

duanebro
12-26-2011, 05:52 PM
How would you put a screw into the kerf'd piece? Can you? Lol.

I would not try it. I don't put screws in the end grain of MDF in general. Just use clamps.

06goat
12-26-2011, 06:07 PM
I saw that happen on the TV show American Chopper a few years back.. and for anyone who has seen the show, it happened to Rick.. whose like a robot when it comes to working with metal. It grabbed his glove and literally turned his hand into what looked like hamburger meat, they couldn't even show it on TV.

I agree in this case, when working with stuff that spins/rotates.. gloves aren't your best bet safety wise. In any other situation I would wear them.

Yeah and I betcha the producers made him wear the gloves to promote "safety"

DonH
12-26-2011, 10:37 PM
How would you put a screw into the kerf'd piece? Can you? Lol.

you cant. it will split. use clamps

mklett33
12-28-2011, 07:38 PM
Edited the original post

mklett33
01-25-2012, 11:52 AM
There has not been much response since this thread got stickied, I would still like to hear what people think and/or additional questions!

cyn
01-25-2012, 12:05 PM
Anyway to make some kind of spread sheet that auto does the formula?

mklett33
02-11-2012, 06:52 PM
http://www.youtube.com/watch?v=bqeOiT1tE7I
:) Part 2

Sketchup
03-24-2012, 02:29 AM
Very helpful