woodworking dictionary

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Blog entry by Cher posted 01-17-2010 10:32 PM 2777 reads 0 times favorited 11 comments Add to Favorites Watch

I have a book called ‘Collins complete Wood Workers Manual’ It has helped a bit but not much. I looked in there for a kerfmaker, it tells what kerf means but not how to use one. I did watch the video maybe it should have been explained in more detail. Can someone Please Patiently explain.

-- When you know better you do better.

11 comments so far

View bluchz's profile


187 posts in 4386 days

#1 posted 01-17-2010 10:49 PM

I like this question i have a need for the explanation also!

-- flash=250,100][/flash]

View zlatanv's profile


691 posts in 4247 days

#2 posted 01-17-2010 10:56 PM

I’m not an expert, but, I think you set the thickness of the kerf the blade makes of what ever blade you use to cut with on one end of the tool, and then you set the thickness of the wood stock you want to use to put into a dado or groove of another piece of wood. Then you use the tool to set up your fence or stop blocks to proper settings to cut you groove. First setting cuts one side of the groove and the other setting for the other side of the groove, leaving a perfect size groove for the piece you set the tool with to go into the groove or dado. Thats the way I understand it.

-- Z, Rockwall, TX

View lew's profile


13317 posts in 4768 days

#3 posted 01-17-2010 11:11 PM

I copied this directly from a web site (maybe you already read it):

Anybody who has been working wood for any length of time understands the pain of sizing grooves with today’s off-size sheet goods.

If you have ever tried to “dial in” a dado head with paper shims, or fussed with a wobble head dado set you know this hassle intimately. We are pleased to announce that those days are over. History. Kaput.

The KM-1 KerfMaker is an ingenious little tool that makes sizing grooves and dado cuts painlessly easy. It is unbelievably fast and accurate. (The video below shows the tool in action) We can’t imagine how you can get anything other than dead perfect results. Precision milled from aluminum, this tool is sure to be one of your most cherished shop aids.

Whether you own a table saw, chop saw, radial arm saw, the Jointmaker Pro, router table or any other tool that makes a clean kerf, you can use the KM-1 to expand that kerf to suit your needs. It is an amazing little tool that has earned our coveted “Bacon Saver” status. This means you will get gallery quality results every time you use the KM-1 Kerf Maker.
The KM-1 is perfect for; Frame work, box makers, shoji screens, torsion boxes,carcase work, drawer making and the list goes on. It is a tool that once used, you will never want to lose.

Hope that helps a little.

The concept is simple-the KM-1 is first “calibrated” to the particular cutting tool’s exact kerf. (See video demonstration). This is a one-time step. You then simply gauge the thickness of your stock with the KM-1, lock and you now can use the KM-1 as a flip stop to create a groove the exact width of your stock! It is fast, and potently accurate. The largest blade width you can use is 1/2”. The largest dado/lap joint you can make is 2”.

The video from here is probably what you saw. At the 3 minute mark it actually explains how to calibrate the Kerf-Maker for use. What they don’t mention is that if you change saw blades, you need to recalibrate.

-- Lew- Time traveler. Purveyor of the Universe's finest custom rolling pins.

View BarbS's profile


2434 posts in 5098 days

#4 posted 01-17-2010 11:14 PM

is this the one you mean, with the video scrolled down the page?
Huh..I didn’t know these were made commercially.
Okay, the only purpose of these ‘kerf-makers’ is to compensate for different thicknesses of the lumber you are using, especially plywood, which varies in thickness by its maker. For tight joints, you will always want to cut grooves or dadoes with a tight fit to the wood you are inserting into them, with no slop. Someone developed a ‘kerf-maker,’ an adjustable gauge that is first fit over the wood you are inserting, then on another end measures your dado blade set up or router bit width, to assure you are cutting the correct width of the dado or groove. They look terribly expensive. Try watching Bridge City Tools video, listed above, to see how theirs works.
The truth is, a common adjustable Vernier caliper such as will do the same thing. One set of teeth measures the thickness of your wood, the corresponding measurement of teeth show the width of the groove or dado you’ll need to fit it exactly. Sorry, but I’m very old school, and the old ways work very well. If you’re flush with money and love new toys, try the ‘kerf-maker.’ That is my two cents worth!

PS- I should add, all the caliper would require is another step to ‘sneak up’ on a fit, which is a skill a woodworker should learn, I feel.


View jlsmith5963's profile


297 posts in 4361 days

#5 posted 01-18-2010 12:14 AM

I agree with barbs completely…

look away from the bright shinny object

(in reality it looks like a well crafted gizmo but still just another gizmo, test cuts and sneaking up on a fit are facts of life in woodworking)

-- criticism: the art of analyzing and evaluating the quality of an artistic work...

View TopamaxSurvivor's profile


20274 posts in 4689 days

#6 posted 01-18-2010 03:13 AM


Take a look at this project. There is a good demo in the comments. Hope it helps.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View Ampeater's profile


442 posts in 4760 days

#7 posted 01-18-2010 04:44 PM

Cher, This is the technique that I use.

-- "A goal without a plan is a wish."

View TopamaxSurvivor's profile


20274 posts in 4689 days

#8 posted 01-18-2010 08:52 PM

Ampeater, So the dog board is the width of the dado and the kerf?

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View Cher's profile


965 posts in 4106 days

#9 posted 01-18-2010 10:20 PM

Hi Everybody, thanks for the info, I think I am going to take the vernier caliper route. I see they are available in digital as well. We work in metric over here and those milimetres are a strain on the eyes.

-- When you know better you do better.

View Diamondback's profile


88 posts in 4152 days

#10 posted 01-19-2010 05:40 PM

I would strongly suggest making yourself a KM like the commercial one, only out of wood. There are many KM’s in the projects area you can take a look at. There are some beauties as well as just fully functional ones. I made a “functional” one and used it to cut kerfs and it worked great! Simple and deadly accurate. No sneaking up on the cut, etc. Making one is very easy. When I saw the commercial kerf maker I couldn’t believe the simplicity and “why didn’t I think of that” factor. Just my thoughts. Good luck and have fun. For me the KF made it more fun for me. Take a look at TopamaxSurvivors link above for a really good example of a very nice simple KM.

-- Oshkosh, Wisconsin

View Jim Jakosh's profile

Jim Jakosh

25937 posts in 4118 days

#11 posted 02-11-2010 04:39 AM

Hi Cher. A kerf is a slot in the wood made by the saw blade. A dado is similar to a kerf, only it is usually wider and made by a routher bit or a dado blade .You can adjust the width of the dado by adjusting the dado cutter itself or moving the fence to make a wider cut.
Plywood is getting thinner than the advertized size just like 2×4’s are now 1 1/2” x 3 1/’2”. Wood suppliers are getting chintzier.
Anyway, if you have to make a groove or dado to fit the plywood or any piece of wood, you usually have to use a smaller cutter and move the fence to get the exact fit you want. There is an adjustable dado sold that many woodworkers look down on, but they do work nicely without shimming stacked dado blades which takes a lot of time for doing a small job.I have an old Craftsman adjustable dado set up permanently on my Craftsman Radial Arm Saw and use it a lot. All you do is loosen the arbor nut and dial it in to the width you want. It goes from 1/4” to 13/16”.
To set it up I use a digital caliper from Harbor Freight ($40 or $10 on sale) and make cuts in scrap until I get the fit I want.
Also, you have to check sheet to sheet on plywood for thickness. Be aware of that when cutting dados to fit.

-- Jim Jakosh.....Practical Wood Products...........Learn something new every day!! Variety is the Spice of Life!!

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