- Joined
- Sep 22, 2007
- Messages
- 636
This topic came up in another thread and it was suggested I create a new post about it. The original post is on another forum and it's dated 9/4/2010. I know others are playing with some ideas on making angles and I don't want anybody thinking I'm stealing any of their ideas. I'm not trying to sell Tan Bars but this is more about understanding how to make your own. [smile]
I was looking for a method of producing any angle on the MFT. I was introduced to what a machinist would use, a 5 inch long Sine Bar. A sine bar has 2 perfectly round cylinders of the same diameter and resemble the head of a Qwas Dogs. The precise distance between the centers of the cylinder's is typically 5.00 inches. The sides and faces are all made parallel to their respective sides. Gage Blocks are often used with a sine bar and they are precisely sized metal blocks of different lengths.
[attachimg=1]
Gage blocks are used to raise one cylinder as shown. Due to the principles of circles and math, no matter how high you raise the end of the sine bar, the points of contact on the cylinders are still precisely 5.00 inches. So you can say that you have a right triangle with the hypotenuse (the long side) being the bottom of the sine bar, the short side being an imaginary line going straight down and through the gage blocks, and the last side being the side of the gold bar (Incra track). In this triangle, the 5 inches between the cylinders will always be the same and the angle can change by varying the height of the gage blocks. The higher the gage blocks are, the bigger the angle. The height of the gage blocks will be equal to the trigonometric value of SINE of the angle of the sine bar times 5, the length of the sine bar. Another way of saying the same thing is the gauge block height divided by 5 equals the SINE of the angle. So in the above picture I have 2 gage blocks equal to 1.109 inches. 1.109/5=.2218. The sine of .2218 comes out be about 12 degrees, 49 minutes (oh yeah, there are 60 minutes in a degree and 60 seconds in a minute). So in the picture the sine bar is at an angle of about 13.8 degrees.
Before we continue I want to clarify that when I talk about a row of holes on the MFT, I am talking about a horizontal row of holes as you face the table. When I refer to a column of holes, I am talking about a vertical row of holes.
A sine bar could work on the MFT just as it is, without using the holes. Simply use some type of "fence" to rest it and the gage blocks on. I want something a little bit bigger than a sine bar (for easier accuracy) and takes advantage of the holes. We know the rows and columns of MFT holes are at right angles to one another. Can't we use this as 2 sides to a right triangle? I can use the hole spacing as a "constant" like the 5 inches on the sine bar. Instead of sine, the trig function "tangent" fits well with an adjacent side (a trigonometry term) of the angle staying constant. The adjacent side could be a row of holes already at fixed intervals. While the sine bar has a constant 5 inches between centers on its cylinders, we will have a constant 96 mm (or multiples of it) between the centers of a pair of Qwas Dogs stuck into the appropriate hole(s). Instead of the gage blocks (although something similar would be great for commonly used angles), I can use some type of rod and track combination that slides up and down but has very little side movement. The sliding rod and track length can be determined from the trig function of Tangent, also known as TAN. Let me post a picture of what I'm thinking.
[attachimg=2]
In this picture you can see the Festool guide rail for cutting on the extreme right. The gold Incra Track will be our fence adjusted to the angle we want. You can barely make out the black Qwas Dog acting as one of our cylinders to keep our contact points constant. Our imaginary triangle starts at the Qwas Dog next to the Festool guide rail, it goes in a horizontal line to the silver bar (drawer slide), makes a 90 degree turn down the silver bar. It turns again at the shiny Qwas Dog head at the end of the silver bar and goes up at about a 45 degree angle to the first Qwas Dog. Moving the silver bar up decreases the angle of this triangle created by that first Qwas Dog near the guide rail. Moving the bar down increases the angle. In this picture, the silver bar is 3 columns to the left of the reference Qwas Dog. It could be 1 column to the left or 2-8 columns to the left. The more columns between them, the better the accuracy and less columns allow higher angles.
How much does the silver bar have to move to change the fence by 1 degree? If it is in the column next to the reference Qwas Dog, it takes about 1/16 inch. If it is 2 columns away then it is 1/8 inch and 8 columns takes more than 1/2 inch movement to get 1 degree change. If we measure the movement with calipers then it should be very easy to get accurate angles and repeatable angles. All we need is a table with the trig function of TAN and then multiply that by the distance between centers, no wait — what we need is a table that has done all the math and gives us the answer. That I can do. It is available at http://www.qwasproducts.com/tantable.pdf and a more detailed table listing in 1/4 degrees is at http://www.qwasproducts.com/advtantable.pdf These tables, in PDF format, can be printed or downloaded. Those of you wanting a more detailed table listing every minute of every degree can look for any good trigonometry table from a good reference book.
The table should be easy to read. The first column on the left lists the angles in degrees. The next column, labeled 96mm, would be used if the silver bar was in the column next to the Qwas Dog. That is because there would be 96 mm between the centers of the Qwas Dogs if the angle was 0 degree. The next column would be for when the silver bars is 2 columns away from the Qwas Dog and so on for the rest of the columns.
Normally you might use a pair of Qwas Dogs by putting them in a horizontal row of holes, put your work piece against them and the work piece is at 90 degrees compared to the guide rail. If the Qwas Dog at the far end from the guide rail is removed and attached to the end of a bar, and we keep this bar parallel with the guide rail, we can slide this bar up and down to create different angles when holding the work piece. By moving the bar a specific distance, we will get a specific angle. This distance and angle can be determined from a table found at a website. Very simple, right?
Now we have an idea as to what we need to make a tool to do our angles. It needs a way to stay parallel to the guide rail. It needs a "linear bearing" — something that can slide up and down and have very little side play. It needs a way we can measure how far the slide has moved. It needs a way to attach the head of a Qwas Dog onto it. It needs to be fairly compact — we don't want some metal bar sticking 2 feet off of the MFT. It would be nice to keep it inexpensive. I spent a week playing with linear bearings and various metal bar combinations without ever finding something I liked or something I could sell to the rest of you. Then I found something, something you will laugh at, but it works and fits our needs to a "T". It is a drawer slide, or more specifically, an Accuride 3732-12, 12 inch, full extension, 32 mm compatible, hold-in detent, drawer slide. Above is a picture of it, assembled for use, on the MFT and set up similar to our picture above with the silver bar. Here is another view showing more of the details that we will discuss next. Construction and alignment is very easy.
[attachimg=3]
First thing we need is a way to hold the slide parallel to the guide rail. You can see the 2 round parts that I call "legs" on the bottom of the drawer slide. I used the bottom halves of 2 Qwas Dogs, the half that fits in the holes, or what I call "hole inserts". These were drilled down the center to accept a 10-24 screw. Since the drawer slide is 32 mm compatible, the mounting slots in the slide are at the proper location to line up with the MFT holes. Be sure to pick out the right holes by holding the slide base over or under the MFT holes. Be sure to get the right end that allows the slide to come out of the same end, not the end with the stop on it.
[attachimg=4]
We will need the top half of the Qwas Dog to make our "nose". It needs to be the same diameter, and thickness, as the top of a Qwas Dog. I drilled and tapped it's center for a 10-24 bolt since the other leg pieces were for a 10-24. You will need a "cover" to fit over the drawer slide to help keep dirt, sawdust, and debris out; and to hold the nose piece in place. I used a piece of smoke colored plastic since it was the right width. You could use plastic or 1/4 inch plywood would do fine also. It will be 1.5-2 inches wide and 13.5 inches long. The front of this piece needs to taper so at least 1/2 of the Qwas Dog nose piece will be exposed.
Now we need to figure out where to drill the holes to hold the cover in place on the drawer slide. We know we want them center to the width of the cover, or as close as we can get to center. Lock the slide in the detent (all the way closed if you have one without the detent) and install the slide into a couple of holes at the top of a column like pictured below. Install a pair of Qwas Dogs, 3 holes down and 2-3 holes to the left and to the right of the drawer slide. Push a straight edge or a fence up against the dogs like pictured below. Put the cover in position so the nose just touches the straight edge or fence. Mark where you need to put the holes to match up with those on the top of the slide. You can slide the cover to the left or right and place a mark for the holes and then transfer those marks to the center of the cover with a square. Drill small holes and use wood screws to hold the cover in place. As you run the drawer slide up and down, while in place on the MFT, you will see the nose piece go over the existing holes. You want the nose piece centered left and right over the holes as it goes up and down. Now you know it is parallel with a properly aligned guide rail. Install a pair of Qwas Dogs, 3 holes down and 2-3 holes to the left and to the right of the drawer slide. Push a straight edge or a fence up against the dogs like pictured below. Loosen the screw holding the nose piece and push the nose piece so it touches the straight edge/fence. This aligns the nose vertically. We need one more optional piece to make life easier. A piece of right angle attached to the back that will come up at least as high as the cover. This will make it easier to take measurements on how far we move the slide. The Angle Unit is now complete and calibrated for use.
[attachimg=5]
One last step before we begin using it. If you are going to use a digital caliper, we can "zero" it out so we don't have to keep adding or subtracting the gap at the rear of the unit. Simply put the inside legs of the caliper between the cover and right angle attachment. Extend the legs as if trying to read this gap and then hit the ZERO button. This is where we will be taking future readings to set up the angle for the Angle Unit. It is easier to get a measurement here than from the front and at the exact point where the nose contacts the fence (at bigger angles this would be extremely hard to do accurately).
So, let's say we want to make a 15 degree angle. We will set everything up pretty much like the first picture showing the Qwas Angle Unit setup on the MFT. We put a Qwas Dog in a hole 3 rows down and install the Angle Unit 3 columns to the left of the Qwas Dog. I prefer to use a fence (any thing that is a solid straight edge) so I will put it in place near the dog and Angle Unit. We will go to the Tan Table and find "15" in the first column (the Degree column) and go across to the 4th column (3*96 column) to find 3.038. I find it easier to adjust the caliper to that number and lock it in place, then go to the Angle Unit and slide the plastic cover until the caliper arms just fit in the space. Bring your fence into place resting against the Qwas Dog and the Angle Unit's nose. Clamp the fence in place. Remove the caliper. Bring your fence to rest against the dog and the nose of the Angle Unit. Bring your workpiece against the fence and under the guide rail. As you are adjusting the caliper to the proper setting, I wouldn't worry if it's off by 1 or even 2 thousandths. As you can see from the table, 1 or 2 thousandths is almost negligible.
What if you need to move the slide more than 6 inches and you are using a 6 inch caliper? Well, you could scribe a mark on the top of the drawer slide base every 6 inches. Then measure from one of those marks and add that distance to your measurement. Another answer is to move the Angle Unit down to another set of holes. Add 3.78 inches for every set of holes you moved down. Another way to accomplish the same thing is to move the reference Qwas Dog (over by the guide rail) up another set of holes. Add 3.78 inches for every set of holes you moved up.
You can mark popular angles with a magic marker or a scribe line on the side of the drawer slide. This will save you from having to measure the distance each time. If you need to repeat an oddball angle for the next few days, a piece of tape could be used instead of a scribed line. Or a block of wood (or whatever) cut to the proper length could fit between the cover and the angle bracket at the end. Just a few pre-made blocks could save lots of time.
It would be nice if there was an easy way to clamp the angle unit with Festool's Quick clamps. This would allow you to secure it in place after setting the angle you want. The quick clamps just don't have enough reach. I have been using some scrap pieces of metal as shown below but I would like something easier and faster to use.
[attachimg=6]
Although I have alway shown examples with the Qwas Dog on the right and the Angle Unit on the left, they can be reversed so the Angle Unit is on the right. The whole setup could be rotated 90 degrees also, so the Angle Unit sits in a row of holes.
For those who don't mind multiple cuts in your table, how about the wild idea of the guide rail being used instead of the fence. It might only work with 1/4 inch or thinner work but something to think about. A Qwas Dog could go in a hole towards the top and the guide rail would rest against it. The Qwas Angle Unit would go in some holes towards the bottom of the MFT and support the other end of the guide rail. Another pair of Qwas Dogs would support the workpiece. This guide rail is just a plain guide rail, without the clamps holding it to the MFT.
So there you have it. I tried to keep this thread short and I may not have covered everything well. I'm also not that good at explaining my thoughts and putting them in writing. It is easier to build and use the Tan Bar than it is to describe it. And it's very accurate. [smile]
I was looking for a method of producing any angle on the MFT. I was introduced to what a machinist would use, a 5 inch long Sine Bar. A sine bar has 2 perfectly round cylinders of the same diameter and resemble the head of a Qwas Dogs. The precise distance between the centers of the cylinder's is typically 5.00 inches. The sides and faces are all made parallel to their respective sides. Gage Blocks are often used with a sine bar and they are precisely sized metal blocks of different lengths.
[attachimg=1]
Gage blocks are used to raise one cylinder as shown. Due to the principles of circles and math, no matter how high you raise the end of the sine bar, the points of contact on the cylinders are still precisely 5.00 inches. So you can say that you have a right triangle with the hypotenuse (the long side) being the bottom of the sine bar, the short side being an imaginary line going straight down and through the gage blocks, and the last side being the side of the gold bar (Incra track). In this triangle, the 5 inches between the cylinders will always be the same and the angle can change by varying the height of the gage blocks. The higher the gage blocks are, the bigger the angle. The height of the gage blocks will be equal to the trigonometric value of SINE of the angle of the sine bar times 5, the length of the sine bar. Another way of saying the same thing is the gauge block height divided by 5 equals the SINE of the angle. So in the above picture I have 2 gage blocks equal to 1.109 inches. 1.109/5=.2218. The sine of .2218 comes out be about 12 degrees, 49 minutes (oh yeah, there are 60 minutes in a degree and 60 seconds in a minute). So in the picture the sine bar is at an angle of about 13.8 degrees.
Before we continue I want to clarify that when I talk about a row of holes on the MFT, I am talking about a horizontal row of holes as you face the table. When I refer to a column of holes, I am talking about a vertical row of holes.
A sine bar could work on the MFT just as it is, without using the holes. Simply use some type of "fence" to rest it and the gage blocks on. I want something a little bit bigger than a sine bar (for easier accuracy) and takes advantage of the holes. We know the rows and columns of MFT holes are at right angles to one another. Can't we use this as 2 sides to a right triangle? I can use the hole spacing as a "constant" like the 5 inches on the sine bar. Instead of sine, the trig function "tangent" fits well with an adjacent side (a trigonometry term) of the angle staying constant. The adjacent side could be a row of holes already at fixed intervals. While the sine bar has a constant 5 inches between centers on its cylinders, we will have a constant 96 mm (or multiples of it) between the centers of a pair of Qwas Dogs stuck into the appropriate hole(s). Instead of the gage blocks (although something similar would be great for commonly used angles), I can use some type of rod and track combination that slides up and down but has very little side movement. The sliding rod and track length can be determined from the trig function of Tangent, also known as TAN. Let me post a picture of what I'm thinking.
[attachimg=2]
In this picture you can see the Festool guide rail for cutting on the extreme right. The gold Incra Track will be our fence adjusted to the angle we want. You can barely make out the black Qwas Dog acting as one of our cylinders to keep our contact points constant. Our imaginary triangle starts at the Qwas Dog next to the Festool guide rail, it goes in a horizontal line to the silver bar (drawer slide), makes a 90 degree turn down the silver bar. It turns again at the shiny Qwas Dog head at the end of the silver bar and goes up at about a 45 degree angle to the first Qwas Dog. Moving the silver bar up decreases the angle of this triangle created by that first Qwas Dog near the guide rail. Moving the bar down increases the angle. In this picture, the silver bar is 3 columns to the left of the reference Qwas Dog. It could be 1 column to the left or 2-8 columns to the left. The more columns between them, the better the accuracy and less columns allow higher angles.
How much does the silver bar have to move to change the fence by 1 degree? If it is in the column next to the reference Qwas Dog, it takes about 1/16 inch. If it is 2 columns away then it is 1/8 inch and 8 columns takes more than 1/2 inch movement to get 1 degree change. If we measure the movement with calipers then it should be very easy to get accurate angles and repeatable angles. All we need is a table with the trig function of TAN and then multiply that by the distance between centers, no wait — what we need is a table that has done all the math and gives us the answer. That I can do. It is available at http://www.qwasproducts.com/tantable.pdf and a more detailed table listing in 1/4 degrees is at http://www.qwasproducts.com/advtantable.pdf These tables, in PDF format, can be printed or downloaded. Those of you wanting a more detailed table listing every minute of every degree can look for any good trigonometry table from a good reference book.
The table should be easy to read. The first column on the left lists the angles in degrees. The next column, labeled 96mm, would be used if the silver bar was in the column next to the Qwas Dog. That is because there would be 96 mm between the centers of the Qwas Dogs if the angle was 0 degree. The next column would be for when the silver bars is 2 columns away from the Qwas Dog and so on for the rest of the columns.
Normally you might use a pair of Qwas Dogs by putting them in a horizontal row of holes, put your work piece against them and the work piece is at 90 degrees compared to the guide rail. If the Qwas Dog at the far end from the guide rail is removed and attached to the end of a bar, and we keep this bar parallel with the guide rail, we can slide this bar up and down to create different angles when holding the work piece. By moving the bar a specific distance, we will get a specific angle. This distance and angle can be determined from a table found at a website. Very simple, right?
Now we have an idea as to what we need to make a tool to do our angles. It needs a way to stay parallel to the guide rail. It needs a "linear bearing" — something that can slide up and down and have very little side play. It needs a way we can measure how far the slide has moved. It needs a way to attach the head of a Qwas Dog onto it. It needs to be fairly compact — we don't want some metal bar sticking 2 feet off of the MFT. It would be nice to keep it inexpensive. I spent a week playing with linear bearings and various metal bar combinations without ever finding something I liked or something I could sell to the rest of you. Then I found something, something you will laugh at, but it works and fits our needs to a "T". It is a drawer slide, or more specifically, an Accuride 3732-12, 12 inch, full extension, 32 mm compatible, hold-in detent, drawer slide. Above is a picture of it, assembled for use, on the MFT and set up similar to our picture above with the silver bar. Here is another view showing more of the details that we will discuss next. Construction and alignment is very easy.
[attachimg=3]
First thing we need is a way to hold the slide parallel to the guide rail. You can see the 2 round parts that I call "legs" on the bottom of the drawer slide. I used the bottom halves of 2 Qwas Dogs, the half that fits in the holes, or what I call "hole inserts". These were drilled down the center to accept a 10-24 screw. Since the drawer slide is 32 mm compatible, the mounting slots in the slide are at the proper location to line up with the MFT holes. Be sure to pick out the right holes by holding the slide base over or under the MFT holes. Be sure to get the right end that allows the slide to come out of the same end, not the end with the stop on it.
[attachimg=4]
We will need the top half of the Qwas Dog to make our "nose". It needs to be the same diameter, and thickness, as the top of a Qwas Dog. I drilled and tapped it's center for a 10-24 bolt since the other leg pieces were for a 10-24. You will need a "cover" to fit over the drawer slide to help keep dirt, sawdust, and debris out; and to hold the nose piece in place. I used a piece of smoke colored plastic since it was the right width. You could use plastic or 1/4 inch plywood would do fine also. It will be 1.5-2 inches wide and 13.5 inches long. The front of this piece needs to taper so at least 1/2 of the Qwas Dog nose piece will be exposed.
Now we need to figure out where to drill the holes to hold the cover in place on the drawer slide. We know we want them center to the width of the cover, or as close as we can get to center. Lock the slide in the detent (all the way closed if you have one without the detent) and install the slide into a couple of holes at the top of a column like pictured below. Install a pair of Qwas Dogs, 3 holes down and 2-3 holes to the left and to the right of the drawer slide. Push a straight edge or a fence up against the dogs like pictured below. Put the cover in position so the nose just touches the straight edge or fence. Mark where you need to put the holes to match up with those on the top of the slide. You can slide the cover to the left or right and place a mark for the holes and then transfer those marks to the center of the cover with a square. Drill small holes and use wood screws to hold the cover in place. As you run the drawer slide up and down, while in place on the MFT, you will see the nose piece go over the existing holes. You want the nose piece centered left and right over the holes as it goes up and down. Now you know it is parallel with a properly aligned guide rail. Install a pair of Qwas Dogs, 3 holes down and 2-3 holes to the left and to the right of the drawer slide. Push a straight edge or a fence up against the dogs like pictured below. Loosen the screw holding the nose piece and push the nose piece so it touches the straight edge/fence. This aligns the nose vertically. We need one more optional piece to make life easier. A piece of right angle attached to the back that will come up at least as high as the cover. This will make it easier to take measurements on how far we move the slide. The Angle Unit is now complete and calibrated for use.
[attachimg=5]
One last step before we begin using it. If you are going to use a digital caliper, we can "zero" it out so we don't have to keep adding or subtracting the gap at the rear of the unit. Simply put the inside legs of the caliper between the cover and right angle attachment. Extend the legs as if trying to read this gap and then hit the ZERO button. This is where we will be taking future readings to set up the angle for the Angle Unit. It is easier to get a measurement here than from the front and at the exact point where the nose contacts the fence (at bigger angles this would be extremely hard to do accurately).
So, let's say we want to make a 15 degree angle. We will set everything up pretty much like the first picture showing the Qwas Angle Unit setup on the MFT. We put a Qwas Dog in a hole 3 rows down and install the Angle Unit 3 columns to the left of the Qwas Dog. I prefer to use a fence (any thing that is a solid straight edge) so I will put it in place near the dog and Angle Unit. We will go to the Tan Table and find "15" in the first column (the Degree column) and go across to the 4th column (3*96 column) to find 3.038. I find it easier to adjust the caliper to that number and lock it in place, then go to the Angle Unit and slide the plastic cover until the caliper arms just fit in the space. Bring your fence into place resting against the Qwas Dog and the Angle Unit's nose. Clamp the fence in place. Remove the caliper. Bring your fence to rest against the dog and the nose of the Angle Unit. Bring your workpiece against the fence and under the guide rail. As you are adjusting the caliper to the proper setting, I wouldn't worry if it's off by 1 or even 2 thousandths. As you can see from the table, 1 or 2 thousandths is almost negligible.
What if you need to move the slide more than 6 inches and you are using a 6 inch caliper? Well, you could scribe a mark on the top of the drawer slide base every 6 inches. Then measure from one of those marks and add that distance to your measurement. Another answer is to move the Angle Unit down to another set of holes. Add 3.78 inches for every set of holes you moved down. Another way to accomplish the same thing is to move the reference Qwas Dog (over by the guide rail) up another set of holes. Add 3.78 inches for every set of holes you moved up.
You can mark popular angles with a magic marker or a scribe line on the side of the drawer slide. This will save you from having to measure the distance each time. If you need to repeat an oddball angle for the next few days, a piece of tape could be used instead of a scribed line. Or a block of wood (or whatever) cut to the proper length could fit between the cover and the angle bracket at the end. Just a few pre-made blocks could save lots of time.
It would be nice if there was an easy way to clamp the angle unit with Festool's Quick clamps. This would allow you to secure it in place after setting the angle you want. The quick clamps just don't have enough reach. I have been using some scrap pieces of metal as shown below but I would like something easier and faster to use.
[attachimg=6]
Although I have alway shown examples with the Qwas Dog on the right and the Angle Unit on the left, they can be reversed so the Angle Unit is on the right. The whole setup could be rotated 90 degrees also, so the Angle Unit sits in a row of holes.
For those who don't mind multiple cuts in your table, how about the wild idea of the guide rail being used instead of the fence. It might only work with 1/4 inch or thinner work but something to think about. A Qwas Dog could go in a hole towards the top and the guide rail would rest against it. The Qwas Angle Unit would go in some holes towards the bottom of the MFT and support the other end of the guide rail. Another pair of Qwas Dogs would support the workpiece. This guide rail is just a plain guide rail, without the clamps holding it to the MFT.
So there you have it. I tried to keep this thread short and I may not have covered everything well. I'm also not that good at explaining my thoughts and putting them in writing. It is easier to build and use the Tan Bar than it is to describe it. And it's very accurate. [smile]
