John Duffyʼs Manual Mill Gadget. Build Instructions

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Coral Horn
5 years ago
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John Duffyʼs Manual Mill Gadget Build Instructions This mill can be assembled over a few days, and has up to 1/1000 th accuracy on X and Y, and about 1/100 th on Z.

The STL and sketchup files are available below and they are very useful for reference throughout the build. 1.

1 John Duffyʼs Manual Mill Gadget Build Instructions This mill can be assembled over a few days, and has up to 1/1000 th accuracy on X and Y, and about 1/100 th on Z. It costs around $50 for the physical mill, and an additional ~$50 for the digital readout. Itʼs mostly made from parts easily found at most hardware stores. The STL and sketchup files are available below and they are very useful for reference throughout the build. 1. Bearing blocks This is the only part that requires anything more than a hand saw, but accordingly, is one of the major parts where the machineʼs precision will be determined. Start by cutting each to size from the original 2x4s, following the pattern shown below (this pattern ensures that all the pieces will fit on three 8ʼ 2x4s). The next two are just zoomed in on either end of the 2 nd and 3 rd 2x4s. Three of the blocks are 15 long, the other three are 3 x3, which requires that you remove some material in both directions, as 2x4s are actually 3.5 x1.5. Once you have

5 x15 face, and about 1/8-3/16 deep. The support rod holes of the 15 piece are 0.75 in from each side, centered vertically, and 3/8 diameter. The hole for the 3 x3 piece is 0.

2 the six pieces, you will need to drill the bearing recessions and support rod holes in the four that need them, and the nut holes in the other two. Each of the four bearing blocks has two holes; one is ¼ and all the way through. The other OD of the bearing (20mm with the bearings I used) goes in the exact center of the 1.5 x3, or 1.5 x15 face, and about 1/8-3/16 deep. The support rod holes of the 15 piece are 0.75 in from each side, centered vertically, and 3/8 diameter. The hole for the 3 x3 piece is 0.6 in from one side, also vertically centered, and ¼ diameter. 2. The base Once the bearing blocks are made, itʼs time to start on the base. Again cut the required pieces of 2x4 in 4 2ft sections, as well as cutting the angle aluminum into another 4 2ft sections. Then, set up all the parts as shown here, but donʼt glue yet.

First, find the two pieces of angle iron that are closest in length, and file them until they are exactly equal. Then, set up the other two pieces as the guides along the Y axis.

3 First, find the two pieces of angle iron that are closest in length, and file them until they are exactly equal. Then, set up the other two pieces as the guides along the Y axis. Lay one of the identical pieces at either end of the Y axis, again, without gluing. Find four things that have an exactly 90 degree external corner (they donʼt need to be the same thing). A shoebox would be bad, a piece of machining stock, good. Lay out the four 2ft pieces of 2x4 in a square with two opposite sides on top of the other two sides, as shown below. Then, place the square objects in each of the corners, and press each of the 2x4s against them, so each corner is precisely square. Now glue them in place, and place something heavy on each of the corners.

4 Finally, Move the pieces of aluminum angle from before on top of the base, with the bottom two parallel to the top 2x4s. Then line them up to be as close to parallel as possible, and set the distance between them using the top two to maintain a consistent distance between them. Then glue down the bottom two, and take out the top two. It should now look like this. 3. Sliders and bearing blocks Now, set up the bearing blocks, sliders, and two pieces of angle aluminum as shown. Glue the two 3 x3 bearing blocks onto the two pieces of angle aluminum, making sure the ends are flush and the bearing holder is facing inward. Then, place, but do not glue, the 3 slider between them. Then, cut a ~3ft piece of threaded rod, and slide it through one of the bearing blocks. Then put on the following series of things: bearing, washer, collar, nut, tee nut (with the shaft facing away from the bearing block), then the slider, and another tee nut, facing the opposite direction. Then a nut, collar, washer, and bearing.

Move the nut, washer, collar, and bearing closest to the bearing block to it, but leave the other set at the end. Move the two collars and the slider to about the middle of the rod.

5 Move the nut, washer, collar, and bearing closest to the bearing block to it, but leave the other set at the end. Move the two collars and the slider to about the middle of the rod. Then comes the most important part of this step, which is removing backlash. Tighten the two tee nuts together toward the slider until they become very difficult to turn. Then loosen one a tiny but, just enough that it can be turned fairly easily. Then insert six brads through the holes in the nuts, and into the block. Make sure they are all the way in, and glue them if necessary, just make sure not to get glue in the nut or on the rod. Once the slider is in place, insert the rod into the far bearing block and move back the nut-collar-washer-bearing group back until a little of the rod sticks out the end (enough for whatever encoder you will use). Then tighten the collar, and the nut to the collar. Finally, press the other assembly into the other bearing block and tighten it as well. Then bend the rod sticking out of that side twice, to make a handle for turning it.

Now inset the ¼ and 3/8 steel rods (you will need to cut both of them from the larger pieces, all of them should be just under 2ft long) into the bearing blocks through

6 Do the same for the bottom slider, but minus the aluminum angle. Instead attach it to the two lower 2x4s on the base. You should put the 15 blocks and slider here, even though the pictures show 3 x3 blocks and slider. Now inset the ¼ and 3/8 steel rods (you will need to cut both of them from the larger pieces, all of them should be just under 2ft long) into the bearing blocks through the sliders and into the far bearing block. Make sure not to bend any of them. Only glue them into the bearing blocks, not to the sliders. Finally, insert the X axis (the assembly with the 3 blocks and aluminum angle) into the base, between the other pieces of aluminum angle, as shown.

Glue the 15 slider to the bottom of the pieces of aluminum angle, making sure not to glue to the slider. Once that dries, you should have a functional X-Y table.

Z axis support The Z support is the easiest part, with just four pieces and little alignment.

7 Glue the 15 slider to the bottom of the pieces of aluminum angle, making sure not to glue to the slider. Once that dries, you should have a functional X-Y table. Oil the rods, and move it around a bit. It might be a little unstable, but it should move smoothly and without a noticeable backlash. 4. Z axis support The Z support is the easiest part, with just four pieces and little alignment. Start by cutting the four 1ft sections of 2x4, and the two 18 sections, making sure all ends are as square as possible. Then, stand all the 1ft sections on end as shown here. Set the 18 pieces between two of the supports, and mark which one went where. Then glue the 1ft pieces to the base (but not to the 18 pieces) and press, clamp, or otherwise apply pressure inward at the bottom, so that theyʼre the same length apart as the 18 pieces. Finally, once the glue for the four supports has dried, slide the 18 pieces into the top of the 1ft supports, and glue them in place. If the friction is not strong enough to hold them while drying, put a clamp below it, on the vertical support, or find something 8.5 tall, and put it under the middle of the piece. 5. Z axis holder This is very similar to the X and Y axes, but is different in load, and that it significantly affects the accuracy of all 3 axes. It is made with two bearing blocks, one 2 long, one 1 long, and a slider that is 4.5 long. Unlike the others, make a ½ deep bearing recession in the 1 block. Make it the same as the others, with two ¼ holes one-quarter of the way along the 3.5 length. Then cut the final 12 piece of 2x4, and mount the 2 block at one end, and the 1 block at the other, with the bearing holder facing inward. Make the same bearing-washer-collar-nut-tee nut-slider-tee nut- sandwich from the 2 block, but only use a collar and bearing on the 1 block. This is because the slider must get close to the 1 block in order to drop the Z axis, and the washer and nut take up a fair amount of space. Tighten and secure it as you did the X and Y, and bend the rod. The slider should move as easily as the other axes, though with only a few inches of movement.

6. Tool mount Now cut the two 2x6 pieces, which are 2.5 and 4.5. Take the plates from the back of the two U bolts, and use them to parallel the 2.5 piece on the back of the 4.

8 6. Tool mount Now cut the two 2x6 pieces, which are 2.5 and 4.5. Take the plates from the back of the two U bolts, and use them to parallel the 2.5 piece on the back of the 4.5 one, making sure that there is enough room for the U bolts themselves. Then glue on the 2.5 piece, and drill the holes for the two U bolts. Bolt them on loosely, and check that everything is secure. 7. Leveling and attaching the Z axis. Now comes the last part of the mechanical build, but also the part where patience is most needed. Make the final cut, a 17 piece of 2x4, and set it between the two 18 pieces. Measure and move it so that the front edge, plus 6 plus the radius of the tool you will use (the tool itself, not the bit) is centered on the mill. Then, using a level or two, and on a level surface, clamp and glue the 17 piece in place. Once it is dry, make sure

again that it is level, and cut it off and try again if it is not.

Make sure that the Z axis moves straight up and down using a laser mounted against something perfectly square, and aimed up.

When the Z axis is moved up and down, the dot should stay in exactly the same place. If it does, move on, if not, take it off and try again.

9 again that it is level, and cut it off and try again if it is not. If it is, then again using a level, but this time on the slider of the Z axis, mount the 12 backing to the Z axis to the 17 piece. Make sure that the Z axis moves straight up and down using a laser mounted against something perfectly square, and aimed up. Tape something to the Z axis slider that sticks out a little bit, and aim the laser at that from beneath it. When the Z axis is moved up and down, the dot should stay in exactly the same place. If it does, move on, if not, take it off and try again. Once the slider is level and straight, get out the level again and attach the tool mount to the slider, again making sure it is perfectly level. Glue it to the bottom of the slider, so that you have a greater Z axis depth. Finally, put the tool into the tool mount, and secure the U bolts around it. Ga-blamo, you have a working mill-sort of. 8. Leveling the table and attaching the vise

10 The next part is to account for error in the leveling of anything. It wonʼt be quite perfect, but it should do fairly well. Cut a piece of scrap wood to 3 x3, and glue it to the top of the 3 x3 slider, and put a router-type of endmill bit into the tool. Then turn the tool on and drop it to about a quarter-inch above the slider itself. Move the mill head back and forth over the whole surface of the slider until it is all the same height. This platform should now be perfectly level with the Z axis. Now, attach the vise to this platform. In my case, it was just something made of scrap threaded rod and hardwood slats, but this had proved very annoying. A cheap drill press vise should work well, but donʼt get anything over 5 or two pounds, as this mill cannot take a large load. 9. The DRO The DRO is a simple way to make more accurate parts faster. It automatically determines the distance traveled by the mill, and displays it as a decimal number, in this case, accurate to 1/1000 th. The DRO uses an arduino board and rotary encoders, and outputs to any NTSC capable screen. The code just needs to be copied and pasted from below: //Ardudro program, revision 2 //#define ENCODER_OPTIMIZE_INTERRUPTS //haven't tried using the above line yet, may make it faster, but may not. #include <Encoder.h> #include <TVout.h> int xminus = 0; int yminus = 0; Encoder myenc(2, 7);//flip "myenc" and "Ecy" if the X and Y axes are backwards Encoder Ecy(3, 6); float anaval = 0; float value01 = 0; float val = 1000; float value; float value10; float value100; int out; int r = 0; float pos = 0; int rd = 4; long np = 0; float incr = ; //1/2560, this number may change for your setup. Make sure to use a decimal, not a fraction. int onx = 12; int negx = 0; long npy = 0; int ty = 0;

11 TVout TV; const int buttonx = 11;//flip these two (x and y, or the numbers) if the buttons are off. const int buttony = 10; unsigned char x,y; char i = 48; int ic = 6; void setup() { pinmode(buttonx,input); pinmode(buttony,input); digitalwrite(buttonx,high); digitalwrite(buttony,high); x=0; y=0; TV.begin(_NTSC,110,30); void loop() { if(digitalread(buttonx) == 0){ //this doesn't need to be read immediately, so we'll use the loop //instead of an interrupt. Plus, the encoders use the other interrupts. myenc.write(0); if(digitalread(buttony) == 0){ //same here. Ecy.write(0); np = myenc.read(); // np = np*-1; //uncomment if the X axis is flipped delay(1); ty = 0; TV.print_char(onx,ty,'X'); if (val!= np) { if (np < 0){ val = -1 * np; negx = 1; else{ val = np; negx = 0; disp(); np = Ecy.read(); // np = np*-1;//uncomment if the Y axis is flipped delay(1); ty = 10; TV.print_char(onx,ty,'Y'); if (val!= np) {

12 if (np < 0){ val = -1 * np; negx = 1; else{ val = np; negx = 0; disp(); void stringer(){ value01 = val; value = val / 10; value10 = val / 100; value100 = val / 1000; value = int(value); value10 = int(value10); value100 = int(value100); value01 = int(value01); value01 = value01 - (value * 10); value = value - (value10 * 10); value10 = value10 - (value100 * 10); void disp(){ val = val * incr; val = int(val * 1000); stringer(); if (negx == 1){ TV.print_char(onx-ic,ty,'-'); else { TV.print_char(onx-ic,ty,' '); TV.print_char(onx+ic,ty,char(value100)+48); TV.print_char(onx+(ic*2),ty,char(value10)+48); TV.print_char(onx+(ic*3),ty,char(value)+48); TV.print_char(onx+(ic*4),ty,char(value01)+48); You will also need to download two libraries. The first is the encoder library, available here (download is at the top of the

13 page, two lines below the title). The second is the TVout library, available here (I believe I used R5.91). Then, attach one encoder to pins 2 and 7, and the other to 3 and 6, two buttons from pins 10 and 11 to ground, a 1K resistor between the center of the RCA plug and pin 9, a 470 ohm resistor between the same RCA plug center and pin 8, and the outside of the RCA plug to ground. Attach the encoders to the mill, using shaft couplers if you have shaft encoders, or (as I did, though I donʼt recommend it) using rubber stoppers and the sciplus.com encoders. Make sure the encoder body does not move when the shaft it spun, but the shaft turns smoothly. Move the mill in the X and Y and try re-zeroing the axes (the buttons on 10 and 11), and remember where it was backward (Were X and Y flipped? Did it display negative when it should be positive?) Both are very easy to adjust in the code. To flip X and Y, go to the 5th and 6th lines of code (not comments at the top) flip, as per the comments, "myenc" and "Ecy". These are the definitions of each, so flipping these will effectively flip it everywhere else in the code. Re-upload, and check everything else. The buttons can be flipped three lines above setup, and the +/- of the axes can be flipped just after each encoder read in the loop (just uncomment the commented code to flip). Once it reads out correctly, congratulations! Youʼre done, and have just made a cheap replacement for a far more expensive machine. Keep in mind that it is not all that sturdy. Aluminum will push the limits of most rotary tools for general milling, and must be moved VERY slowly. Even pine usually does not cut quickly. Just take your time and stay within the toolʼs limits.

END FRAMES. End frames built using pressure treated 2x4 (1 1/2" x 3 1/2") 36" 34" 7/16" pilot hole. 5 1/2" x 1/2" lag bolt 8" wheel 23"

END FRAMES. End frames built using pressure treated 2x4 (1 1/2 x 3 1/2) 36 34 7/16 pilot hole. 5 1/2 x 1/2 lag bolt 8 wheel 23 END FRAMES End frames built using pressure treated 2x4 (1 1/2" x 3 1/2") 23" 17 1/2" (B) (B) Measure from the bottom of your stone to 1" below the lip to get your measurement. 17 1/2"(B) 36" 34" 1/2" flat