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March 23, 2016:
Another build based on the original OX design. Currently, the cutting area will be about 26" (680mm) x 50" (1300mm). I do not have access to a CNC machine for plate cutting, so I challenged myself to do it on my little Craftsman bench-top drill press. I was surprised to find how well the drill bit squared up with the work surface. I purchased a bunch of 3-6mm bits from aliexpress since I had no metric bits. The 5mm bits have gotten a workout so far. To make the templates, I used Kyo's link in the second post of this thread (Printable plate files | OpenBuilds) and then used spray adhesive to attach them.
I am using NEMA23s (269 oz) for X and Y, and NEMA 23 (174.5 oz) for Z. The machine's y axis will be driven by 1018 Carbon Steel Precision ACME Threaded Rod 1/2"-10 Size, 1/2" Travel/Turn inch (5 start) (McMaster-Carr). The X and Z will be driven by 1018 Carbon Steel Precision ACME Threaded Rod 3/8"-8 Size, 1/2" Travel/Turn inch (4 start) (McMaster-Carr). The controller I have purchased, and played around with, is a Protoneer (clone I believe) and DRV8825 drivers for an arduino board powered by a 36V 11 Amp power supply. I have purchases micro switches to be used for limit switches and homing. I started my design process by copying the Screaming Ox and then combining features of the Cebu and the Frog CNC machines (plus many others).
First, I think pictures speak volumes, so I took a bunch. I will also apologize ahead of time for being longwinded. Off to the build.
Originally, I was planning to use C-beam for everything, but then it became unavailable so I switched to 8020 v-slot linear rail. I will double it up using the 3D printed v-slot connectors if I can convince a friend to print them for me (V-Slot connector | OpenBuilds). After joining them I will drill holes and bolt them together, as well. For the Y axis, I will use a single 8020 on each side.
I used my table saw and a new crosscut sled to cut the aluminum plates. I started with the easiest (and the smallest = cheapest) plates first to get the feel of it. Boy did I ever get the feel of it...at least the feel of the high speed aluminum shavings hitting me I (I wore long sleeves and eye protection). So I made a quick modification using a scrap of acrylic. What a difference this made.
and it's adjustable
The first plates I cut were for the z axis. I hit the center of the template holes with a screw after rough cutting them. On the longer ovalish holes, I drilled two and connected them with my scroll saw. Not all turned out pretty. To finish them up, I sanded them to the lines on the templates with 80 grit and a benchtop sander. Then I tried to make them pretty with a random orbital and 120 grit. This also knocked down the edges so they were not sharp. I used a 3/8" endmill in the drill press to make all the countersunk pars of the holes unless the screw needs to adjust in spacing, then I used a 7/16" endmill.
z bottom with 8mm pillow block bearing.
I did the z plate and the x plates the same way. Then I did a test assembly and found my hole spacing was a bit tight so I re-drilled the 5mm holes with a 6 mm bit which did the trick. I used a 19/64 bit for the eccentric spacer holes.
I used a redneck turning lathe to turn down the 3/8 inch acme rod to 8mm. Basically, I chucked the rod into a drill and fired up the bench grinder. Surprisingly, it worked. However, I found a friend that has a real lathe and has offered to turn down the much longer 1/2 inch rods.
When I got to parts that needed to properly line up, I cut two plates the same size drilled them and tapped one of them with a 5 mm tap. I then screwed them together (screws were countersunk) then repeated the cutting/drilling process.
I was only able to cut so far on some with the table saw. Then, I switched to the scroll saw with a metal cutting blade. With a lubed blade, it cut surprisingly fast, and well. The beer helps steady the hands. Plus it's Portland--You can't do anything without a delicious craft beer.
I bolted the plates together so I could cut off the angle piece the original screws were in with the chop saw. After cutting that off, I used this sander to sand everything down to the template lines. The multiple screws kept the pieces level on the sander.
These scared me the most, but they seemed to have turned out.
As a side bet with myself, I bought a piece of White Delrin ® Acetal Resin Sheet, 3/4" Thick, 6" x 6"
(McMaster-Carr) for about $19. I figured, if successful, I could make many 1/2" ands 3/8" nut blocks for the price of one. To tap them, I cut small pieces of each rod and, using a metal cut-off saw (abrasive blade) and a jig I made to hold the rod and keep my fingers, I made my own taps by cutting grooves across the threads. The 3/8" works, but I am concerned about the 1/2 inch. I may have to rebuild that one.
So, on to the home made 3/8" nut block. I cut the blocks to the size I chose (copying the openbuilds template somewhat) then drilled the required holes after taping on the paper templates. For the rod hole, I drilled it slightly smaller than the 3/8" rod.
For the slot, I drilled a hole at the inner end then used the scroll saw to connect it to the edge.
I put it all together, just to see how everything moves.
Now I need to get on the torsion box table top so I can start cutting v-slot to size and assembling.
March 27, 2016:
This weekend, I built the torsion box table top (1520mm x 900mm)to mount the cnc router on. I recycled the 3/4 particle board from the sides of some old kitchen cabinets for the framing. The flattest place I could find to build on was the floor in the house. Luckily I had a bunch of large landscape tiles around (I haven't had a chance to install them yet) to pile on top for weight while the glue dried.
I put the finished torsion box on the table saw temporarily. It was, as expected, very heavy. Sadly, there is a 1 mm dip in the middle over the 1520 mm length along one side. The other side it is barely noticeable. I guess my floor wasn't as flat as I hoped. I figure if the crown is up, after the framing and spoil board is installed I can surface the whole thing to true it up.
April 4, 2016:
I finished building the 80X40X838 gantry beam. A friend printed out the v-slot-connector parts (V-Slot connector | OpenBuilds ) to line up the two pieces of 20x80 v slot. I pounded 3 in on each end. Then I drilled and tapped 12 holes to screw the two beams together. Technically I only tapped 11 since my tap broke off in the 12th.
I then finished assembling the gantry after figuring out my chop saw was not quite square in one direction. Good thing I started cutting longer than I needed.
A lot has been done since I last posted. I posted here Making Taps for 1/2 inch and 3/8 inch Acme precision rods how I made my 3/8" 4 start and 1/2" 5 start taps and I made the Y-axis 1/2" anti-backlash nuts (basically a similar design to those sold by Openbuilds).
For my y axis, I wanted to support the entire length (1500 mm), and this was the cheapest solution I could find. I purchased two 1/8 inch aluminum cut-offs (each about 5 feet long and cut them to the proper length. At $3.00 per pound with no cutting charge (since they were leftovers), it was much cheaper for me than purchasing pre-made aluminum brackets. I drilled several holes on both the top and bottom of the plates and attached the plates to the 20x40 mm extrusion, which is attached perpendicularly to my 20x80 mm y-axis rails, with t-nuts. I also attached it to one of the 20x40 mm extrusions serving to stiffen the base. These are attached to the torsion box base by angled brackets in multiple locations. I did the sketchup drawing on a plane while flying cross country and I did not have the model for the 20x80 rails so I cheated and stacked 20x40s instead. Forgive me. The cross and centerpieces are not shown in the drawing, but visible in the following photos.
Mounted to y-axis
I only had enough 2040 left to make one cross brace so, since they only had to support the table and add a little lateral stability, I made my own 19x40 out of particle board. I did this by cutting strips slightly over-sized and used the screws and t-slot nuts to hold them securely on the 2040. Then, I used the flush cut bit on the router table to size them down to 40 mm.
These particle board supports were attached to the torsion box with wood screws and the aluminum extrusion base was attached in numerous locations with angle-brackets to the torsion box.
The first layer of particle board was attached to the 20 x 40mm bed support rails with t-nuts and with wood screws to the 40 mm particle board supports. This was done to stiffen the whole machine laterally.
The next layer was laid down and screwed to the first in a few places. A grid of counter sunk pilot holes will be created with sketchucam to screw the top layer to the bottom layer. It will be a fun test run of sketchucam for me.
My VERY temporary electronics set-up.
I decided to go with the Makita RT0701C 1 1/4 HP router so I purchased a 65mm spindle mount then drilled holes and tapped the plate on the z-axis. I made sure it was square to the cutting surface
I made a "pen mount" by drilling a hole in closed cell foam and zip tied it to the router mount. My version of 3D printing. Surprisingly it worked very well. I drew a star with a g-code test someone posted then I cut a few with an old v-bit I had laying around. I have a bunch of new endmills and Ellaire collets on order.
Now it is time to go figure out Sketchucam. I have successfully been able to draw circles and squares (that are actually square) and engrave a few shapes, so I am happy so far.
August 7, 2016: I did some Sketcucam experimenting and I think I have it mostly figured out, so I drilled and countersunk a grid of holes to attach the top layer of particle board to the bottom layer. Due to the low level of my table top, I had to order a couple extra long end mills to drill these holes from Kodiak Cutting Tools. Then, I made another grid of larger holes because I am making different spoiler boards that will be attached to the table top by 1/4-20 screws and a grid of these E-Z lock inserts. E-Z Lok Threaded Insert, Brass, Knife Thread, 1/4"-20 Internal Threads, 0.500" Length (Pack of 25): Helical Threaded Inserts: Amazon.com: Industrial & Scientific
I mounted the E-Z lock inserts prior to facing because I figured that there would be a slight raising around each hole after inserting them.
In the facing portion of the video, you can see both grids of holes.
Here is a quick video
After this was all done, I carved a prize plaque for a little kayak Salmon fishing competition some friends and I do out at Dismal Nitch in August (the name indicates Lewis and Clark were a little sick of camping in the rain by the time they got out here). It is near the mouth of the Columbia River. I grabbed a couple pieces of clipart from the web, combined them in the Gimp, traced the Bitmap in Inkscape, then carved it with F-engrave. Free, free, and more free! My only regret was using oak because the grain messes with the image. The winner caught a 31 pound salmon. Good times and good eats.
I also came up with a plan for upgrading the electronics:
**Edit See Kyo's video. He does a great job explaining different methods. UNO GRBL DQ542MA Wiring Methods
**Edited: I had originally used the pin 8 stepper Enable and this did not work. I switched to +5V pin.
I got a little more done today. I soldered on the additional screw terminals to the screw shield As pictured on the previous post. The top looks decent, but the bottom is not as pretty. However there is continuity throughout all the grounds. The pins on these screw terminals I installed (the six not professional looking ones) are bigger than necessary so I had to ream the holes prior to mounting. Amazon.com: 30Pcs 2 Pole 5mm Pitch PCB Mount Screw Terminal Block 8A 250V: Computers & Accessories
Now I just need to track down some .47 uf capacitors.
8/23/2016-- I swung by Frye's today and grabbed some .47 uf capacitors. Rather than soldering them to the board, I removed some pin headers from an Arduino board I damaged, soldered that to the screw shield and connected it to ground. Then, I installed the capacitors to the ground pin headers and their respective limit switch pin header.
9/5/2016: I finished updating the electronics and put everything in a computer case. I made a z probe and I wired it up using an old car cell charger wire and an old headphone jack. Since I am using a computer case with a headphone jack, I used those existing wires inside from the jack as the z-probe wires to the Arduino board. I did the same with the USB wires. If I do hold and resume buttons, I will use the existing computer tower power and reset switches, as well. I am using a 36 V power supply so a "cheat" I did was to wire three 12v computer fans in series since an additional fan was cheaper than other options.
Now I just need to build the bench that the entire thing will sit on.
Got around to updating the Sketchup file today.
December-January 16, 2017
I finally got around to building the permanent base for my CNC router. I started in December, but progress slowed as I pondered how to finish the interior and route wires down below.
Until this base was made, the CNC router, that was mounted on a torsion box, has resided on my table saw due to its comfortable working height and flatness. I had an old jointer I never use sitting on an HTC Adjustable Mobile Base (Adjustable Mobile Base for Power Tools HTC-2000 - Give Your Workshop Breathing Room by Making Your Larger Tools Mobile (up to 500 lbs.!) - Toolstand - Amazon.com). It wasn't quite big enough so I ordered the extension kit (HTC K1218 Extension Rail Kit for HTC2000/PM1000 Universal Mobile Base - - Amazon.com). I assembled the bench portion of the 2x4basics Workbench (Amazon.com: Hopkins 90164 2x4basics Workbench and Shelving Storage System: Home Improvement), but rather than using fir 2x4s, I made much more dimensionally stable 2X4s by gluing up 4 pieces of 3/8 inch plywood for the cross members. For the middle shelf, I ripped a couple of these for 2x2s so I would have room for my computer tower which I used for an electronics enclosure. I cut two shelves out of the pieces of 1/2" particle board left over from my torsion box build.
Then, I assembled the mobile base to the right size. I basically stretched this thing to the limits.
I had to notch out the plastic on two legs to get it to fit.
One of the things I thought I would miss was the height of the machine, but the new base was only about 1/2" shorter than the saw, which made it easy to just slide it right off. It would have sucked to have to lift it. It weighs a ton.
After putting it on I started pondering doors to access the shelving below and to keep them mostly dust free. So, I took measurements and drew up the doors with Sketchucam.
I also started drawing some drawers for tool boxes, but that will be another day.
Today (1/16/17) I cut out the remaining door panels. In this video, I was using the default Sketchucam feed rate of 2540 mm/min. I forgot to change it. On subsequent cuts, I sped it up to 4000 mm/min and I used a shorter 1 flute cheap Chinese endmill which did an impressive job. I think I will be ordering more soon.
After cutting with this thing since August, I figured I should probably calibrate it. It seemed to cut fairly accurately, but I figured this would be a quick little project that would put my mind at ease. My calculated steps/mm for both the 1/2"-10 five start (Y axis) precision Acme Screws and the 3/8"-8 four start Acme screws (X and Z Axis) were 125.984 at 1/8 microstepping. They both move the nut 1/2" per revolution. To calculate this I used this formula: step per inch = (motor steps * microstepping) / (travel at one turn of the motor in inches) .
So, (200 * 8) / (.5)=3200 steps per inch. Converted to millimeters: 3200/25.4 = 125.984251968504 steps/mm
Prior to calibration, when I sent the Y axis 1000 mm it traveled about 1000.3 mm. The X axis went about 500.99(ish) when sent 500 mm. To obtain the correct steps per mm, I used the following formula:
(Commanded distance/Measured distance) * Calculated Steps/mm = New steps/mm
1000/1000.3 = 0.999700089973
0.999700089973 * 125.984 = 125.946216135158
New Y: 125.946 steps/mm
500 / 500.99 = 0.998023912653
0.998023912653 * 125.984 = 125.735044611676
New X : 125.735 Steps/mm
The Z did not seem to need correction, although I could probably use the new X axis value since the Z screw was cut off of the X screw. I put this info in the video, but if you want to watch it after reading this, feel free to fast forward.
Lead Screw Driven Ox Derivative (850x1500)
Another build based on the original OX design with a cutting area will be about 26" (680mm) x 50" (1300mm) and driven by lead screws.
- Build License:
- CC - Attribution - CC BY