W7 - Computer-Controlled Machining A Full body scanner¶
SAFETY FIRST fun later¶
- IF ANYTHING HAPPENS: THIS TWO.
After EMERGENCY STOP, it keeps the last line of GCODE, but you have to Zero again, and make sure you start not from the last line but from the previous last line with a POSITIVE Z
Make sure the collector is on when you cut to prevent fires!!!
- Turn off the collector if you cut fast (rpm) and slow advance.
To prevent the cut pieces to fly into your face, set up bridges when you set up your cut.
Be clever, be smart, use these: a facemask is also recommendable as you won’t be breathing wood dust. (yes those are reebook pump, ‘m-mazing yes)
Preparing the files withRhinoCam¶
CREATE THE BOARD WHERE YOU ARE GOING TO CUT
DRAW WHATEVER YOU ARE GOING TO CUT
SELECT THE TOOL OR CREATE IT
FEED AND SPEEDS
CUT LEVELS (how much cuts with every pass total=cut+finish)
SiMULATE END (if you do the whole simulation may hang up on you)
Measure and fix material¶
Fix the board to the sacrifice board, usually is fixed within the first 10 cm of the edge, that edge shall be kept free in your design, better put a square inside the square that depicts your board to be safe. Put enough screws to make the board flat and steady.
The XY size is standard, discrepances are negleactable.
Measure the thickness as flor humidity and wood cutting and wood characteristics may cause discrepances in the Z, and Z is important to have your piece out of the whole board.
The 0 is set to the bottom left corner
Install end mill¶
- If necessary, you can remove the dust collector to make it easier to change the tool. Use the machine’s wrench and key to release the collet and holder.
- DONT TOUCH THE FLUTES, they and sharp and your filthy grease can affect the thing. Hold the shank instead.
To get the collet out of the holder is to press it laterally untill it makes a metalic click, the same to put the thing back.
- Leave around 2-3mm of the shank out of the collet and then tighten with the wrench. Press it tight and then… press it more.
If you placed the board aligned with the machine bed, X,Y could be set by sending it to home, if not, move then to the origin of your board and set the 0 there.
- To set Z, we have the auto-leveler, that should be set right under the tool.
- Make sure to put it back were it belongs
After doing all that, is time to start the machine, but first, a couple of checks:
- MAKE SURE THE COLLECTOR IS ON!!!
- move the axis away so you can reach the cutout pieces,
turn off the machine and dust collector,
Then, proceed to remove the material.
Don´t be a pig, clean after yourself and store all the tools and protection gear.
About removing the material.
Remember that most probably you used bridges to prevent the cuts to fly away into your face.
- Use a formón (chisel) to cut the pieces free.
Chip load Calculation¶
A really basic calculation is to multiply the spindle RPM x number of flutes X chip load, to get the appropriate feed rate.
We got 2440x1220 15mm spruce plywood boards. After a quick search, we found that the chip load is between .011”-.013”. Since our machine is set up in millimeters, we did the following calculations
18k x 1 x 0.28 5040 20k x 1 x 0.28 5600 22k x 1 x 0.28 6160 24k x 1 x 0.28 6720
Even tough we had the numbers, we wanted to try the possible combinations, varying from 18k RPM with 2k feed rate, up to 24k RPM with 7000 feed rate.
But, the math does not lie. The best results were the ones we previously calculated. This are the results with a downcut end mill.
We repeated the test with a up cut as well and got batter results. But probably the main reason is because the tool was newer and more sharp.
Turn on machine
To set origin: Place the button device and move the mill till center of button. Then check pressing with the mill tip if it hits the centre to set the 0 position. Align mill to border to set x axis. Do same for y axis.
Set again the the dust collector.
Load screws file on pc. Put on glasses. Turn on vacuum
Z align Z align
x align y align ready cutting job done
pass 1 2k 18k smell burned wood and making dust
pass 11 2k 22k turned air off to prevent fire
A grade which may have open splits and knot holes according to EN635-3. Grade III offers the full technical strength of spruce plywood and it is recommended for use in applications where surface appearance is not of primary importance. Grade specification according to EN 635-5.
Plywood 1/4” tool .011”-.013” (0.28mm - 0.33mm)
RPM x Flutes X chip load
18k x 1 x 0.28 5040 18k x 1 x 0.33 5940
20k x 1 x 0.28 5600 20k x 1 x 0.33 6600
22k x 1 x 0.28 6160 22k x 1 x 0.33 7260
24k x 1 x 0.28 6720 24k x 1 x 0.33 7920
- Even in a hurry is recommended to use up to 70% of the flute length, otherwise there might be the hazzard of breaking the tool or significantly reducing the lifespan of the tool, the so if you cut deeper, reduce feedrate and mantain or increase rpm .
My Idea is to build a 3D Scanner support to make the fullbody scan I wanted to do in W4.
… comes from W2 & W3, original files there, here the cnc gcode files.
I prototyped with the lasercutter
NO GLUE, NO SCREWS, NO BUGGERS, NO BUBBLEGUM.
The scanner will have a 3D printer fixture, pulley and will have a counterweight to allow the scanner scan with a controlled free fall, the scanner will then be pulled back on top and the angle selector will be moved 10º according to the divisions of the base.
The bearing will be made with to concentric pipes
I used the parametric capabilities in order not only to change scales, but to take into account a very good study of tolerances made by Gustavo Abreu, rearch for tolerances in his page (after group assignment).
Everything came out just fine exept for the cubes that join the carry upper and lower part and the slits made to accomodate the two long suports that we will call canes. The slits are not the problem but the area of the wood where the canes came from is slightly thicker. With a little bit of sanding they get in perfectly.
After some happy sanding to make the rails on the canes smooth like a baby cheek to let the slyders for the weight and the kinect fixture to slyde, a set of concentric pipes were used as a bearing, my gess is that one of the pipes will wear out sooner than the other due to the material, but it was impossible to get one of that size on that material.
I had to repeat the cubes and make a base for the whole trinket.
Now in order to fix the two canes together a set of palitos of 1cm in diameter will be used.
NO GLUE, NO SCREWS, NO GUM, NO BUGGERS.¶
The rotation arm is too short ?! the rails must be farther from the body, buhu. If I make it larger the Center of Masses goes to cuenca (to hell). Anyhow, things fit. (the base is missing)
The rotation will have two concentric pipes as a bearing
The pivotal (static) pipe can be “nailed” to a pocket in the base for the person to stand thanks to an chamfer made on the pipe’s fringe.
To reduce friction vinyl can be used between the rotation support base and the rotation arm loop (hole has to be made), it really works, but doesn´t last forever, specially if you have particles under the vinyl.
This project may continue as our group MACHINE DESIGN PROJECT.