Project description

My project will be linked to the assignment “make something big”
I have always problems with my TV's furniture to move it because cables stay below the wheels and I have not enough place to put my computer or any other electronics materials. So, I will make a furniture big enough to solve the problem I have spoken previously. Furthermore, I want some decoration on it.

1.1 concept

First use the picture of the furniture for which I have problem and then increase the size and think about what type of new cut in the wood, could be helpful to improve the furniture and also to decorate it.

I decided to use almost the full board that Alex offer us to use to make something big.
A board called sheet industrial standard = 2,44 x 1,22 meters with a thickness of 12 mm.

1.2.1 First part of the drawing on my laptop

To do that I did use the software called Inkscape running under Ubuntu 10.04 LTS - Lynx Lucide
I did make 5 drawings to cut my furniture which will allow me do edit on the Partworks software used in the Fabalab of Amsterdam.

measure of each pieces:

2 squares ( I will call them Squares) of 60cm * 60 cm, on this squares, the machine will cut 4 rectangles of 1.2cm*3cm spaced out of 16 cm. This will allow to make joints overlapping the 4 pieces which are setting up the furniture.

After that, there are 2 rectangles (I will call them rectangles) of 60 cm * 110 cm. The machine will cut 3 rectangles holes or pockets 11,128 mm (around 12mm which is important later during the cut) * 16 cm ( at 1.5 cm from the edge of the wood). These holes will be separated of 3 cm of wood. I will add furthermore a path to add another piece of wood in the middle of the furniture. To do it, I will cut a path of 5mm of depth and width and 60 cm of length, set at 55cm, in the middle of the each rectangles.

Finally, another cut 58.8 cm * 61.2 cm (I will call it non-square as it looks like but it is not). In this cut, I will make another cut in sharp of “L “, 9,2 cm * 9,2 cm * 3,3 cm * 5,2 cm * 5,9 cm. The first “L” is placed at 16 cm and the second one at 40 cm from the bottom of the piece. This piece of wood will split the furniture in 2 parts.

I did add later drawings for the decoration of the furniture. Both drawings were set on the squares of 60 cm. One drawing is the Breton flags and the other one is a triskelion.

breton's flag:

triskelion:

When I open the file with PartWorks tool to prepare the path that the machine is gone take to make the cut on the board, it is not working some part of the all drawing is missing. I did check with other peoples' computer and saw that on Macintosh computers that my DXF format was not readable also on these machines.
To make it works,  after several tests, I did finally export my drawing in "pdf" format, version 1.4. This time it is working. I can see my drawing on the Partworks software and preparing the path the bit of the machine is gone take to cut the wood as on my drawings.

1.2.2 Second part of the drawing on the Partworks

When the drawings are imported on Partworks, I did check if the all measures I have done are respected as sometimes, it can be a problem when you load a file which has been exported in a different format that the file which has been first created.
When this check is done and if needed some part of the drawings corrected.No problem of size for me but I had to do some change in the drawing just for the cut test.
We can continue the work. Be sure also not only drawings are corrected but also the size of the piece of wood you are working on, is set correctly on PartWorks.
In that case it has to be 2,44 x 1,22 meters.

We need now, to have an error free toolpath, so no over lapping and vectors for each drawings need to be closed. Otherwise, it won't works.

Check this with Partworks tool available and join and remove vectors (see link below for more advises and help)
In my case, I had a lot of mistakes (duplicates vectors and opened vectors) but I corrected them. In fact I should have been able to do it before with Inkscape but it was not correct. So, I did corrected it. Regarding the decoration, my drawing was not correct neither on the first time but for them, I corrected them later on Inkscape and the second time when I load them, they were all good and can be used directly.

http://www.youtube.com/watch?feature=player_embedded&v=wSHQsthRajg

1.3 First cutting test

If you need some help for you first step, I invite you to read this link which is providing the most import information to start to use the CNC router.
http://wiki.fablab.is/wiki/Shopbot

and a lot of links can be found on this link too, but you have to found out which one is interesting for you:
http://www.shopbottools.com/index.htm

Now, I can start ShopBot CNC console on the computer plugged to the milling machine and turn on the button of the milling machine and turn on the key. Now, I can start to work with this machine.
It is very important to follow the all steps (read the checklist of http://wiki.fablab.is/wiki/Shopbot ) for security reasons. But before that, you will have to prepare the machine, by adding the bit. I have decided to use a bit 1/8 straight 4FL end for the cut of the wood board and to use this bit, I need to use a collet imperial 1/8 to set the bit in the milling machine.

to found out which bit to use, you can check this site:
http://www.onsrud.com/files/pdf/OC-09CatalogR.pdf

Keys, collet imperial, the bit and spindle

I did install now the bit by using the fixing wrench for shopbot tool holder. New bit can not be add without using these keys. One of those keys is linked to the key which is switching off the milling machine. This means when someone is changing the bit, it is technically not possible for the machine to turn on as it has been switch it off. When the bit is changed, don't forget to set back the key to switch on the the milling machine.

See the key security system in the Amsterdam Fablab

Now, before to go further, I did set the Zeroing point and set the X and Y value to 0, matching to the wood board where the bit is set to 0 for X and Y axes.
See below the quick reference guide for commanding the machine:

http://www.shopbottools.com/files/SBDocs/SBG00109090803CommandQuickRefLaminate.pdf

The milling machine

You can see the table where the cut is occuring, the red button for any urgence to stop, the screen which is plugged to the computer itself connected to the milling machine.
This is the machine to make something big :-)

This is very important to get the drawing cut as it is on the screen. If the values of any of them are wrong, then the cut won't be done as it should be. In case of doubt. Set again the values correctly.
XY Origin Position: Most of the time, it is matching to the bottom left corner. For me it is also the case regarding the X and Y position.
You can alos use this document to set it but it is a long document to read:
http://www.shopbottools.com/files/docs/SBG00142080923UserGuide.pdf

or this video to provide you an idea how to do it:
http://www.youtube.com/watch?v=iznNP9MzzgY

Picture of my tests

During this test, I figure out that I needed to set some tolerance when I was doing the pockets (holes). Indeed, the thickness of the board is 11.80 mm but to be sure it fit together some tolerance is needed. I mean a pocket (hole) little bit larger. Otherwise it won't fit. This is the mistake I have done on several of my tests. I only managed to get the good setting after 8 tests with some advises from Alex Schaub.
If you want to add or remove extra material around the vector object, define the distance between the boundary of the selected vector object and the profiling tool in the Allowance box. Type a positive value to add material or a negative value to remove it.

According what I read, the best was to add 1/100 of the size of the thickness. I did also add some “dog bone fillet” on each corner of the pocket which is allowing corners joints to go inside the pocket without any problems. And it is working.

How looks a dogbone

Pictures of the pocket and joints and how they fit together

1.4 Finalising the drawing according the feedback of the first cutting test
So, I did apply on my drawings the setting which needs to be set on the pocket. Allowing later to make sure that the pieces would fit together well at the pocket joint. As drawing are good now, we can create tool path for the machine.

1.5 Create the toolpaths for each part of drawings
When you have selected the drawing you need, click on the toolpath button on the right side of the screen.
To get an idea how it looks and how it work, you can read this link:

http://fab.cba.mit.edu/content/tools/machines/shopbot/

For the all cuts, please Selected “create pocket toolpath”
Regarding all the drawings matching to the cut of the furniture, the setting are the same.
I only need to be careful which part I am cutting first.

Value of the cutting parameters:
start depth: 0 (starting on top of material)
Cut dept:13mm
tool:click on select and set:
First the bit used: 1/8 straight 4FL end
cutting parameters:
pass depth:4 mm
stepover: 3mm
Feeds and speeds:
spindle speed:1200 r.p.m (round per minute)
feed rate:60 mm/minute
pluge rate:20 mm/minute
Machine vectors:
outside/right
tabs,corners, leads and ramping. I keep them as there are.

Regarding the drawings' decoration, I only changed the 3 parameters on the machine
start depth: 0 mm (it did stay the same)
Cut dept:3 mm
and
cutting parameters:
pass depth:2 mm
stepover: 1 mm

For each drawings, I need to click on calculate when parameters are set. A warning is appearing, click “yes”. Then I can click on preview to get a view of what it will be done by the machine and what should be visible on the board.
At that step, when drawings are fine, I save them by clicking on the disk icon and the file is saved under a “sbp” format.

3 D view of the drawings before I saved under "sbp" format and I cut each pieces

When file is saved under “sbp” format, it can be loaded under the ShopBot CNC (computer numerical control) console.
As the Z, X and Y values were already set previously, there is no needs to set it again but if you have a doubt, please reapplied for Z,X and Y the 0 value. place the bit as it is supposed to be set for cutting corectly.
When we load the file to CNC console, we have the message with a new window,”continue?”.
Click “OK”. Then, new message “Now starting router/spindle: click ok to start /spindle and run the port file”. Well, if spindle is not starting, don't continue. If spindle start to run, then you can click “ok”.

How the shopbot console looks on the screen:

Example of the content of a sbp file:

'SHOPBOT FILE IN MM
IF %(25)=0 THEN GOTO UNIT_ERROR 'check to see software is set to standard
C#,90 'Lookup offset values
'
'
TR,12000,1
PAUSE
'
'Turning router ON
SO,1,1
PAUSE,2
'
'Toolpath Name = coupe
'Tool Name = End Mill (0.125 inch 3.175 mm) (for MDF, layer chair)
MS,59.8,14.9
JZ,20.000000
J3,54.306664,503.063965,6.000000
M3,54.306664,503.063965,-4.000000
M3,149.815948,503.063965,-4.000000
M3,149.815948,598.573242,-4.000000
M3,113.516884,598.573242,-4.000000
M3,113.516884,545.941650,-4.000000
M3,54.306664,545.941650,-4.000000
M3,54.306664,503.063965,-4.000000
M3,54.306664,503.063965,-8.000000
M3,149.815948,503.063965,-8.000000
M3,149.815948,598.573242,-8.000000
M3,113.516884,598.573242,-8.000000
M3,113.516884,545.941650,-8.000000
M3,54.306664,545.941650,-8.000000
M3,54.306664,503.063965,-8.000000
M3,54.306664,503.063965,-12.000000
M3,149.815948,503.063965,-12.000000
M3,149.815948,598.573242,-12.000000
M3,113.516884,598.573242,-12.000000
M3,113.516884,545.941650,-12.000000
M3,54.306664,545.941650,-12.000000
M3,54.306664,503.063965,-12.000000
J3,54.306664,503.063965,6.000000
J3,297.751160,503.117859,6.000000
M3,297.751160,503.117859,-4.000000
M3,393.262238,503.117859,-4.000000
M3,393.262238,598.628601,-4.000000
M3,356.961395,598.628601,-4.000000
M3,356.961395,545.995544,-4.000000
M3,297.751160,545.995544,-4.000000
M3,297.751160,503.117859,-4.000000
M3,297.751160,503.117859,-8.000000
M3,393.262238,503.117859,-8.000000
M3,393.262238,598.628601,-8.000000
M3,356.961395,598.628601,-8.000000
M3,356.961395,545.995544,-8.000000
M3,297.751160,545.995544,-8.000000
M3,297.751160,503.117859,-8.000000
M3,297.751160,503.117859,-12.000000
M3,393.262238,503.117859,-12.000000
M3,393.262238,598.628601,-12.000000
M3,356.961395,598.628601,-12.000000
M3,356.961395,545.995544,-12.000000
M3,297.751160,545.995544,-12.000000
M3,297.751160,503.117859,-12.000000
J3,297.751160,503.117859,6.000000
'Toolpath Name = droitedecoupure
'Tool Name = End Mill (0.125 inch 3.175 mm) (1)alu
TR,12000,1
MS,59.8,
J3,589.582336,600.186096,6.000000
M3,589.582336,600.186096,-3.000000
M3,589.582336,-0.226314,-3.000000
J3,589.582336,-0.226314,6.000000
J3,589.582336,600.186096,6.000000
M3,589.582336,600.186096,-6.000000
M3,589.582336,-0.226314,-6.000000
J3,589.582336,-0.226314,6.000000
J3,589.582336,600.186096,6.000000
M3,589.582336,600.186096,-9.000000
M3,589.582336,-0.226314,-9.000000
J3,589.582336,-0.226314,6.000000
J3,589.582336,600.186096,6.000000
M3,589.582336,600.186096,-12.000000
M3,589.582336,-0.226314,-12.000000
J3,589.582336,-0.226314,6.000000
JZ,20.000000
J2,0.000000,0.000000
'Turning router OFF
SO,1,0
TR,0,1
END
'
UNIT_ERROR:
C#,91 'Run file explaining unit error
END

Once each toolpath is created for each drawing and saved in “sbp” format.
We need to run the machine and cut the pieces as planned. The file logs visible above are show what type of information the milling machine is using to make the cuts.

1.6 Order of the cut and the decoration

1- The 2 squares
2- The pockets of the rectangles are done before the rectangles because otherwise, when rectangles are cut, the loose won't allow the machine to cut correctly the pockets. So, this is the reason, I start by the pocket (or holes)
3-The path of 5mm of depth and width and 60 cm of length set at 55cm, in the middle of the each rectangles.
4-The non-square
5- After I make 4 drills in the non-square piece of wood. Machine can cut the sharp of “L “ in the non-square.
6- After I make 4 drills in the one of the square piece of wood. Machine make the Breton flags
7- After I make 4 drills in the one of the square piece of wood. Machine make a triskelion

2 the pieces of wood cut, decorated and all fit together and the wheels added