Sunday, June 26, 2011

SpinArt Desk



Making things is just so much fun and taking on new projects is a rewarding experience where you can learn something new.  Take this SpinArt machine for example.  I went to the local ReUse center last week and as usual, I didn't know what I was going to find.  I didn't have the desire to make a SpinArt machine at the time, but the idea came to me when I found an old school desk there for $10.  I thought it would be a great "ReUse" to put a rotating platter inside the flip up top and call it a SpinArt machine.  Of course, the "Art" part of the name as it relates to the methodology is subjective and I really want to call it a "Centrifugal Pigment Accelerator", but in the name of effective communication I will reluctantly call it a SpinArt Machine.

Now, a SpinArt machine, no matter how good it looks, really isn't a piece of furniture I need around my house.  It was great fun to make and even the first few paintings were fun, but it should find a new home and I know just the place where this will be right at home and that is the Mt Elliot Makerspace in Detroit.  I have been spending a fair amount there recently helping my friend John setting up the wood shop.  There is a lot of work to do still, but it is nice to see progress being made.  This weekend we were painting the ceiling in the wood shop.  I also took a break to paint the SpinArt machine desktop when I was there.  I plan on taking the SpinArt machine down there next time I ride in a truck and hopefully I will be able to get some video of the thing in action.  It is a little hard to film and operate it at the same time.

According to the Wikipedia entry for Spin Art, this method of painting has been documented since 1958.  The way "SpinArt" works is that you have, whatever it is that you want to paint, attached to the platter, then you turn on the machine to spin the platter and when it is up to speed, you drop paint onto whatever it is that you are painting.  If the platter is spinning fast enough, the coefficient of friction between the paint and painted surface is high enough and the viscosity of your paint is low enough, the centrifugal force acting on the rotating paint will draw itself out radially from the center of rotation.  Several things will affect the pattern as it is painted.  Most notable are the aforementioned angular velocity and paint viscosity ,but also, the rate of change in angular velocity will impact the finished painting. 


Here is the "before" pic of the desk as it sits outside the ReUse Center






I think the picture below will give you a good idea of everything that is going on here.  There is a motor underneath the wooden disk inside the desk.  Outside is the speed control (more on this later) attached to the side.  You can also see a lamp and the cord to power it all on the ground.  It really is that simple, but I will go into some details in a moment.


The motor came from a box fan.  I mounted it to the inside of the desk using a couple of pieces of poplar wood.  Where the poplar wood makes contact with the ribs in the desk, I cut out some neoprene sheet to put in between.  This is not so much for vibration dampening as it is to keep things from slipping and subsequently loosening the screws.




The fan motor is an induction motor and as such, cannot be speed controlled with an ordinary incandescent dimmer switch.  I confirmed this to be true by trying to use a lamp dimmer to control the speed of the motor with nothing attached to the output shaft.  Then, I tried adding a 60W light bulb in series with the motor.  This allowed me to have the speed control I desired using a cheap ~$8 triac chopper dimmer (aka ordinary incandescent lamp dimmer).  I believe this changes the power factor of the motor allowing the necessary speed control.

So, the wiring goes like this.  The hot leg of the 110VAC coming into the blue speed control box on the side goes to one lead of the lamp dimmer.  The other lead of the lamp dimmer goes to one lead of the lamp base cord, I chose the center pin lead to be consistent with conventional wiring and not the threaded part of the lamp base.  The other leg of the lamp cord goes to what used to be the hot side of the motor switch and the neutral side of the fan switch goes to the neutral lead of the wall power.  Turn the 3-way power switch that came with the box fan to the highest setting and pack it all neatly in a plastic 2-gang switch box making sure all wires are properly and securely connected.

Here is the original motor speed selector switch getting wired up to be put in the blue speed control box.  I set it to the highest setting before connecting the dimmer and closing up the box.




I made the rotating platter by cutting a disk from a piece of 3/4" birch face plywood then cleaning up the cuts on an upright belt sander.  A thru hole was drilled for the diameter of my motor shaft and a counterbore was made for the left hand motor shaft nut to sit in.  This way the motor shaft nut will not protrude above the surface and "dome" your painting.  I chose 13.9" as O.D. (outside diameter) of the platter because Pythagoras told me to.  That is the "hypotenuse" of a standard sheet of paper 8.5"x11" thus, a piece of printer paper will fit just right on the platter.  You can download a drawing I made of the platter here.

After installing the platter on the motor shaft I measured the runout on the O.D. to be no more than 0.01".  It is important to remember that this platter is going to be spinning pretty fast so you want it to be well balanced.  Mine actually has a vertical deflection when it rotates and I need to look into this as it creates a vibration at a particular speed.  Currently, I just don't run it at that speed instead, going faster or slower.




And speaking of mounting the platter to the motor shaft, it was necessary for me to buy a motor shaft collar from the hardware store.  You can see it on the motor shaft in the picture below.  I set it so that the distance from the top of the shaft to the top of the shaft collar was less than the thickness of my wooden platter (3/4") and then turned the grub screw with an allen key to lock it in place.  In the picture below the collar is not set to the correct height yet, it is intentionally set too high for the sake of picture clarity. 




I decided to paint the top of the desk "SpinArt" style before mounting the motor in place.  I found a couple of cans of house paint in the woodshop at the Mt Elliot Makerspace so, that is how the color was decided.  I quickly found out that I needed to thin the paint with water instead of using it straight out of the can to help it flow better and fling out.  To spin the top I very carefully measured the center of the desktop and mounted the box fan propeller to the underside of the desktop with 3 screws.  I slipped this onto the motor shaft and with paint applied set it spinning.  You can see how that all went in the raw and unedited footage below.




Weird stuff happens in the end of the first video here.  I think the way the camera draws the lines of each frame of video and the rotating of the desk lid makes it look like it is morphing into a different shape.  I assure you it is not.  There are some pics below of the same phenomenon.






After the spinning stopped this is what the desk lid looked like.  I can see where some of the paint started drying before it got all the way out to the edge.  I think it looks pretty neat and it figuratively says "I am a SpinArt desktop", but as you can see in some later pics it literally says "SpinArt" on it because my mother was nice enough to cut out a custom stencil and stencil the word on there for me.




Here is a pic I took while the desktop was spinning and paint was getting on my leg hairs.  There is a pretty interesting digital photography anomaly going on here.




For a finishing touch I bent a coat hanger and put some heatshrink on the ends to hold this wire basket for the paint bottles.  As far as paint goes, I have both washable and Tempera paint.  Again, thin it out before use. 




I use "Removable Mounting Putty" to stick the paper to the platter.  It seems to work pretty well.




As an extra precaution, I decided to make a cardboard paint guard to stop stray paint exiting the desk cavity.  It also keeps the inside of the desk a bit cleaner and you can just throw the cardboard away when it gets to much paint on it and make another one.  It folds up when you are done and can be stored inside the desk.




So, this was a pretty fun project and I think a good "ReUse" of the school desk.  It took about two days and ~$30 to make but I did have a lot of materials already.  There isnt much more to say about it so I think I'll just bang a few more photos up here and maybe a vid and call it a day.








In this video, you can hear the paint splattering off and hitting the cardboard.








2 comments:

Nikoli said...

WANT! That is most excellent. Well done Sir.

Unknown said...

great idea with the desk man. quite ingenuitive to use that fan motor, and school desk.