Monday, March 25, 2013

CNC Machine Enclosure Take Two

This week at the Tinker's Workshop I have been rethinking my original design for the CNC machine enclosure that I posted last week.  My first attempt at the design looked great but actually still needed a bunch of work to make it less expensive and be able to have some sound proofing built into it.  Here is what I came up with. 

The enclosure for my Solsylva CNC machine will be nothing more than a large four foot box with doors that open on all sides.  Only the front doors will have windows in them.  All other door will be solid with foam pyramid foam for sound reduction while the machine is in use.  The original design had no sound reduction foam in it so it looked good but did nothing to make it quieter to use.  All the doors will allow for easier cleaning and maintenance of the machine.

The base of the enclosure is made up of 2 x 4 lumber, 1/2 inch plywood, and four casters.  The original design had a slated base which still could be designed that way but with the plywood deck it was no more expensive and a lot faster to construct.  All good.  This platform will hold the PC tower and electronics (black box) that makes the CNC work.  With the base being as large as it is it will also be a nice place to store anything else that I will need for the CNC machine or for the shop itself.   The  one piece deck also will be easier to clean than a slatted floor too

This is what the front doors will look like from the inside of the enclosure.  The pyramid foam I found online from a  company named The Foam Factory.  It will cost around $42 for the 12" x 12" foam panels that will be needed in the project.

Here is the other door panels with all surfaces covered with the foam sound deadening panels.  The foam can either be glued in place or possibly set in using Velcro strips.  I will have to experiment with some scrap pieces before I decide which direction I will go with it.

Even the top of the enclosure will have foam sound deadening panels inserted into it.  I figured that this will  be worth the effort as anything that can be done to make the machine run quieter will be a plus on my nerves and on my neighbors should they be close enough to be listening in on what I am making at the time.  The top panel has small mounting blocks attached to it so that it can just be dropped into place on the top of the enclosure and it will be ready to go.  
  Now for the cost savings in the project.  I crunched the preliminary numbers on the cost of the enclosure and this is what I came up with .  The original design which looked pretty but would be noisy  to use would cost roughly $412 to build.  This did not include the cost for paint or varnish and misclanious hardware (eg..screws, bolts, nuts, etc.).  After reworking the design to make it the same size but with sound deadening foam to reduce the noise the cost was  came down to $264 to build.  The big cast savings was mainly due to the expense of all the Plexi-glass that the original design called for.  Pretty and expensive.... not a good match.  All the windows did was allow enough light into the machine so you could see what you were milling.  The new design will have electric lights built into it so all the windows will not be needed. 
  So with the new design I get an enclosure that is easier to build, less expensive (Savings of around $150), and quieter to use while running the CNC machine.  I think we have a winner!  Once I get all the drawings put together for the design I will have plans put up on the plans page here for anyone that also needs this enclosure for their CNC machine.  Stay tuned for further updates when I start putting this project together.  

Wednesday, March 20, 2013

Spring Is Coming..... Time For A New CNC Project

  After several weeks of putting up with even more cold winter weather, shoveling more snow, the ever present tax man, and hassles with my home loan company I am finally getting back to getting another post out about a new project that again is long over due. Life is just to short to not have fun and so I hopefully will have better times ahead with this project and other projects that I have planned.  
  This project that I have been designing will involve making an enclosure for my CNC machine in the workshop.  I have used the machine in the old Tinker's Workshop with some great projects but have always had to hassle with the cleanup of the machine afterwards.  The CNC machine is a great tool to have in the shop but it tends to throw dust and chips of material everywhere while it is doing it's thing.  This got to be old really quick but with the old shop I was not able to make an enclosure for it simple because it would not fit into such a small space.   The new Tinker's Workshop is more than twice the size of the old shop so this is not a problem.  

  I have been spending a lot of time on my computer designing the enclosure for the CNC machine and still have a ways to go before I can start construction.  Lots of drawings still need to be created of  all the parts that go into the enclosure.  So for the time being at least I can show you what I have in mind for this project.

The enclosure for the machine is quite large as you can see from this computer image.  It is four feet square and stands six foot two inches tall!  This is a big enclosure to be sure.  The base is made out of 2 x 4 lumber and 1 x 4's for the base platform. 

In this image you can see the CNC machine inside the enclosure with the two front doors opened.  The sides of the enclosure will open up in the same way that the front doors do so that cleaning or maintenance of the CNC machine can be done easier.  All of the panels that make up the doors are exactly alike so it's just a matter of duplicating the parts for eight door panels over and over again until you have all that you will need.  The back panels for the enclosure will not need to be able to open up but could be just the same.  It might be a good idea should I need to replace the belt that drives the two side shafts that run the gantry on the X-Axis of the CNC machine.  It would be easy enough to allow for this and the cost is just a couple dollars more to add this feature. 
The big expense of the enclosure is not the wood to make it but rather the lexan (plexi-glass) windows for the project.  I priced out the cost for the twelve lexan 1/8th inch windows and I am looking at around $250 just for this part of the project.  Expensive to say the least.  Unless I can find a cheaper price or something else that will fill the bill I have no other choice but to go with this material. I suspect that the entire enclosure will run close to $350 once it is completed.  Not a cheap piece to make due to the cost of the windows.  But like anything else in the long run the CNC machine will be safer to run and easier to clean because of the enclosure.  Hopefully it will also cut down on some of the noise of the CNC machine makes while running.  I will have to see how my budget looks when I finally get the drawings for the enclosure completed.  Hopefully by then my old home will be sold and that will free up my cash flow once again for this project.  In the mean time it does not cost me anything to at least get the drawings ready for the project so when I can find the cash to put this big box together I can tear into it without delay.  I'll post more about this project once I start putting it all together. 

Monday, March 4, 2013

From Video Animation To The Real Thing

This week at The Tinker's Workshop I came across an interesting video on Youtube. 

This video animation is of a planetary gear set in motion.  This kind of mechanism is used in automatic transmissions and is a key assembly in making it all work.  I was so intrigued by the animation that I immediately had to see if I could make one for real.  So I set about spending some major design time creating the assembly and its parts in Inventor 2013  cad software.  Even with the cad software it was a real trick to get everything lined up and working properly. This is how it turned out.

 The mid-section of the gear set I laid out in Inventor with a 26 toothed ring. This would be the track for the four inner gears to rotate around on. 

The large inner ring was then flanked by two outer rings which allow the blue gears to rotate and not slide out of the assembly.  This is where the animation is incorrect.  I could not build the actual working model the same way the animation was depicting the assembly.  It simply would not hold together.  It needed an outer lip on both the front and back of the assembly to hold the inner gears in place while they were being rotated.

The four outer sprockets were the next pieces that needed to be created.  The first attempt at these pieces did not work out quite as planned.  The spacing or thickness of the center white ring was half an inch and the blue sprockets were three eighths.  Just was to much slop in the assembly so I redesigned the blue gears to be just under a half inch thick.  This would allow the gears to rotate without side to side friction (or at least very little friction) and little or no slop.  

The center sprocket was another problem in the assembly.  The first go around in putting it together looked good in the computer but not in real life.  I assembled the center gear and tried to spin the assembly like the animation.  This worked but not as smoothly as I had hoped.  I removed the center gear and started taking measurements and seeing what could be done to free up the assembly to make it run smoother.  I reduced the number of teeth from ten to eight thinking that this might be the cause.  Not so.  I printed an eight tooth center gear and it would not even go into the assembly.  So I went back to a ten tooth sprocket and decreased the overall diameter of the part along with the diameter of the inner valleys of the part.  This did the trick.  Now I had a working assembly.

To hold everything together I mounted a white outer plate to the front and back of the center assembly as shown in the photo above.  This held all the blue sprockets in place with an inner bushing so that the gears would rotate freely and all the hardware could be tightened down so as to not interfere with the rotation of the gears.  The center gear did not need a center bolt or shaft as the four blue outer gears hold this gear in place.    
  The final assembly is a nice size standing five inches tall and wide with stabilizing feet at the front and rear. All the bolts in the assembly are 1/4 inch and 1 1/2 inches long. 
  This was an interesting project that stretched my designing skills just a bit. Which is always fun to do once in a while. No matter what I think my efforts paid off once again with something challenging to create and a nice conversation piece for my computer desk when company comes by to see what new project I have been working on in the shop.