CNC Router Build - The Stand

The stand for my Solsylva 25x25-inch CNC router is made from 1x4-inch pine boards. Two of the supports are hinged so you can fold the router down so it takes up less storage space.

Building the stand for my Solsylva 25×25 CNC router was pretty simple.  The hardest part was attaching the hinged support.  I also had some trouble finding straight lumber for it and the rest of the router.  David Steele’s instructions and drawings are excellent and are easily among the best I’ve ever seen.

The stand supports the router and it provides you with a work table to build it on.  It can be put on casters so you can easily move it around and it’s designed so the CNC router can be tilted down to take up less storage space.  It’s a pretty good design but I wish I’d just built a table out of 2x4s instead, because the fold-down feature doesn’t really save much space and it may never get used.  Such a table would be stronger and unlike David’s design you could add shelves to it for storage, or compartments for a computer and/or dust collection system (shop vac).

The Plans & Design Goals

There are 109 pages of instructions and drawings that are very well written and drawn.  David Steele doesn’t just provide you with some drawings and general instructions and then leave it to you to figure out the rest.  He breaks the entire construction process down into a series of small steps that almost anyone can follow, even someone who doesn’t have a lot of experience building things or working with tools.

He designed this CNC router so it could be built with very basic inexpensive tools and so you can buy most of the materials at your local lumber yard or home improvement center.  Those are huge advantages for many.  But the downside is the router isn’t as good as it could be if were designed to be built with better materials and by someone with more skills and access to better tools.

I hope that someday David will offer an “advanced” design or add more options to his current plans, such as an extruded aluminum or welded steel frame.  In the meantime you can learn about modifications and upgrades by reading about what other builders have done.  CNCZone.com is one of the best places to do that and you can find some great builder’s logs there.  Unfortunately, the best message threads have often grown to contain dozens or hundreds of messages and it can be very time consuming to read through them all.

Buying Wood

It’s really important to use the straightest boards with the fewest knots you can find, especially for the router’s frame and gantry.  It seems that lumber quality is getting worse because of “factory forestry” and I spent almost two hours patiently sorting through entire piles of lumber to find the best boards.  At one point I thought I might have to come back again or go somewhere else to find enough good 2x4s and 2x6s.  I’m glad I purchased extras because when I got home I found that some of them weren’t as good as I’d thought.


Continue reading → CNC Router Build – The Stand

Casting Lots of Small Parts

I spend about half of my time writing CAM software, and the other half doing product development for a bunch of companies.  Usually my prototypes are one-off, sometimes I have to make lots of them.  I happen to be in the middle of just such a project- I need to make about 50 of these:

Luckily, they’re not very big, only the size of a dime.  I tried using our CNC mill to machine one but it quickly became apparent that it was going to take too much time like that since it would have to be machined from two sides and with a good finish.  I decided to turn to one of my favorite techniques- casting the parts.

Other people have written very extensively about casting techniques, my favorite is at http://lcamtuf.coredump.cx/guerrilla_cnc1.shtml .  For the time impaired, the basic idea is that you make a mold of the part that you would like to make and fill it with a two-part resin to make the finished product.  The mold can either be a soft silicone, as the site above shows, or a hard mold that you machine directly in a CNC mill.  For small parts like this one I like to save a step and directly machine a hard mold.  Since I only need to make 50 pieces, I decided to machine them from Delrin- a very strong plastic that happens to be relatively non-stick.  The non-stick part ends up being a huge benefit here to make it easier to remove the finished parts.

Making the Molds

The fist step was to reopen my part in SolidWorks and design a mold to produce the parts.  Since the part is symmetrical, I only need to make half of the mold and machine them in multiples of two.

 

The mold shows a lot more stuff than the original part that are worth an explanation.  A big part of designing a mold, whether it’s for casting like this one, or injection molding for high-volume production is making sure you provide a way for the material to flow freely into the mold.  This includes providing a way for any air in the mold to be pushed out.  The flow of resin will be something like this:

Red lines show the path of the resin

The resin is pushed in from the left and eventually overflows out through to the right, hopefully taking most of the air with it.  Any air left in the mold will create a void in the finished part.  Note that without the bottom-most runner, there would be no way to get resin into the bottom legs of the part since air would be trapped in there.  There are certainly better ways to approach this part but this was easy and I was in a hurry to get started.

Machining the Molds

Machining these molds is easy.  I exported an STL file from SolidWorks into MeshCAM  to make a toolpath.  Some users have found the SolidWorks STL export options confusing so I’ve put up a SolidWorks CAM page to show that process in more detail.

Continue reading → Casting Lots of Small Parts

Pamper Your Tools

I saw this on MadModder.com and thought it was a brilliant idea.  So I asked John Hill, also known as The Artful Bodger, for permission to republish it here.  MadModder is one of my favorite forums and if you visit the discussion about John’s idea you’ll be able to learn more and see a beautiful storage case someone made using it.  — Rob (Chief floor sweeper and editor)

Start with one of these

…and one of these…


Continue reading → Pamper Your Tools

Free Plans: David Kerzel’s C02 Engine

Here’s another set of free plans and construction notes by David Kerzel.  These are for a CO2 engine which is much smaller than his very beautiful hit & miss engine, which you can also get free plans for.  David says the flywheel is too thick, which should be easy to fix.  He also thinks the cylinder looks too long.