One evening of CAD. One evening of CAM. One evening of CNC. And it fit together (quite well). This is just held together with precisely located wooden dowel pins. We will add screws tomorrow.
The only missing piece is the actual guide for running the blocks through. That is separate so that it can be “dialed in” to the perfect cutting depth.
Here is an action video of the [M003] Auto Loading Jig in action on our CNC router. Strong spring pressure is exerted on each wooden block up so the top of the block is always flat against the bottom of the Lexan panel on top. This results in consistent routing depth.
The Barrel Sander is coming along again, after a small detour to build the (M003) Auto Loading jig. Here is the nine sides bolted inside the barrel. They do three things:
- Make the barrel stronger so the wheels that it turns on have more support than just thin metal.
- Provide a disrupted circle which will cause the materials to actually turn instead of sliding.
- Protect the inside of the barrel from the sanding action.
After years of making the same part repeatedly on the CNC router, I finally decided it was time to make the router load it’s own material.
Friction is a valid way to hold a part for routing. That is how most vices and clamps work. The key here is to calculate an amount of friction that will resist the cutting forces while at the same time keeping it low enough for the router to be able to overcome it while loading and unloading.
I’ll post more on this when we have it working. For now, here is a cool picture of the jig.
The inside of the barrel tumbler needs a polygon (made from wood) in order to (a) give enough “traction” to turn the contents, and (b) protect the barrel from repeated impacts. I’m going to use Oak or Maple to do this. Based on the width and thickness of available material, I chose a 9-sided polygon.
Here is a picture of the CAM operation prepared using Fusion 360. I will make nine of these with just a fraction of an inch extra that I can remove on the jointer while getting a tight fit.
The cable winding pulley was the most complicated part of the machine due to it’s multiple set screws, flat surfaces, precise bore, and threading. One set screw holds the pulley on the shaft. The other set screw holds the cable firmly attached to the pulley.
Here is a picture of the pulley mounted to the DMM Tech Servo Motor. In the background you can see the cable go up through the top of the machine, over the free pulley, and back down to hold the main slider mechanism.
In the Stain Dipper Machine, we have a top pulley which is mounted on a 10mm shaft that is seated in 10x26x8mm bearings. In the last post on this topic, I showed the pulley holder assembly. In this post I’ll show the pulley and the final assembly.
Here is the finished pulley, made from a 1″ long by 1.5″ diameter piece of brass.
Here is the pulley mounted on the top of the machine. This is a satisfying point in the project because of all the ways this could have been solved, we chose an elegant, smooth, and accurate one. You can’t buy this specific part anywhere in the world – we designed and made it just for this purpose.
Here is a picture of tapping the pulley for a M5 set screw.
This is a picture after the first operation was complete. Now we need to turn it around in the lathe, recenter it, and finish the other side.
Here is a picture of the part in the lathe. Notice the difference in surface finish? The shiny area is freshly cut. The dull area was original surface. The semi-dull area was shiny just an hour before, but oxidization got to it that quickly.
A view of the spinning 4-jaw chuck and quick change tool post.
One of the key components in the Stain Dipper Machine is the top pulley assembly. It is crucial that it normalizes the unspooling location of the cable so it does not put lateral forces on the slider rod below. To this end, we designed and created 3 components out of UHMW (Ultra High Molecular Weight Polyethylene). It’s a nice plastic to work with, and super tough. It cuts like butter but has a lot of strength too. This is a 10mm hardened shaft with two bearings pressed into the UHMW.
Here is a picture of the 3D model. As you can see I haven’t trimmed the shaft yet.
In my last post I had an image of one of the guides and the slider in the background. The slider is an aluminum extrusion and the guide is 0.75″ thick Oil Filled Nylon. Nylon is resistant to stain and other chemicals we are using as well as having a low friction coefficient.
Here is a close up of the 3D Assembly taken straight from my computer screen.
Here is a photograph taken with my phone of the actual part that has been machined and installed. There is something satisfying about designing something and then making it exactly (within tolerance) to the size and shape you wanted.