Monday, July 14, 2014

Ramrod: Project Update #3- Renderings and Descriptions

Hello again!

I've created some fantastic renderings (all on the Flickr album) of the prototype with Lagoa, a 3D rendering service. Here's a peek:


Unfortunately, FreeCAD hasn't been exporting STEP files very nicely lately, so you would be right in saying that you can see the mesh rendering (those are STLs). For a closer look at what I mean, see this:


Anyway, I have made lots and lots of pretty renderings (some with layers stripped away) to explain what all of the different parts do. Hopefully you can get a better understanding of what is going on while the prototype gets built. Without further ado, I present Ramrod's prototype, explained!

Frame



The frame is made of Schedule 40 3/4 in. PVC pipe. Why? PVC pipe is sturdy, very inexpensive, and great for building approximately sized structures. Most of all, it is simple to put together and modify- all that is needed is a little sawing and mallet-ing. As you can see in the far above image, the printer rests on top of the structure, and the interesting stuff sits down below.

Part Insertion



The final version of Ramrod should put the tool back on the in/out platter. This prototype will not do that, but it will retrieve the part from the scanner bed automagically. Simply enough, a NEMA 17 stepper will sweep the part off the scanner bed and into a chute. To protect the bed, a piece of 1/8 in. acrylic is laid over the glass to protect it- I still want to be able to use this scanner afterwards.

Part Storage



This prototype only has six storage spaces, which is definitely less than the final version. After all, this is but a demonstration, and a refined one at that. These storage spaces are cheap and cost-effective- they are ordinary cans from canned food. The principle is that the tool from the scanner bed will land in a can, which is attached to a rotating platform. The platform can spin (another stepper) to provide another empty can, lined up for a fresh tool to go into.


Part Retrieval



Wondering what the mysterious upper stepper motor with the spool on it is for? Attached to that spool are six lengths of fishing line that go around every can. Ordinarily, the spool has the lines spooled around it, keeping the cans taught and upright. The upper stepper rotates at the same speed as the lower one, and none of the cans spin downwards. But what happens when a part needs to be released?



The upper stepper will not rotate in sync anymore, loosening the lines. This will cause all of the cans to tilt outwards, but only one can will spin in the MDF blocks and dump its contents. That can has no cardboard rack surrounding it (see the very topmost photo). All of the other cans will just rest on the rack until the line is respooled and they all become upright. The part will be unceremoniously dumped onto the table.

That's it for the prototype. Pretty simple, but we'll see how it actually turns out! Anyway, in case you didn't understand, here are some more renderings (also on the Flickr album):










I bet you are a bit tired of hearing about "rendering this, rendering that." Me too! I've started to order the parts for the prototype, and many parts are already here. I'll be posting the completed BOM soon, some build notes should get posted, and there should be a video with expectations for the final product coming as well.

Thanks for staying tuned- there should be another update later this week!