Working The Big Steel

Unrelated to any project here at CATEA but still quite interesting:

Tripp Edwards from the COA’s Design Lab stopped by yesterday to do some work on the metal lathe. He has a roller style single-run printing press. The roller is about 34 inches long and 6 inches in diameter of solid steel. It weights a lot!

Anyways, some of the undergrads in the architecture program heard “press” and thought they could use the machine to press one shape onto another. Ha! Big mistake. Kids were apparently using this thing to press all sorts of metal objects into softer objects to create a relief. Well this is not at all what this machine is for. Its meant to press a printing template onto paper. So as you can imagine these rollers sustained a ridiculous amount of abuse. The surface was covered with all sorts of markings resulting from running anything and everything through the machine: keys, threaded rod, bulldog clips, BB shot.

So we had to turn down the roller enough to take out all the indentions. It was some serious work for two grown men to lift the roller up and mount it in the lathe. We ended up removing the tail stock and sliding the cylinder on from the end. The lathe, being the beast that it was, took the load no problem. In about 3 hours, Tripp had turned down the cylinder and had it looking better than brand new.

Moral of the story: don’t use the wrong tool for the wrong job!

Updates to the Buttock/Thigh Model

Once some decisions were made about the desired range-of-motion and orientation of the thighs, Taylor did an excellent job trimming down the models and setting them up in a more permanent configuration. We’ve also added the necessary weights to simulate either a 46, 70, or 84 kg person. We are now in the process of testing the model and see how it compares to the butt model without the thighs and the old ISO model where the entire buttock/thigh was one solid, non articulating piece. Here are some pictures of these updates:

Reworking of the Cyclic Loader

In the cushion testing lab we have several cyclic loaders to test new wheel chair cushion designs. The devices are basically up-and-down pistons which cycle a specified number of times. The machines are controlled through LabView on a PC. Well over the years the machines have evolved and things have been slowly added, usually in an ad hoc sense. Well the past week I’ve completely disassembled the thing and rebuilt it with only the necessary hardware. The piston is pneumatically controlled by several switches and regulators and the old setup had quite a few redundancies. After properly documenting how the old setup worked, I drew up plans for a more streamline setup. The reason for the split in the flow diagram is that the “down” pushing pressure has to be adjustable, sometimes set very low. The force on the cushion needs to be constant and we have some very light and some very heavy buttock models, so the “up” lifting pressure needs to lift a large amount of weight.

Here is my schematic for the setup. I’ll take some pictures as it nears completion this week.

flow diagram

Articulating Thigh Mechanism, First Round Complete

The articulating thigh mechanism is pretty much finished. It certainly doesn’t look like a real thigh/buttock but that’s what the next phase is for. We will begin to set the parameters and make cuts into the actual thighs to form them to correct shape. I had to cut some weight out of the right thigh because I overcast it. Some quick tests were run with on the Zwick with a Tekscan Conformat pressure mat. Part of the next phase will require reading the in-board buttock pressure sensors with and without the thighs attached and look for variations.

Open Source, Makers in the Medical Industry

Cool editorial in Makezine about the future of open source in the medical industry. Just wanted to share that with everyone.

Secondary Grab Bar Mechanism

I am also working on a prototype grab bar (those bars mounted to the walls in handicap accessible bathrooms). This is an attachment to existing bars that will fold out out of the way. The secondary bar needs to lock as soon as any normal force is applied to it. I’ve found these shaft couplings on McMaster-Carr and thought they would be ideal.

Yesterday, after receiving the parts, I was a little disappointed in my choice. The parts fit together only at specific intervals. If the teeth didn’t line up perfectly, the two parts wouldn’t interlock. Well today Jowers had the idea to bevel the edges and it seemed to work. I turned them down on the lathe. I honestly expected the teeth to look like crap afterward. I expected a lot of knocking as the teeth passed the cutting tool. However they turned out 100% professional looking. I needed the mental win after yesterday.

Unbeveled and beveled teethUnbeveled and beveled teeth.

I also wound some springs to hold the interlocking pieces apart until a load is applied. I used a tool we have called the Universal Spring Tool. It worked pretty well. See the how-to video below.

Silly Tools For Silly Fools

I needed to enlarge the space in the foam of the AP cushion to accommodate the new housing. So to cut the foam, I used an electric kitchen knife. It worked perfectly. The foam didn’t tear or rip. It made very smooth cuts and the cushion now fits perfectly over the new housing.


Alleviating Pressure Cushion, My Two Cents

Most of the Alleviating Pressure Cushion has been built and developed for a while. We are about to send it out for some long term (about a month) of continuous usage so everything has to be in perfect, robust, working order. The hardware cover and plugs needed to be replaced and be a bit more aesthetic. I heat formed some polycarbonate, by hand. After some cutting, drilling, and sanding I think it looks pretty good; like a fish tank! Its certainly capable of sustaining a serious beating.

Darrell Huff, “No Buttons Headset” Inventor, Visits CATEA Today

Today, we had a special Innovation Meeting. You know its special because it happened on a Tuesday instead of the usual Thursday. Today Darrell Huff came by to talk to us about his two AT inventions. The first is a modification of a Blue Ant bluetooth headset which removed the existing on/off/sleep push-button with a magnetic proximity switch. The details of the device are available at his site but from looking at and holding the headset, I can really see his craftsmanship. There was zero evidence that he had opened up the original device, which is about the size of a quarter, removed the mechanical push button, replaced it with a magnetic proximity switch, and repackaged everything. Its true when they say “Fit and Finish Sells”.

Darrell’s other invention was a Wiimote hack to allow for hands free navigate of a computer. The user holds in their mouth a modified bite switch with two infra red LEDs attached. One LED is always on and the second turns on when the switch is depressed. The wiimote is stationary and pointed at the user and communicates with a PC via bluetooth. Special software then translated the position of the always-on LED to move a cursor and the relative position of the on/off LED to mimic mouse clicks. A single bite is treated as a left click. A hold bite is similar to a click and drag. The coolest part is that when the user tilts their head and then clicks, the software recognized that as a right click because it senses the presence and position of the on/off LED.

Darrell Huff definitely had his inventions together and most of the meeting was about how to best get his product on the market. Its good to see he’s made it this far and not fallen into the traps that affect many individual inventors.

Adjustable Webcam on the WMD

This was a last minute addition to the wound measurement device before it goes to clinical trials this week. The built-in cam was total crap so I added this webcam and gave it some ability to be repositioned. It doesn’t look very pretty, for sure. I really had hoped that we’d have the camera nailed down before I built an entire device around it =(. If we continue with the third party web cam, I envision version 5 of the device will be a Wiimote + Wii nunchuck style device: the camera and lasers in one hand and the computer in the other.


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