7/31/14 Fingers & Phalanges and Finishing Up Modular Beast

Today was a pretty productive day.  Frankie's back and because he gave me the files to his fingers, I was able to make progress on the arm today.  I beefed up the tricep cuff with some ribs to support it and tweaked the palm to fit Frankie's phalanges.  Through Inventor's assembly mode, I was able to look at how the fingers would fit to the palm and was able to adjust the knuckles accordingly.  Here's a shot of how it should look.

Now that I know they fit, the next thing to do is find a way to connect the phalanges to the palm.  I would like to do it without cutting them in half and screwing them together.  Feel free to message me on e-NABLE if you have any ideas about that.  I'll talk to Frankie tomorrow to see if he has any ideas as well.  On the bright side,  I won't have to do any work when it comes to putting pins in the fingers, because Frankie already did it. 

Tomorrow is a short day, so I plan on taking some quality pictures of the RIT Arm and Modular Beast.  I will probably end up ordering some springs for the variable grip too.

Work continued on the modular beast today, all of the parts finally printed! After talking to Frankie and going over the e-NABLE feedback about our compression fit design I decided to adapt a dovetail design instead. This design is still very simple to print (minimal supports needed) and it works very well.

The new dovetail design.

The Modular Beast in the real world!

After putting everything together Frankie pointed out that the gauntlet seems to be scaled smaller than the rest of the hand. This is a fairly quick fix and hopefully after tomorrow I will have a larger gauntlet to print. I also started printing Sam's bike attachment, that should be done printing tomorrow.

Overall today was another busy and productive day!

Alex + Sam

7/30/14 Printing Continued and Publishing Modular Tensioner

Printing continued.  Printing issues continued.  The day was spent managing the printers as we printed parts for the modular hand and arm.  Not much to say about that.  I spent some time drawing up a claw to demonstrate with the modular beast. The claw intended to be an attachment for biking.  In the end, it turned out to be quite terrifying.

See what I mean?  The lower claw closest to the palm is meant to support the biker leaning up against the bike handle bar. The longer front claw is supposed to wrap around the brake handles.  When the biker wants to stop, he or she pulls the claw towards themselves to pull the brake.  That's the plan at least.  I know this will be a pain to print though.  And it might not be strong enough.  However, if it doesn't work, it can still be used for demonstration at our presentation.  

As with Sam I (Alex) spent most of my day printing parts for the modular beast. In between prints I redesigned the mid gauntlet (it looks much better now and should hopefully be stronger) and published the completed modular tensioner block to e-NABLE. 

The compression fit gauntlet and tensioner block published on e-NABLE.

Hopefully the last modular gauntlet design!

The modular tensioner block wasn't met very well by the e-NABLE community who don't like to rely on compression fittings. I kind of agree with them because every printer is setup/calibrated differently but these types of designs are very strong and easy to print (no supports needed). Either way I think I'm going to stick with this design for the presentation.

We are trying to get all of our design work done this week so we can spend all of next week printing/assembling and getting ready to present our poster. This has been and will continue to be a very busy week but time flies when you are having fun!

Alex + Sam

7/29/14 Printing Parts and Starting Poster

While we wait for new parts to print, Alex and I have done a bit of preparation for the final symposium. First, I did some work on the final designs for the RIT Arm.  As it turns out, my idea of cutting material cost on the forearm cuff was a huge waste of time. I thought it would be a good idea to save time and material by cutting holes in the cup.  Turns out, it takes more plastic to print the supports with holes than it did without the holes.  Talk about a waste of time.

The original forearm cup took about 5 hours to print and only used 69 grams of ABS.
The "material saving" version takes 77 grams and 2 extra hours.

 After putting the finishing touches on the RIT Arm redesign, I began work on the poster.  This included typing the intro for each of our projects.  We plan to have a section about the e-NABLE community and it's purpose, as well as sections for the work we did on the RIT Arm and Modular Beast.  We hope to show our progress and spread the word about e-NABLE at the same time.

While Sam was working on the poster I (Alex) began printing parts for the modular beast. I finally got the tolerance on the tensioner block to fit perfectly! I also squared off the tensioner pin holders on the gauntlet that I talked about yesterday. After doing this I added some extra support to the gauntlet so the tensioner block doesn't appear to be "floating". My modified modular gauntlet was printed today but it turned out to be too flimsy so I added some extra material. It doesn't look the greatest but that can always be changed later.

The new gauntlet with extra support for the tensioner block and square tensioner pin holders.

The new mid gauntlet, not great looking but hopefully functional.

That's all for today.

Alex + Sam

7/28/14 Finish of Arm Editing and Modular Hand

Today, I (Sam) believe I finally completed the editing of the RIT Arm.  Thank god.  I'll go over them with Alex to see what else needs to be done, but I think it's good for now.  I think we should start printing it in blue or teal to be able to tell the difference between our arm and the RIT Arm.  Then we can use that in our presentation.

The palm was finished today.  The fingers are splayed and staggered, which will be paired with variable grip to increase strength.  Work was done to the tubes inside the palm to make stringing easier and make movement lag less.  A bar drawn in the knuckle joints to allow for a finger to close around it.  The file also allows for changing the bars into hole for pins.  Here's a picture of the progress.

While Sam was hard at work on the the RIT arm, I (Alex) continued work on the Modular Beast. Today I adapted the tensioner block connecting design I talked about yesterday to the gauntlet. I am still having a few problems getting the tolerance correct, but that should be a quick fix. Unfortunately, I printed the entire gauntlet before realizing that the tensioner rests were still set up for the old hex style tensioners. This is just a minor detail so it's not worth reprinting, but I will have to change that for tomorrow.

Yesterday's design adapted for the gauntlet.

Today, I also added slots to our mid gauntlet, which should allow for our new tensioner block to be easily attached and detached without restringing. This is a very minor detail but will be extremely important when assembling this hand.

A small detail but extremely important.

On another note, we began working on our UR@UWM poster today. John made a similar poster, which now hangs outside the DCRL, and he offered to share his files so we can match it as best we can. We have our layout set and now it's just a matter of sitting down and actually doing the poster.

That's all for today, overall it was a very productive one!

Alex + Sam

7/24/14 New Game Plan, Another Modular Tensioner Design

Today Alex and I came up with new goals to have done by the time this program ends.  First, we should have a working model of the Modular Beast and at least one attachment for it.  For now, that is primarily Alex's job.  Our next goal is to have a printed model of our version of the RIT Derek Arm.  We plan on applying splayed fingers and variable grip to it to make it more effective.

I looked on e-NABLE for ideas about variable grip.  The two best options I found were made by David Orgeman and Steve Wood.

Steve Wood tensioner balancing design

 I decided not to do this one because the strings get bunched together and tangled inside the tubing.  I'm afraid this would cause more problems than it is worth.

Orgeman spring design

Instead I have decided to adapt the above Orgeman design. By adding springs to the existing tensioner variable grip is achieved in a very consistent and simple manner. This has the down side of requiring non-printed springs but we believe that the benefits outweigh the cost.

As with yesterday I (Alex) continued to try and find a way to make the modular tensioner work. As I feared, the pins had a tough time printing and when I printed with PLA instead of ABS plastic they had nowhere near the flexibility required. After talking to Frankie about this problem we decided to adopt a design inspired by the bearing belt guide from a RepRap 3D printer.

My new modular tensioner design

This friction fit design is very simple and easy to print while still remaining strong. A few modifications will need to be made to prevent the tensioner assembly from rotating but overall I really think this could be the final design.

That's all for today, we have a field trip with our other undergrad research students tomorrow so we won't have anything new to post. See you next week!

Alex + Sam

7/23/14 RIT Arm Editing and Printing Pins

I spent today in Inventor with the Derek Arm.  Improvements were made in all the pieces except the fingers and knuckles.  First, I fixed up the trouble with the thumb tube in the palm by making the curve less extreme.  All it took was some quick dragging of control points.  Now the string should be able to tread through with less resistance.  Hopefully this helps with the lag in the closing of the thumb.  Next, I made the tensioners square.  After that, I edited the gauntlet to accept the new shape.  Here are some screenshots.

I put some holes through the gauntlet to reduce the amount of material used as well.  It should hold up just as well as it did with all the excess material.  

I decided to do the same for the forearm cuff, however, I'm not sure how it will turn out.  

I'm hoping to do a bit more editing with the arm tomorrow.  Then, I plan on printing it to show what Alex and I have done to improve it.  However, I don't think putting a few holes in it would make it worth printing another arm.  

I'll have to do more work on improving the overall functionality of the arm.  While I think it works fine now, we should do some brainstorming to see if there's anyway to make it better.  For example, the shape of the palm works, but it doesn't seem right to me.  I think we should come up with a better shape for it. We should also consider ways we can use the palm to get better grip out of the hand.  Maybe we can use the space inside the palm or pipe to apply the variable grip mechanisms.  Maybe the palm itself can slightly to better grip the object.  Maybe adding another thumb on the other side would help grip.  

I would like to make the first pair and second pair of fingers closing time be slightly staggered, splayed, and closer together as well.  In order to do this and make it effective, I think the arm needs variable grip. I'll come up with some sketches for that tomorrow hopefully.

While Sam was working in Inventor I spent my day in Rhino trying to sort out our modular tensioner problems. After searching around the web for awhile I decided to try a snap pin design similar to the pins used in the Cyborg Beast fingers. I already had one of these pins drawn up from when I was working with the Cyborg Beast earlier so all it took was some clever extruding and scaling.

My new pin design (shown in green)

Printing pins vertically like I have drawn above can sometimes be problematic but hopefully with some supports the print will turn out okay. Further testing on this will be conducted tomorrow.

Well that's all for today!

Alex + Sam

7/22/14 Inventor, Fusion 360, Modular Tensioner Problems

We finally got around to installing Inventor today!  I spent the day re-familiarizing myself with the Inventor while Alex continued work on our modular tensioner idea.  After fixing, printing, and refixing, we determined that the prongs are not flexible enough to be used here.  If they were longer, it might work, but that would significantly increase the size of the tensioner housing.  Tomorrow we shall discuss other solutions.

A example of how the prongs continue to break.

Meanwhile, I began work on editing the RIT Derek Arm.  So far I removed material from the Triceps Cuff to make it a bit cheaper (less material = less $$$).  Tomorrow I will probably do the same with the forearm cup.

Today we also published our modular tensioner idea to the e-NABLE community which received a very positive reaction. I (Alex) spent the majority of my day trying to come up with ways of beefing up these clips while maintaining flexibility but in the end I believe we will have to find some other type of clip.

One of several concepts I drew up today to try and beef up the prongs (sadly this didn't work)

The e-NABLE community is pushing hard for all designers to use a single program, Autodesk Fusion 360, so we spent some of our day installing and playing with this program. Fusion 360 is cloud based so it didn't run nearly as smooth as Rhino does. This combined with a more constraining (as opposed to the more free flow Rhino gives you) led to a negative reaction towards Fusion 360. The program appears to be very powerful but I just don't know if we will be able to break our Rhino habits and get into using it.

Well that's all for today!

Alex + Sam