Knife molds

After 2 coats of lacquer, it is time to try to make the mold. Our chemically bonded sand is a phenolic urethane coldbox system. In the picture below the Tinker Omega system is shown which has a supersack capacity of sand. The sand is fed by gravity to an auger where the sand is mixed with the 2 part binder contained in the drums pictured in the lower right of the image.

The mixed sand with binder is roughly about 2% binder by weight and hardens in about 10-15 minutes after mixing. Therefore, we run the sand through the system, pack it into the mold box, scrape the top surface to make it level, and set it aside until we are ready to extract the hardened sand mixture.

At the end of this time we can extract the sand by setting the mold box on some 2×4 to support the edges and rap the back of the pattern with a hammer. If everything lines up well then the sand will fall out in one piece. If there are undercuts or if the sand twists then the mold can get locked up and can be difficult to extract.

After both sand mold sides are extracted, the mold lock can finally be put to the test in the assembly. Pictured below is the two mold halves before putting them together.

Finally the mold is assembled and I’m going to let them rest because the sand is not quite set up until about 24 hours or so. By setting them on top of each other, and relaxing and dimensional changes will help them match the other side. Before we melt metal and pour, it is required to cut the spruce and gating system which I’m still considering the best size and direction to add them. We are planning to try to pour these with cast iron because of some testing we are doing on Friday this week.

Hopefully the alignment and parting line works as well as the mold assembly went today.

Knife pattern update

So, the entire week was filled with failures of getting the other side of the knife mold cut on the desktop cnc. I ended up adding 1mm of stock to the machining surface to prepare it because I couldn’t quite get this wood piece flat. Also, I made some improvements to the control system. Specifically, I upgraded the raspberry pi controller to an Intel Compute Stick which was nice because now it has an easy headless interface that is more stable on the WiFi than the raspberry pi. If this machine stayed on a personal wifi network, the raspberry pi would probably be fine. The other update was to add a webcam to check in on the machine progress, added a connection for the vacuum, and connect everything to an uninterruptable power supply. Unfortunately, even with all the updates I was having the machine stop arbitrarily in the middle of the job.

In my frustration, I ran across a blog post about the same problem. It was an excellent thread with some nice brainstorming about troubleshooting this system. My personal takeaway was to disconnect and disable the hardware limit switches to see if they were accidentally causing the machine to shutdown. After making that change I started my job yesterday about 3pm and left it to finish over night. My result is pictured below. Note, I already dissembled the hold downs for the pattern wood.

The two pictures below show the cope and drag sides of this pattern. The top down shot looked like an optical illusion to me so I also took a picture from the profile with a pencil lying on it to show what goes down and what sticks up. 

Next step is to create the box for these patterns and see if I actually hit the dimensions of the mold lock I was aiming for. Everything looks nice right now, but I have some feeling that I may need to back the lock edges from each other to make sure they sit deep enough. I certainly don’t want these to rest on the lock edges and not on the parting surface. Anyway, a small victory to start the week after frustration…

Jobs

There are some strange parallels between searching for a mate and searching for a job. For example, it feels always like the best one is taken. Or, it should be easier to find one that recognizes my value, skills, and interests. Also, when someone finds a job/mate, it’s in an unexpected and unique circumstances that everyone can’t repeat. Often, I find myself thinking about this again for my students looking for jobs.

Let me post a couple of suggestions and links for those of you searching. First, please update a LinkedIn account. What are the important features? Basically things you think and employer would want to know. Accomplishments, things completed, etc. I’m not sure we emphasize completed tasks enough in our resumes. Not listed on my LinkedIn account is my first job, airport detailer. Basically, I washed airplanes at the local Lake in the Hills (LITH) airport. It was a pretty simple job, planes take off and hit a whole bunch of insects… Then they land and hit more insects. When the planes would finally taxi and park they were covered with bug guts. Why am I telling you this? Because I learned a lot about finishing tasks while I was cleaning planes. I may have started to clean every plane on the jet way but the only ones that counted to my supervisor were the ones that were totally clean. Really you want to be able to tell stories about finishing tasks from your classes, work, hobbies. No one really cares that you started to learn to play the piano… But if you’ve performed for as many people as Victor Borge then you’ve probably got something to say.

Anyway, you may have gotten my point. It’s easier to sell yourself if you have some interesting material to work with, so do something interesting. And, it’s hard to find all these positions so you need to treat your job search with more importance too. Look for a job like it’s your job! I have a number of different pages that I keep tabs on because I’m interested in manufacturing engineering jobs so here you go. I actually have them send me the jobs too so I can circulate them to all students.

https://afsinc-jobs.careerwebsite.com

https://www.fefinc.org/job-listings.html

https://www.aeroindustryjobs.com

http://spe.4careersolutions.org/jobs

I’m adding one more paragraph to comment about salary research. Desland Robinson sent me a link to an awesome site to research position, titles, salaries of similar positions in the state and way more. The site is maintained by the US department of labor and is called O*NET Online. I think if you are looking for a position this is a great place to do some background expectation setting. At some point, I’m going to post about estimating costs and expenses that I think will be interesting for anyone reading this blog.

One more thought to leave you with. The best way to get connected is to know someone, so use LinkedIn, and email, and your work to get to know everyone. That way you aren’t the only one saying you are capable to do the job.

Forge day at UAB

We went to the pull apart and retrieved 3 sets of leaf springs given the availability and condition of the springs. Fortunately, there were two pickup trucks that looked prepared just for us because their beds had been removed. The picture below shows Zeb Dahlke unbolting the axle from the leaf springs. It was raining, so if you do this bring the right equipment. For us, this included rain coats, set of large ratchets (1/2″ torque were choice to provide the most leverage), sockets (13/16″ was the needed size for our project), hacksaw, and PB blaster. 

The leaf spring cost about $25 apiece with the core charge which is not free but still less than about $1 per pound for the steel so I consider it a pretty decent spend. We checked out and brought these back to the lab to start the disassembly. After some attempts to unbolt the remaining fasteners we switched to the angle grinder to remove the hardware.

Afterward, we laid these separated spring sections out to survey. The section at the bottom of the picture, I cut to length for my first sword. This section is about 20″ approximately.

We worked on these pieces and some rebar sections to continue form double sided hooks. Overall a good day, thanks to everyone who came…

Swords from Leaf Springs

There’s a lot of discussion boards and blog posts about using leaf spring steel to make swords. I’m going to collect some information I find about this topic here so that it’s easier to get started with and I’ll probably post some info about our project (since I’m headed to the pull apart tomorrow to see if we can get a few leaf springs to start with).

All leaf springs are made of spring steel which is commonly assumed to be AISI 5160. Removing leaf springs is straightforward but if the bolts are rusted then you want to make sure to bring some lubricant and big wrenches! I’d also inspect the springs because old springs may have fatigue cracks initiating along the edge which may be difficult to remove and finish the sword. Also, leaf springs come in various sizes so starting with an idea of the size of the sword may narrow the choice of the vehicle you are choosing to remove the springs from. I found this video about removing a Jeep Axle to be helpful with getting access to the leaf spring and beginning to remove it.

Once you have the springs in hand then you could take a look at an instructable for swordmaking or various videos of making swords like below. I’ll be posting how we do with our own efforts soon.

 

Email

I don’t know exactly how to give advice about this… But I need to share some information with all my students looking to be email experts. Everyone suffers with the email spam issues so just deal with it.

My personal take on email is not too far away from the ideas of Elon Musk. He says “Anyone at Tesla can and should email/talk to anyone else according to what they think is the fastest way to solve a problem for the benefit of the whole company.” You should reach out to the person you need that can get the work done. That person probably has the most at stake for getting things done. With that in mind, remember a couple important “tone” issues. First, don’t read into email “tone”. I personally like shorter and direct emails that I can take action on. Check out this email writing aid for Gmail called boomerang. Maybe use it if it helps you figure out some pointers for getting email responses.

Also I received this cool wall hanging chart from The Advisory Board Company about being an email ninja! It’s also got some good pointers. One last idea, take some lessons from the news and treat your emails at legal documents. So, be to defend anything you write in an email because the idea that the email will disappear is foolish. It’s probably out there to haunt you forever… So use your head.

CAD

I’m going to post a short discussion about CAD packages and some of the current trends I see. A little background on me, I was initially trained on a drafting table at community college and only briefly exposed to ProE as an undergrad at Penn State. At Caterpillar, we used Teamcenter and ProE for most 3D modeling work I was involved with.

Also, there are many, many good CAD tools out there now for anyone to get started using. The basic division of approaches to CAD falls into two methods: parametric and direct modeling. These two methods were part of sales pitches in the past and currently it’s hard to see the difference these days. All 3D modeling requires watertight shapes that are constrained in some way by dimensions or relationships. So really you should work with the one that best suits you. This being said and in an effort to give you more directions to try…

I’ve had good luck with the free tool, FreeCAD, to mess around in to make STL files for 3D printing or other process modeling. Recently, I’ve been using Onshape to look at collaborating with students on geometries and it looks really powerful. Seems like it’s going to be limited to educational accounts for the free use, but this serves almost like an educational PLM which is definitely a great idea. For other shapes and more open part sharing, I recommend Thingiverse and GrabCAD.

As for trends, it seems like the basics will stay the same so if you’re happy with your CAD tool then I wouldn’t panic. But as for upcoming innovations, I want to highlight some things. First, integrating process modeling (heat transfer, fluid flow, solid deformation) is likely to continue in the CAD package world. ProE, Solidworks, AutoCAD and others all have options for directly doing analysis from their CAD interface. Also all the process modeling software offer some modeling capabilities such as ANSYS and MAGMAsoft. But as an academic soothsayer, I would say that the future has to feature optimization and machine learning. In this way, OpenSCAD probably has an interesting role to play in the future. OpenSCAD creates geometry from a programming procedure essentially like parametric modeling but driven from written lines of code instead of point and click operations. This approach and other software that uses this method has huge value to optimization because the parameters can be modified easily to experiment with the design.

I’ve got more to say on this considering implicit and explicit geometry but I’ll leave that for a future post.

Hello world!

It’s 18 minutes into july 3rd and I decided to setup a blog. I’ve decided to be a tidbit blogger just short and sweet. Hopefully pictures and comments about happenings. Best wishes world!