Presentations

I want to share a story from my graduate school days. So, I used to get really excited when something finally worked and I had a couple friends that I would rush to with the latest discovery to share it with them. One of those friends, Justin Garvin, brought something to my attention once that was really helpful for me later in life. Let me show you what I mean, take a look at the chart below. See how cool it is? Wiggles, flat spots, something is related to something, they even cross at some point… Man, there is a lot going on!

But, you can probably guess why my buddy, Justin, was laughing at me. No matter how insightful I am, or careful in the analysis and work… Because no matter how much work or painstaking care I put into generating the data in this plot, it is garbage without axis titles or a label or just about any details to describe what in the world I was thinking!

Seriously, it may seem trivial but these days I’m extremely focused on the details of plots, figures, and background information to make sure that we haven’t made a mistake in the interpretation of any result we make. These days especially given the data at our fingertips, it is even easier to draw conclusions from completely unrelated information just because they happen to be produced in the same sequence or at the same time. Take a look at Tyler Vigen’s site if you need some practical examples.

So, I’ve mentioned practicing presentations in an earlier post. In fact, I have more research to do (thanks, Alex Monroe) on the topic of assertion-evidence presentations. Let me offer a couple suggestions about preparing for this because the little I know about A-E is in support of this. I’d use the same approach to drafts of reports and proposals as well.

Your presentations need to tell a message, so ask yourself when you prepare it whether it communicates the message you intended to present. If it can’t answer a straightforward question, then it’s probably wasting a lot of effort and time. But that is in the end. In preparation, I will usually dump more information into my presentation before trimming back to the relevant stuff. Besides, you should know your audience enough to agree on a common language to discuss your topic. So the boring introduction stuff can sometimes be extremely valuable when you don’t even realize that the introduction is where the disagreement or discovery is. So consider that when you make your presentation. I hope to have more examples soon to post.

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.

First pattern using desktop CNC

This is just a quick update on the pattern I started this morning after the activities yesterday. I made several adjustments to the parameters of the gcode path, including reducing the layer height and the stepover to reduce the drag on the router which I’ve decided is underpowered (300W). Those adjustments increased the machining time from about 4 hours up to 9 hours. So, this finished about 6pm which means the estimated was about right from my start time of about 9am. I’m happy with the finish quality but I’m not going to use this pattern except to explain the process due to the first mistake in the pattern of the knife on the right. About midway in the handle you can see where the wood was scarred by an operator error (I was trying to show how the machine could return to the G54 zero and the tool ended up dragging through the surface). If this hadn’t occurred then I would have used the saw to trim the ends and then build the box for the pattern.

So, next step is to cut this pattern again. I’m debating additional modifications to the gcode to speed up the roughing cut and using an angled cutter to add some natural draft to the edges. I’m pleased with the mold lock and the overall quality of the cut so far, keeping my fingers crossed about the quality of mold that we get from this.

Suggestions from speeding up so far include: cutting a border first to the depth slowly and then speeding up the internal roughing cuts, choosing a bigger router, better end mill.

Ideas made simple

One of the things that I cannot stand is describing something as complicated or complex. That is to say, there are some really complicated and complex things in this world but that should never be the way your research or presentation should pass on information. I challenge myself to take anything that I’m trying to explain and make it as clear as tying my shoes…

In fact, that is not a bad way to practice explaining yourself. If you choose something you are comfortable with like cooking, playing a sport, or tying your shoes and then explain it in video or using a presentation then you will get some practice with handling more difficult topics for example your PhD research proposal or defense. I recommend to have a steady diet of TED talks and 3MT to give yourself the cultural context to communicate your ideas. Remember, that the evidence that you have been successful is not making it through your material but instead hearing that same concept passed on by an understanding audience.

Just don’t practice without any content, I’d rather you be boring than say nothing.

Those old papers are worth something…

So, other than the desktop cnc mill that I appear to be spending all my time on… I try to teach and research too. When I find an article like this one, I like to share it with my graduate students and offer some thoughts on a positive side. This thought is to offer some context to protect our research group from similar pitfalls. So, what am I talking about.

Inadequate literature reviews can get you retracted!

Even innocent co-authors are impacted by retraction!

Science corrects false information slower than you expect!

Thanks to Craig Beard at UAB Library for being a good resource for me. I think the best thing to do is to make sure your work is your own and that you’ve made the best possible effort to get criticism from the best experts in the field to make sure you haven’t missed any details that catch you by surprise. And I admit, engineering seems to be weaker at this than you would expect based on knowing all the work we put into the studies we do and the tests and experiments we run. I think there are just too many ways to publish this information and strong disagreements about what is a contribution enough to publish.

I’ve been looking for better tools for making this easier for my students and myself. Heres a short list of ideas if you are also interested in the world of bibliometrics and systematic review.

1. Use a reference manager, several I’ve tried include Jabref, Bibdesk, Papers, Mendeley, and Zotero. Most of these will let you exchange via a .bibtex file so you won’t really lose time playing around with all of them until you get one you like. Once you find the solution though, I’d stick with it because it makes it super easy to add comments to papers you want to use in writing.
2. Explore bibliometrics software, for example, Bibliometrix for R, SciMAT, VOSviewer, Network Workbench, and CiteSpace may work for you. I’ve had varying degrees of progress getting these tools to work.
3. Make you own mind map using Docear,  FreeMind, or other. Honestly, when I first discovered mind mapping I though “wow! this is going to be so useful” but I think my engineering mind is just wired up to sort information as I receive it. So whenever I mind map it just turns into an exercise of prioritization of how important the information I get is.
4. Define a stopping point, don’t use your research as a jumping off point to connect to every paper ever written. Use the papers you do find to narrow the scope of your research until what you say gives you the references you intended to find. In other words, the first thing you write to describe your research is probably not correct.

In my process and I think I’m pretty quick at this, I typically take an idea or hypothesis and find the best paper I can possibly find. This means that this first, key paper is highly cited, published in a reputable journal (not on a blog site), written by researchers with proven background in the field. Then use that first paper to search for related material (a) in it’s reference section, (b) by the same authors, (c) citing this paper. That is the start of your comprehensive literature review. You will probably find in that initial search about 10-20 papers. Hopefully another paper you find will also be pretty key and important to you. Take this second key paper and do the same thing. Repeat perhaps a 3rd or 4th time. Hopefully you will find that if you have a good scope to your research work that you can define your stopping point now and you should have by the 4th time about 80 papers or so. Now it may take me a couple weeks to really digest this information for a new field… But, you can be smarter than about 99% of everyone on a topic using this approach in about 3-4 hours if you have access to the references. The other benefit to this… You will also know who are the 1% of people that are smarter than you on that same topic. Use these skills carefully, because you only get to make first impressions once.

As Charles Caleb Colton and Oscar Wilde said “imitation is the sincerest form of flattery that mediocrity can pay to greatness.” Don’t be mediocre, be great.

Gcode for Knife pattern

So a little primer on how to go from STL file to gcode to run the desktop cnc mill. First, make sure you are absolutely happy with the STL file. If you export the file with too few facets then your machine paths will also be blocky. So this really is one of those circumstances where what you see is what you get. Also, I like to go ahead and reassemble the stl files together into it’s own model to check that the alignment is good, also that the coordinate system is in the right place and generally things are going to work out the way I like it. The picture shows that I’ve placed the origin at the lower left of the pattern and I’m showing the cope on top and the drag underneath. Maybe you can see that the knife sections line up and the corner of the mold lock matches as well. 

Next import these into your preferred gcode tool. Let me take a short aside on that topic because these are not as simple as the wealth of information on plastic 3D printing. In 3D printing looking at the free software world alone you can choose from Repetier Host, Cura, Slic3r, Skeinforge, just to name a few. These support gcode generation for many different 3D printer flavors and have many options for support materials, overhangs, and infill. I highly recommend looking at all of these if you are interested in 3D printing. Confusingly for experts in 3D printing, the cnc world breaks down into 2D, 2.5D, and for lack of better word 2.5D+ which would include the 3 axis mill and beyond. If you are just getting started with desktop CNC milling then I would suggest looking specifically at 2D such as jscut, FlatCAM, and PyCAM. Remember those tools are only going to cut completely through material, so they can be used for the mill, plasma cutter, laser, water jet, etc. For patternmaking, I’m interested in 2.5D machining which basically exercises the same muscles as the 3D plastic printing changing profiles from layer to layer in the height. It is similar to the 3D printing but instead of building up from 0 to the full height; it is subtractive taking from the full height down to the bottom.

For my 2.5D approach to the desktop cnc mill, I am using several tools because I haven’t settled on the best approach to teach with. First, Kiri:Moto is kind of amazing. If you even have a little interest in this stuff, you should check it out. Easy to set up, shows the machine paths, lots of default values that make sense, even integrated directly into Onshape. My experience with Kiri:Moto has been good, works quickly, and is useful for the initial check if you are going in the right direction. I have high hopes that this tool continues to get some love and attention because it is awesome! As is my style, I have broken it as well both when adding in new complicated stl files as well as on the export side. Unfortunately, there is not a lot of easy to debug log information about why the slicing or export fails. So, there are other alternatives… HeeksCNC, FreeMill, and for the low budget (but not free) hobbyist MeshCAM. I went ahead and bought a license of MeshCAM because the other alternatives I mentioned above are only Windows based, awkward to install, or a little gimmicky (as in not clear what the terms and capabilities were) I’m sure all of these issues could be overcome if I had more time. There of course are other established programs like GibbsCAM or MasterCAM. I hope to revisit this specifically in the future, pending I find a solution I like.

My simple instructions are assuming you are using Kiri:Moto and you don’t run into the issues that I faced with exporting the final gcode. So… In the menu on the left, choose your mode, in my case CNC milling. Second, choose the device, in my case it is a tinyg mill. Then, choose the tool and I have a 1/8″ end mill installed on the desktop mill which they already have some parameters for. Make sure this tool is selected in all the slicing steps you have activated on the right. So use the dropdown tabs to select the 1/8″ tool. Make sure you’ve loaded the geometry and rotated it into position. At this point, I can slice the geometry and see what the path looks like for the cutting tool. Once it completes the path generation, you can even use the slider at the bottom of the page to watch the cutting layer by layer. If you like it, then you can export the gcode for the mill. I love the little bar at the bottom of the screen where you can scroll through the roughing and finishing steps to see exactly where the tool goes.

Finally, if you can save the gcode out from whatever package you have then it’s time to setup the mill. I used the wood that I prepared yesterday and secured it to the spoiler board. I’m pretty novice at setting this up so hopefully someone will school me in the comments on the best way to prepare the spoiler board and setting up the workpiece. Basically, I moved the end mill within the approximate operating range and setup rails that I could secure the workpiece to so that it would stay in my preferred location and give me the most access to machining my features. For running the desktop mill, which is an OX CNC, it interprets gcode through a tinyg controller which is hosted by a json server. Honestly, seeing the other options I think the GBRL controller seems a little more common, but you have to walk in the shoes you own. You can move the machine with coolterm but I just jumped straight into Chilipeppr for sending gcode instructions to the tinyg controller. Again, my advice if you are getting started with this is go to Chilipeppr’s website and start pressing buttons and trying it. I was pretty impressed with the ease of use once I finally got the communications side hooked up. In the end, for the drag side of the knife pattern I started milling today as shown in the picture.

Some concluding remarks, the milling above failed today. First, the hold downs you see there were not adequate to secure the wood while the tool was traveling (thanks to Kat Steel for noticing my overconfidence). Second, my first gcode was stepping down 1mm deep each pass for the roughing cut. This stalled the machine because it was too much for the little 300W router on my system. Third, when I started the shopvac to vacuum some of the sawdust… it popped the circuit breaker on the power strip I was using and stopped the mill. So with those three interruptions, I decided to call it quits on the mill today and start it early tomorrow morning to see if I can finish something to show. Given the above discussion, I’m sure I’ll need to add some posts about setting up the machining parameters and other details but later on that.

Wood for CNC

One thing that I haven’t quite figured out is wood for the desktop cnc machine. Ideally for my purpose of quickly getting ready for building patterns, I’d like to source some wood to build patterns and teach everyone in the lab how to make larger pieces of wood from smaller ones. By the way, I’d like it to be quick and cheap too, see rapid prototyping post about difficulties with this. So, there are some nice discussion about the types of wood for pattern making in the patternmaker’s manual published by AFS. However, for my purpose I just want to go with the easiest available white pine that we get in various quantities from shipping containers or cheaply from local suppliers in 2×4 dimensions. For better machining, I’d probably get 2×10 or 2×12 but I just want to illustrate what I’m trying. Also, for this post I’m going to discuss the dimensions in inches unless otherwise specified.

Given my mold lock (which I’m going to change the outer dimensions to 10×16 for the knives, thanks for pointing this out @workshopshed), I’m ready to start machining if only I had some wood. Now, probably the best thing to do is get some 2x10s but I’m going to talk about making essentially a 2×10 using 3 sections of 2×4. For that purpose, I gathered all the miscellaneous 2×4 sections around the lab and began to cut them to 16″ lengths. Of course the horizontal band saw is probably not the preferred method, but it was effective for me. I made about 6 pieces that I can take to the planer.

The objective if I want to join them together is to prepare an edge to join them together that reduces the gap as much as possible. Don’t assume the wood is square and use a planer to create the square surface to mate. I went ahead and planed the 4″ wide section of each 2×4 top and bottom to make consistent surfaces removing any roughness on the as received pieces. Then I needed a way to secure these sections together so that I could plane them all at the same time on edge. So I built a small frame using some strut channel that we had lying around from some earlier projects and a short 12″ length of 3/8″ threaded rod. Basically, I was going for a way to hold this section of 6 sections of 2×4 together so that the planing would remove the same thickness from all to then be able to join.

Next I used a joiner to cut a slot into the side of the 2×4 for a #20 biscuit. This method is quick and easy for joining these 2×4 together on edge. Couple pointers here, make sure the depth is set correctly and that your angle is set for 90 degrees on the joiner. My joiner kept slipping below 90 degrees and the biscuits wanted to be inserted on an angle.

You can see the final product (prior to glue drying) of the wood base for my CNC milling. I used 2 biscuits between each 2×4 and the final dimensions are about 9 5/8″ by 16″. After the glue dries, this should be ready for milling. The circumference around this piece will be cut one last time at an angle to build the box for the molding once the CNC milling of the part is complete. So the fact that this is not quite flush on end and not quite flat between the 2×4 sections don’t bother me too much.

Mold Lock

In the effort to develop pattern making expertise, I was disappointed in the lack of information about various types of mold and pattern locks to align the cope and drag sand molds for a flaskless sand casting process. The most common discussion I’ve seen is the flask alignment approaches which are primarily used in green sand. There are some really good backyard casting websites that overview the process. Let me start by acknowledging them, hats off to Gingery Foundry, Workshopshed, Backyardmetalcasting, kylehausladen’s instructables, Steven Chastain’s book, AFS Patternmaker’s Manual and others I’m sure to forget to include links. Let me give the caveat that I’m looking specifically for good strategies for pattern/mold alignment that I can just build into the patten for a flaskless mold.

Let me tell you things that don’t seem to work well, to start out with. First, you could depend on the edges of the mold to align the pattern. If there are no features in the either the cope or the drag then I believe this method would work well. That’s an obvious one. Second, you could add “pins” to the pattern. In fact, there are options like the Freeman Concentric Mold-Lock Buttons that are commercially available. I think a solution like this would work well if you take care to install them both in the right location and with three of them that are not symmetric so that the orientation of the mold cannot be reversed. But frankly, I really want to discuss an alternative mold lock that I’ve been playing with. Using Onshape, I created a 1/2 inch platform that the cope and drag patterns could be built from. This is simply a “picture frame” approach to aligning the cope and drag. The drag lock is simply creating a raised surface which when matched with the cope lock which creates a recessed surface. The outer edge is 10.5″ square which is roughly the limit on the desktop milling machine. One corner has been prepared with a corner knocked off to make sure the mold is oriented properly.

Drag lock in Onshape.com

Cope lock from Onshape.com

Please note that I’m probably a little premature in claiming this is my solution for this alignment issue. But the example below is the cope side of a little cast knife project I’m working on to see if we can cast some steel knives as part of an AFS student activity.

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.

Rapid Melting Applied to High‑Pressure Die‑Casting

… is the title of Carlos Larrazabal PhD dissertation work that he successfully defended last Thursday. Of interest was the power outage that occurred immediately after his presentation. The committee continued to question him in the dark and everyone persevered until he answered all aspects of his work.

Stay tuned for his first publication that is focused on modeling the electromagnetic and thermal aspects of induction heating a cylindrical billet of aluminum. This work is the basis for designing a rapid melting system. We believe that this effort will serve as a building block for designing several heating stages toward delivery of high-quality aluminum on-demand.