Adventures in 3D Printing, Part 1: What an Engineering Firm Learned from Printing Parts
Paul DeWys owns DeWys Engineering and the Forerunner 3D Printing service, both located in Western Michigan, near Grand Rapids. After many years making 3D printed parts for customers, Paul offers some pointers on how to design parts to take advantage of—and avoid the pitfalls of—3D printing.
The following article is based on a presentation delivered by Paul at the 3DEXPERIENCE World 2020 event in Nashville, Tennessee.
Paul DeWys, founder of DeWys Engineering and Forerunner 3D Printing, operating in western Michigan. (Picture courtesy of DeWys Engineering)
Paul started the engineering portion of his business in 2009, operating out of his college dorm room. He was working for a tool and die company and saw an opportunity to get hired to work remotely while still in school.
After he was hired, Paul immediately went out and bought himself a seat of CATIA. He ran CATIA for the first year and then purchased a seat of SOLIDWORKS. He transitioned to SOLIDWORKS almost completely and now does 90 percent of his work with SOLIDWORKS. From 2009 to 2016, Paul working together with other engineers grew into the company DeWys Engineering. Their customers today include companies in automotive, aerospace, automated equipment, agriculture, foundry, furniture and some new product development. The business is pretty diversified, he says.
The Making of a 3D Printing Business
Between 2009 and 2016, DeWys did a lot of product development for one company—including, of all things, a cellphone case with a built-in Taser. This required a lot of 3D printing. Paul found a service bureau nearby and started sending them all their work.
“I’m a sales guy, I like to talk,” says Paul. “I would go over there and pick up parts from the guy who owned it. He was a sales guy, he liked to talk, so we’d just talk for an hour or two every time I’d pick up parts. I find out he didn’t have a succession plan for his business, and he was getting close to retirement. Offhand, one day I said ‘Ross, when you’re ready to sell this business, you should give me a call. I’ll buy it from you.’”
“Well, maybe I will,” Ross said.
Two years went by, and Paul almost forgot about that conversation—until one Tuesday morning in 2016, he gets a phone call.
“Hi, it’s Ross Gates,” the caller said. “I’m done. I’m selling it. Do you want it?”
“I’d love to buy your business.” Paul agreed on the spot, then hung up the phone and went straight to Google: How to buy a business.
By summer 2016, Paul had bought the assets of the 3D printing company, two SLA machines, and moved everything over to his own location, starting up Forerunner 3D printing.
Shortly after getting into the 3D printing business, it became clear that end-use parts, not just prototypes, were possible with these machines. However, you needed to design for them, just like you would for injection molding or stamping or sheet metal fabrication.
3D printed credit card holder fits in a cellphone case. (Picture courtesy of DeWys Engineering).
Does 3D Printing Give Unlimited Design Freedom?
You do have unlimited design freedom, Paul begins his presentation, but as with any other process, if you optimize your design for 3D printing, there are lots of cool benefits to unlock.
One of these is isotropically stronger parts. Typically, 3D printer parts are strong in X and Y directions, but weak in the Z direction, i.e., weak between the layers. There are ways around that, however. For example, you can orient the parts to have strength in all the directions that you need, and sacrifice strength in a direction that doesn’t matter.
Another trick reduces post processing time. With anything from a $500 MakerBot FDM machine to a $500,000 3D Systems SLA, you should know that when you take that part off the build platform, only half the work is done. You still have to take all the supports off. You can spend a lot of time and be frustrated and have scrap parts from dealing with supports. But there are ways you can design around that, too. You can design parts to have no supports, or minimal, easy to handle supports.
There’s more. With additive, you can add functionality and unique features. 3D printing allows for things such as integrated springs, printing assemblies as a single part, trap components, non-machinable, non-injection moldable and non-stampable features. Because you have that design freedom that 3D printing affords, you can do some really wild stuff.
Lastly, there’s lower cost. Anyone who has dealt with 3D printing over the years, especially if you don’t own the equipment yourself and if you’re coming to a service bureau or an additive manufacturer, will realize very quickly that 3D printing can get eye-wateringly expensive. But if you design your part with 3D printing in mind, there are ways to get around that.
You can take a part that might cost $1,000 per piece and drop that down to $250 per piece by getting a little creative with how you design it. The following examples are going to be parts that were either specifically designed for 3D printing, or parts that we took in from customers and ran through our engineering department to redesign them to be 3D printed.
Designed in SOLIDWORKS, manufactured with NC and 3D printing at DeWys Engineering.
Let’s summarize the three machines in our shop. The first is an SLA (stereolithography) machine. SLA was the first 3D printing technology that was brought to market back in 1990. With SLA, you’re using a UV-curable resin in a vat, and a UV laser. Wherever the laser touches the top surface of the resin, it will cure a layer of that material between 1 to 10 thousandths of an inch thick, depending on the machine’s settings. Layer by layer, that laser hardens up each layer of material—then you recoat, and harden up the next layer. Recoat, harden up the next layer, and so on.
This technology has been around for a very, very long time in the world of 3D printing. There are still a lot of great applications for it, though it is a little bit limited due to the material science. Many people use SLA just for prototyping, especially prototypes of big plastic enclosures—but I have an example of an application where we actually used SLA for an end-use part.
The grippers shown above needed to have vacuum lines running through them—not a problem with 3D printing. (Picture courtesy of DeWys Engineering.)
We had a customer that came to us with a part for a machine that required this part. The challenge: design a block that could both route high pressure air for blow off and have a strong vacuum to remove blown off dust—all in one part. We used computational fluid dynamics (CFD) inside SOLIDWORKS, and that analysis guided the designer to angle the high-pressure air holes in a very awkward way for manufacturing.
The design included an area on the top where it would be very difficult, if not impossible, for traditional machining to put those holes. The block also had many internal air and vacuum channels that would have required multiple setups in the mill. We also would have had to gun drill this block and actually turn it into an assembly. There would have been a lot of places with sharp corners where eddies could form, resulting in materials being trapped inside the block. It would also not be easy to clean.
So, we designed this part specifically to be 3D printed in an SLA 500. It had to stand up to a shop environment, and SLA parts are not known for their strength, so we encased it in stainless steel. The SLA never came in contact with the strip media that was rolling through it, which we were blowing dust off of and then vacuuming. The stainless steel took all the wear, and the block was for air and vacuum management.
To do that with traditional machining would have been extremely difficult. The four vacuum chambers had to have the ability to be tapered to a very specific mouth size to achieve the optimum draw based off the CFD analysis.
With 3D printing, we could get very, very exact about how the vacuum chambers were to be created. After placing all the HPA ports and vacuum chambers in the block, we plumbed it. All of our air and vacuum come in through the bottom, and once we had those chambers in place, we routed all of the supply lines through unused areas of the block. Wherever we wanted to put the supply lines, we could put them—which was really convenient.
You have to think ahead when designing for 3D printing. You will want to be sure not to end up with a trapped volume, because you cannot remove liquid or supports from an internal chamber after you print it.
Think ahead and use high angles from the horizontal plane in your part design. Anything over 45 degrees is self-supporting, and will not need additional supports. You won’t have to worry about anything being inside those chambers. SLA is a liquid process, which means whatever liquid resin is trapped in there can be blown right out with compressed air.
An arch is also self-supporting. When you have an arch, you don’t need supports—so don’t make it square, and don’t put a flat top on it, because you will have to support that. Instead, think ahead to that kind of stuff in your design phase, and determine what you will need for internal structure. If you do not have supports to deal with, then you can completely unlock a whole new design for 3D printing that you couldn’t create with any other process.
The bottom of a part is a different story. If a part has a flat bottom, it is easy to support off of the build platform. When you’re done printing and rip the part off the build platform, 30 seconds with a piece of sandpaper is all the postprocessing the part will need.
As someone with a 3D printing company, I can confirm the machines are expensive—but manpower is expensive, too. I bill $60 an hour for a modelmaker. If my modelmaker sands a part for four or five hours…well, you can do the math. Your part price increased by that much per part. Anything you can do to reduce sanding or reduce bench time is going to go right back into your pocket.
SOLIDWORKS Tip: Draft Analysis
Here’s a SOLIDWORKS tip for you: draft analysis. You may have used it for castings or injection molding. Draft analysis is used for parting line analysis. You can also use it for 3D printing, to answer questions such as, “What areas inside of my part are violating the 45 degree rule, or violating the arch rule?”
You can use draft analysis to very quickly select the bottom plane of your part, turn it on, and boom: everything is either green or red. You know exactly what your problem areas are. Draft analysis is a really handy SOLIDWORKS tool for evaluating this stuff.
HP’s Multi Jet Fusion
Unlike 3D Systems, DTM laser sintering machines, or EOS machines that use a laser to sinter powder, HP’s Multi Jet Fusion offers a new spin: there are no lasers involved.
Multi Jet Fusion is HP’s take on SLS. There is a print bed, and on the print bed we’re printing a part. When we finish a layer and get ready to start the next layer, the machine first spreads a 0.0003” thick layer of white nylon powder across the top of the part. Then it coats the entire bed in one pass with a fusing agent and detailing agent. The detailing agent gives you really crisp geometry, with crisp sharp edges. The black fusing agent, when exposed to high-energy IR light, absorbs all the IR light. This drives the temperature up in the black region of the print bed, and melts and sinters all those nylon particles to each other and to the layer below. However, the detailing agent prevents sintering to any of the white powder around it.
This of it like a black car and a white car sitting on a blacktop parking lot in summer. Black cars are always going to be hotter inside than white cars. With a white powder bed and a black part region, the black area gets much hotter. The white powder around it reflects all that IR energy and does not melt. The advantage to this method over SLS comes down to speed. You can run an MJF machine faster than you can run an SLS machine. This is why our MJF machine is one of our favorite machines for low volume manufacturing.
Original design made of machined Delrin (gray insert on left) was redesigned to work when 3D printed with Nylon PA-12. (Picture courtesy of DeWys Engineering.)
We had one part (a ratchet safety cover) and a challenge to take a machined Delrin plastic and design a part that is 3D printed out of Nylon PA-12. The decision to move from machining to 3D printing was driven by two factors: lead time and cost. The annual usage for this part was between three and 500 units, with a diameter that changes for every run. The customer could not justify an injection mold, so they were machining the parts. The lead times and machining costs had steadily increased for the CNC machines used to produce these over the years, to the point of frustration for the owner of the company. He was open to anything that would get him away from having to CNC machine plastic. We were working on another machine design project for the owner, and asked him for an opportunity to convert this to an HP MJF part printed out of nylon. And that’s what we did.
But Delrin has different properties. It can elongate a little bit more than the nylon, and nylon is a little stiffer. We had to make some changes in the geometry of the part to accommodate the difference in material property. When we originally printed the parts and tried to press them together in an arbor press, the nylon part would crack—whereas Delrin would stretch a little bit and work just fine.
When the initial design didn’t work, we had to come up with petals. Think of petals of a flower coming open. The petals had to momentarily stretch and then snap back over a detent. With 3D printing, you will hear it a thousand times: complexity is free, it’s size that will cost you. In this case, adding slots to make the petals was not a separate setup. It isn’t like we went from a three-axis part to a four-axis part on an NC machine. It didn’t matter with 3D printing.
The “petaling” solved the cracking problem.
“This is great,” said the customer. “But there is one more thing. We have to have a guy writing the size on every part with a Sharpie. Would it be possible for us to actually print the size on the outside of the part?”
No problem. Complexity is free. We put text showing the size on the outside of the part. It cost them nothing to print text on it. Anytime you can add text, logos, texture, anything like that to a 3D-printed part, do it. 3D printing is not like machining or injection molding where if you want to add a logo you have to add a slide to get that part out of the mold.
It literally does not cost you anything extra to add those features to your parts.
A little trick: If you get into a product where you will be iterating a whole bunch of different versions, and you’re going to be constantly changing the text on the outside of the part, you can link the text inside the SOLIDWORKS model in the sketch to a field in your property tab manager.
We use a start part, and have done hundreds of different sizes of these. We have a start part that we start with every single time and it has all of this already built into it. When we pop open our property tab manager, there is literally a field that says “Notes” and we type the size in there. When we hit rebuild on the part, it propagates it right on the side of the part.
Stay tuned for Part 2 with more tips on part design for 3D printing.