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How To Make Polished Product Prototypes Using Everyday Shop Tools

When I tell people what I do for a living, they’re always curious about the inner workings of the shop and what a model maker does day to day.

My “3 Top Prototyping Tools” post provides an overview — I run the shop here at Bresslergroup, and I build prototypes — but that post doesn’t venture too far into my tips and tricks, which is what most people seem to want to know about!

A couple of weeks ago I did a shop presentation for my mechanical engineering colleagues to share techniques I’ve developed for making models come together in a more professional way. These are little tricks have mostly come about from a whole lot of trial and error. Although they seem quite common to me, I find that most people are amazed by them.

They’re easy to replicate in your own shop with the everyday tools such as sandpaper, silicone, syringes, and Super Glue that we all have around. Here are ten of my most common, reliable prototyping hacks:

Shop Tip #1: How To Release Hot Melt Glue with Bestine

When you use hot melt glue on a model, you can release it with Heptane, or if you’re lucky, Bestine. Bestine is the brand name for a chemical that was easier to find back in the days when mechanical printing layouts dominated the graphic design world. If you can’t find it, non-lab grade Heptane will do the same thing. To release the hot melt glue, just soak down the joint with the Bestine solvent and work the part back and forth until it comes loose. Heptane will also remove decal residue and most tape residues.

Shop Tip #2: How To Use Cyanoacrylate (Super Glue) For Pretty Much Everything! 

Otherwise known as CA, Super Glue, or Krazy Glue, cyanoacrylate is part of a large family of very strong fast-acting adhesives. Pretty much every day we find ourselves needing to join parts and materials. Despite the wide variety of adhesives on hand, there’s usually only one answer: CA. It’s the most frequently used adhesive we have in the shop, and as a bonus you can either de-bond it with CA Debonder or speed its curing with accelerant. And if that wasn’t enough, it comes in different viscosities, which really helps when you need to fill gaps or wick down between two parts’ surfaces. When the gaps are really large, you can add some baking soda to bridge the joint. CA is the everyday hero of adhesives.

Shop Tip #3: How To Make a Metal or Plastic Part with Layout Ink

When you need to make a metal or plastic part quickly, and accuracy isn’t a top priority. … layout ink can help! Applying ink to your part creates a backdrop on which to mark out your design using digital calipers, scribe, radius gauges, or a center punch. Once you’re finished drilling, cutting, or filing, you can easily wash off the ink with acetone.

Shop Tip #4: How To Keep Parts Chill on the Mill with a DIY Part Follower

Despite your best efforts, some parts just don’t want to stay still on the mill. When the plastic extrusion pictured below started to move around, we made a follower out of leftover hardware from a previous project. The follower applies just enough pressure to the part to keep it from creeping up the end mill. The follower not only made cutting this part safer, it also helped keep the setup repeatable. Sometimes it takes just a little bit of outside-the-box thinking to get a job done.

Shop Tip #5: How To Make Sanding Sticks For Tough-To-Reach Areas

 I use sandpaper to make DIY sanding sticks that help with models’ tough-to-reach areas. All you need in addition to sandpaper is double-sided tape, sticks (which can be made of anything; we happen to have a lot of tongue depressors hanging around), and a knife. Apply the tape to your stick, and attach the stick to your sandpaper. Using the stick as a guide, cut though the sandpaper, and don’t forget to write the grit level on the stick.

Shop Tip #6: How To Brush Up Surfaces with Scotch-Brite

Appearances can make all the difference in the world when you present a part or model. However, not every job has the budget or time for a full-on polishing treatment, or even for a simple sanding. When budgets are tight on time or money, the Scotch-Brite pad is there to help! These pads are designed to be flexible and only remove a slight amount of material. Unlike sandpaper, their open structure allows dust to pass through without clogging. Suitable for all material types (metal, wood, plastic, glass) it helps brush up surfaces for a uniform look that keeps models looking burr-free without spending a whole lot of time on them.

Shop Tip #7: How To Create Flexible Joints with Silicone

When you need an adhesive that won’t react with paint, can be disassembled, and is water proof, silicone is your solution. Using silicone in the shop enables the flexibility to join parts together with the peace of mind that if they need to come apart, they can. Loading silicone into a syringe with a dispensing tip on it lets you lay down small beads of sealant exactly where you need them. If and when you need to separate them, flood the joint with Isopropanol to weaken its grip. As a bonus, you can repeat the whole process many times over far more than you can with most adhesives, including cyanoacrylates.

Shop Tip #8: How To Precision-Dispense with Syringes

The simple syringe is one of the most versatile tools we have in the shop. Use these for tasks that require precision-dispensing, for example of a glue, solvent, sealant, or even just water. Keep a couple of grease- or silicone-filled syringes nearby to save you from making trips to the storage cabinet to grab them. They also make really sweet hydraulic cylinders.

Shop Tip #9: How To Match a Hole Pattern onto a New Part with a Transfer Punch

Seemingly simple tasks can create more head-scratching than you ever thought possible. What if you need to match the hole pattern of an existing part onto a new one? Your good old transfer punch set will come to the rescue! Transfer punches come in kits of fractional, letter-, or wire-gauge sizes to match the drill bits they represent. There will most likely be one that fits your needs. Here we had to make block-off plates for the HVAC vents in our office. We used the existing vent housing as a pattern for the holes in the new plates. Lining up our existing part onto the new one, we picked the biggest punch that would fit though the hole and gave it a tap. The mark left behind by the punch guided our drill bit to the correct location, and all without an ounce of math.

Shop Tip #10: How To Create a Glossy Sheen with Vapor Polish (Hint: Carefully!)

When we need a part to be as glossy as it can be and painting isn’t an option, we use vapor polish. Vapor polishing is when we expose a printed ABS part to acetone vapors in an airtight container. The interaction of fumes with ABS material causes the exposed surfaces to begin to flow as if they were being heated. This flow of material helps blend the roughness of layers in a 3D print and gives the part a glossy sheen. This will also work on just about any ABS part you have that needs a little shine. By varying the amount of time the part is left in the chamber, your resulting part can range from sporting a slight sheen to melting into a sticky pile of goo — so err on the safe side.

We’ll post these and more shop tips on Twitter and Instagram over the next few months, so follow along at #shoptips — and let us know how they’re working for you!

Read more of our thoughts on prototyping.