Mechanical Manufacturing Hack Chat

Based on the discussion this afternoon, here are some of the most popular resources from the Fictiv Hardware Guide on mechanical design and more:

• Design for Manufacturing Terminology: https://www.fictiv.com/hwg/design/design-for-manufacturing-terms
• How to Design Living Hinges: https://www.fictiv.com/hwg/design/how-to-design-living-hinges
• Strain Relief - Design Tips for Durability and Aesthetic Appeal https://www.fictiv.com/hwg/design/strain-relief-design-tips-for-durability-and-aesthetic-appeal
• How to Design Light Pipes: https://www.fictiv.com/hwg/design/learn-by-example-how-to-design-light-pipes
• Enclosure Design 101: https://www.fictiv.com/hwg/design/enclosure-design-101
• Best Practices for Adding Ribs and Gussets to 3D Printed Parts for Structural Integrity: https://www.fictiv.com/hwg/design/best-practices-for-adding-ribs-and-gussets-to-3d-printed-parts-for-structural-integrity
• Guide to Excellent Button Design: https://www.fictiv.com/hwg/design/right-on-the-button-using-button-design-as-a-showcase-for-excellence
• How to Conduct a Failure Modes and Effects Analysis: https://www.fictiv.com/hwg/design/how-to-conduct-a-failure-modes-and-effects-analysis
• Heat Sink Design Guide: https://www.fictiv.com/hwg/design/heat-sink-design-guide
• PCB Design - How to Balance Functionality in the Context of Mechanical Constraints: https://www.fictiv.com/hwg/design/pcb-design-how-to-balance-functionality-in-the-context-of-mechanical-constraints
• How to Conduct Tolerance Analysis for 3D Printed Parts: https://www.fictiv.com/hwg/design/how-to-conduct-a-tolerance-analysis-for-3d-printed-parts

There are many, many more in the Hardware Guide (fictiv.com/hwg) - and we are always looking for additional suggestions. If you have feedback, questions, or ideas on what guides we should write next, email Fictiv's Community Director at madelynn@fictiv.com, or help@fictiv.com

sylvia : Hello everyone, My name is Sylvia. I'm a manufacturing engineer at Fictiv. Prior to Fictiv I worked as a product design engineer and dabbed in industrial design. Here to take your product design, manfuacturing, and DFM questions.

Lutetium : welcome @sylvia!

Shulie Tornel : PSA: *If chat is lagging, pls refresh!*

anays : Yay

Maksim Surguy : Hello @sylvia

Lutetium : We typically fire questions but use the sheet https://docs.google.com/spreadsheets/d/1PA_oiwXWhUOlCm1dZIhK6nVjsuoL1e09FHLdHXpSJoc/edit#gid=0 as a conversation starter

sylvia : I can start off with @altometer's question about button sourcing. Button feel is a combination of the underlying switch, optional springback device, and button top.

Scott : I'm here from the reminder email as well.

sylvia : The common switches are pushbutton vs metal dome. These give you "clicky" button feel.

sylvia : if you don't like the clickiness you can use a conductive pill to short across contacts. See Fictiv's Nintendo and Xbox controller teardown articles to get a sense of what that looks like.

https://www.fictiv.com/blog/posts/nintendo-controller-teardown-part-1

https://www.fictiv.com/blog/posts/xbox-controller-teardown

Lutetium : @altometer are you thinking about making custom buttons?

altometer : Yeah. I like the tactile feel of a click, but the sound drives everyone around me mad. I need something like a surface-mount Brown switch that's about 5mm in diameter.

sylvia : button tops have a small impact on overall button feel, in most cases the switch makes the most difference.

sylvia : You can also look into microswitches, it's the switch used under most mice's L and R buttons.

altometer : @Lutetium Think like the Super Nintendo buttons. I can't find caps for a reasonable price that don't look like cheapo skittles.

Erin RobotGrrl : how do you get 2-stage buttons?

Erin RobotGrrl : (like on a camera button?)

davedarko : there are click buttons with different activation force btw

sylvia : @Erin RobotGrrl that's a specialized switch, not a button top thing

Erin RobotGrrl : is there a name for that switch?

sylvia : @altometer i agree off-the-shelf button tops are pretty industrial looking. they are mostly for panel mounting. If you are doing at least ~1000 pieces you can get a custom button top injection molded for a reasonable cost.

sylvia : alternatively, use SLS Nylon to print the button tops, tumble polish to get a smooth matte texture. Great 3D printing process for production.

Lutetium : want to move on from buttons?

davedarko : @Erin RobotGrrl you could stack a low force button on a high force button

Lutetium : next up question from @Maksim Surguy: What are different ways to make a plastic box that is affordable in mass manufacturing?

sylvia : @Maksim Surguy what kind of plastic box are you looking for? food-safe? for electronics? injection molding comes top of mind as a process

altometer : Thanks @sylvia

Maksim Surguy : @sylvia electronics, for a clock, but bigger (50cm x 10cm x 2.5cm )

sylvia : @anziclone you can try solvent welding

Erin RobotGrrl : @davedarko Oh! and have a plunger on the button top that stikes both button components? maybe there's a teardown of a camera somewhere that shows this!

Maksim Surguy : @sylvia I need really nice finish on the front panel, glossy

sylvia : @Maksim Surguy injection molding in ABS

anays : Thank you @.Sys

sylvia : gloss is achieved by polishing the mold, so every molded piece is glossy without secondary operations

anays : Thank You @sylvia

Maksim Surguy : Great! Thank you!

Lutetium : Next Q is from @anziclone What is the best way to seal acrylic cut objects? Also, if we need to join acrylic pieces at an angle where teeth are not possible, what method do we use to join the two surfaces?

sylvia : solvent welding https://www.amazon.com/Weld-Acrylic-Adhesive-Applicator-Bottle/dp/B0096TWKCW

Lutetium : @Erin RobotGrrl has a question that builds on that: ^ Building on the above question, what are techniques to biulding waterproof enclosures, with wires coming out? Do you have recommended connectors?

anays : Will the solvent leave a residue on the joins? I do not want to lose the transparent nature on the joins.

sylvia : @anays that entirely depends on the workmanship! can be a little tricky

davedarko : maybe bending on that particular edge?

anays : Okay. That helps. :)

anays : Appreciate it. Thank you

sylvia : @Erin RobotGrrl have you thought about using waterproof connectors instead of having the wires come out of the enclosure?

anays : And how about joining acrylic sheets at an angle? I'm looking to construct a tetrahedron.

sylvia : the low tech way to get a waterproof seal for wires coming out of an enclosure would be to use silicone caulking, but that won't last with repeated use

Erin RobotGrrl : @sylvia do you mean connectors on the enclosure? where would they mount?

Erin RobotGrrl : @sylvia also ideally the enclosure will have to open. it's for protecting a battery from waves

sylvia : @anays I haven't tried, but you could build a fixture then use it to constrain the angle of the sheets you are connecting. Solvent is pretty agnostic about angle.

madelynn : @anays I've had luck joining acrylic at an angle with solvent welding as long as you clamp the pieces together before welding. It's a tricky setup but makes the workmanship easier.

Erin RobotGrrl : (water waves)

sylvia : @Erin RobotGrrl you have to make the connector a part of your enclosure design. Suppliers of waterproof connectors provide documentation on how to best use their connectors, for example http://www.molex.com/molex/products/group?key=sealed_connectors&channel=products

anays : Thanks @sylvia & @Madelynn Martiniere... :)

Lutetium : Next question: What are some tools or machines that you use for your work that have been the most useful? Or are there any in particular that you've had a lot of fun using?

Lutetium : from @vijilij

sylvia : I'm currently an unpaid OnShape evangelist, great free tool to get started with 3D CAD

Kevin : Oh, ty Sylvia. I hadn't thought about looking for waterproof connectors.

sylvia : unpaid and unofficial

Erin RobotGrrl : @sylvia thanks for the link to those connectors!

anays : I would like to second @Maksim Surguy question: What plastics are best for diffusing light evenly?

sylvia : in mass production the go-to way is to add titanium oxide into polycarbonate, usually 0.01% or lower

sylvia : different % get you different levels of diffusion

sylvia : in prototyping you can buy off-the-shelf smoky acrylic, or put diffuser film on acrylic or polycarbonate

Erin RobotGrrl : Wow!

sylvia : you can laser etch acrylic to get a matte surface good for diffusion

samy kamkar : ooh interesting

sylvia : 3D printing waterclear material is challenging but VeroClear is a great diffuse semi clear plastic https://www.fictiv.com/hwg/fabricate/how-to-3d-print-light-pipes

Kevin : I'm going to have an enclosure for a prototype 3D printed but I'm not sure how thick I should make the walls of the enclosure. The box is only going to be on the order of 1.75" x 1.25" x 0.75". Is 1mm enough or should I use 1.5mm? What would be a good typical value for the walls?

anays : Brilliant. Exactly what i needed.

sylvia : @altometer had a question about domestic vs. foreign manufacturing... I have worked extensively with foreign and domestic manufacturers, and not all all foreign manufacturers are the same. Domestically, you get good and bad suppliers and it's the same overseas, just harder to vet if you can't visit them.

sylvia : @kcozens you should always go with thicker unless there's some compelling reason to do thinner.

sylvia : totally depends on how much abuse this thing has to take

Erin RobotGrrl : @Kevin i've had bad luck w/1mm thick walls

sylvia : what is the nozzle diameter of the 3D printer you'll be using? you want the wall to be a few multiples of that

esot.eric : seems a zig-zag would be stronger than three parallel-runs, eh?

sylvia : would be, which 3D printing slicer can do that? I'd love to try it.

Kevin : It is an attachment that will sit on top of a camera. I'm not expecting it to be subject to a lot of abuse but stuff happens and it might get dropped or might get bumped up against something. I don't have a 3D printer. A friend of mine is the one that has. I'll check with them as to the nozzle size. Good thought to keep walls a multiple of nozzle size.

altometer : @vijilij You need to increase temperature if you are able to pull apart a wall at any seam. You aren't getting good enough layer adhesion.

altometer : I regularly print .4mm wall things that crack perpendicular to the print lines before they look at a seam like a weak point.

sylvia : alright everyone, I gotta run in 5 mins, any last minute questions?

Kevin : @Erin RobotGrrl: ty for that comment. I'll go for a thicker wall thickness. I'll have to do some experiments with the wall thickness in the modelling programming I use to see how it will work out.

Lutetium : Sylvia, can you quickly tell us about Fictiv?

altometer : @Sylvia hiring?

Lutetium : Also if you just got here, we're wrapping up but there's a transcript here: https://hackaday.io/event/20158-mechanical-manufacturing-hack-chat/log/54730-edited-transcript-for-mechanical-manufacturing-hackchat

sylvia : Fictiv is a prototyping and manufacturing platform. We have a web interface through you can order 3D printed and CNC machined parts. We love community building and knowledge sharing, Check out our hardware guide: https://www.fictiv.com/hwg/

sylvia : we are always hiring! fictiv.com/jobs

Kevin : Where can I find transcripts of past #Hack Chats. There were a couple I wanted to participate in but was not able to do so.

sylvia : we turnaround 3d printed parts in 24 hours and CNC parts in 3 days

Lutetium : Nice! Thanks @sylvia!

sylvia : we pride ourselves on our DFM feedback to help you design better and save money.

Lutetium : @Kevin past transcripts are on the event pages at hackaday.io/events

anays : Thank you Sylvia.

sylvia : you are welcome!

Shulie Tornel : Thanks, Sylvia!

vijilij : Thank you!

Lutetium : thanks for coming, it was great having you

sylvia : if you have questions about Fictiv, 3D printing or CNC machining, reach out to us at help@fictiv.com. Bye for now!

altometer : ! it was awesome

Neil Cherry : bye, thanks

altometer : Thanks!

Kevin : @Lutetium, ty

Dan Maloney : Bye all. Thanks Sylvia.

altometer : oh neat, there is actually a guide to excellent button design on their site! https://www.fictiv.com/hwg/design/right-on-the-button-using-button-design-as-a-showcase-for-excellence

Kevin : @Sylvia, ty for the link to the Fictiv hardware guide. I see a link to a guide on designing snap fit enclosures. That is another feature of the enclosure I'm working on. Adafruit had a video about that topic so I will be interested to see the information provided by your site.

Lutetium : Link to transcript: https://hackaday.io/event/20158-mechanical-manufacturing-hack-chat/log/54730-edited-transcript-for-mechanical-manufacturing-hackchat

madelynn : @kevin let us know what you think of the snap fits article: https://www.fictiv.com/hwg/design/how-to-design-snap-fit-components compared to the Adafruit video!

+ we're always looking for suggestions on more guides to write, so if there's topics you want to know more about, ping help@fictiv.com or myself - madelynn@fictiv.com