Archive for the ‘railway design’ Category

Thermoformed Plastic Boss Design

Monday, April 26th, 2010

Many electronic products are held together by machine screws (into bosses) and snap fits. Such features are designed into the latest release by model train specialist Bachrus Inc., designed by (featured on the cover the May 2010 DPN edition )  as this fastener technology is used for final assembly.



The model train controller product has some nice architecture features built into the electronic housing to help the form fit with the function – the outside that is seen in the creative exploration of shape and style. As the goal here was to wow the end user and add value to the product line, but with that said the inside was meticulously engineered to give that outer appearance a good first impression.

Here I’m focusing in on the architectural structure of the product’s boss designs. Because to get those right means that there is added strength without added wall thickness – as surface blemishes due to sink marks in the plastic show up more with an increase in plastic. As well, wall thickness uniformity is important to cycle times and generally the ribs and bosses are based on a 60/40 percentage ratio. So there are some minor tweaks that can make a design even better if you find the right source.

As you’re probably aware, Googling this topic will drop a great amount of resources onto your screen and a handful of fastener manufacturers’ documentation is there to sift through. However, I thought I would compile a little bit of information on the topic here in a handy, easy-to-access blog report.

The preferred thermoforming machine screw, which is engineered for plastic, is a thread forming screw like the EJOT PT cross recessed raised cheese head style screw – sourced in many places such as the Fabory Catalog. The key advantages of this thread forming fastener are many:

1. Is that it works in all types of thermal plastics.

2. It gives a maximum resistance to pull out with its 30° thread profile and narrow thread pitch.

3. Finally its recessed thread root design gives optimal material flow into the cavity recess between the threads on the screw as it cuts into the boss. This is highly desirable feature on very small screws like a KB 22×6 Pozidriv EJOT PT machine screw (Ø2.2 mm x 6.0 mm).

So once you’ve found the perfect Machine Screw, the structural design of the Boss to receive the PT EJOT thread forming faster is a bit more than a tube profile with draft. Companies like Acument, of Sterling Heights, MI, give some general guidelines online to create the qualifiable boss design you will need (see the chart below or look at: ).

ffp final 44

Machine Screw

Acument recommends to keep-in-mind that specific applications need to allow for various molding conditions, tool design, weld lines, and proximity to any injector gates, etc. will affect the boss.

With all that said though, the laboratory testing and in the field applications have produced great results for product designers to rely on, instead of the educated guess approach or the simple tube with draft.

Also a designer needs to notice the different recommendations for the inner diameter (i.d.) hole size for the screw – as it is dependant on the specific thermoplastics being used in the product design. As each plastic has its own molecular composition, some polymers are prone to cracking under expansion stress, while others are more capable of resisting those pressures when the screw is driven into place. Knowing your product material early on in the design process helps you create the optimal boss dimensions.

The surface finish on the final part might be high-gloss and capable to reflect subtle changes in the surface. So in a micro level, this is where form meets function in the design process because it’s truly here that the devil is in the details - and it will show. So go ahead and get the right boss design built into your parts and you will be on your way to making great designs.

Railway Design - Canadian Connection

Tuesday, March 31st, 2009

Industrial Designer

Industrial Designer | Claude Gidman

I had the opportunity to work for Claude Gidman a few years ago where I learned about a man who had many years experience in Vehicle Design from working at Ford to designing VIA Rail interiors to off highway vehicles with Gidman Design.  It was just after I left that Claude retired the Gidman Design Company. The following article is a tribute to both a mentor and a friend.

David Duncan  IDWS

Red Rocket man reflects on 40 years as designing mind

By Christopher Hume
Toronto Star Design Critic

Few Torontonians know Claude Gidman’s name, but most know his work.

The 65-year-old Industrial Designer ranks among the most respected Canadian practitioners of this ubiquitous yet invisible art.

Though Gidman’s credits include everything from front-end loaders to vacuum cleaners, his best-known design is the Toronto streetcar.

It qualifies as a genuine civic icon, one of the things that makes this city unique. But for Gidman, it is only one of hundreds of projects he has completed to date.

“I don’t want to be known just for the streetcar,” insists Gidman, who recently retired as head of Ontario College of Art and Design’s industrial design department. “I’ve done so many different things.”

Just how many can be [was] seen in [the year 2000]  a small tribute exhibition [was] on display in the Atrium at the college, 100 McCaul St., until [that]  Friday. The drawings, paintings, models and photographs in this wide-ranging survey document a career that dates back more than four decades.

The earliest works are a series of small futuristic scenarios done in the late 1950s. They illustrate Gidman’s vision of transparent workplaces decorated with sleek furniture, streamlined greenery and ocean-liner cars outside.

Gidman smiles at these youthful imaginings. “Back in those days,” he recalls, “small meant cheap.”

How things have changed; now, neither big nor small means cheap.

“It doesn’t matter whether you’re designing heavy equipment or ski boots,” Gidman argues. “The design process is a process. It should start with a team of people from many different disciplines - engineering, marketing, design and so on.

“Canada is so well-placed. We’ve got such bright, educated people with lots of experience. But we need to start working together.”

Gidman has fought to bring a team approach to design. A highlight came in the 1980s when he persuaded the presidents of the art college, the University of Toronto and Ryerson to sign an agreement committing their institutions to teaching product design.

“All along Claude has emphasized teamwork,” says Lenore Richards, dean of the art college’s design faculty. “He also focuses on the pragmatics of mass production, such as materials and processes. Ultimately, though, it’s about developing meaningful designs for users.”

So far, his dream of a multi-disciplinary product-design centre remains unrealized. And although Gidman continues to teach at U of T and run his own studio in the Albion Hills, he has abandoned the fight to bring light into the ivory tower.

“I don’t think I’ll miss it,” he confesses. “I’ve made my contribution.”

That has been recognized many times, most publicly in 1987 when Gidman became the first industrial designer to win a Toronto Arts Award. Gidman oversaw the production of the Brita water filter and a second TTC vehicle, the “kneeling” Orion bus for disabled passengers. But Gidman’s most enduring legacy is his streetcar. Each time one rumbles by, he’s reminded of how well it turned out. You don’t have to be a Red Rocket scientist to figure out why.

“There’s a certain romantic aspect to what a streetcar should be,” he notes. “The question was whether you want the streetcar to blend in with the city or stand out. We decided it should stand out.”

The design process, which began in 1974, lasted several years and was steeped in controversy. It turned out that Torontonians were deeply attached to the original Red Rockets, which had travelled city streets since the 1930s.

“We had delegations of people who tried to stop the development of the new streetcar,” Gidman remembers. “The question was how futuristic it should be, or how traditional. Had we followed the style trend of the time, we would have produced a less-successful result.”

But as he loves to point out, design must address function above all.

“I thought we should get the driver up high enough so that he was at eye-level with passengers,” says Gidman. “Before, it was quite demeaning, drivers were down at belt-buckle level.”

Then there’s the impressive front window, curved to reflect interior glare away from the driver. A few minor modifications and a quarter of a century later, Gidman’s streetcar is an urban fixture, with 196 in service in Toronto along with 52 articulated vehicles.

“I knew the streetcar had been accepted years ago,” Gidman laughs. “Back when it started to appear in cartoons.”

(Published by Toronto Star on April 5, 2000 4:40 PM)
In 2000, the Exhibit honoured the man behind TTC streetcars