Tag: shop

After a long summer of brainstorming, ideating, prototyping, and revising, the picture frame is finally ready for deployment in the shop. Last week’s “wrap-up” frame design prompted the comment that most people print 4×6 pictures, not 5×7, leading to some quick dimension changes and the construction of a final prototype. This new frame holds 4×6 pictures snugly (a practical, appealing function), takes about 2 hours to make under ideal circumstances (commensurate with the wall hook), and lowers the cost by almost a dollar, down to $5.02 per frame (coverable by a small lab fee, as discussed in last week’s post).

As of now, the picture frame is officially a training option for those looking to use the yellow zone tools. All of this project’s goals were met successfully: the frame adds interest to the project, covers every tool in the yellow zone and incorporates some from outside, and is easily manufacturable by those new to the shop. With luck, these frames will soon grace shelves all across engineering dorm rooms at Tufts.

After a third prototype and some experiments with acrylic forming, the picture frame is, I believe, nearing completion. This prototype, shown below, goes for more of a “polished-industrial” feel that hides a larger purpose: the cap nuts securing the vertical frames to the acrylic plate allow for zero-tools insertion of a picture, something that was not possible in the previous two designs and could preclude many students from using their frames.

Compared to the wall hook, this frame has several key advantages that I believe make it an ideal shop training project, either as a supplement to the hook or as a complete replacement.

• Scope: The wall hook required only three yellow zone tools: the horizontal bandsaw, the drill press, and the jump shears. Students used the vertical bandsaw for a single cut, but with the caveat that they weren’t really supposed to use it for what they were doing—an odd thing to say during shop training. The picture frame, by contrast, requires five yellow zone tools, incorporating the hand drill and laser cutter into the original three. Additionally, the plate stock, while cut entirely on the jump shears for the prototype, could be cut properly on the vertical bandsaw with no caveats, thus making for six tools used properly.
• Variable tool usage: Of the wall hook’s 31 required power tool operations, a whopping 26 of them (84%) took place on one of the shop’s three drill presses. This high percentage of drilling and countersinking operations created major bottlenecks when large numbers of students were trained at once. The picture frame spreads out the tool usage much better, with only 18 of its 32 operations (56%) taking place on the drill press. The plate work on the supports could be split evenly between the jump shears and vertical band saw, reducing bottlenecks even further. The only real potential for a major bottleneck is at the laser cutter, but I believe efficient management of it so that multiple students are trained and cutting their single part at the same time could make its use manageable.
• Variable parts: The wall hook’s five pieces were all very similar (or, in two cases, exactly the same), each requiring almost the same order of operations. By contrast, each of the picture frame’s three unique components (two components are mirror images) requires a completely different set of skills from the others: the acrylic backing plate is laser-cut; the bar stock frames are cut on the horizontal bandsaw and drilled on the drill press; and the plate supports are cut on the jump shears or vertical bandsaw, hand-drilled, and countersunk on the drill press. And because the drill presses are split, two for drilling and one for countersinking, there is no tool usage overlap between parts as there was with the wall hook. If there is a line at the drill press, those not in line can work on a part that does not require the drill press, something that was not possible with the wall hook.
• Less tapping: The picture frame has half as many tapped holes as the wall hook, giving students the opportunity to get a feel for the process but giving them fewer chances to break a tap.
• Interest level: The wall hook perhaps received the most grief because of its lack of utility in a college dorm. Because the dorms forbid screwing into walls, most students could not make use of their hooks, leading to a lack of interest from those students who were not interested in the act of making something. The picture frame, requiring no mounting, presents a desirable end goal for those more results-driven than process-driven.

All of these advantages together, I believe, outweigh the one major disadvantage the picture frame presents: cost. Considering only the cost of materials in the finished product—that is, not accounting for students breaking taps, remaking parts, etc.—the frame costs $5.96, compared with the wall hook’s mere $0.74 price tag. I would argue, however, that the expanded scope and heightened interest level present a compelling case for adopting the picture frame and adding a small lab fee to the course. I believe most Tufts students would be fine paying a small price for a more useful end product; furthermore, it is almost expected in other disciplines here that courses with lab components are going to have a lab fee. For biology or chemistry, these fees can reach into the hundreds of dollars; by contrast, a $5 or $10 fee would seem insignificant, especially if it is clear that it pays for a concrete end product.

Several prospective students on a tour were asked about shop training projects, and while they thought the wall hook was decent and liked the pen holder more, they all agreed that the picture frame held the most appeal for them. I think many students would feel the same, given the choice between something they cannot really use and something that they may already want. And the more concrete advantages only add benefits.

This week saw great leaps forward on the picture frame, but ultimately proved something of a disappointment. The great leaps: a new design and two prototypes! The drawings showcased in last week’s post were prototyped, resulting in a proof-of-concept model that actually worked fairly well.

This design did turn out to have some issues, however. Most notably, it proved much more difficult than anticipated to accurately bend the frame’s aluminum legs; additionally, the bending process slightly warped the frame’s center sheet, preventing the picture from laying flat.

These considerations—difficulty bending and a warped image support—led to picture frame, rev. B, the designs for which are shown below. It replaces the single bent aluminum sheet frame with two aluminum sheet legs that are screwed into the vertical picture clamps, with the picture backed by a 1/8″ acrylic sheet.

As this design did not include any sheet bending, it proved much easier to build using only the tools currently in the yellow zone than the initial design. This new design was prototyped as well:

As suspected, the new design proved much simpler to build. However, I still believe it fails on two counts. First, it incorporates two tools that are not used in the wall hook: the laser cutter (to cut the acrylic), and the hand drill (to drill the holes in the leg plates). Second, and more important, this design costs over $7 in raw materials, several cents more than the initial design and far more than the $0.50 wall hook. As such, if we were to proceed with this design, we might need to incorporate a “pay-to-play” model, where the wall hook is the default option, but students can pay a materials fee to make something larger.

One of the leading contenders for new shop training project was a picture frame. These drawings are a first pass at designing a picture frame that could be built with the yellow zone tools. It consists of a bent aluminum sheet frame with two aluminum bar stock supports on the front; the picture is inserted by sliding it under the supports and then tightening them down to secure it.

Cost will possibly be a major issue with this design, with initial estimates putting it at more than 8 times more expensive than the wall hook. This extra cost is mostly incurred due to the expense of aluminum sheets, so next steps are to brainstorm ways to cut down on sheet stock usage and then start prototyping.