Drawing a hard line between the engineering office and the machine shop creates waste. The high capital cost of machining equipment and the detailed expertise needed to safely run the equipment creates three bottlenecks: limited machine availability, limited budgets for actual machining projects, and lengthy approval processes. I know because I dealt with this myself for years. It’s one of the things that inspired me to start a company whose products make machining capabilities more accessible. Let’s talk about how a typical company operates and how a hybrid machining platform can change all of that.
As a design engineer at several large and mid sized companies, I ran into barriers in getting prototypes made. The process always involved submitting a request thru an internal system with a generalized form with “requested by” and “need by” dates. Fully toleranced drawings were required and the form was approved by 2 levels of managers before the shop received it. In most cases lead times were 4-6 weeks.
Separating engineers from the equipment they need to make parts.
This is a terrible way to do development work.
Long lead times kill projects by limiting the number of iteration cycles a team can fit in a given timeline. They also disrupt the design process by inserting long pauses between when a design is created and when it is tested. After six weeks it’s hard for the engineer to remember the reasoning behind all of the features of a design. An embarrassing number of times, I’ve found a tapped hole where I wanted a clearance hole. Then, after drilling it out, I remembered why I wanted the threads.
It doesn’t have to be this way. And hybrid equipment like the H-Series can be an important part of helping researchers and engineers around the world improve their workflow.
Often when you’re trying to get a prototype made, you’re willing to give something up in order to get the parts in your hands quickly. Sometimes you’ll accept slightly looser tolerances or rough surface finishes for a first pass. Sometimes you just need a simple custom bracket. This is exactly where a machine like the H-Series can fill a critical niche for many companies. With the open, approachable benchtop design, we’re targeting the most costly part of short run machining- the setups.
Effective prototype machining at a fraction of the cost.
Take the example below. This is a product that we prototyped for the rock climbing industry. It is a component for a pregnancy harness that shifts the loading points from the center of the waist out toward the sides - what the rigging industry would call a spreader beam...a reference that I’ve found pregnant women don’t appreciate. The design is relatively flat, but with a curved exterior, making it challenging to fixture.
This part was a good candidate for a 4th axis setup given that both sides needed smooth 3D contoured features. By clamping an oversized piece of stock in the rotary axis vises, we were able to machine all of the features of the part from the top and bottom sides without the need for secondary operations. The strategy here is to leave tabs along the perimeter of the part, holding it in place while the bulk of the material is removed. Then we come back and machine the tabs away until the part is hanging by just a few threads.
Although the plan for this part was to machine all of the features without the need for secondary fixturing, the first round of functional testing resulted in some changes to the design. Thus a second round of machining was required. This is again where the versatility of the H-Series platform can provide real value. Rather than machining a new part from scratch, we fixtured the existing part using standard H-Series tooling. The easiest way to do this was with 2 stationary fixture blocks and one clamping fixture block. Using the cylindrical heads of socket head screws in the tapped holes of the fixture blocks, the part could be easily clamped on its curved edges. After locating the part using the touch probe, the new features were milled without difficulty.
The standard spindles on the H4 machine are lightweight, optimized for performing finishing cuts on plastics. So using this machine for harder materials, like aluminum requires very different feed rates and depths of cut from a typical CNC mill. The light duty spindles require light passes to be taken. One major advantage of taking such light passes is that low-force fixturing strategies (like the one shown above) are feasible since the tool loads are also low.
Although the H-Series does not represent a fundamentally new technology in the CNC world, it does offer a new paradigm in the way that an operator interacts with the machine. It is more akin to 3D printing where we load a large sequence of toolpaths and let the machine run for a long build cycle. It is also a machine that enables novel strategies for getting quickly from idea to prototype. It’s a machine that belongs in the hands of designers and engineers.