When it comes to CNC machines, your SureFine has screws on its axes, and the Bodgeport does too. A shopbot has an amazing rack gear system, but when you start to dig into the small CNC routers available for under $2,000, you’ll only find belts moving a router back and forth. This isn’t to say belts won’t work — you can create a fine CNC machine with bits of rubber. However, belts stretch, they wear out, and if you want more precision screws and racks are the way to go.
The WorkBee CNC machine is the first desktop CNC router we’ve seen that uses screws instead of belts. It’s a project on OpenBuilds, and a reasonably well-configured machine is now available from ooznest for about £1,700 ($2,200 USD), or just a bit more than other CNC routers that consist of a Dewalt router and some aluminum extrusion.
The WorkBee CNC is based on the OX CNC machine, another cartesian router machine built around the OpenBuilds aluminum extrusion. The OX, while a fine machine for DIY tinkerers, uses belts. The WorkBee trades them out for screws, and should gain better accuracy, much lower maintenance, and deeper cuts. Screws are slower, yes, but do you really need that much acceleration when routing a thick piece of wood?
Machine shop wisdom says the lathe is the king of machine tools. We ascribe to that belief, although the common aphorism that the lathe is the only tool that can make copies of itself seems a bit of a stretch. But in the shadow of the almighty lathe is a tool without which even the simplest projects would be vastly more difficult: the lowly vise. Trouble is, finding a good vise can be a tall order. So why not take matters into your own hands and build this very sturdy vise from scratch?
Most commercially available vises are made from a couple of large castings, but as complete as [MakeItExtreme]’s metalworking shop has become, casting molten iron is not a tool in their kit — yet. So they turned back to what they know and welded up the body and jaw of the vise from mild steel. The video below shows the long sessions of welding and grinding that bring the body and the jaw into being, in the process consuming miles of MIG wire. The main screw is cut from stainless steel and threaded with the correct Acme form for such a high load application, especially given the mechanical advantage the long handle provides. The jaws have dovetails for replaceable inserts, too, which is a nice touch that’s hard to find on commercial units.
With more and more research in the field of autonomous robotics, new methods of locomotion are coming on the scene at a rapid pace. Forget wheels and tracks, forget bi-, quad-, hexa- and octopods, and forget fancy rolling BB-8 clones. If you want to get a mini robot moving, maybe you should teach it to do the worm.
Neither the Gizmodo article nor the abstract of [David Zarrouk]’s paper gives too many details on the construction of this vermiform robot, but there are some clues to be gleaned from the video below. At the 1:41 mark we see the secret of the design – a long corkscrew in the center of the 3D-printed linkages. Continue reading “Single Motor Lets This Robot Do The Worm”→
The handheld screw driver is a wonderful tool. We’re often tempted to reach for its beefier replacement, the power drill/driver. But the manually operated screw driver has an extremely direct feedback mechanism; the only person to blame when the screw strips or is over-torqued is you. This is a near-perfect tool and when you pull the right screwdriver from the stone you will truly be the ruler of the fastener universe.
A Bit of Screw Driver History:
The kind of fun you can have with really cheap bits.
In order to buy a good set of screw drivers, it is important to understand the pros and cons of the geometry behind it. With a bit of understanding, it’s possible to look at a screw driver and tell if it was built to turn screws or if it was built to sell cheap.
Screw heads were initially all slotted. This isn’t 100 percent historically accurate, but when it comes to understanding why the set at the big box store contains the drivers it does, it helps. (There were a lot of square headed screws back in the day, we still use them, but not as much.)
Believe it or not the “Robertson” screw came out before the Phillips. Robertson just hated money and didn’t want to license his patents. So it’s only now that they’re in common use again.
Flat head screws could be made with a slitting saw, hack saw, or file. The flat-head screw, at the time, was the cheapest to make and had pretty good torque transfer capabilities. It also needed hand alignment, a careful operator, and would almost certainly strip out and destroy itself when used with a power tool.
These shortcomings along with the arrival of the industrial age brought along many inventions from necessity, the most popular being the Phillips screw head. There were a lot of simultaneous invention going on, and it’s not clear who the first to invent was, or who stole what from who. However, the Philips screw let people on assembly lines turn a screw by hand or with a power tool and succeed most of the time. It had some huge downsides, for example, it would cam out really easily. This was not an original design intent, but the Phillips company said, “to hell with it!” and marketed it as a feature to prevent over-torquing anyway.
The traditional flathead and the Phillips won over pretty much everyone everywhere. Globally, there were some variations on the concept. For example, the Japanese use JST standard or Posidriv screws instead of Philips. These do not cam out and let the user destroy a screw if they desire. Which might show a cultural difference in thinking. That aside, it means that most of the screws intended for a user to turn with a screw driver are going to be flat-headed or Philips regardless of how awful flat headed screws or Philips screws are.
The incredible screw drive tractor is back. We’ve covered the previous test ride, which ended with a bearing pillow block ripping in half, but since then, again, a lot of repair work has been done. [REDNIC79] reinforced the load-bearing parts and put on a fresh pair of “tires”. The result is still as unbelievable as the previous versions, but it now propels itself forward at a blazing 3 mph (this time without tearing itself apart).
[REDNIC79] walks us through all the details of the improvements he made since the first version. After the last failure, he figured, that a larger screw pod diameter would give the vehicle a better floatation while smaller thread profile would prevent the screws from digging too deep into the ground, thus reducing the force required to move the vehicle forward.
[REDNIC79] found four identical 100 pounds, 16 inch diameter propane tanks to build the new pods from. The tanks were a bit too short for the tractor, so he cut open two of the tanks and used them to extend the other two before welding a double thread screw onto each. He also tapered the front ends of the tanks to make the ride even smoother. After mounting the new pods to the speedster, a pair of custom steel chain guards were added to prevent rocks from getting into the chain. And then, it was time for another test ride. Enjoy the video:
[REDNIC79] lives somewhere in Canada where key terrain features include mud and snow. Half pontoon boat, half auger, screw-propelled vehicles excel in this kind of terrain as long as you’re okay with going really slow.
In his 11-and-counting part video series, [REDNIC79] goes through the conversion of a lawn tractor into a slow, theoretically unstoppable, Canadian screw-propelled tractor. He welds a frame, plonks some beefy chains on it, and throws a few hefty looking bearing mounts on there to boot. Then he makes some screws out of gas tanks; which was an enormous amount of work.
It was time to fire up the tractor. On the first muddy incline encountered, the tractor ceased to move. The culprit? A cracked transmission housing. Ouch. The end of the shaft holding the chain for the right screw was unsupported. When the shaft turned, it imparted its rotational force, but there was also an unconsidered down force on the end of the shaft, which resulted in a moment the bell housing wasn’t designed for.
Undeterred, [REDNIC79] welded the housing back together and threw a bearing on the end of the offending shaft to balance the moments. He fired it up, engaged the transmission, and the right screw bearing pillow block completely shattered. Ouch again. We can safely begin to assume that screw-propelled vehicles see a lot of forces.
[REDNIC79] hasn’t shelved the project yet. His next plan is to beef up the supports and build a much larger set of screws with smaller blades out of some propane tanks. This should reduce the force the power house needs to put out. Video of the first fail after the break. Continue reading “Screw Drive Tractor Hasn’t Conquered Canada Yet”→
It seems that some of the Nexus 7 models have an assembly issue that makes the bezel uneven with the screen. It’s just in one spot but your shiny new toy shouldn’t have this kind of problem. Of course it comes as no surprise that Google wants you to send it back for service. What is a surprise is that the fix involves tightening just one screw. Now we can’t stand for shipping something round trip when it comes to this low-skill fix. Luckily neither can [Baddspella]. He shows us just how easy it is to repair the Nexus 7 yourself.
The only tools you need are a guitar pick (or other thin plastic prying device) and a very small Phillips screwdriver. Starting at the top of the tablet he uses the plastic pick to pry off the back of the case. This exposes the screws which hold the bezel in place. Find the loose one, and give the screwdriver a turn. Now just snap the back cover in place and you’re done. We’ve embedded the video after the break for your convenience.
It’s super simple…. so don’t be afraid to crack that thing open.
