WoodworkingONLINE.com

If you’re into ShopNotes Magazine and enjoyed building with an Erector Set as a kid then chances are you’ll enjoy the 80/20 website.

The 80/20 company has a product line that they call “The Industrial Erector Set.” Basically it’s a framing system that uses T-slotted extruded aluminum tubes and bolt on connectors.  But, that is an oversimplification because there are thousands of different parts and variations available which makes the system highly adaptable for applications such as machine frames, automation, furniture, lineal motion, displays, and (to borrow from their catalog) “modular anything.”

So, visit the 80/20 website and think of all the cool stuff you could build for your shop!

Recently I’ve been working on a prototype for a sharpening center for ShopNotes 107. Building a machine is one of my favorite shop projects. It’s always a thrill to watch turning shafts, sheaves, and moving belts in action on a tool I made myself. Experience (making poorly functioning machines) has taught me that much of the success in shopbuilt machines lies in the bearings and their installation. You won’t be proud of a machine that vibrates, or is feeble, or is inaccurate due to misaligned bearings.

There are, of course, many requirements for bearings and so there are many types. One type that I find quite handy for low rpm applications is a bronze sleeve bearing. They are easy to work with, durable, and inexpensive.

In a sleeve bearing, the load is supported through the sliding motion of one solid surface against another, very simple. The sleeve bearings you’ll find at your local hardware store are made of oil impregnated sintered bronze. Sintered bronze bearings start as a powdered bronze alloy that is molded into the correct shape and heated to fuse the bronze grains together thus creating a porous structure. Oil is then forced into the voids. As much as 18% of the bearings volume is oil and this creates a permanently lubricated bearing.

Sleeve bearings typically come in two different styles. Those that look like a short piece of tube are designed to carry radial loads, like a spinning shaft. The other style includes a flange on that piece of tube. This bearing is designed to carry both radial and thrust loads. For example, a spinning shaft that’s being pushed on from one end. The style that you choose depends upon the application.

Even though they are simple, there are a few things to keep in mind when using these bearing.

One simple way to install a sleeve bearing is to press fit it into a wooden part. However, if you plan on press fitting  a bearing  get the largest shell diameter available. Thin shell bearings will actually compress somewhat into a smaller internal diameter if forced into a very tight hole. The result will be a shaft that will not turn freely, if at all. (This will make you very angry.) And, always make sure to seal any wood that touches the bearing with some shellac or varnish. Remember that porous structure impregnated with oil? The oil will wick out into raw wood leaving a dry bearing on the road to failure.

Another way of mounting a bearing is to use an oversize hole with epoxy paste allowing the bearing to seat into the correct alignment with the shaft in place. I think it’s a good idea to rough up the exterior of the bearing with coarse sandpaper to allow the epoxy to get a “grip” on the bearing.

Whether you’re using epoxy to mount the bearing or even applying finish around it, protect the interior of the bearing with some wax and plug the opening. It’s hard to ream glue or paint out of the bearing  without causing damage. (This will also make you angry.)

I’ve found it’s often better to build your machine around the bearings with the shaft in place. This ensures proper alignment rather than to just hope that things will turn out right down the road. Remember, there’s more to an accurate machine than precisely cut parts. Accuracy must be part of the whole process of building a tool.

The last thing to consider is the shaft. Here it pays to spend a little more and  get a precision ground shaft. You can’t expect smooth performance from a piece of not  quite round hot rolled stock from the hardware store.

Simple, durable, and inexpensive, a sleeve bearing is a great option for a shopmade machine tool.

When you design for ShopNotes Magazine you can’t help but develop an appreciation, even an obsession, for hardware. Not just flashy hinges and knobs, but mundane bearings, springs, brass rod, plastic sheets, cranks, pipes, motors – even threaded rod. There are more bits, parts, and stuff out there than you can believe. (Just sit down with all 3,602 pages of the McMaster-Carr industrial supply catalog. You’ll be amazed. And you’ll be inspired.)

A few years back in ShopNotes, we did a version of an English carving vise that appeared in Issue No. 71. (Editor’s Note: This issue is available as part of ShopNotes Annual Volume 12, a hard-bound collection of Issues 67 — 72.) I have an early prototype in my home shop that I use often. At the time we designed this project, the only reasonably priced and available option for the screw mechanism was to use standard threaded rod. The size I used was 3/4″-10 NC threaded rod. It works well, but you know how it can be if you need to go a distance on regular threads, spin, spin, spin, yawn, spin, spin some more. Standard V- thread is more for sealing and fastening applications rather than quick movement. What I really wanted to use was ACME threaded rod.

So what’s so great about ACME thread? This stuff has the guts you want for strong clamping and it won’t put you to sleep spinning the handle. What sets it apart are the shape of the threads. The threads are large, broad, and square, which provides great strength. And, because there are fewer threads per inch, it offers rapid lateral movement. ACME threaded rod and fittings are available in two grades: general-purpose grade or precision grade.

General-purpose ACME thread has one start, or one continuous thread, the same as standard thread on bolts and screws. Precision acme thread can have up to five starts delivering much more lateral movement per revolution.

General-purpose ACME threaded rod has a looser fit, better for dusty shop environments. Precision ACME threads are made to much higher standards as it’s often used for lead screws in lathes, milling machines, and industrial equipment requiring great precision and durability. This precision and durability can cost 3-4 times as much as general-purpose ACME rod.

General purpose ACME rod is the type we’re interested in. It’s now available through two of my favorite suppliers (McMaster-Carr and ENCO) and priced reasonably enough for projects in the home shop.

Of course, there needs to be something for the threaded rod to engage. Square, hex, and cylinder nuts are available for general-purpose use. Brass and bronze nuts are also available. They’ll travel move lightly than steel, but I find that plain steel hex nuts are the best option as they are versatile and also inexpensive. So, I don’t have to cry over a nut buried in epoxy that didn’t work out.

A few simple design rules. First, when I build any mechanism out of wood, I don’t strive to build with perfect precision. Instead, my aim is to build the structure around the mechanism, altering and adjusting to it to accommodate the movement that I want.

What I mean is rely on accuracy rather than precision. (Precision means building to a tight standard. Plus or minus 1/8″ might be precise for a house. Plus or minus .0001″ might be precise for a wristwatch.) Accuracy is building toward what’s right or true. In the case of a shop made vise or clamp, this means it should work smoothly and effectively.

The second rule is to design mechanical projects from the beginning with a bit of float in them. If it rattles a bit more than you like in winter be satisfied by knowing it will still work fine in the summer.

Finally, just like a powered machine, moving parts benefit from lubrication. In a dusty shop environment greases and oils collect dust, dirt, and other shop grime. So, the best choice is a dry lubricant. There are convenient spray dry lubricants available, but I prefer the old-fashioned paste wax I use on my woodworking projects. Is it the best choice? No, but I always have some around and it’s easy to apply.

“Working tools” such as vises, hold downs, and clamps are great projects for your shop. Not only will you get the satisfaction of using a tool that you’ve made, but, the tool can be built specifically to suit your requirements and style of work. Additionally, there will be a whole new range of things to learn including the strength of individual materials, the strength of assemblies, and principles of simple mechanics. Designing and building tools can be a fun challenge to your ingenuity.

If you decide to build one of these working tools take some time to consider all your hardware options. Even a small upgrade like using ACME threaded rod will make a huge difference in how your project will turn out. Your project will look and work like a “real” tool.

Spoiler Alert: I’m in the early stages of designing a benchtop vise that will possibly appear later this year in ShopNotes Magazine. I’d like to hear what you’d include in the way of design, materials, and features.