1.Turn man-time into machine time.
This philosophy is popular for saving time. It goes with the idea that you should never hold back on technology. From a business standpoint, the philosophy makes sense. You can also turn man-time into machine time with thoughtful planning. This is easier said than done. The fast paced environment many of us work in today often doesn’t allow for proper planing.
2.Have lots of tools.
An easy ways to improve speed is to have lots of tools. I like to have and use my own tools—even if the shop is well stocked. Shop tools are never put back in exactly the same place and you’ll never know what condition they’ll be in when you find them.
If you’re just starting out in the trade, I recommend buying a set of tools from a retired machinist. This way, you’ll hit the ground running and you’ll immediately be worth more to your company. Machinist’s tools hold their value well, so be prepared to pay a fair price. You can upgrade later as you see fit.
Avoid borrowing tools over and over. If you use a tool often enough, then either buy one or make one!
Don’t waste your time making easily purchased tools like 1-2-3 blocks and V-blocks. Instead, make custom tools and fixtures that aren’t easily purchased; you can tailor these tools to the machines you use and the type of work you do.
3.Use dedicated tools.
This business of having one tool that does everything isn’t very efficient. You often see these kinds of tools advertised in the back of the mechanic’s magazines or on television infomercials. For the most part, each tool you have—whether it is a hand tool or a power tool—should serve just one purpose. You want the tool to be ready when you need it.
I suppose you could get carried away with this type of thinking. I wouldn’t go so far as to buy a handle for each socket I have. Nevertheless, having and using dedicated tools can greatly improve your speed.
A simple example is a screwdriver.
You could buy a screwdriver with interchangeable tips. The idea is that with the one screwdriver handle, you could cover all of your screwdriver needs. I suppose this is true if you want to fiddle around with the tips, changing them, dropping them, and, yes, losing them. However, it’s faster to grab a tool that is ready to go than to keep changing tips.
Another example is having an assortment of dedicated air tools. I have a drawer full of cheap die grinders. Each is mounted with different cutters or abrasives. If I need to cut off a pin, I can be cutting within seconds, instead of fiddling around with wrenches, collets, and Murphy’s little surprises.
Figure 1–1 Full-width cuts are the fastest way to clean up a surface and also make parts look better.
4.Make all your parts the same.
This suggestion is a great way to expedite just about any job. If you’re making multiple parts, then by making all the parts the same, you’ll always know exactly where you stand with the job.
If your parts are all over the map dimensionally, you will constantly be re-measuring them, dealing with “special cases” and hassling to get consistency and control over a job.
5.In a milling machine, when practical, use a large enough cutter to cut across the entire surface of the part in one pass. (see Fig. 1-1)
This step provides an effective way to save time and also to make parts look better.
Taking several passes with a small diameter cutter to clean up a surface is usually a waste of time. When practical, it is much faster to cut an entire surface in one pass. This is especially true when milling with a manual machine. With a CNC machine, it is not as important because CNC machines execute with greater speed and efficency.
6.Turn the shanks of your larger drill bits down to common collet sizes. (See Fig. 1-2)
I dislike cranking the knee of my mill up and down to accommodate a drill chuck. If you turn the shanks of your larger drill bits to a common collet side, you can avoid that hassle. You’ll be able to use standard size collets to hold your modified drills, without having to use a drill chuck. You can also do this with reamers and other cutters.
| Common Fractional Collet Sizes | |
| 1/8" | 1/2" |
| 1/4" | 9/16" |
| 5/16" | 5/8" |
| 3/8" | 3/4" |
| 7/16" | 7/8" |
|
|
Figure 1–2 The shanks on these drill bits have been turned down to common collet sizes so they can be mounted in the spindle without having to use a drill chuck.
7.Use stub drills (see Figure 1-3).
Anytime you can drill a hole without first center drilling, you simply save whatever time it would have taken to do that center drilling. Normally, a high percentage of holes in parts are simply clearance holes used for bolting parts together. Clearance holes are usually anywhere from .015" to .030" larger than bolt diameter.
If you know you’re going to be drilling clearance holes or other non-critical holes, you can use stub drills without center drilling. A stub drill that has been properly web thinned will cut with little pressure (see Figure 7-4). It will produce a surprisingly accurate hole. You can either buy stub drills already made or you can make them by cutting off standard-length drill bits and regrinding the tips.
Even if the stub drill runs out a little bit as you start a hole, you’ll probably have enough tolerance on a clearance hole so that it won’t matter. If the hole is deep, or has to be located precisely, it is best to center drill first to maintain accurate location.
Figure 1–3 Stub drills can be used to drill holes without first center drilling.
8.Use chip color to determine speed, feed, and depth of cut in ferrous materials.
Most machinists in small shops using conventional equipment-set feeds, speeds, and depths of cut based on feel and experience. With a little practice, a newcomer can soon get the hang of these.
The best rule of thumb regarding this subject is the tan chip rule: If you want your cutter to last, then your chips should come off the workpiece no darker than a light tan in color if you are using highspeed steel or cobalt cutters, and brown if you are using carbide cutters.
If
