Because even the material strip needs to nest somewhere.

The idea for a nest gauge is to surround or encapsulate the workpiece within the rest. The purpose of the nest gauge is to locate and position the workpiece.

The most common use of a nest gauge is in dies where a secondary operation is to be performed on the workpiece.

Nesting Gauge Requirements

Nesting gauges need four important conditions to be met, in order to meet its function: accuracy, loading ease, unloading ease, and fool proofing. Good ol’ toolmaker always with the dummy proofing things.

Nest Gauge Accuracy

Like I said at the start of this article, one of the main purposes of a nest gauge is to register the piece part. All that is required to achieve this is for the piece part to make sufficient contact on the main areas. For efficiency of machining, all that is needed is really three contact points if the part is round or triangular; however, sometimes more contact points are needed, depending on the shape of the part. As long as there is contact with strategic locating of the part accuracy of the die will be maintained.

Load Easy

In manufacturing, time is everything because time is money. The easier it is to load the piece part or stock strip and, thereby, the faster the process of making the piece part the better. The factors that will affect the ease of loading are the thickness of the nest arrangement, the shape of the workpiece, visual identification of the nest with the workpiece, and adequate lead.  The right height will depend on the workpiece. Large workpieces need a deeper nest. Being able to see where the workpiece is to fit in the nest is essential for ease of loading, this could be considered foolproofing. Having the right amount of lead is critical for ease of loading without adequate leads on the nest the piece part may get hung up.

The idea is that the lead has a funnelling effect which contributes to ease of loading.

The previous steps will affect the ease of unloading, having inadequate lead would affect how the part would be ejected, therefore making it important to keep in mind.

Foolproofing

If a nest is built in such a way where a workpiece or piece part can not be loaded incorrectly, that would be considered a foolproof nest.

This is normally achieved by thinking of your piece part in terms of its three-axes X, Y, Z. For a part to be foolproofed it should be confined in its three-axes in a manner where it cannot be rotated, flipped, or placed upside down.

One parameter that is difficult to foolproof for is the burr side at the same time, it is not practical or affordable to make a nest completely foolproof.

When the best option is to have the operator load the work correctly, an instruction plate should be permanently installed on the die with clear and specific instructions for the operator. Another method of indicating to the operator which is the burr side is to have the die designed in such a way where a mark is left on the part indicating which is the right way of loading the piece part in the next station or operation.

Foolproofing is such a large part of what toolmakers do that it is worth summarizing the key points in foolproofing a nest gauge:

1. Foolproofing is important and a toolmaker must be aware that it is a mini role of the nest gauge.
2. Nests can be foolproofed easily for most axes, except the burr side.
3. Nesting for asymmetrical parts can be foolproofed for both integrity of the burr side and contour relationship.

Pin-Type Gauges

Pin-type nest gauges are commonly used because they can be easily built. Pin-type nest gauges are when the cylindrical pin is used to surround the workpiece, confining it and touching the tangent of the part. There are some variations to pin-type gauges, which I am going to try to describe next.

Fixed Pin Gauges

In fixed pin gauges, straight cylindrical pins are pressed or driven into the die section. Dowel pins are normally the pin of choice given that they are cheap and sized. Some clearance is needed to allow ease of loading and unloading. The amount of clearance will be limited by the dimensional specification of the piece part. One rule that I mentioned earlier is, for smaller parts, clearance of 0.0005 of an inch is adequate for ease of loading and unloading.

When using dowel pins as a gauge in very accurate dies, the nest should be purely built in a way in which it is too tight for the part. Then polish or, if need be, grind the required clearance for the pin. This makes it easier to maintain accuracy when installing pin gauges and is faster when maintaining tight tolerances locating the pin gauge holes. In ordinary situations, small to medium gauge pins should be a light drive fit in the hole whenever possible. Clearance holes for that gauge pin should be drilled through the die section to facilitate removal.

Disappearing Pin for Nest Gauges

There are situations in tooling builds where the die designer won’t have enough room in the opposing side of the die to allow clearance of the gauge pins. In these cases, disappearing pins can be used.   Pins are pocketed while still gauging the piece part. The ease of loading having a lead and a disappearing pin also helps in misfeeds because the disappearing pin will be jammed down and won’t return to the position if it is misaligned with the part. This will be a tell for when the next part doesn’t locate or register in the die that something isn’t right with the die or part.

There is mostly only one advantage to disappearing pins, which is that you don’t need to have clearance holes in the opposite die. Keep in mind, though, that fixed pins are considered superior to disappearing pins.

Shoulder Type Nest Pins

Shoulder type nest pins are normally used in dies where the gauging pins are near the die edge because the toolmaker is relying only on the edge of shouldered rest pins to gauge the part. One can almost completely finish the die and bring the outer diameter of the shoulder pin to the right size to locate and gauge the part. Shoulder style nest pins are recommended to be made of oil-hardened drill rod. The main reason being that it comes in standard sizes is easy to machine and is easily oil-hardened. The lead angle on the head of the pin be for the shoulder can have a 15° to 45° angle or may even be conical to facilitate ease of loading and unloading.

Plated-Type Nest

As its name sounds, a plate-type nest is simply a plate with the contours to confine the part cut into it. Gauging is accomplished by confining the piece in the proper location and position. It is not desirable or necessary for the plate to completely trap the part but only to touch the part in enough areas or locations to actually gauge the workpiece. Depending on the production run, this type of gauge could be made from mild steel in low volume situations; however, with huge volume production runs, it is important that the rest gauge is hardened to last and maintain accuracy. For speed and efficiency, a plate-type gauge may not necessarily need to be completely hardened, instead just the contact points can be locally hardened. Also, plate type gauges need not be a single piece but can be as many sections as necessary to confine the part and allow ease of machinability. Some shops will opt to chrome plate their plate type gauges for durability. As a toolmaker, just keep in mind chrome plating can add 0.0005 to 0.005 of an inch to the periphery of the gauge and this is not desirable. It is important to let the chroming shop know what areas can not be chromed, as this will make your life easier according to the text.

Approximation Nest

Just as the name suggests an approximation nest doesn’t completely confine a part, but just allows the part to be in the approximate location, in order for another die component, sometimes a pilot, to locate the par and gauge it as it is in the right location for the next process. The gap allowed between the engaging pins is all determined by the size of the component that is going to pick up the piece part to locate it. If it is going to be a larger pilot, sometimes the gap in the approximation nest can be large. As a rule, the text suggests 7-10% of the pilot diameter for pilots up to 1.2 of an inch. For larger pilots, the gap can be kept to 1.8 of an inch. The only thing that differentiates this gauge from any other is the gap.

Pusher-Type Nest

A pusher type nest gauge is similar to other gauges, except that at the time the part is only gauged by two stationary points and the third point will be activated by the pusher. The function of a pusher is to locate and hold the part in the right location and act as the third contact point. Pusher gauges are used when there may be variations or discrepancies on the workpiece. In some situations, there may be more than one pusher as part of the gauge, obviously if the part requires more than three contact points.

Conclusion

I hope I have just familiarized you with some of the variations of nest gauges, their applications, and general ideas and precautions when building and matching them. Like everything in this trade, time is money.  These articles are summaries of the text I was provided in school and I am writing about what I think will be useful in preparation for my C of Q exam. If you want further reading,  I encourage you to get the textbook.  If you liked this article, please share it and if you want more of this type of content please subscribe.