Spline rolling machines can range from very simple to very complex tooling set-ups. This section will deal with the fundamentals of spline rolling machine set-ups as well as a discussion on complex set-ups.
Each spline rolling machine has a given opening that must be filled with tooling and piece parts. This opening is called the daylight opening. The daylight opening is the distance between the rack mounting surface of the bottom wedge and the rack mounting surface of the top wedge (fig.2). These mounting surfaces are called adjusting wedges.
The first step in doing a set-up is to figure out how to fill up the daylight opening. The following elements are used to fill up the daylight opening, the blank diameter (pre-roll diameter), height of rack at starting end (doubled because there is a top and bottom rack), any shims for under the racks (reground racks come with shims to bring them back to there original height), and finally the verniers.
Example No. 1:
Our example machine has a 6.00 inch daylight opening. This set-up is with a new set of racks which had no shims sent with them.
2.065″ — Height of rack at start end
+1.857″ — Blank diameter
6.000″ — Daylight opening
Take the 0.013″ and divide by two,…0.0065, add 0.002″ for machine spring back,…0.0085″. Now set both machine verniers at 0.0085″, and install racks.
Example No. 2:
Our second example machine has a daylight opening of 5.500″. This set-up is with a reground (sharpened) set of racks which have shims sent with them.
2.130″ — Height of rack at start end.
5.500″ — Daylight opening.
0.247″ — Thickness of shim.
Take the 0.500″ and divide by two,…0.250″. Now subtract the thickness of the shim(s) supplied with the racks. In our example 0.247″,…0.003. Now add 0.002 for machine spring back,…0.005″. Set both machine verniers at 0.005″ and install racks.
Some reground racks may come with two sets of shims. In that case, in the example above, you would subtract the total of those shims from 0.250″ to get your vernier settings. Also, please understand that when it comes time to subtract the shims, we have already divided our figures by two. Therefore, we only subtract the thickness of the shim(s) for one rack.
In the samples above we could substitute the minor diameter (root diameter) for the blank diameter and then substitute the height of the rack at the finish end for the height of the rack at the start end. By using minor diameters and finish end rack heights some job-setters find they are closer to proper size on the first part. Obviously, the job setter must be provided with slightly more information to use this method.
In some cases the job that is currently running in a spline roller has worn out a set of racks. There is a very simple method of determining the vernier setting for a replacement set of racks.
The current set-up has a rack plus shim height of 2.223″. The verniers are a 0.009″. The replacement set of racks have a rack plus shim height of 2.220″. Therefore, the new vernier setting should be 0.012″ (0.009″ + 0.003″). If the replacement set of racks and shims are higher than the current racks, the new vernier setting must be lower than the current vernier settings.
It doesn’t matter where the height of the racks is measured, as long as both the current and replacement racks are measured in the same place.