SquareTech High Precision 90° Indexer: Real-World Test

We make great claims of the quality and accuracy of our SQUARETech High Precision 90° Indexer:

Accuracy: Total indexing error is less than 2 arc seconds, creating a true 90 deg index. As an example grinding four sides of an 8” by 8” block will result in a block which is Square & Parallel less than 0.0001” TIR.

Repeatibility: Ensured by use of System 3R reference.

So how does the SquareTech Indexer actually measure up in the real world?
We tested it. Here are our results.

Results of SquareTech Precision Test

The SquareTech system was used to surface grind 80 pieces of fully annealed 1018, initially rough milled square within 0.001”. The workpiece size was 8”x8”x1 ¼”.

The goal was to be able to have a resultant accuracy of 0.0001” square and parallel. The surface grinder we used was a two year-old Okamoto ACC1224EXB. Measurement results are considered accurate within +- 0.000010” (ten millionths).

All four sides of the blocks were ground on the fixture. These measurements are total squareness and parallelism of all four sides. Results are summarized as follows.

Maximum Value		0.000060”
Average Value		0.000030”
Median Value		0.000025”

The average is ½ of the maximum value, with the mean value falling below the average, which shows that the majority of the measurements were toward the lower values.

Another way of looking at this is as follows:

85% of the parts were within 0.000050”
35% of the parts were within 0.000025”

This shows the accuracy of the system in a production environment. Remember we are measuring processed parts, so we are also dealing with the errors in grinding; we are not just indexing and measuring.

The above errors result in a total indexing accuracy below 2 arc-seconds.

An easier way to look at it is linear error based on part size.