A quick google search says steel turns brown at 480 degrees fahrenheit and purple at 520 degrees fahrenheit. So it was probably just hitting 520 when I held it in front of the camera. I should have also mentioned that the more the arbor wobbles unsupported (bent) it will cause extra wear and heat at the arbor support bushing due to the support forcing it to run true to the spindle. Or in my case if had I not made the .7188" pilot diameter concentric with the 1" arbor diameter it would have the same effect by causing the 1" diameter to run out while it held the pilot concentric with the spindle. Also use caution when selecting a size for your press fit. the .001 interference I used may have been a bit heavy there are formulas that range from .0002" to .0015" per 1" of diameter. The lower .0002" for a light press fit and the higher heavy .0015" thermal fit that I used. My fit probably should have been more like .0008" also I said the arbor was 1 1/4"-14 threads. Correction it was 1"-14 threads and I turned them down to 7/8"-14. If they wouldnt have ground the threads down so much I could have made say a custom 14 pitch thread diameter by simply chasing the threads till I got them cleaned up then single point threading a nut to fit whatever size that was. For example I could have maybe made a 63/64"-14 thread so I wouldnt have lost as much thread diameter strength. The only drawback to doing that is it would be possible to still use the 1"-14 nut on a 63/64"-14 thread which could be dangerous. You would have to make sure the custom nut stayed with the custom bolt!