Equipment rack/Speaker spikes

Hello,
I am looking for recommendations and sources for spikes to put under an equipment rack I am building. In particular, I would like a spike which is threaded all the way down to the point of the spike, so that if you are turning the spike into a threaded T-nut, the spike would continue traveling through the T-nut and out the top. Most spikes that I have seen are threaded down to the place where the machined taper begins, and the spike can be turned no further.

I have a couple of Silent Running platforms which have spikes similar to what I am looking for. I have of course left a message for them, but I would like to find some alternative manufacturers or brands in case they ar unwilling to sell their spikes separately. Thanks in advance for your assistance and suggestions.
All the best,
Dennis