Are chainring bolts alone strong enough? Because of a custom application, I need to be able to use 104BCD chainrings. However, I need a stand-alone spider to hold the chainrings; the chainwheel will not be mounted directly to a 104BCD crank.
The only 104BCD spider that I can find is the Profile Racing BMX spider, which has a hole that is too big for the spindle it will go on, and will require machining to adapt.
https://www.amazon.com/Profile-Racing-104mm-4-bolt-Spider/dp/B001GSQQDA
I have access to a laser cutter, so I can have a 104BCD spider cut out of plate steel with the size of hole that I need. The problem is that for a spider made from a plain piece of plate steel, there is no &quot;ridge&quot; machined into the spider to hold the chainring centered. The chainring will be held to the flat spider entirely by the chainring bolts. This is a little different than usual because most cranksets and spiders have machined ridges to hold the sprocket, and the chainring bolts only take part of the load. The question is, are chainring bolts alone strong enough to hold a chainring? Should I use steel chainring bolts?
I assume by 'ridge machined into the spider to hold the chainring centered' you mean the edge of the shoulders machined into the spider arms.

The edges are not there to position the chainring nor transmit torque. The chainring bolts do that. Remember the force transmitted to the chainrings by the bolts is perpendicular to a radial line drawn through the spider arm.
The chainring bolt holes in your spider need to be accurately positioned and sized to accept the bolts. I doubt laser cutting will achieve the required accuracy for the holes and these will need to be machined.