Check guitar center, both Pearl and DW offer those type of bolts as parts (for pedals) and most GCs (at least the ones I go to) stock them. You'll have to determine what thread you need. I think the DW ones use the standard SAE 1/4-20 thread, Pearl is probably metric although some of the older 70s stuff like their tom arms did use American threads.
I did some googling and found that is called a wing bolt and should be a 1/4 x 20 x 3/4. This is a Slingerland flat base cymbal stand. The top wing bolt is a replacement and the wings are not wide enough to give good leverage to make it secure. The bottom wing bolt looks to be 1/4 x 28.
Your responses are appreciated.
It looks like you've got the first-generation #33 Flush-base cymbal stand. That small wing screw is correct and was also used on the tilter. I'm attaching pictures of my stands, showing these wing screws.
Thank you. And thank you for correcting my thinking that I had lost the original. I guess I just need to man-up and tighten the screw a little harder. My cymbal came crashing down last week because I hadn't tightened it enough. It was the first time that had happened. Thanks, again.
Sorry, I misunderstood the question. I thought you were looking for the type of bolt with the square head like a tension rod that you use a drum key to adjust.
Most pre-70s hardware used the regular wing bolts with the "mickey mouse" ears. Then in the late 60s early 70s they started to switch over to the types that looked more like drum keys. By the mid 70s Ludwig had gone to the big black plastic knobs on its heavier hardware. At some point Slingerland also went to a plastic knob on some stands but they used an off the shelf generic type that you can still find in some hardware stores.