T-post in rock

If needing to put t-post in solid rock should you drill a 1 1/2 ", 1-3/8" or 1 1/8" hole size
I thought a t-post is 1 1/2" diameter but I've heard you can tap t-post in a 1 1/8" hole
This is solid rock not rocky soil

Also how deep should you dig the hole in rock

Anyone have any experience with this.

Are you putting up a fence or anchoring something down?

Fence.
I've use the 1/2 " hole with rebar and that worked great for anchoring

What are you drilling it with. I wanna say last time I used a jackhammer it was a 2 inch hole.

I'm going to try using using my rotary hammer that I have and just get a 1-3/8 or 1-1/2 inch bit
It worked great for the 1/2 in. Holes but now I want to try a larger hole for t- post

I've had great results with a 1 3/8 bit in near solid limestone. Some places have less than 6" of dirt/clay cover. I use a large hammer drill I got cheap at a pawnshop and a bit that will drill in 16" You may have to hammer off the t-post spades but the posts hammer in real snug without too much effort, and they won't go anywhere once in.

I checked today and my rotary hammer only take sds or sds-plus drill bits meaning the largest bit they make is 1-1/8"
Do you think I can pound a t-post into a 1-1/8" hole?

Scoop what kind of drill did you get at the pawn shop?
Does it take sds-max or spline type drill bits

I think the model is a thunderbolt? by Milwaukee(sp) and it takes spline bits up past 1 1/2" but nor sure of max. I originally got the 1 3/8" cuz they had it in stock cheap, and it woulda cost double to order in a 1.5".

Not sure you could get a t-post in 1 1/8" hole in solid limestone. Also, can you get enough depth with a smaller drill?

You can get a 3pnt hyd. post driver with rock spike and get the job done quick... not cheap though lol

You have to be careful with the SDS bit, small shank, can break unless you go slow. Let the drii/hammer action do the work. Of course the spline is a better deal.
Check some of the better tool suppliers for a larger SDS bit, Fastenal, Hilti, etc.

They do rent an electric jack hammer, if you have access to a generator.

hammer drill..