Milling adapters

I am having some adapters milled down from like 31mm to maybe 22mm. The question is the machine shop that said they could do it is not sure exactly how to. Meaning do they shave from the back or press the studs out and shave from the front?

I thought the back but that will take away from the mounting metal needed for the lug nuts to use bolting onto the car. is it feasible to press out adapter studs mill the press the same studs back in?

it has to be from the back, there will be plenty of space to shave since lugs should be  deep inside the pockets.. atleast mine are. i have good 10mm, possibly  even more on my 25mm spacers.
wouldnt really suggest pressing out the studs tho...

It should be done on the back side. It wouldn't be milled down tho. It should be turned down on a lathe. I was going to attempt it myself since I'm going to school for cnc/toolmaking but decided not to. If a machine shop doesn't know how to do it, you shouldn't take it to them.

just going to sell them I guess. These adapters had the studs counter sunk too far in so the shop that would do it, won't. Doesn't leave a lot of metal for the lug nuts and wheel to grab on to.
Will run them until i can get a proper set made.