I was wondering since i don't have a mill should i take it to a local machine shop and have it drilled and tapped so the four screws will be indexed properly ? I'm not sure i can do this on the old drill press i have and get it right.

Build it on your lathe. Your Spider makes not much difference. If you indicate your barrel, it don't make a hill of beans difference.

I used a longer piece of stock and used the lathe to drill the holes,then tapped by hand.

I have been using a spider i made when i first got my lathe and i got one of the screw holes off center when trying to orientate it in the drill press vice, it has worked fine but just though i would build better one . I'm building the new one in my lathe, but not sure how to set up the round stock in the lathe and get the four holes orientated right in the chuck for drilling. I'm using the three jaw chuck because i don't need the precision of the four jaw for this project. I already have the tap and drill bit 3/8-24 NF tap, 21/64 drill bit and the brass tip screws .

Hold the piece in your lathe chuck. Measure around the circumference of the chuck, divide by 4, then mark the chuck in quarters. You can use these marks to rotate the piece to mark. It aint perfect, but it'll be close enough you probably won't see any error.

I have my 4jaw scribed and marked in 3, 4, 5, 6 and 8. Comes in handy sometimes.

Spin it up and scribe a line where you want them on the length of it then slip it into your 4-jaw and scribe by each jaw - don't even need to mount the 4-jaw simply use the jaws for spacing 4 marks evenly. If the lines don't intersect where you want (maybe you can't slip it in far enough) then throw it back into the 3-jaw and scribe the line using a tool bit to extend it farther.

Well yeah,...

If the piece is indicated in the 4 jaw, a sharp flat sided scribe drawn down the jaw flats should give one almost perfect 90* / 180* counter opposed marks.

....a sharp tool in the tool post, correctly set for neutral height can than be used to scribe the ends from outer to inner circumference.

With a common V block beneath, and a tool setter's level the piece can than be viced in the drill press and the holes poked square.

GTC

This is basically what i did on the first spider i made , but drilled it in the drill press and this is where i made my mistake by not just using the lathe to line up the holes. Thanks guys i got it now on how to line up the holes with the four jaw
Thanks

That was the first thing I built on my lathe. I did just like somone said already I marked it in quarters and drilled it on a drill press. It works great.....it was the first thing I ever cut internal threads on..

You can get pretty dang close....and get some setup experience to boot. Indicate it in on a 4 jaw and scribe to circumferences for your bolt centers. Move your indicator to the chuck. Spin it around till any number you wish comes up on the indicator. Travel the carriage with a tool across the scribes. Rotate the chuck to the next quadrant measurement. .....repeat as necessary.

To drill it. Square the drill table to the quill. Place the spider in a vice and use your protractor to level the cross to the drill. Use a center finder or wiggler to come down on the cross.....Once you hit it, lock down and drill. Tap in a second op after the drilling and chamfering. When you are done. ....it's closer than it needs to be and you gained some practice in setup and patience.

i got it done using the four jaw to mark the holes to be drilled, it turn out pretty good. Thanks to all for the info