bolt pattern diameters

[dannyho]

I'm going to be redrilling my hubs on a nice DNC bridgeport, one of the perks of still being in school, and I need to know how fat to space the holes from the cente. I'm going to be drilling for a 4x4.5 bolt pattern. Since the bolt pattern is measured in that crazy way, it would take some going at it to get the number i need. I was hoping someone just had the knowledge already?

so anyone, what's the diameter of a 5x4.5 bolt pattern?

[astroracer]

Ahhh... 4.50 inches... The radius is 2.25. The angular spacing of the bolts is 72 degrees.
If your shop has a rotary table you can set it up at the 2.25 dimension and simply rotate the table 72 degrees for each hole.
Mark

[dannyho]

thanks, but that's definately not correct. The bolt pattern is measured by the vertical distance of the center of the top bolt hole to a horizontal line that connects the centers of two bolts at the bottom. 2.25 is not the radius of a 5x4.5 bolt pattern. If it were that simple i would not have asked.
however, 72 degrees is correct.
anyone?

[Rubes]

uh...they wouldn't call it a bolt CIRCLE if it wasnt a circle
Do some grade school math and dont expect people to spoon feed you the information. Oh yeah...and obviously STAY IN SCHOOL.
http://www.metalwebnews.com/formulas...ordinates.html

I'm usually not this rude...but come on!!!

[Samckitt]

thanks, but that's definately not correct. The bolt pattern is measured by the vertical distance of the center of the top bolt hole to a horizontal line that connects the centers of two bolts at the bottom. 2.25 is not the radius of a 5x4.5 bolt pattern. If it were that simple i would not have asked.
however, 72 degrees is correct.
anyone?

Are you seriously asking what the diameter is of a 5 on 4.5" bolt circle is?

5 holes equally spaced on a 4.5" diameter circle/2.25" radius. Holes 72 degrees apart.

Sounds like you are referring to the bottom right part of this image:


That works for figuring out on an existing wheel, but not if you are drilling on a CNC machine. You should be able to program a bolt circle into the CNC machine once you have determined the center of the hub.

[astroracer]

Thanks for backing me up guys... I don't know where DannyHO got his info from but it is DEFINITELY not correct... It IS that simple Danny... Bolt "circles" are called that for a reason.
Cletus

[Rubes]

I guess it's kind of like "Who is Burried in Grant's tomb?". And only something a (this is directly from his profile) " Regular mechanical Engineering college kid, with a firm grasp on the technical stuff... Currently interning in aerospace..." can understand. Wonder what his sponsors would think if they saw this
Now I know we all have brain farts now and then, but when someone gives you the answer, and you tell them how wrong it is when you dont even know how to figure it out for yourself...that's messed up. Besides like Sam said, you dont even have to know it if your on a CNC.

Sad commentary on our educational system as well.