# layout bolt hole question - clarification please

• posted

A month or so back I needed help with laying out 3 bolt holes for a project. The long and short of it stirred up some great help by the group, and MARV KLOTZ chimed in with a calculator formula. I am hoping to get some hand holding help here with how exactly I need to enter this into my calculator, because I am not getting the right numbers it seems.

For example, here is the formula that Marv posted:: The center-to-center distance is referred to as the 'chord'. If that's known, then calculate the 'angle' between adjacent bolt holes as:

angle = 360 / (number of bolt holes)

Then the bolt circle radius is given by:

Regards, Marv

• posted

Your calculator is probably not RPN, and you are not using any parentheses.

Re-work the problem, and write down the interermediate steps as numbers. I think you will wind up with a very different answer.

The problem you are punching in on the calculator is a very different one than the one you want to solve.

Using Marv's formula for example,

and sin [(.5)(120)] = sin60 = 0.866

So it would seem that R in this case is going to be something like .75/.866 according to that formula.

Jim

Jim

• posted

Ron I e-mailed you a bolt hole and trig. program.Just enter the number of holes then radius and the starting angle of first hole and it will give you the xand y locations. Tim

• posted

If you own a PalmOS handheld device, download the free trial of "Geo-Matic Complete for the PalmOS" from my website and calculate as many bolt circles (plus triangles, circular segments/sectors, rings and ring sectors, regular polygons, chamfers, fillets, parallelograms, etc) as you can in the next five days. Find it at

Carmine Castiglia ISOFits! - ISO 286 on your PalmOS handheld InfosystemsPro LLC PalmOS apps for engineers and machinists