How To Do Lay Out For 8 Holes

Transfer screws are so useful, so easy to make! I mostly work in Metric, so it's not a long job to make ALL the sizes, any specials (my lathe's all BSF and BA threads) get made as and when needed, stored in old 35mm film cans with labels. My Grandad showed me how to use them when I was about 4, sat on the end of his workbench (he was a toolmaker, then spent WW2 calibrating and test-firing field guns, died of his war wounds without going to fight - went stone deaf, didn't hear the bus coming...)

It occurs to me that Kroll could initially skip the turning / cutting the ring and use transfer screws on the raw plate, then use his nice new punch marks to find the centre for machining / marking and cutting before drilling the bolt circle, after drilling he'd then have some useful holes to locate the raw material on e.g. a faceplate to trepan the ring from the sheet (assuming he has a lathe).

Dave H. (the other one)
 
Guys thanks for all the great ideals which I do understand the directions given.I was hesitant to ask this question cause I thought the answer would just be to complicated for me to understand.I do think that I will order me couple of those screw transfer sets.I already need one for finishing my back plate and now a size for this project.Guys thanks again for all the ideals
 
If you ever find an answer to a question is too complicated for you just say so and we will pull it apart till you do understand it. That is why we are the Forum we are. No one is left behind. It's an equal playing field here.

"Billy G"
 
We will also give a few different ways to do things depending upon skills and equipment. Some may be easy with minimal tools and some may be real easy with some machinery. You get to chose the way you feel more comfortable with.
 
If we assume a 1" radius circle and the first hole is located at the 12:00 position (we will call this zero degrees) or 12 oclock as on an analog clock for instance, and the center of the circle is at X 0.000 and Y 0.000 the first hole position in the X axis will be the sine of the angle multiplied by the radius, in this case 0.000" as you are already at X 0.000, so you now need to determine your Y axis position which will be the cosine of the angle multiplied by the radius, in this case the Cos of zero degrees is 1, multiplied by a 1"radius circle is 1". The next hole is rotated 45 degrees at the same radius therefore, sin 45 times 1" = .707" in the X axis and cos 45 multiplied by 1" = .707" in the Y axis, this is where hole number 2 is located.

Hole number 3 is located 90 degrees from hole number 1. sin of 90 Degrees = 1 multiplied by a 1" radius circle is of course 1, the X axis position is 1" and the Y axis position will be zero as the cosine of 90 is zero.

Hole number four will be at 135 degrees from zero, this hole has exactly the same positions as hole number 2 with the Y axis position (as is common in small machine shop practice, this will be a negative number) .707" in X and -.707" in Y and so on around the circle.
In my experience I have never known of any Government or industry rule making body that determines which side of the 0.000 by 0.000 position is positive or negative so roll your own.
Good luck
 
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Hope this isn't a real dumb question (senior moment?)
I understand how to measure a bolt circle for even number holes--with opposing bolts, but how do you measure say bolt circle with only 3 holes?
 
With a bolt circle calculator. Look on line, enter a couple known measurements and it will give you your x and y coordinates. Or use a d.r.o. its kinda like cheating. I have too because i suck at math.
 
Bill Gruby said:
If you ever find an answer to a question is too complicated for you just say so and we will pull it apart till you do understand it. That is why we are the Forum we are. No one is left behind. It's an equal playing field here.

"Billy G"
Click to expand...

I agree Bill!
 
Kroll It sounds as though you have got many fine ways to lay out the holes so I will leave that part alone.
But I have a question on one thing you said. You said the ring was worn, and even with the bolts tight it was still loose. Are you saying the bolts do not squeeze the ring tight to the gear? If so is the new material thicker? Could you be missing washers? Not sure how the ring could wear in a way to make it to thin to bolt up tight. Seems the bolts are bottoming in the holes. Is this right? Am I missing some thing?
Ok so that was more than one question.
Mark
 
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