# Bolt Circle



## jwdanie (Jul 28, 2021)

Hello,
When setting up a bolt circle, in my case I'm at 0,0 and using 4 holes at 0.8 radius and start angle of 45 degrees.
I was confused at the displayed points, expecting all values to be 0.5656 with sign differences.
I then realized they are showing absolute coordinates.

Is there a way to display incremental coordinates in the point listing? 
All axes were in incremental, and it was confusing to get offsets that were unexpected.
I had to select each point and verify the X,Y offsets instead of just looking at the list.

Thanks!
Jim Daniels


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## mmcmdl (Jul 28, 2021)

I'm not understanding this .


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## jwdanie (Jul 28, 2021)

mmcmdl said:


> I'm not understanding this .


In bolt circle,
radius: 0.8
units: in.
# holes: 4
Angle alpha: 45
Angle theta: 270
Create Circle.

Results in this screen:






The list of points on the right is confusing when I'm sitting at 0,0 and expect to see values that I can use to ensure the pattern is correct.

I expected something like:
Circle - 1
x:0.5656,y:0.5656

Circle - 2
x:0.5656,y:-0.5656

Circle -3
x:-0.5656,y:-0.5656

Circle - 4
x:-0.5656,y:0.5656

Instead, the values are absolute coordinates which is of limited value.

If I select each point, one at a time, I can see the correct offsets in the main pane.





What I'm asking for is for the list of points in the workspace to show incremental coordinates, not absolute coordinates.

Jim Daniels


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## jocat54 (Jul 28, 2021)

When I do a bolt circle with my DRO when I go to the next hole I move the x & y axis until the DRO reads zero and drill the hole.


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## mmcmdl (Jul 28, 2021)

Bolt Circle Calculator
					

The premier source of tooling, parts, and accessories for bench top machinists.




					littlemachineshop.com
				




I would think the bottom screen should be correct . Did you reset 0 0 at the center of BCD ?


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## mmcmdl (Jul 28, 2021)

Bolt Circle Calculator
					

The premier source of tooling, parts, and accessories for bench top machinists.




					littlemachineshop.com
				




Results didn't post .


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## Larry$ (Jul 29, 2021)

My DRO bases hole location in reference to the center I select. I put the table at the center and enter the parameters. Locations are + in one direction and - in the other. The +&- #s may be different depending on the start angle and the # of holes selected.


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## ycroosh (Jul 29, 2021)

Jim,
The "holes" or "points" are sub-datums. They are absolute coordinates by design. I.e. each one is an offset from the absolute 0; when you click one, it becomes an incremental "0" point. If you want to quickly preview the circle, you can use the graphical view. In your case, it would look like this. 






There is no good way for me to handle this otherwise. The point list would need to be re-calculated every time you set a new incremental origin. It gets even more interesting when you are in mixed mode (i.e. some axes are in absolute mode and others are in incremental).
Regards
Yuriy


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## BGHansen (Jul 29, 2021)

You may try adding one to the number of holes.  On my DRO, if I say a 0 - 360 pattern with 4 holes the holes will be at 0, 120, 240 and back to 360.  Or actually a 3-hole pattern.  If I enter 5 for the number of holes with a start at 0 and an end at 360, it gives the desired spacing of 0, 90, 180, 270 and the last one back to 360.

Bruce


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## ErichKeane (Jul 29, 2021)

ycroosh said:


> Jim,
> The "holes" or "points" are sub-datums. They are absolute coordinates by design. I.e. each one is an offset from the absolute 0; when you click one, it becomes an incremental "0" point. If you want to quickly preview the circle, you can use the graphical view. In your case, it would look like this.
> 
> View attachment 373720
> ...


Ok, just a passer by, but that is a REALLY cool interface that I would love to have any time I'm doing one of the pre-planned-holes thing on a mill.  That seems really useful.


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## ycroosh (Jul 29, 2021)

BGHansen said:


> You may try adding one to the number of holes.  On my DRO, if I say a 0 - 360 pattern with 4 holes the holes will be at 0, 120, 240 and back to 360.  Or actually a 3-hole pattern.  If I enter 5 for the number of holes with a start at 0 and an end at 360, it gives the desired spacing of 0, 90, 180, 270 and the last one back to 360.
> 
> Bruce


Bruce,
You don't need to do this with TouchDRO. When you select 4 holes, it creates 4 distinct holes. In your example, it would be 0,90,180, and 250 degrees. That is, unless you explicitly set both angles, starting and ending. Then the DRO will place the first hole at the starting angle, last hole at the ending angle, and the other two spaced equally in between.
Regards
Yuriy


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## jwdanie (Jul 29, 2021)

Thanks Yuriy,
I just thought I was doing something wrong when I entered my parameters and expected the list to show the offsets.
After clearing and re-enting the data about four times I finally figured out the points were listed in absolute coordinates.

No big deal, thanks for the help!

By the way, the graphical bolt pattern is what made me go this route. The EL-400 is on the bench if I ever want to go back.
Jim Daniels


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## ycroosh (Jul 29, 2021)

jwdanie said:


> Thanks Yuriy,
> I just thought I was doing something wrong when I entered my parameters and expected the list to show the offsets.
> After clearing and re-enting the data about four times I finally figured out the points were listed in absolute coordinates.
> 
> ...


Jim, 
I see how this can be confusing. I've been thinking about this and one idea I have is to have a "preview" button or tab (still need to figure out what I can do there without a lot of work) that shows the points that will be created. Since I already have all of the context there, it's easier to show absolute and/or incremental positions for the points, depending on the user's preference. I added this to my "TODO" list and will play with it once I get through the other stuff. 

Regards
Yuriy


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