[How-To] Translating Bolt Pattern

[woodchucker]

Thank you Charles and RJ for your detailed responses, it’s really helpful.

I decided to tried measuring the distance between the holes and using the bolt hole pattern on my DRO. I used the little machine shop calculator to work out the diameter of the bolt hole diameter and plugged the values in to my DRO BHP function. It was clear that something had gone wrong as the X,Y coords it gave me weren’t even close to the pattern needed. I then used the Bolt Circle Calculator on LMS and got the correct X/Y coords. After drilling the holes, they were a little off. Even though I’d measured everything several times and taken the average measurement, I’d obviously done something wrong. Measurements taken again, second attempt was much closer.

(Please ignore the bad state of the bracket at the moment, the bolt hole pattern was going to be the hardest part for me, so I wanted to get that done before cleaning everything else up)

Still not perfect, but close enough for this job. I need some more practice on my measuring, but I’m really happy to have a new skill.

Now for the DRO - I think I need an end angle set (in this case to 240) in order to get proper values. Otherwise, if I set it to 360 or 0, I get no Y coordinates. I’ll dig up the manual for the DRO and read up on it tomorrow. It’s nice to know the LMS site has all of the details to work out the coords if I need it though.


Sent from my iPhone using Tapatalk

Try using 4 points and make the 4 point the starting point. and use 360 as your end point.
If that doesn't work, then yes, you have to calculate your end angle.

 

[Ben17484]

Glad you got it to work! A cumbersome way I've done it is to clamp the original part to my mill table and the one to be worked/drilled in the vise. I found the center of the original part and made that my ABSolute coordinate (0, 0). Then moved over to the part to be worked and found its center, switch to INCremental coordinates and zero'd there. Then back to the original part in ABS, with a tap drill in a drill chuck and found the center of a hole. Switched back to INC and moved to that same coordinate on the part to be drilled. Pretty sure that's how I did it.

Bruce

I like the thought process behind this one. I wouldn’t have thought about it, but now you say it it sound like a good method.


Sent from my iPhone using Tapatalk

 

[RJSakowski]

When using a canned routine for the first time or infrequently, it is a good idea to do a dry run first to make sure everything looks good. A run in a piece of scrap would have proven or disproven the routine and saved the good part.

 

[Ben17484]

I had another chance to try replicating a bolt hole pattern today for another bracket I need to make, so gave the measuring between outside edges of the hole, minus the diameter of a hole to find the distance between centres, find the bolt hole diameter and then use my DRO to find the hole coords. I also used this opportunity to try the initial angle offset as I was drilling 4 holes in a square, so needed the initial angle offset to be 45 degrees. This time, it was almost perfect!

It probably doesn’t seem like a lot to most people on here, but I’m really happy to have this new skill that I know can use for future projects.


Sent from my iPhone using Tapatalk