Distance/Measuring Help

[ICS Vortex]

Hello, I've decided to start working a little with AutoCAD to make a bracket that I need cut out. The bracket will have 4 bolt holes that are 6.7mm in diameter each. I am having trouble getting my bolt hole center distances the exact distance I need.

Here's a rough image with some measurements.

 

I have got the red (19mm) circles perfect since they didn't have any angles to worry about.

I am currently trying to do the top right side circle, but I guess I'm just too unfamiliar with AutoCAD (I've been watching a few videos on it) because I cannot get the distance from orange and blue to be 80mm and 61mm exactly..... I hope you guys can understand what I'm having issues with, I think I explained that pretty badly.....I need the distance from the left two circles to be exact to the top right circle. I don't know how to make it an exact distance. I've tried drawing lines from the left two circles the distance I need, but I don't know the angles so that never worked. The closest I got was like orange 79.xxx mm and blue 60.xxx mm.

 

I'll be needing to do the same concept to get the distance from the top 3 holes to the bottom one after I figure out how to do it. Can anyone help? Thanks.

[rkmcswain]

Draw a circle, using the left most circle as the center point, and use 80mm as the radius.

Draw a circle, using the other circle as the center point, and use 61mm as the radius.

Where they intersect, is the center of the upper-right circle.

 

Repeat for the lower right circle.

 

Erase the construction circles.

 

Example for the upper left one:

 

[ICS Vortex]

Draw a circle, using the left most circle as the center point, and use 80mm as the radius.

Draw a circle, using the other circle as the center point, and use 61mm as the radius.

Where they intersect, is the center of the upper-right circle.

 

Repeat for the lower right circle.

 

Erase the construction circles.

 

Example for the upper left one:

 

 

I'm not sure that worked? I got it very close doing some triangle math yesterday. I just reconstructed what you said to do on my "completed" version and this is what I end up with:

[SLW210]

80-19=61, which means the intersection will be in a straight line from those 2 holes. One of those numbers is wrong.

 

I drew the lower hole and worked back to the upper hole, the 61mm blue line should be 63.

[BIGAL]

Like SLW210 the measurement 19 is incorrect when using the whole distances, would have posted earlier "500 error"

[ICS Vortex]

I've been trying to replicate this mounting bracket but have been unsuccessful. I drew up what was posted in my previous post and had it cut out at a machine shop for $30 out of 1/4" steel. However, after tapping the holes one of the bolt holes did not line up and it was an unsuccessful first attempt. Do you guys have any pointers of "perfecting" replicating this? $30 is a lot to spend to have it cut out, so if I do attempt it again, I want to make sure it's 100% correct.

[BIGAL]

The cross check would be put bolts in the mounted part and use a vernier to measure to the bolt shank. Was it wrong on all holes ? Is the bracket metric or imperial ? Please dont laugh at that question. Metric bolts do not exist for 6.7 mm. This would be a tolerance size.

[ICS Vortex]

The cross check would be put bolts in the mounted part and use a vernier to measure to the bolt shank. Was it wrong on all holes ? Is the bracket metric or imperial ? Please dont laugh at that question. Metric bolts do not exist for 6.7 mm. This would be a tolerance size.

 

That's how I measured them, with a digital caliper. The bolts are m8x1.25 which requires a 17/64" drill bit, which converts to 6.7mm.

[BIGAL]

Ok if I read correct all holes are tapped metric. Take a M8 bolt and using a lathe turn a point on a bolt. Place bracket onto a plate clamp together, insert bolt with point into each hole till it stops tap with hammer repeat you should see the dimple mark measure the dimples. Ps no lathe cut off bolt head put in drill spin and find a bench grinder.

[ReMark]

I would have had the part laser scanned.

[SLW210]

Nothing really wrong with the way you did it, you just have one of those distances wrong. Measure again and make sure you have all of those centers written down correct.

[ICS Vortex]

Ok if I read correct all holes are tapped metric. Take a M8 bolt and using a lathe turn a point on a bolt. Place bracket onto a plate clamp together, insert bolt with point into each hole till it stops tap with hammer repeat you should see the dimple mark measure the dimples. Ps no lathe cut off bolt head put in drill spin and find a bench grinder.

 

That may work a little better. I don't have access to many machine tools, definitely not a lathe, but do have a grinder, so if I attempt this again, I may try that method of measuring center/center.

[ICS Vortex]

I would have had the part laser scanned.

 

I thought about that, but they said it would have been double the price to have them draw it up/scan it and cut it and I also wanted to take this challenge on to learn a little bit about AutoCAD in case I needed to do any more small work on my own.

[ICS Vortex]

Nothing really wrong with the way you did it, you just have one of those distances wrong. Measure again and make sure you have all of those centers written down correct.

 

Doing it the way I did it wasn't ensuring that I found center to center perfectly, and I'm assuming that's what messed it up in the long run. BIGAL suggested that I round off one end of a m8x1.25 bolt to a sharp point and while having the original clamped down on top of another piece of sheet metal or really anything, center punch the holes with the homemade center punch. Anyone else have any other methods? I think this sounds promising if I go to do it again.

[ICS Vortex]

Sorry for the spam posts, trying to reply to everyone. Also, maybe an adjustable center hole punch would work well?

[ReMark]

What method did the shop use to create the bracket they made for you the first time around?

[BIGAL]

Take some real photos of the objects the actual parts etc be aware of image size to be posted.

 

Like Remark which holes were wrong all of them ? I drew it up and the 19 was not 19mm rather 20mm something,

 

Did you check what they made ?

 

If it is all tapped holes can you put pointed bolt in non bracket holes with some black ink on point, pen etc, use stiff cardboard etc.

[SLW210]

I have done hundreds of similar items using just a caliper and steel rule and in some cases just a tape measure with no problems. If the holes are threaded, you can use bolts or set screws to help, for smooth holes they make pin gage sets.

 

Pretty simple to find the center of same size holes, put the caliper inside one hole and zero the caliper on the hole diameter, then measure with the caliper to outside/outside of hole for the center distance.

[rkent]

Post #7 is how I do this all the time. Measure outside to outside of the bolts, subtract the dia of one bolt and you have your center dims.

 

Using parametric constraints I get a length of 20.336 for the horizontal line, or if the horizontal line is held at 19.0 then I get 63.074 on the inside upper diagonal.

[AdamW]

I agree with SLW210. 80mm-61mm=19mm Hence a straight line. I think you should be measuring to a higher precision for example XX.XXmm. I work with diagonals all the time and can often be a couple millimeters out over 5,000mm or more. An accuracy of 2/5,000 and this is acceptable for our site measures. As you are only working to 10’s of millimeters. A couple of decimal places will certainly help you. Notice Rkent's dimensions are to three decimal places. I know this may be difficult to measure but try. I would also check the angles using the “cosine rule” and or the “law of sines”. Remember the angles of a triangle must add up to 180°. Failing measuring Bigal and Remark have good real world solutions. May be a silly question but can you not just give the bracket to the steel fabricator and ask them to replicate it?