Help measuring locations of circles within other circles
Help measuring locations of circles within other circles
(OP)
Ok... so I got this piece in and we have been spending a bunch of time trying to reproduce a solidworks drawing of the front round plate with a bunch of holes... see the picture...
Anyone have any ideas of a quick way to measure this up to get a good solidworks dwg? Hoping to get things within .005" or so... so far we have been trying to measure things up with some 6" digital calipers... not going very quick...
The hard part is that there are the tubes sticking out in the Z direction... and the tube that looks like its centered is centered in the x direction but not in the y... I'm not super experienced in measuring things up like this... so any advice would be appreciated. Thanks!
Anyone have any ideas of a quick way to measure this up to get a good solidworks dwg? Hoping to get things within .005" or so... so far we have been trying to measure things up with some 6" digital calipers... not going very quick...
The hard part is that there are the tubes sticking out in the Z direction... and the tube that looks like its centered is centered in the x direction but not in the y... I'm not super experienced in measuring things up like this... so any advice would be appreciated. Thanks!





RE: Help measuring locations of circles within other circles
RE: Help measuring locations of circles within other circles
Please recognize first that the solid model drawing is only that: a simplified drawing intended to show what (in an idealworld of perfect dimensions and zero tolerances) should fit exactly into what should have built exactly.
0.005 accuracy? Your real world piece will be very, very difficult to get that dimensions.
First clean your steel up as best you can. Once nce and bright and smooth, decide exactly what dimensions you need to 1/16 (botl holes for the flange for example?), which ones to a 1/32 (thickness of the flange, CL of the heater/pipe elements), which one (or two) you need really be precise.
Spray blueing over the flange. Get a centerfinder (I use "Flangewizard center head from ht
to get the TRUE top center and exact side points on the side of each side of each of your penetrations. (It does NOT appear that even the big one is on centerline of your large flange.) Once you know true top center and 90 degree points, scribe (with the bluing and a good scribe) the centerlines on each penetration. (That will be for measuring to later.)
Now you need to get the reference points on your big flange. I assume it is round enough. Get an accurate (digital recommended!) protractor, and the center finder two-side fitting from your straight edge kit. (I use the classic Sterrett sets in 12 inch, 16, 24, and 48 for various sized head. But even a Sears or Home Depot set will work.) Again blue the face of the flange, and determine exact 90 degree points on top, bottom, left and right sides.
Put the centerfinder straight edge on these four points and try to draw (scribe) the from the four lines back to a common center, drawing the inscribed (scratched) lines exactly up and down and horizontal. Usually, none will intersection exactly right. 8<)
With the eccentric center penetration, you'll have to adjust the centerfinder straight edge to go as deep as possible towards the center.
At the end of this exercise, you should have four perpendicular lines defining the two reference axis for your flange face, and have the 90 degree points for the three penetrations scribed as lines.
Now you need to measure from the reference point axis up (or down) to the 90 degree points on the penetrations. If I could tolerate a 1/16 accuracy (0.062) in my drawing, I'd use a Sears self-leveling laser on a tripod aimed at the reference axis on the flange. Then measure up or down or over to the laser "planes" with a straight edge and right angle: They will be in the same Sterrett set as the centerfinder.
You have an unusual 5 hole bolt pattern. Determine angle of each bolt hole from the center of the flange by aligning your centerfinder across the center of the bolt hole. Get the angle of tthis line by placing the magnetic base protractor on the centerfinder. Get the radial distance of each hole by measuring from the edge of the flange in to center of each bolt hole. Plot the five points, plan on drilling the bolt holes +1/16 (or even 3/32) oversize.
For fun, try to fit a regular 5-point star on your points and see how close they are drilled.
To get your distance "out" from the flange face to the top of each penetration, use one straight edge across the top of each penetration. Measure "up" from the flange face to the bottom of this straight edge. Check for perpendicularity by measuring "up" from top an dbottom, right and left sides. The four sides will probably be different.
Do you know how they made your penetration? Pipe nipples? Machined pieces? Pre-fabricated parts that you will have to duplicate? Do you know what threads they used?
Repeat this process for the tubes and back of the piece.
RE: Help measuring locations of circles within other circles
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RE: Help measuring locations of circles within other circles
You're using gravity to define your reference conditions (steady state conditions.)
Put the assembly in a vise as soon as possible to avoid rotating the flange hile you emasure it. (Off of the desk and office.)
RE: Help measuring locations of circles within other circles
As mentioned, I wonder why you think you need .005" (I figure you're doing some reverse engineering here so you can make more). Do you know what the fabrication tolerances were for the original piece?
To start, take a high resolution digital photo "dead on" and print it out as close as possible to actual size.
Then tape the print to a drafting board and it should be all simple geometry from there.
RE: Help measuring locations of circles within other circles
I'm working too hard.
Get a piece of masonite or 1/4 inch plywood about 18 x 18 - just a little larger than your flange diameter.
Put it on the end of your piece. Press firmly on to the end of your longer pipe to make sure the board doesn't move. Rap it sharply ONCE! with a 2 lb hammer right near the centerline of the pipe. (Don't use a regular construction hammer, is not heavy enough.)
With that hole location marked, drill out that hole as accurately as practical. (jig saw will work too if you can't find a hole saw. You will need to allow for the fillet weld at the joint of the large pipe tot he flange.
With that hole drilled, slide the plywood down the center pipe until it touches the next two pipes. Repeat, marking by indent the locations of the two shorter pipes.
Drill out their holes, slide the plywood down once more and repat to mark the bolt hole points. Drill those out and mark the OD for cutting.
Now measure your plywood, deciding where you want your origin, centerlines, and axis of the new part.
RE: Help measuring locations of circles within other circles
Huh. I got an even better idea.
Take some of that goo they use on Mythbusters to cast stuff, make a mold and work from that.
But make sure you trim off the flash/sticky bits once it's cured as those will register as anomalies in 3D software.
RE: Help measuring locations of circles within other circles
Measure from the inside of any hole to the inside of two convenient, nearby bolt holes. Make sure you measure the shortest dimension. Add 1/2 the inside diamter of the hole of interest and 1/2 the inside diameter of the bolt hole to each hole to hole measurement. This will give you two radii from referenced known bolt holes. Where the two radii intersect is the center of the hole of interest. Repeat for each hole of interest.
Ted
RE: Help measuring locations of circles within other circles
I've tried various ways - the best way I've found is by using a modified set of pipe flange alignment pins I bought from one of the shops at www.pipefitter.com
I took the "two-hole" flange alignment pins sets (one side for large bolt holes and one for small bolt holes) and put them on a lathe, then used the lathe to "drill" a cener point on the pins. That small center mark does let me measure to or from a hole, but the original poster apparently has no such jogs and tools already made up.
But un this cae, he faces a bigger problem because the center pipe sections extend out from the surface of the round flange. That means you can't directly measure hole to hole distances because the height changes. To measure only radial distance, you'd need to get a bar compass and two needles, one longer enough to touch the flange, the second short enough to touch whatever you used to indicate the center of the pipe stubs. And finding accurately the center of the pipe stub like he has in the photo is very tricky. (Well, finding the center is very easy. Accurately marking it to measure that center point from place else is very tricky.)
RE: Help measuring locations of circles within other circles
racookpe1978, have we ignored "fit-for-purpose" here?
RE: Help measuring locations of circles within other circles
If the flange is relatively sound you could use height gauge of maybe a bigger caliper on a smooth surface to find the the location accurate enough.
Check the edges of the flange to see if there are witness marks like 0,90,180, 270. If so this will help a lot.