Pipe OD measuring with KY-008 Laser transmitter & reciver module

I need to measure 8" to 24" Tube's OD (Outer
Diameter) KY-008 650nm Laser & Reciver module and a stepper motor to either moving the pipe or moving the KY-008 650nm Laser & Reciever module. Anyone have any suggestion on how best to go about it.

That's an awfully big ventilator tube to stick down someone's windpipe.

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How to move the stuff? No, that is a mechanical project. Get that all designed and then worry about an Arduino.

One way might be to mount the pipe horizontally in a cradle. Use a stepper and lead screw to raise and lower the laser sensor. Find the minimum distance and calculate the OD from the known distance from the sensor to the cradle.

Can you elaborate a little please? Thanks

What's this got to do with the COVID emergency?

I meant wildbill elaborate on their suggestion, I didn't meant you to elaborate.

I was thinking that you could have two V shaped cuts in two bits of two by four (or more precision material) connected by eight foot (or whatever) lengths of the same material. This forms the cradle that sits on the floor/bench. The pipe sits in the two V cuts.

The laser is mounted to the left or right of the pipe and measures horizontally. It can move up or down, and measures at any point of travel. At the lowest, it will measure the distance to the cradle. At the highest it will measure to whatever is behind the cradle.

Since the laser distance to the cradle is fixed and known, simple math can tell you how big the pipe is once you find the minimum distance measured as the laser is moved from lowest position to highest.

My initial reaction would be to move the lasers and hold the test sample still. Thought being the test sample is going to be various sizes and maybe lengths.

I would mount the lasers on slides or maybe a simple delrin block mounted between a rod (thick) and an acme screw.

The stepper would turn one of the acme screws and the other would have a cog belt to keep it in sync. Unless you need very precise measurement I think the Acme screw and counting steps will be adequate. You could have two plates one mounted very low (below the tube) and one very high above the tube. These could be your calibration points.

I know by moving the lasers there are wires that need to be dealt with but I don't see that as much of an issue.

I actually built a similar device and was able to get repeatability of < 1 mm. I had originally planed to use a electronic vernier (similar to the digital calipers) but determined it was not needed.
If you decided you need a measuring device I'm sure there are a number of new devices that will work well.

If you don't need that accuracy, you could move the lasers cog belt and keep them in sync with a rod from on side to the other.

So the questions are:

  1. Accuracy
  2. Calibration required?
  3. Speed of measurement
  4. Usage: 1/day or 500/day

@siv-ide, your topic has been moved to a more suitable location on the forum. This is not an emergency ( :wink: ) and has nothing to do with Covid as TMFKAA pointed out.

Do you know the approximate size before making the measurement, so you have a fixed set of positions for either the pipe or the sensor? How many variations in pipe size?

Thank you all for your suggestions and help so far.

There are few things we have thought in similar manner. The pipe should be fixed in place and I need to have the KY-008 Laser & Reciever module move in line of sight to each other (transmitter and reciever) but orthogonaly to the pipe.

The transmitting unit emits a laser beam that is recived at the other end, both modules are connected together on a one vertical axis CNC rail with stepper motor moving them together at known speed. So this setup need to be on the one end of the pipe face. Also this contrapment should start from one far end of the CNC rail and travel at known speed across the measuring range.

The pipe OD should be measured very accurate. So every pipe placed in the measuring field interrupts the laser beam and casts its shadow into the receiver. By measuring the shadow time (where the laser beam got blocked by the pipe OD), the outside diameter of the pipe can be exactly computed by Arduino. I would need suggestions on how the coding goes on this.

So a micro switch on starting end and another one on finishing end will trigger the measurement time. As I would know the travelling speed of the laser transmitter / reciever, I can measure the pipe OD accurately.

Please feel free to suggest something. I do require accuracy and I need to measure many different sizes of the pipe. I can slow the stepper motor much as I need to get the accuracy. i.e. compromise speed to get high accuracy.:

I need help with coding for this pleass.

Sounds more and more like a commercial product.

What do you mean commercial? I am a hobbyist and my requirement for this is for an audio experiment project that I will eventually be used for academic purposes. I am a lectuerer at a local college.

How do I put together arduino code for measuring the 'shadow time'? I will have to incorporate the Laser transmitter/ reciever traveling speed.

And you do this fro free? Doubt it.

Can you NOT turn off the laser measurement device?

Only those with useful thoughts / information that can help me with my project respond please. I am sure that would be welcome by the forum.

Wildbill & JohnRob,
Any more thoughts please? Any suggestions on the arduino code?

Can you share with me your code for your project that you've done. I may be able to get ideas from it. Thanks.