Texas_Ace BLF Calibrated Lumen tube / Sphere No math skills needed - Several spheres still available

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jeff51
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Getting the tube/lux meter to readout directly in lumens that are close to the actual value of the light really takes some fussing.
On the one I built, a few mm in pipe length throws things off. But that is also part of the calibration process on my tube. Changing one of the tube lengths moved me closer to my desired readings.

When I tried to use the hardware store diffusion stuff, how it was cut relative to the pattern made a difference. How it was oriented inside the tubes made a difference.
How tightly the tube sections fit together made a difference. I used thin spacer rings to adjust the fit for consistency and naturally this changed the reading too.

On my version the insides of the straight sections are lined shiny metal duct tape so very little light is lost. I covered the outside with the stuff initially. But I felt that more or less light was getting absorbed into the tube plastic depending on the throw of the light being measured. So I did the inside treatment.
And yes, just covering the outside of a tube with tape or foil – makes a measurable difference in the readings….

I found no need to scuff up the insides of the curved tube. The light is well defused by the time it gets to the elbow. But I did anyway because I wanted to get more consistent readings when changing the elbow sections. Different elbows had slightly different finishes.
I am still testing, I’ve got versions with the outside of the elbow covered in chrome paint. And another with chrome paint on the inside as well.

The project got put on hold for a while and I’m about to dive back in. I want to experiment with elbow finish.
I also want to add a photo diode at the end of the assemble so I can use the setup to get runtime plots that can be adjusted to the lumen values. I’ll use my USB O-Scope and logging software for this. My cheap lux meter hasn’t got a way to do data logging.

All in all it’s a good way to waste a goodly amount of time. Getting close and using a correction scale is a viable option.
If you are at all OCD, just step away, or keep the meds handy.
Or convince TA to build just one more…
All the Best,
Jeff

Yokiamy
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Exactly my experience Jeff!
I’d buy one from TA, but i’m frugal. But the time and money ive spent into my setup (tube and sphere) is worth more than TA’s price of the tube Facepalm

jeff51
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CNCman, I completely missed the thread about your adventures.
I found the larger tubes harder to control, so I stuck to the 4” (actually 3” – had a brain fart and didn’t remember) for sanity and costs sake.
All the Best,
Jeff

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Yokiamy wrote:
Exactly my experience Jeff!
I’d buy one from TA, but i’m frugal. But the time and money ive spent into my setup (tube and sphere) is worth more than TA’s price of the tube Facepalm

Yeah, when I started, I thought “How hard could it be?” Still I’m glad I did it, I’m semi-retired and have always been a tinkerer.
When I get mine to a point to where I’m happy with the end product, I’ll do a DYI build POST.
Build one for someone else?
I don’t think so Tim..
All the Best,
Jeff
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FYI, I don’t read BLF much anymore, so I never saw that thread CNC otherwise I would of been happy to help you.

Just a quick glance and I saw where some of your issues came from, those diffusion sheets in the pictures are no good. I tried those and had nothing but issues, 4 or 5 options later I found this local place that had some and it worked WAY better.

When you put the diffusor over the light in a room, you should not be able to see any simblence of a beam coming out of it, just a perfectly smooth wall of light. And even then multiple layers are important due to how the light reflects inside the tube.

Texas_Ace
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jeff51 wrote:
Getting the tube/lux meter to readout directly in lumens that are close to the actual value of the light really takes some fussing.
On the one I built, a few mm in pipe length throws things off. But that is also part of the calibration process on my tube. Changing one of the tube lengths moved me closer to my desired readings.

When I tried to use the hardware store diffusion stuff, how it was cut relative to the pattern made a difference. How it was oriented inside the tubes made a difference.
How tightly the tube sections fit together made a difference. I used thin spacer rings to adjust the fit for consistency and naturally this changed the reading too.

On my version the insides of the straight sections are lined shiny metal duct tape so very little light is lost. I covered the outside with the stuff initially. But I felt that more or less light was getting absorbed into the tube plastic depending on the throw of the light being measured. So I did the inside treatment.
And yes, just covering the outside of a tube with tape or foil – makes a measurable difference in the readings….

I found no need to scuff up the insides of the curved tube. The light is well defused by the time it gets to the elbow. But I did anyway because I wanted to get more consistent readings when changing the elbow sections. Different elbows had slightly different finishes.
I am still testing, I’ve got versions with the outside of the elbow covered in chrome paint. And another with chrome paint on the inside as well.

The project got put on hold for a while and I’m about to dive back in. I want to experiment with elbow finish.
I also want to add a photo diode at the end of the assemble so I can use the setup to get runtime plots that can be adjusted to the lumen values. I’ll use my USB O-Scope and logging software for this. My cheap lux meter hasn’t got a way to do data logging.

All in all it’s a good way to waste a goodly amount of time. Getting close and using a correction scale is a viable option.
If you are at all OCD, just step away, or keep the meds handy.
Or convince TA to build just one more…
All the Best,
Jeff

Yep, the tiniest changes make a surprising difference in the readings. I am still surprised.

This is why I glued everything into place on the ones I make, this helps massively to keep things consistent.

Texas_Ace
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For anyone interested, I did manage to find a few more lux meters (they need to be a specific kind of sensor body to fit properly and they are going out of production it seems) and I had someone order a tube awhile back that required me to get more stuff laser cut. So I do have the important parts needed to build a few more tubes if anyone wants one.

They will just take a week or 2 as I will have to order the rest of the parts.

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Texas_Ace wrote:
FYI, I don’t read BLF much anymore, so I never saw that thread CNC otherwise I would of been happy to help you.

Just a quick glance and I saw where some of your issues came from, those diffusion sheets in the pictures are no good. I tried those and had nothing but issues, 4 or 5 options later I found this local place that had some and it worked WAY better.

When you put the diffusor over the light in a room, you should not be able to see any simblence of a beam coming out of it, just a perfectly smooth wall of light. And even then multiple layers are important due to how the light reflects inside the tube.


.
You have helped me on several occasions TA, Thumbs Up Thank You. Big Smile
.
I had hoped there would be more input on the tread I started so I could learn more about why I was having so much trouble tuning it. In the end, it is clear to me the variables are not controllable to any satisfactory degree. The smallest thing can affect readings, so sensitive, I now just use them for fun, not accuracy. The work I do revolves around accuracy, that drives my thought process. Lumen tubes for me is a failure. Most of the time Lumens are arrived at by led type, voltage, and current for a ball park value.
.
I Apologize that my frustration has offended anyone or everyone. Facepalm
.
jeff51
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CNCman, I don’t think anybody took offense at anything you said. Certainly not me.
Farting around with these things can be frustrating. I have pages (and pages) of notes taken of test builds and the results.
I got pissed off more that once as I made changes and seemed to be getting me further away from something that worked.

Just taking the tube apart and putting it back together yielded different readings.
I got that ironed out using spacer rings to control how tightly the parts fit together along with using witness marks to make sure the tubes went back together in the same orientation.
The diffusion stuff I used is so consistent, at least that wasn’t a problem orientation wise. Yet moving it in relation to the tube placement by 2mm made a difference in the reading.

On my setup, I found that room light did indeed make it into the test setup until I covered and/or lined the PVC tubes. So do your testing in a controlled light environment or shield the setup.

As TA said, even the smallest changes makes surprising differences in the readings.
All the Best,
Jeff

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Cncman, great info thank you. And I am interested in the build but not so if the experience is lot ha of aggravation, especially since I will not have calibrated lights. That is my biggest deterrent at the moment. I already bought the PVC connections but obviously can return them. That was $50 alone. But if I cannot calibrate it then it’s no good to me. I want it to compare when I change leds and emitter in my lights, which I do often. I hardly will use a lumen tube for a stock light. It’s more about I have put 5 different emitters in my KR1’s and I’m curious how they rank and where they stand . Information that is impossible to find from someone else and is very Interesting to me.

Texas ace- that is a great philosophy. Do you want have any 3.5” calibrated lumen tubes for sale? Big Smile

Check out some of my new lights (picture heavy) and quick first impressions of them here: https://budgetlightforum.com/node/77180

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Artielt59,
My local hardware stores are happy to take returns on stuff as long as I have the sales ticket.
All the Best,
Jeff

CNCman
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Thanks Jeff for sharing your experiences. Thumbs Up
For a long time I felt alone working on the tubes. Trial and error and a never give up approach can give someone a heart attack.
.
In the 8” tube, my Diffusers are rattle can sprayed with Matte White, 4 coats on the top Diffuser, 2 coats on the one 6” below it. They are 2 inside glued in place with no leakage around the edge. Using all the data on the MT09R, it was possible to adjust the tube to that light. An additional Diffuser is required for throwers. Both thrower and flooder lights have a slightly different number for calculations. I’m guessing about +/- 500 lumens at 6000 to 30,000 lumens, best I could do guessing.
.
The 6” × 4” tube was more difficult than the 8” to tune, worked on it for the better part of a year, off and on. Same problem you stated about getting close to 1.0 then .760, then 1.192. Not to mention light meter additional calculations. I used ‘maukka’ Calibrated Light set on this tube. Give up a while, then back at it. Not sure it was worth the trouble after checking and documenting the few lights I have, LOL. Silly

Texas_Ace
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CNCman wrote:
Texas_Ace wrote:
FYI, I don’t read BLF much anymore, so I never saw that thread CNC otherwise I would of been happy to help you.

Just a quick glance and I saw where some of your issues came from, those diffusion sheets in the pictures are no good. I tried those and had nothing but issues, 4 or 5 options later I found this local place that had some and it worked WAY better.

When you put the diffusor over the light in a room, you should not be able to see any simblence of a beam coming out of it, just a perfectly smooth wall of light. And even then multiple layers are important due to how the light reflects inside the tube.


.
You have helped me on several occasions TA, Thumbs Up Thank You. Big Smile
.
I had hoped there would be more input on the tread I started so I could learn more about why I was having so much trouble tuning it. In the end, it is clear to me the variables are not controllable to any satisfactory degree. The smallest thing can affect readings, so sensitive, I now just use them for fun, not accuracy. The work I do revolves around accuracy, that drives my thought process. Lumen tubes for me is a failure. Most of the time Lumens are arrived at by led type, voltage, and current for a ball park value.
.
I Apologize that my frustration has offended anyone or everyone. Facepalm
.

lol, no worries no offense taken. More felt bad you had to struggle through that alone, it is never fun doing that from scratch.

Yeah, people would ask a lot at first how accturate these tubes would be and kept being surprised when I would say not to treat them as an accurate lumen reading and more use them to compare readings between lights and between others with the same style tube.

All my tubes should be pretty comparable as they were all calibrated to within a ~2-3% of each other. That will grow over time though as things are moved around etc.

Texas_Ace
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Artiet59 wrote:
Cncman, great info thank you. And I am interested in the build but not so if the experience is lot ha of aggravation, especially since I will not have calibrated lights. That is my biggest deterrent at the moment. I already bought the PVC connections but obviously can return them. That was $50 alone. But if I cannot calibrate it then it’s no good to me. I want it to compare when I change leds and emitter in my lights, which I do often. I hardly will use a lumen tube for a stock light. It’s more about I have put 5 different emitters in my KR1’s and I’m curious how they rank and where they stand . Information that is impossible to find from someone else and is very Interesting to me.

Texas ace- that is a great philosophy. Do you want have any 3.5” calibrated lumen tubes for sale? Big Smile

Yeah, I can build another 3.5”, PM me and we can go over the details if you want to go that way.

jeff51
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Hoop wrote:
Some types of the inflatable air pillow material used for filling voids in boxes when shipping packages is just slightly opaque / diffuse. This stuff is sold in rolls. Stack layer on layer to get just the right amount of blockage to fine tune the calibration to read 1:1. This may work best at the sensor side.

I used this method to calibrate a different lux meter for use with my TA tube and got it to read 1:1 to a Maukka light.

I have used this stuff to control brightness in the setup I use for run-times.
The thin white closed cell foam used to package some of our lights or other electronics works also.
The semi-transparent frosted plastic from gallon milk jugs (and the like) can be used as well.
And the best part is they are free. But don’t expect consistency from different sources of the material or even across a sheet of it.

Stuff designed to be used as a diffusion material is better choice if you want to go that route.
The biggest hurdle I had was getting the setup to work with throwers and floodies. Other than getting the readings close to some sane value…
Getting the beam diffused early and lining the tubes to prevent escape prone photons did it for me.
I suspect there are many ways to approach the build. Just have at it – and keep repeating:
It’s only a hobby – It’s only a hobby…
All the Best,
Jeff

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jeff51 wrote:
and keep repeating: It’s only a hobby – It’s only a hobby…

But before you know it, you’re deep into it and it will drive you crazy sometimes.
I’ve had days i only could think of it and how to improve it.

I found out a white sheet of cotton cloth between the elbows works well, also used dicarded jugs as you mentioned.

When you have a reference light you don’t even need exact lumen readout, just correct it with the reference number to get the correct Lm output.

Artiet59
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jeff51 wrote:
Artielt59,
My local hardware stores are happy to take returns on stuff as long as I have the sales ticket.
All the Best,
Jeff

Yes, returning is no problem Thumbs Up

Check out some of my new lights (picture heavy) and quick first impressions of them here: https://budgetlightforum.com/node/77180

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