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

[SKV89]

I don’t think the threat of no electricity will work. You have so many beautiful flashlights lying around, they can just grab some of those and they produce more light than any ceiling fixtures. They can also play on their tablet and cell phones.

[beam0]

@teacher

@beam0

@Man Without Shadow

Could some of the problem be that white PVC pipe isn’t made for reflecting light and therefore the illumination tolerances across tubes are not uniform. Not that you can’t make an accurate lumen measuring device out of one, just that across materials non-uniformities can create the need for the calibrating you are describing. Sure they all look perfect white to the eye inside, but I wonder if the inside surface of the pipes are optically dissimilar in small but significant ways.

Years ago when I was researching building one of these I recall people were painting the insides with flat white spray paint, I wonder if this was the reason for doing it?

I remember that. :+1: . Weren’t they painting the outside flat black also? Seems like I remember that……

Yes as I recall they were painting the exteriors flat black to prevent the possibility of any light escaping directly through the PVC.

[Texas_Ace]

@SKV89

I don’t think the threat of no electricity will work. You have so many beautiful flashlights lying around, they can just grab some of those and they produce more light than any ceiling fixtures. They can also play on their tablet and cell phones.

LOL, quite true but the batteries will run down at some point then the truth will sink in.

[Texas_Ace]

@beam0

@teacher

@beam0

@Man Without Shadow

Could some of the problem be that white PVC pipe isn’t made for reflecting light and therefore the illumination tolerances across tubes are not uniform. Not that you can’t make an accurate lumen measuring device out of one, just that across materials non-uniformities can create the need for the calibrating you are describing. Sure they all look perfect white to the eye inside, but I wonder if the inside surface of the pipes are optically dissimilar in small but significant ways.

Years ago when I was researching building one of these I recall people were painting the insides with flat white spray paint, I wonder if this was the reason for doing it?

I remember that. :+1: . Weren’t they painting the outside flat black also? Seems like I remember that……

Yes as I recall they were painting the exteriors flat black to prevent the possibility of any light escaping directly through the PVC.

Painting the outside black would stop the tube from glowing but would not help the inside readings. The black would simply absorb the light, not reflect it.

Painting it silver would make more sense but in my testing it didn’t do much either even on the inside.

[teacher]

[beam0]

I wasn’t actually suggesting painting the tubes inside or out, just remembered it was considered in the past and thought of it. It was from many years ago, probably around 2012-2013. I figured all previous methods had already been considered for these.

I only need this to see what improvements my mods make, and maybe get a ball park number of output for new lights.

[Texas_Ace]

@beam0

I wasn’t actually suggesting painting the tubes inside or out, just remembered it was considered in the past and thought of it. It was from many years ago, probably around 2012-2013. I figured all previous methods had already been considered for these.

I only need this to see what improvements my mods make, and maybe get a ball park number of output for new lights.

Not to worry, I was not offended and I understand what you meant.

I just don’t have time for a lot of extra words at the moment.

[teacher]

@Texas_Ace

@beam0

I wasn’t actually suggesting painting the tubes inside or out, just remembered it was considered in the past and thought of it. It was from many years ago, probably around 2012-2013. I figured all previous methods had already been considered for these.

I only need this to see what improvements my mods make, and maybe get a ball park number of output for new lights.

Not to worry, I was not offended and I understand what you meant.

I just don’t have time for a lot of extra words at the moment.

Good… cause I was not suggesting either…. just remembering & wondering.

[JasonWW]

@Texas_Ace

It depends on how many people I “hire” to help out (aka, how many family members I can beg, bribe and blackmail into helping out, the threat of no electricity should be pretty good motivation lol).

Threaten to turn off the wifi. Lol

I’ve got xfinity cable with the xfi app. I can turn off individual or groups of devices with a push of a button on my phone.

[Texas_Ace]

@JasonWW

@Texas_Ace

It depends on how many people I “hire” to help out (aka, how many family members I can beg, bribe and blackmail into helping out, the threat of no electricity should be pretty good motivation lol).

Threaten to turn off the wifi. Lol

I’ve got xfinity cable with the xfi app. I can turn off individual or groups of devices with a push of a button on my phone.

LOL, yeah I have similar powers but that might qualify as cruel and unusual punishment in today’s world. :person_facepalming:

[Texas_Ace]

Ok, it was an all day marathon run yesterday with all hands on deck but we managed to get all of the 3” spheres finished!

I started work on the 4” spheres but they are proving to be MUCH harder. I spent a few hours messing with them but just can’t see to get them to come out correctly.

I still have a few ideas to try but if they don’t pan out I am left with a bit of a choice.

Option 1: Calibrate them for the most consistent readings and they will need to use a multiplier like most spheres in order to figure out the lumen values.

Option 2: Get them to read the correct lumens on the meter but give up some consistency (basically pointing the light at an angle can effect the readings more then I would like)

[Micael]

If its not possible to get them right om the meter

Option 1: Calibrate them for the most consistent readings and they will need to use a multiplier like most spheres in order to figure out the lumen values.

Will you provide a multiplier so its calibrated to your normal readings? If you do that its ok to me./Micael

[Texas_Ace]

@Micael

If its not possible to get them right om the meter

Option 1: Calibrate them for the most consistent readings and they will need to use a multiplier like most spheres in order to figure out the lumen values.

Will you provide a multiplier so its calibrated to your normal readings? If you do that its ok to me./Micael

Yes, naturally I would calibrate them to a known multiplier. Most likely something around ~1.5x.

The issue is that if I install all 3 diffusing sheets like the 3” spheres to get the readings consistent, then the meter readings are around 33% low. If I remove diffusing sheets to get the numbers up then it becomes less consistent.

I am experimenting now with ways to reduce losses but don’t have very high hopes.

[hIKARInoob]

How about using different diffusing sheets that transmit more light; something more transparent?

[Texas_Ace]

@hIKARInoob

How about using different diffusing sheets that transmit more light; something more transparent?

Yep, tried that as well. The clear sheets are what I am using now, they still drop the readings too low unless I go to sheets that do very little diffusing.

Right now I am testing a theory that could increase the readings with no downsides, I should know in a little while if it worked.

[hIKARInoob]

@Texas_Ace

The issue is that if I install all 3 diffusing sheets like the 3” spheres to get the readings consistent, then the meter readings are around 33% low. If I remove diffusing sheets to get the numbers up then it becomes less consistent.

I am experimenting now with ways to reduce losses but don’t have very high hopes.

A 4” tube has 33% more circumference than a 3” tube (= 3.14 x D), therefore absorbs 33% more light. This means that your lux meter will show a 33% lower value.
So this makes sense… Or am I saying something obvious?

[hIKARInoob]

The primary purpose of the bends in a lumen tube is to diffuse the light. However, you have dedicated diffusers in your tube, so the bends might be redundant? You could perhaps reduce total length of your 4” tube to increase output of your lux meter to equal lumens.

[DavidEF]

@hIKARInoob

The primary purpose of the bends in a lumen tube is to diffuse the light. However, you have dedicated diffusers in your tube, so the bends might be redundant? You could perhaps reduce total length of your 4” tube to increase output of your lux meter to equal lumens.

Well, that would actually work, except… this contraption doesn’t use any straight runs of PVC pipe, only fittings. There isn’t really a good place to cut out anything. However, another option might be to replace one of the 90 degree elbows used in this design with a 45 degree elbow.

[hIKARInoob]

^ So remove a 90 degree bend. Total length to be removed is one third, or 33%.

[Texas_Ace]

@hIKARInoob

@Texas_Ace

The issue is that if I install all 3 diffusing sheets like the 3” spheres to get the readings consistent, then the meter readings are around 33% low. If I remove diffusing sheets to get the numbers up then it becomes less consistent.

I am experimenting now with ways to reduce losses but don’t have very high hopes.

A 4” tube has 33% more circumference than a 3” tube (= 3.14 x D), therefore absorbs 33% more light. This means that your lux meter will show a 33% lower value.
So this makes sense… Or am I saying something obvious?

Yep, you are spot on. The issue with the 3” spheres is getting the readings low enough so I just assumed that it should line up ok (I have to use 4 diffusing sheets to get the readings to the right level on the 3” + some calibrating).

Technically the readings are more like 50-60% lower on the 4” with an equal setup. But the extra surface area of the diffusing sheets could explain that. I just didn’t expect such a large change.