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

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Texas_Ace
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Ok, almost a week and countless hours of work later and I officially have the first sphere calibrated and put together!

It has been way more work then I planned on to get these sorted out. I went through a dozen different options to get these sorted out but in the end it is just a matter of trial and error on each sphere.

All the parts are here now.

So the next several days are me putting together a bunch of spheres and calibrating them.

On the plus side they are matching mine very nicely once calibrated. Looking like I will be able to be well within the 5% tolerance range I was hoping for, I am aiming for 3% between spheres. Getting closer then that is very difficult as even details like how hard the pvc is pressed together comes into play at that point.

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I’m def in…

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Glow_Worm wrote:
I’m def in…

PM sent.

Also just so everyone knows, I had to raise the prices on the spheres for new orders, after calculating all the costs involved both monetary and time, the existing prices were just not worth it.

For example I just had to spend $60 to buy boxes to ship these in, on top of the shipping costs being a lot higher then planned. The little things add up quick.

Not to mention the time involved, it is taking around ~2-3 man hours per sphere start to finish to get these ready, that is of course if you don’t factor in the 6 months I spent setting up my own sphere to get the design and calibration.

The new prices are:

3.5” – $135 + $17 S&H in cont US

4.5” – $200 + $25 S&H in cont US

I will be putting up any that are left over on ebay for $150 + shipping and $225 + shipping respectively to cover the ebay fees.

Now since I did not give any warning on the price increase, anyone that wants one today I will honor the old price.

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If you have to take money out of your pocket to send my to Sweden send me an mail and i’l put in som more money.

Micael

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Micael wrote:
If you have to take money out of your pocket to send my to Sweden send me an mail and i’l put in som more money.

Thanks, I will let you know when I get to shipping them. Thus far just been going off general calculations, things are usually a bit different once you ship the real things (sadly usually higher).

I am still working on the spheres, had to change the way I was doing them a few times, so you will notice that the centering rings were painted silver as an attempt to make it look better then the reflective tape, but that didn’t work lol.

End results are I now have about 15 spheres mostly ready, just have to double check them and then glue them together. We are tripping over spheres in the living room lol.

I am hoping to start shipping early next week if all goes well.

After a lot of work they are lining up with my own sphere quite well.

Now Back to work….

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Thanks for all the hardwork. Even with the new pricing, it is still a good value. Now forum members around the world have a standardized method for comparing their flashlight brightness with other flashlight enthusiasts.

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SKV89 wrote:
Thanks for all the hardwork. Even with the new pricing, it is still a good value. Now forum members around the world have a standardized method for comparing their flashlight brightness with other flashlight enthusiasts.

What he said Smile

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Ok, after a solid day of work on these spheres I have 12 finished, in boxes and ready to ship.

About half of the remaining 3” spheres are done with the “1st stage assembly” and another half is done with the “2nd stage”. It is complicated, way way more complicated then I planned on. Each and every sphere has to be calibrated individually sharing very little of the process with the others.

I was really hoping to have a “recipe” for them that would get me within 5-10% and then just fine tune from there but that is not the case at all and for the life of me I can not explain it. I tried to figure it out for a whole day earlier this week and just got frustrated lol.

Gonna take tomorrow off for Mothers day.

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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.

It won’t matter for the final product, as you are calibrating them, but as you mentioned…takes more work than to just slap them together…

Interesting finding on your part. Curious how singular lumen tubes made by people can compare with each other’s.

At least your batch will all be giving similar readings to all the people that bought yours—a true standard!

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Quote:
I have 12 finished

 

When I put my name on the list (#5), I assumed it would take a while. I was prepared to receive it anytime in June.

You're ahead of my expectations.

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Man Without Shadow wrote:
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.

It won’t matter for the final product, as you are calibrating them, but as you mentioned…takes more work than to just slap them together…

Interesting finding on your part. Curious how singular lumen tubes made by people can compare with each other’s.

At least your batch will all be giving similar readings to all the people that bought yours—a true standard!

This is quite probable. As 2 seemingly identical pipes can have slightly different readings. In some cases the ones that you would swear should ready higher will actually read lower and vice versa. I have given up on figuring out any rhyme or reason and just go at each one by trial and error until I get it dialed in.

You bring up a point that leads to a pet peeve of mine actually when it comes to lumen numbers posted in the flashlight world in general.

Anytime I see something like “light A made 846 lumens” I just laugh, there is no way in heck that a DIY sphere is anywhere close to accurate enough for that kind of reading. Some are better then others but even the best I would not put better then 10-20%.

Technically all Cree LED’s we use have a 14% tolerance from cree, meaning that no sphere can be more accurate then that. The flashlight driver/batteries ect add even more variance issues on top of that.

This is why you virtually never see exact lumen numbers from me, I always round them (usually down). I like my sphere and I think I have it reasonably well calibrated but I am under no delusions that it is still a DIY home made PVC version of a $10k sphere. These are NOT precision devices.

I would recommend and ask that people using these also round the numbers so as not to give the allusion that these are more accurate then they are. Posting exact numbers down to the single digit makes people think you can actually get a reading down to the single digit.

So back to the original question, from the comparisons I have made and looking at others (My and Djozz talked about this a few years ago) the DIY spheres you see in the community vary widely. 15-40% variance is common from sphere to sphere.

A lot of this comes down to calibration method, flashlights are simply not a remotely good way to calibrate a sphere, you have to take hundreds of readings and average them out to get something even close to a reasonable calibration. That assumes you can trust the manufactures ratings in the first place (which unless they measure each and every light, still has a 14% tolerance for the LED itself).

LED data sheets are much more consistent since Cree has a big motivation to get the numbers right but still have a 14% tolerance range built in.

So in the case of these spheres, I calibrated them with LED datasheets, this means at the very best they can be ~14% accurate to actual lumens since that is the tolerances on the LED’s themselves. The end result can not be better then the calibration method. That is simply how things work. This is why professional calibration LED’s cost thousands of dollars.

I would add a few more percent to that range as naturally there are more tolerances to take into account besides the LED’s themselves, such as heat, power supply variations ect.

Now consistency is another item altogether and that is much much better. People like to confuse consistency and accuracy. On my sphere I have a few “standard” lights that I will regularly check the output on (the same lights I am calibrating the new spheres with) and over time excluding dust build up, I get maybe a 1-3% variance at most (although I would officially rate it at ~5%). This is mostly due to the atmospheric conditions like humidity and such.

The spheres themselves seem to be coming out to well within ~3-4% on initial calibration compared to each other here. Figure that needs to be widened some once the post offices gets done with them and they are put back together but still very comparable. So the most important thing is the consistency between them as you said.

I just don’t want anyone being under the delusions that these are precision instruments. For that you will need to spend 100x the price.

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Man Without Shadow wrote:
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?

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beam0 wrote:
Man Without Shadow wrote:
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. Thumbs Up . Weren’t they painting the outside flat black also??? Seems like I remember that….. ??

      You never know how a horse will pull until you hook him up to a heavy load. / Paul "Bear" Bryant ~/~\~ "Slow is Smooth, Smooth is Fast"

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beam0 wrote:
Man Without Shadow wrote:
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?

There are many different shades of white spray paint as well as finishes (low gloss, high gloss, flat, semi flat, etc…) and the humidity and temperature that it’s painted in can effect the finish (various degrees of flat). So there’s probably just as many variables, if not more, that just leaving the pipe stock.

When I was considering building my own, I was thinking of scuffing up the interior with Scotch-Brite pads to get both a more uniform level of reflectivity as well as more uniform color. That’s fine for a one-off build, but too much work for TA to do on a bunch of lumen tubes.

In order to get a consistently reflective finish, professional integrating spheres use a coating of barium sulfate (BaSO4). Using this in TA’s lumen tubes would be completely impractical, though. It would be a lot of extra work and money and probably not give any improvements.

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beam0 wrote:
Man Without Shadow wrote:
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?

This was one of the many things that I tried to figure things out. I tried both white and silver but painting the inside actually made things worse in my case so I gave that up pretty quick.

Most of the variations are rather small in the sense it is only a few lumens one way or the other but I like things to be done to a high level so that annoys me.

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I would suspect trying to identically spray paint the insides would be more of a challenge than just adjusting for the factory finishes of the PVC pipes.

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Man Without Shadow wrote:
I would suspect trying to identically spray paint the insides would be more of a challenge than just adjusting for the factory finishes of the PVC pipes.

Yep, which is why I gave it up pretty quick. It made things harder rather then easier.

I am starting work on the rest of the spheres today. Hoping to finish up the 3” today and start on the 4”. Hopefully finish the 4” tomorrow and ship the day after if all goes well.

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).

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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.

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teacher wrote:
beam0 wrote:
Man Without Shadow wrote:
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. Thumbs Up . 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.

"Over 2000000 hours (about 200 years) standby time"  (DQG Tiny 4th)

"27,157 results for zoomable flashlight" (ebay)

 

 

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SKV89 wrote:
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.

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beam0 wrote:
teacher wrote:
beam0 wrote:
Man Without Shadow wrote:
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. Thumbs Up . 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.

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Thumbs Up

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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.

"Over 2000000 hours (about 200 years) standby time"  (DQG Tiny 4th)

"27,157 results for zoomable flashlight" (ebay)

 

 

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beam0 wrote:
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. Smile

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

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Texas_Ace wrote:
beam0 wrote:
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. Smile

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. Wink

      You never know how a horse will pull until you hook him up to a heavy load. / Paul "Bear" Bryant ~/~\~ "Slow is Smooth, Smooth is Fast"

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Texas_Ace wrote:

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. Wink

My Convoy L6 thread with XHP70.2, Texas Avenger FET driver, Narsil v1.2 ramping firmware (old), lighted side switch and cut down SMO reflector. Lots of amp draws on stock driver as well. 

My Supfire L5-S thread with XHP70, Texas Avenger FET driver, NarsilM v1.0 ramping firmware and lighted side switch. My mini L6! 

9 NarsilM user videos for BLF Q8, GT, GT Mini and ROT66

Texas_Ace BLF Calibrated Lumen tube

Maukka Calibration Lights for DIY Lumen Measuring Devices

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JasonWW wrote:
Texas_Ace wrote:

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. Wink

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

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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)

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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

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Micael wrote:
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.

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