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

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.

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?

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.

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

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.

This is one of the options I am considering, testing showed that it should work. The issue with this option is that it will not stand up with only 2 bends and becomes either a U on the desk or a very award shape that does not balance.

The readings turn out close enough to calibrate though.

Well if you do so you can call it the Texas Ace U-tube. Pretty catchy name! :smiley:

Might work with a 45 degree bend in place of one of the 90 degree bends, though. :wink:

Ok, I think we just figured out the issue and the good news is it is semi-easily correctable.

The 4” only has an adapter that steps down to 2”, I need another adapter to step down to 1.5”. This adapter was the issue. After modifying it so it does not shroud the meter as much the readings are right in line with what I expected them to be at the start. I never would of guessed that little bit would make such a large difference.

So now to start building the 4” and hopefully finish those today and start shipping tomorrow.

Sounds good man. Good luck. :+1: :beer:

Great news! It’s good to know it was fixable with a slight mod, and no need to buy more parts (or scrap parts already bought).

Best one this month :slight_smile:

Ok, Quick update.

After another marathon sphere building session with the whole family helping out we managed to get all the spheres built, calibrated and packed up. Tomorrow I will start the shipping process.

Now to go fall into bed….

Thanks for all your hard work TA

Nice going TA!! . :+1: . :beer:

Wow, ahead of deadline and under budget. :+1:

And let the Shipping saga begin!

Tracking numbers should start going out via paypal over the course of the day.

Within the deadline but I wish it was under budget, more like way over budget in both costs and massively over budget in time. :weary:

Wow, I can’t wait……

Thank you

:+1: