projectors comparison

[max]

Hi
I've build my own machine and first I tried vivitek d910 with EC500, the results were great. But my projector broke and it was my fault. I tried to replace it with another model dh558. I couldn't even print with that projector so I replaced it with a dh913 and again I was satisfied with the results.
Can anyone tell me what should I actually look for when buying a projector? There's little difference between D910 and DH558 when I look their specs. I'm a little confused and I don't know what was the problem exactly.

[Italyy]

This is a big mystery for me too.

[mikej]

Generally speaking (and there are a lot of variables) you can ignore lumens and focus on the wattage of the lamp.

[Italyy]

Thank you Mike for your answer.

[max]

You're right Mike, I think lumen is not an accurate number

[Italyy]

Mike, can you please share with us another important factor beside the lamp wattage?

[mikej]

Well, the key factor is energy output in the 385-420 nm range. Most projectors filter out UV harder than 400nm. We replace the UV in our v1.2 machine with one that allows that to pass through but still rejects much of the IR (heat).

Also, you'll need to modify the optics to allow up close focus without distortion.

[Italyy]

Thank you again super wonderful Mark.

[max]

But something I can't understand, 385 to 420 nm isn't the uv range, then how do they measure the power of this range with a uv meter, is it possible?
They say some resins are for visible range and others are for uv range, Do they refer to a range of wavelengths or a specific wavelength? And you said you remove the uv filter, why? isn't the 400 to 420nm enough for curing?
And besides when I remove the filter, and when I want to print other materials, the parts become so thick, Is it because the power is too much for that resin?
And another thing I really want to know is that if we lower the brightness, will it also lower the power output?
And, if we filter the 420nm to higher wavelengths, won't it affect the printing?

[max]

Hi

I did a test but didn't get any good results.
We discussed about the projector power, so I changed the lamp from 190 w to 280 w. But unfortunately my projector became weaker. Does anyone know what's the problem?

[mikej]

Maybe has a strong UV to violet filter in place?

[Metalcaster]

This very tiny filter is in the interior wall gong into the lense.
It is very small. If this is cracked or broken, the prints will bw horrible.
If you remove this filter, Then the filter Mike sent will work much better.
If the small filter is not broken... remove it anyway.

[mikej]

That is not the filter we send for replacement. That filter should remain in place at all times.

The larger thicker filter that is on the lamp housing is the only filter that should be considered for any changes.

[Metalcaster]

Sorry Mike for possibly causing confusion, but this is the filter that broke on my second projector. Then I received another projector and that small filter was missing, but the big filter was in place... I am still printing with that one!

[max]

i've tested a new projector, vivitek dh833, the lamp watage is 310, so it should be stronger than d912, but it's not. how?

[max]

help me please, I'm really confused, how is it possible?
I can't understand why d833 is weaker than d912. both its lamp wattage and its brightness are higher than d912.

[Robert Howle]

When u say it is "not working" exactly what do u mean?

Robert Howle

[max]

I mean its light output is weaker than d912 and so it can't cure like d912, I measure their output with a photo sensor and the d833 is really weaker. I can't figure it out.

[Robert Howle]

Was it a used projector, or new? All lamps are not created equally, u may just have a bad lamp. Afterall the lamp is the only "output" u are measuring. If its a new projector u could order a new lamp or lamp assembly and keep the original one as a backup. Don't think it would help to contact the mfg, because they dont' make the projectors as parts of 3d printers. If it projects a 3d HD image, that's what it was designed to do.

The B9 software ages the lamp output and increases the exposures times based on the life and diminishing output over time and is based on a "typical" lamp. Many users have had to decrease MSM and others increase the MSM on new projectors and or replacement lamps because the default settings are for a "typical" lamps output.

Just increase the MSM and print. If the print times are longer than u like, get a new lamp or assembly. This will not guarantee the new one will have a higher output. I believe printed tech info on any projector is going to be an average of lamps tested.

JMO

Robert Howle

[max]

Thanks for your reply, both my lamp and projector are new, what really makes me sad is that I thought buying a more powerful projector will lower my print time, but I even have problem printing with this projector. So now I can't trust manufacturer's written specs and I don't know what should I really look for when buying projector.