Finally setting up my Nuarc 26-1K ... a few problems ... any help appreciated.

[Zero_Equals_Infinity]

And so, I finally found a place to setup my Nuarc 26-1K, and have discovered a couple of problems.

1) The vacuum pump runs, but there is no suction on the input hole in the rubber mat.
a) People have suggested using Isopropyl Alcohol (Methyl Hydrate) to flush the pump, but to be aware of creating a rocket engine. I will try this as it is the quick and dirty fix.
b) If the diaphragm needs replacement, I don't know where to find it, (or confirm that what is shown is what I need.) I have been visiting M&R and have a couple of links below. Please advice if any of the products indicated are what I need
https://store.mrprint.com/mr_pls/oo...rt_mode_c=ITEM:DESCRIPTION&p_page_view_c=LIST
https://store.mrprint.com/mr_pls/oo...rt_mode_c=ITEM:DESCRIPTION&p_page_view_c=LIST
c) The rubber mat was attached to the metal frame by two sided tape which is crumbling. Will any two sided foam center tape work to replace this, or is there something specific that is needed.

That's about it. Any advice is appreciated, along with anything to be aware of when opening up the bottom part of the unit or pump to replace the diaphragm if it is needed.

Thank-you.

 

[gmikol]

I don't have a 26-1K, but I have a NL22, which shares some of the components. I would check the integrity of the vacuum hoses...there may be an open connection or a cracked hose. There's also a little disk that sits in the output side of the pump that allows it to pull a vacuum. Mine had fallen out and the pump couldn't pull a vacuum any more. It's a little plastic disk smaller than a dime, so it's hard to see if it's in there, and hard to find it if it fell out. It looks like the vacuum pump is the same as my NL22, and taking apart the diaphragm head to clean it and maybe apply a little silicone grease to the gasket is pretty trivial. If the diaphragm is shot (which I think is probably unlikely), the first link (Part # LC161) looks like it would be the right part.

I don't see any reason to "flush the pump", I've always read that recommendation for rotary-vane pumps, not for diaphragm pumps. I can't see what benefit it would have for a diaphragm pump.

Any 2 sided foam tape or possibly "carpet tape" would work. This may be where my NL22 differs from the 26-1k, but my vacuum mat is screwed in at the corner opposite where the vacuum hose is, and the rest of the blanket just floats.

BTW--There's a big difference between methyl hydrate (methanol), and isopropyl alcohol.

--Greg

 

[Zero_Equals_Infinity]

Thanks Greg that is very helpful... Somewhere I had confused Methyl Hydrate with Isopropyl alcohol ... probably because I drank to much of the former when I was young, and while it certainly altered my perspective, I am afraid something has changed irreversibly.

 

[gmikol]

Oh...and did you make sure the bleeder valve on the vacuum line was closed all the way?

--Greg

 

[Zero_Equals_Infinity]

Yes, the bleeder valve was checked. Now, I will just have to discover how to safely open the bottom unit. I expect it will be self-evident, though to me it is a bit like doing surgery without having been to a human physiology class. (From what I have heard these are remarkably robust and easy to maintain machines, but they are heavy and awkward to move about.)

I must admit I am very excited about getting it up and going.

Thanks again, Nick.

 

[Zero_Equals_Infinity]

I took the vauum portion of the pump apart ...

When I got the pump out of the unit, there were two female threads side-by-side on the vacuum assembly at the top of the pump. One had a filter with a t-valve on it. One line on the t-valve went to the rubber mat, and the other ran out to connect to the bleeder valve on the upper unit. The second female thread had nothing attached to it, (as it was the outflow.)

I turned on the pump and it functions, but the amount of draw is < 1 psi with the bleeder valve fully closed.

I decided to open the vacuum assembly with the two female side-by-side threads. Four screws sit at the corners and came out easily, as there was nothing explicitly sealing it. Upon opening it, there is a circular rubber piece with acts as the vacuum piston. I unscrewed it and all looked normal inside. (I am assuming that the rubber piston has to be sealed on one side or the other, either against the housing with the two female side-by-side threads or against the main body that the housing is screwed onto.

My question then, is what sealant should I use, and should I seal the outer portion of the rubber piston to the main body, (which seem logical), or the housing?

The pump itself looks to be in good shape, though I was a little surpised to see a label indicating that it was made by the Barrant Co, of Barrington Illinois, not by Nuarc. That may be correct, but it may also be that somewhere along the line somebody changed the pump.

That is about it, I cleaned the unit, removed the old two side tape that attached rubber mat to the unit, and used new tape to secure the mat.

The light intergrator seems to work, though the units do not seem to correlate with seconds. (Initially it counts down very slowly, as expected, and eventually settles to approx 1 full unit every 5 seconds.) The light strikes without a problem, though the bulb is no doubt quite old. If it is old would that effect the amount of light thrown by it, or this simply a matter of recalibrating the light integrator, (by some means currently unknown to me?)

Wow, I wrote a book ... sorry.

Thanks in advance for reading, and any assistance is graciously received.

Thanks,

Nick.

 

[gmikol]

Nick, you should try bypassing the vacuum blanket and connect the tube from the vacuum gauge directly to the pump. If that pulls 20-25 inches (10 or so PSI), then you know that the tubing that you've bypassed is leaking, or the glass is not seating against the vacuum blanket gasket. If you still can't pull a vacuum, try pressing your thumb very lightly over the "output" side, if you pull a vacuum when doing that, then the little disk in the output side is either missing, or not seated properly. It's also possible the filter bowl is not seated properly, or the drain valve on the bottom of the bowl is leaking or not seated correctly.

The vacuum pump in my unit was not made by Nuarc, either, though I don't remember who made it. As far as I know, it was original equipment.

Do not use a "sealant", i.e. an adhesive like a RTV silicone gasket sealant. I used silicone grease on the gasket of vacuum pump, as I had it laying around. I'm not convinced that it was necessary, but I did it anyway, it should seal alright just by cleaning it with a little isopropyl alcohol.

Don't worry about the integrator, as long as it seems to be working. It's the "units" that's critical. An old bulb will output less UV than a new bulb. If your exposure is, say 50 units, that may take ~250 seconds with your current bulb. With a new bulb, the output will be higher, but the 50 units may take, say 200 seconds. But the integrator measures the actual UV output, so as long as you keep your units the same (and assuming that your bulb is not grossly beyond its service life), then your exposures will be the same with old bulb vs. new bulb. There may be a way to adjust the integrator to be closer to "seconds" but that's just a convenience, or if you want to have more granularity in setting the exposure. On my unit (an NL22-8C), there was a jumper that I could move among 1X, 2X, 4X ... all the way to 64X connectors. I think higher numbers meant 1 unit took more actual clock time. But I don't remember. You'll have to play around with that. Also, check to make sure the integrator is aimed directly at the bulb, and that the "eye" is clean.

I know there has also been some discussion on getting 26-1K units up and running over on APUG, as well. So you might want to check there, as well, if you haven't already.

Good luck--

Greg

 

[Zero_Equals_Infinity]

Hi Greg -- Thanks for your advice. There is a rubber piston attached via thin metal threading to the metal piston driven by the motor. What surprised me is that there was no gasket in-between the rear of the vacuum housing and the front plastic piece, (where the two threads for the vacuum hoses are found.) The disk on the exhaust thread is present because I can feel a push. I unscrewed the filter bowl, checked it for leakage and seating to no effect. The valve and sprint assemble appears to work as expected, (i.e. I can push it in, and it pushes back to normal when I release my finger from it.)

I will avoid the sealant, and try the isopropyl alcohol. I may also place a bit of silicon grease on the rubber piston / gasket to see if that yields benefit.

I am not too worried about duration unless exposures take more than 15 minutes each in which event, I would like to improve the print speed if possible, (as in I will buy a new bulb as this one is looking a little long in the tooth.)

I will head over to APUG to see what I can find.

Thanks again for writing back. I appreciate it.

Cheers,

Nick.

 

[gmikol]

What surprised me is that there was no gasket in-between the rear of the vacuum housing and the front plastic piece, (where the two threads for the vacuum hoses are found.)

There was no separate gasket on mine...The diaphragm overlapped the "fixed" part of the housing (the part that contains the cam & piston), and had a molded-in ridge, kind of like an o-ring, on the upper face, which fit in a mating groove on the upper part of the housing (where the 2 threads are found.

Good luck with your debugging.

--Greg

 

[Zero_Equals_Infinity]

Things are getting better, but still I have issues.

To summarize:

1) disassembled, cleaned, and closed the pump, and now when I put my finger over the hole in the mat it shows 20 PSI.

2) When I turn the vacuum off, (with my finger still over the hole), the pressure drops to zero in about 4 seconds.

3) The release valve is permanently closed, (it can be turned but no effect.)

4) When I close the glass over the mat, the vacuum gauge never registers.

My suspicions are, that the valve should probably be replaced, and there is a leak in the mat or in the tubes that run between the pump and the mat, and/or the pump and the gauge and valve.

I could paint a sealant of some sort on the inside of the mat to deal with any cracks which are not visible, and that probably is harmless, (though any recommendations about this, including what sealant to use will be gratefully acknowledged.)

I can probably order a new valve from MR Printing, and hopefully that is pretty cheap, and easily installed.

Tubing I can probably get at Home Depot, though the inner diameter appears to > 1/4 inch and < 3/8 (likely 5/16, which may be an oddball size to find.) It is probably wise to just re-tube the beast and not worry about trying to test for leaks.

If I am mistaken as to the best next steps to take, please let me know. If I have a leaky rubber mat, that might be an expensive replacement, so I would like to try a fix before ordering a new one.

Thanks in advance,

Nick.