Vibration-Durst 1200 with Ilford multigrade 500H

[Steelbar]

Well I thought I had better update my progress or lack of progress. I found a source for a replacement fan and was able to install it with little difficulty. It is almost an exact duplicate of the fan that was in the original Ilford head. So I was hopeful until I got it onto my enlarger and it didn't make a difference in the vibration. After having several darkroom friends look at it we agreed that it must be effecting the sharpness as the vibration is significant. The only answer I can come up with is to remove the fan and hook up an external fan system. At this point I am thinking about how to do that.

 

[Leigh B]

There's something really wrong here.

Muffin fans (aka Boxer fans) are very carefully balanced so they don't vibrate.
This is necessary because of their high speed of rotation.

Muffin fans are made in standard sizes, both English and metric. They're not expensive.
They're available from many manufacturers. One excellent choice is Pabst (a German company).

I suggest you buy a non-chinese fan from Mouser or Digi-Key or Newark.
All you need is the dimensions and voltage. Select one with ball bearings rather than sleeve bearings.

www.mouser.com
www.digikey.com
www.newark.com

- Leigh

 

[Steelbar]

Hi Leigh
I agree that there is something wrong. I have almost no knowledge about fans but I did some research and it seemed from the information I found that a sleeve type fan was quieter and had less vibration especially when it was new. Do you know if that is incorrect? I did not go for a china built fan unless Papst is now making their fans in China.
I just took a look at the original fan and think it probably sleeve but I can't say for sure.
Here is a link to the fan I put in:
\http://canada.newark.com/ebm-papst/...Categories&searchView=table&iscrfnonsku=false
Hopefully I will not need to order another fan but if ball bearing fans are significantly better than I will need to bite the bullet and accept another life lesson.
Thanks for your comments
Bruce

 

[Leigh B]

Here is a link to the fan I put in:

Hi Bruce,

That's funny. I have one of those sitting on my desk at the moment.
I bought it for an RF amplifier I'm building.

Ball bearings are considered much more robust, with better long-term reliability.
Given the very short duty cycle of an enlarger fan compared with one in a computer, sleeve would likely work OK.

Pabst gives the noise level (db) for its fans.
It's a simple matter to compare ball bearing and sleeve versions of the same product.
Most of the noise from a fan is due to air movement, not mechanical issues.

- Leigh

 

[George Nova Scotia]

Thanks for posting the update Bruce. Sad to hear the new fan hasn't helped ( although good to hear it is still available). I wish I had some suggestions but none I can think of. I'm using mine on a Beseler 45 which seems to have a bit more isolation. There is a very squashed layer of foam between the head and the mounting plate on the enlarger, then the top bellows. The bellows is also compressed but seems to help. Yes I do feel some slight vibration with my hand on the top but much less if any by the negative stage or the lens.
I found the installation instructions online for the Durst and it doesn't look like there is any good way to add isolation. It looks like the negative stage mounts directly to the Ilford head, adding any damping would likely cause alignment problems. How tight is the fit between the head and the mounting bracket(13) and the Durst chassis? Maybe some high density foam in the yellow area might transfer some vibration and dampen it slightly?

Going with and external blower would be the best solution but a lot of work to get everything just right.

 

[bdial]

There are silicone gaskets and fan mounts that may help isolate the fan.
This site has lots of options, but I'm sure there are other suppliers;
http://www.quietpcusa.com/Anti-Vibration-Products.aspx
They also carry a number of fans, though most of them are 12v for running from a computer power supply (and what they sell emphasizes quiet vs vibration).

Another option might be to put a switch on the fan so that you can shut it off during exposures, assuming your exposures are reasonably short. Just don't forget to turn it back on. FWIW, on my LPL I can feel a slight vibration from the fan if I touch the head, but I can't tell any difference in prints made with it running vs with it off.

 

[rthollenbeck]

I've seen people remote mount the fans and pipe in the air with dryer hose on l138s and larger Durst. Maybe that is worth considering on your L1200.

 

[adelorenzo]

For the sake of interest I just went and switched on my Ilford 500H head. The fan is noisy and putting my hand on the box I can definitely feel some vibration. Similar to George, it is much less noticeable at the negative stage but still there. Mine is mounted on an Omega D2.

By comparison my LPL 4550XL has basically no vibration at all that I can detect.

I guess the question is, does it affect the image?

 

[Steelbar]

Hi George
That is exactly how the head is mounted and the problem is the base of the head is in direct contact with the negative carrier so it would be almost impossible to isolate the vibration. I may be able to reduce the movement but I really would like to eliminate and vibration. I may be able to take the fan box out of the enlarger and mount it on top and separate it with a bracket or foam but that is going to take some thought and some wiring.

Hi bdial
The gasket can help but because of the contact with the negative holder it is still going to have shake. A switch is a problem because the bulbs put out such a high temperature it would be really hard on the bulbs.

Hi rthollenbeck
An external fan seems to me at this stage the most reasonable option. I could go back to filters but the multigrade head is so convenient.

Hi adelorenzo
That's interesting because if I'm doing a long exposer of say 50 seconds it would seem that any vibration of the negative stage would reduce the resolution of the image. Just as if you are taking a photo at a half second hand held would create a blur. If that is correct than any movement could be a problem. So theoretically your LPL should produce a sharper image.

Thanks again for your helpful input and it looks like I will need to sit down and figure out my next step

Bruce

 

[Steelbar]

Well I thought I had better update my progress or lack of progress. I found a source for a replacement fan and was able to install it with little difficulty. It is almost an exact duplicate of the fan that was in the original Ilford head. So I was hopeful until I got it onto my enlarger and it didn't make a difference in the vibration. After having several darkroom friends look at it we agreed that it must be effecting the sharpness as the vibration is significant. The only answer I can come up with is to remove the fan and hook up an external fan system. At this point I am thinking about how to do that.

Well I thought I should update my ongoing saga. I finally decided on a way to try and cut the vibration from my fan. I considered taking the fan right out of the enlarger head, but because of the hoses and wiring it didn't seem practical. A friend suggested that I use rubber washers that are used to keep wires away from metal(see photos) as it passed through a sheet of metal. So I removed the box that contain the fan and some wiring than used the rubber washers to isolate the box, the screws, and the fan from directly touching the main body of the enlarger. Now if I touch the enlarger head or the lens there is almost no vibration.
By using the rubber washers I was able to isolate the fan and all the screws from the main body of the enlarger which reduced the vibration. I only had to do some minor adjustments to the front lid so the screw heads didn't block the hinge.
I have not printed any thing yet but will do that soon.
Thanks for again for all the help
Bruce

 

[Patrick Robert James]

That is great Steelbar. It is always satisfying to get those pernicious issues resolved.

 

[Leigh B]

Hi Bruce,

Those "washers" are called rubber grommets.

Congratulations.

- Leigh