Betterscanning Variable Height MF Holder Experiences (Warping)

[asf]

Wanted to see if anyone here has experience with this holder
http://www.betterscanning.com/scanning/vb_mfholder.html

I have this one and the Variable Height Mounting Station (the larger one that can take up to 5x7 or full plate but not 810)

I'm actually on my second MF holder as my first one warped after about a year. When that happened Doug was very gracious, took it back and sent me a new one. All good, went back to scanning.

Now after a little less than a year the 2nd holder is warping too. I asked Doug, he told me the one I sent back is now flat as a pancake in his storage so it must be my environment causing it. This is very possible but I can't see what could be causing it.

I've had the larger VHMS holder for a much longer time and store it the same way in the same place, no warping at all.

The warping on the MF holders both started in winter time (I'm in NYC) but they aren't stored near a heater or in the sun, the temp is relatively constant and it's dark, the surface is flat.
Since the new one warped I've moved it to a different location and kept it with a large flat weight on top for several weeks - no improvement
The second holder isn't as badly warped as the first so I'm still able to use it for 6x6 or 6x7 scans without problem

In comparing the MF holder with the larger VH Mounting Station I noticed the plastic used is much softer in the MF and wonder if this is the issue

NYC winters aren't especially cold, dry, wet, etc, so I'm wondering what could be happening and how I can solve this issue.

[Steven Ruttenberg]

I have had great results with mine. One thing is your environment. Humidity, temperature, how hot the scanner gets when scanning, how you hold the frame when moving it around. Also, are all the screws at the same height so the frame is perfetly level? It would have to be due to your environment/handling of it. I had one where the little tabs all started cracking. Doug had never seen that before. Neither had I. But to be sure, with the replacement holder and the new one I bought, I leave it sitting on the scan glass and only handle the ANR with wet-mounted negative (4x5). I avoid handling the frame as much as possible. What fluid do you use to mount your negatives? If any. Try taking the screws out, place the frame on a flat piece of glass, like the scanner glass with scanner off and no heat. Just let it sit there under its own weight for a few days.

Have any pictures you can share of the issue?

[asf]

I have had great results with mine. One thing is your environment. Humidity, temperature, how hot the scanner gets when scanning, how you hold the frame when moving it around. Also, are all the screws at the same height so the frame is perfetly level? It would have to be due to your environment/handling of it. I had one where the little tabs all started cracking. Doug had never seen that before. Neither had I. But to be sure, with the replacement holder and the new one I bought, I leave it sitting on the scan glass and only handle the ANR with wet-mounted negative (4x5). I avoid handling the frame as much as possible. What fluid do you use to mount your negatives? If any. Try taking the screws out, place the frame on a flat piece of glass, like the scanner glass with scanner off and no heat. Just let it sit there under its own weight for a few days.

Have any pictures you can share of the issue?

Thanks Steve, I'm referring only to the MF one I linked to (roll film), if the one you have can do 4x5 that's a different version (which I also have and have had 0 issues with)

I store both versions the same way and in the same space so environmental conditions for the 2 are the same. Screws are all the same height, stored on perfectly flat surface, no wet mounting. I've tried leaving it on the scanner glass. I've also tried to flatten it under large heavy books on top of a large flat polished marble surface for over several weeks. I'm very careful handling the plastic so can't tell what's happening exactly.

Possibly I'll know in the spring/summer if it goes back to being flat as Doug said my first one did

[Steven Ruttenberg]

It could also do with the casting that is used and what the grain structure is in the material. If it is random, I would not expect warpage, if it is in one direction I might expect it to warp under certain conditions. It also has to do with how it is manufactured. That could induce residual stresses within the part that will become evident with a changing environment.

[Steven Ruttenberg]

That design could be susceptible to warping, a lot of material that needs to play nice with itself.

[asf]

It could also do with the casting that is used and what the grain structure is in the material. If it is random, I would not expect warpage, if it is in one direction I might expect it to warp under certain conditions. It also has to do with how it is manufactured. That could induce residual stresses within the part that will become evident with a changing environment.

The MF holder feels and looks different to the larger VHMS version. It appears to me the plastic used is completely different (softer, more matte, more flexible) so possibly the way it is manufactured is different too. I don't know but I wonder if it is 3D printed.

The first one I had became so badly warped I couldn't use it anymore (it bowed up on both ends,starting with the rear right corner near the calibration notch)
The one I have now is still usable so I'm hoping it doesn't progress but it's more warped now than it was 2 weeks ago. The warping on the 2nd one started on the rear left but has now affected the right side as well.

[Steven Ruttenberg]

Hmmmm....