What is the screw size for the Lee Filters holder?

[radu_c]

I am trying to get some extra brass inserts for my lee filter holder (it's the 100 foundation kit, or however they name it).
Need to know what is the size of the original screws that are used to sandwich the filter slots together?
I have some M2 hex nuts, tried them on, and the original screws are definitely not M2. I also tried an imperial 2-56 nut and they don't seem to fit either...
I'm suspecting M2.2 or M2.5. Could someone confirm this?

[Heroique]

I'd like to know the specs too, should I ever need the info for my Lee system.

However, you can also call Lee cust. service: 800-576-5055.

In the past, I've called with specific technical questions like yours, and they've sent me small items in an envelope as a complimentary gesture.

[radu_c]

Thank you. That’s not a bad idea. I was kind if assuming that since they used an oddball size, they did it to protect their design and not have copies out there. But it won’t hurt to give them a call.

[Sfroza]

Measure the threads diameter with a micrometer or a very good caliper then count the number of threads per inch. With that information you will be able to look up the screw/fastener size using the net or the machinist hand book. Or go to a machinist and they could do the same. It is very unlikely that the fasteners are a custom/proprietary type do to the expense and supply chain problems.

Michael

Measure the screw not the hole.

[radu_c]

That’s exactly what I did. And that’s my predicament. It doesn’t seem to fit any column A standard threads, either ANSI or ISO. It might be that the screws are a little stretched or that the brass inserts are a little oxidized and don’t turn smoothly.
What I ended up doing was that I turned a couple standard screw sizes on the lathe to see which one would fit best.

[Sfroza]

What is the reference that you are using? What is the major diameter and the threats per inch. The major will run a few thousandth under nominal. Let me know I'll see if I can identify your thread.

Michael

From the photos at the lee filter site the possible imperial basic sizes will be:
#10 .190, #8 .164 and #6 .138. They may be rolled threads and most likely be as much as .010 below nominal diameter.

[Steven Ruttenberg]

Try a #4 as well. I have the lee and hitech holders and I think they are same. Just email lee I am sure they will tell you.

[Tin Can]

Don't forget some shops use odd sizes. Maybe production mistakes.

China is famous for using everything, even the scrap.

Bearing are not always standard in China. They mix and match as I found a few years ago trying to fix our Large Format Hiker's wheeled treker. PITA

[Drew Wiley]

Looks like a fine thread metric to me. I can't test because I simply cemented mine back together when it got old, and the adhesive filled the holes, which I personally have no use for (I only use this as an adapter for the Lee bellows shade).

[Mark Darragh]

Try 2.2 x 0.45 Metric Course.

[radu_c]

Alright, a quick update. Today I spoke over the phone (thank you @Heroique for the tip) with the Lee Filters rep. He said and I quote, "nobody knows what size they are, it's a special size and you can get replacements of different screw lengths from BH or other stores".

This brings me back to my original claim that they made it as a custom size so (probably) they don't get their design copied.
I made on the lathe a couple screws in that ballpark, both imperial and ISO and none fit smoothly. Though they were tested for correct fit.

For the brass inserts, the only screw that came close was the imperial 2-56. It goes in nice about 4 turns max, then the brass starts squealing. Luckily there are not many turns in the insert so a steel screw can deform the brass and now you got a standard thread. It's really close but no cigar. An M2 threads in nicely (feels like that's the pitch) but the thread play is a bit too much and I'm sure once you put some load on those threads, it'll slip.

When I have the proper time to experiment with this, I'll cut more screws on the lathe with the size of a 2-56 and different pitches and see what happens.

@Sfroza the major diameter averages at 2.14mm though it's biased towards 2.10mm. The pitch gages didn't give definitive answers unfortunately...

[radu_c]

Try 2.2 x 0.45 Metric Course.

I tried that size too and it’s also not a fit :-(

[Sfroza]

I'll keep looking. Although it is possible to create any thread form you desire the cost for tooling is not cost effective. They are charging close to nothing for replacement screws. Less than a dollar each.

Michael

See if you can find a #2-64 it is a bit of an of oddball but not to far from the 2-56. That will explain the lock up of the 2-56 in the insert as you run it in.

[radu_c]

I'll keep looking. Although it is possible to create any thread form you desire the cost for tooling is not cost effective. They are charging close to nothing for replacement screws. Less than a dollar each.

Michael

See if you can find a #2-64 it is a bit of an of oddball but not to far from the 2-56. That will explain the lock up of the 2-56 in the insert as you run it in.


That’s a great point. Tooling is really expensive and starts making sense only in high volumes.

I’ll look for a 2-64, see if that’s a good fit. It crosses my mind to just run a 2–56 tap through all the inserts and be done with it. I just wanted to make it as stock as possible. Though it’s just a filter holder, what difference does it make?!

[Steven Ruttenberg]

It can make several hundred dollars of difference. Why not just order the screws/kit for the filter holder? They are dirt cheap to get one or even several. I did that with my Formatt-Hitech filter holder. Lee would have the same. Cheaper to do it right than to modify it.

[radu_c]

It can make several hundred dollars of difference. Why not just order the screws/kit for the filter holder? They are dirt cheap to get one or even several. I did that with my Formatt-Hitech filter holder. Lee would have the same. Cheaper to do it right than to modify it.

It’s not the screws I’m interested in, but the metal inserts from the filter holder. The inserts are not available anywhere because the holder is not serviceable.

[Steven Ruttenberg]

Ahh, then oversize and tap to a standard size.