You might think about working with Juergen Heiland on that. I have a 23CIII that he and I custom-configured with his LED light source more than a decade ago, before he started making direct-fit products for that enlarger. It was a very satisfying collaboration.
I'm definitely open to that; thank you for the suggestion!. After thinking on the matter it seems that the ideal situation is to make this conversion friendly to any Beseler 45 head - condenser, Aristo, LED, Beseler color heads, etc. -because that increases the versatility and usefulness; I'm not a fan of one-trick ponies. That being said: this may be difficult because of the varying weights of the various heads, but I think some kind of replacement spring would go a long way to solving that issue, should it come up.
Another thing you might consider is offering a kit to accomplish this conversion. Like you, I print small. My LPL-4500II sits in boxes in a closet, and needs to be assembled/disassembled on those occasions when I summon the motivation to enlarge 4x5. I'd be interested in converting the Beseler so it wouldn't require so much effort to make an 8x10 from 4x5 negatives. Could be a lucrative business for you.
Longer answer...
Whenever I build things, I generally try to keep "Is this a potential product for other people?" in my mind. That perspective is not so much about monetizing an effort, but rather, refining and improving the design; by thinking about a project from the perspective of someone that doesn't have a printer or a mill or a collection of specialty wrenches or whatever, I usually come up with much simpler and nicer solutions.
This being said: most of my designs don't become products because they're incredibly unique to my own requirements...but a compact 4x5 that can be made from readily-available, standard-issue parts and a single box of conversion bits is something that a few folks may be interested in. I think you just highlighted a key use-case: small workspace, occasional need for larger-negative capacity, and a portion of the necessary parts already on-hand. If I can make a kit that essentially solves that problem with an hour of work, give or take...yeah, I might be able to do something with that. Or, someone may want to condense two enlargers into one, or scale up their negative capacity without getting a second enlarger at all, or maybe even repair a 23C head and upgrade it at the same time; there are all kinds of reasons. Even so, I can't see that this would be a large-market product, but it might help out a few people here and there. Of course, the economy of scale helps out tremendously in this kind of situation: the more kits I make, the less expensive they get per kit...but that's a bridge for another time.
That being said: if anyone else is potentially interested, please let me know. And if there are specific features that people would like to see incorporated into this conversion, please let me know that as well. In the meantime, I'll be continuing with the prototyping, which is a phrase that here means "bolting stuff together that the print-bot made for me overnight."
Pictured: Thank you, print-bot; you've done well.
[ Aside: I hate having to downsize these images to 800 pixels wide. It's killing the resolution, but I can't get anything larger than that to upload. Apologies to all.]
So, that's the first workable prototype of a three-piece bracket that bolts onto the back of the stage mounting bar, and it has a few problems...but I already knew about them so they're not a serious issue. Chief among said issues are size and shape of the small mounting tabs that hold the 23C pivot shaft; there are two #6 screws holding each one of them into the back side of the main body of the bracket - and that's more than enough, because a #6 screw will hold somewhere between 70 and 140 pounds, depending on what kind of force we're talking about - but they're only .750" apart from each other, on center: that's putting a ridiculous amount of force on a very small area of the printed bracket body. This force will almost certainly cause some deformation in the bracket when a 20-lb. head is slung from it...but for now, I'm more interested in getting this piece fitted and working well with the stage mounting bar.
Pictured: Thusly.
There are six fasteners in total that are holding this thing in place: the large 3/8-16 bolt at the top (countersunk, here), three #6-32 screws that sandwich the stage mounting bar between the bracket and the rack gear on the opposite side, and two #8-32 screws that were part of the factory mounting system for the tilt bracket, and which are now threaded into recessed hex nuts. Interestingly, the MCRX stage bar only has two holes for the tilt bracket; the MXT that I rebuilt in the past had four, if I recall correctly. The vast majority of the load is being taken by the big 3/8-16, which is the only load-bearing fastener in the factory confusion; all of the other fasteners present are basically just maintaining the attitude of the bracket in relation to the stage mounting bar; rather, they're keeping it flat. The small tombstone-shaped mounting tabs interface with the stock 23C pivot shaft; thus, they support the entire weight of the 45 head on the carriage. They're held on by two 6-32s each, threaded into captured nuts...and since a single #6 machine screw will hold between 70 and 140 pounds (depending on the load direction) I think they're more than adequate for the task at hand.
All this being said, the design is going to fail. To explain...
Even though I printed these parts on a structural setting, I think a flat bracket with no perpendicular reinforcement is just too flexible; the PETG is strong, but not strong enough. The 6-32 screws are perfectly cable of holding it flat against the stage mounting bar, and the 8-32 screws at the bottom of the bracket can do that and take some shear load as well...but even though the 6-32 screws are spaced only 3" on center, I'm willing to bet that the force being exerted by the pivot shaft tabs is still going to deform the flat bracket somewhere below their mounting points. This could probably be solved by placing the tabs higher up on the bracket, close to the 3/8-16 screw; that would basically eliminate the lever arm of the head's weight, and likely keep the deflection out of the bracket and the stage mounting bar itself. Also, yes: I have the suspicion that the stage mounting bar will bend slightly, despite being a piece of 1/4"-thick steel.
All of that, however, is a problem for a future time; right now, my main focus needs to be continuing to prove the concept by actually getting the condenser stage mounted-
Pictured: Oh...well that was anticlimactic.
I, uh...actually, I didn't think that was going to work...so, okay then! Party on? Bonus?
Nope: let's analyze things.
First of all: the lower parts of the 45 condenser and negative stages really are significantly taller than they are on the 23C. The image is a bit out of focus, but you can probably see that the 45's stage mounting bar extends quite a bit lower than the lens stage on the 23 would extend. Specifically, the distance between the pivot point and the lowest-extent of the negative stage on the 23C is about 8.5"...but on the 45 it's 17". That seems like a big increase - and it is - but I don't think it's a huge problem for most people because the lowest extent of the carriage travel on the 23C is kind of useless: at a certain point the lens stage is literally too close to the baseboard to be useful. So, I'm not exactly worried about losing that room.
Second: shown below the head (on the blue towel) is a pre-prototype bracket mockup that attempted to impose a measure of yaw prevention into the mix by widening the mounting points of the condenser, similar to the method that the 23C head uses. It was a good idea, but it was WAY too flexible, and it introduced more problems than it solved: yaw control is likely best handled by replacing the pivot shaft bracket on the 23C carriage with something more robust and adjustable, which would let the conversion bracket in question only handle the load of the head. I think that would be an improvement over the factory system, which essentially relies upon gravity and the straightness of the chassis itself to control the one axis of the vertical alignment of the head.
Lastly: exactly none of these issues are either important or solvable until the actual head of Enlarger A is test-grafted to Chassis B, because that amount of weight being added is going to provide the information necessary for the design of the conversion bracket and all of its ancillary pieces...and that's why I just decided to go ahead and send it in the hopes that a rather rash A-B grafting didn't end up destroying something important.
Pictured: Abby Normal?
It might be a mockery of nature and established convention, but that, Dear Reader, is a fully-dressed 45 condenser head suspended on the chassis of a 23C, and I'm rather happy with it being there. That being said, there's just one tiny little problem with this arrangement, and it's not the random orange plastic dingus that I'm using the prop the stage mounting bar into an approximation of perpendicularity.
Pictured: "Now pay attention, 007..."
It might not seem like a lot, but that's exactly .0055" more clearance than was present before the weight of the condenser head was added; the flat portion of the conversion bracket is flexing exactly where I suspected that it might. Thus, we now know that a redesign of the conversion bracket is absolutely needed, but even so, the test-mounting of Abby's head gave me a lot of additional and relevant information:
- It's likely that the small mounting tabs that have been used thus far will morph into stiffening rails that are the full length of the conversion bracket itself...and in addition to adding a lot of structural rigidity, this might enable multiple mounting positions for the pivot shaft.
- It's not just the bracket itself that's flexing; it's the stage mounting bar as well. There's not a huge amount of flex but it's definitely present...so a rigid bracket on the back of that bar would go a long way to solving that issue as well.
- I will likely start working with carbon-reinforced filaments very soon, because those may give the conversion bracket the stiffness it needs to remain stable and rigid under the weight of the head, as well as being strong enough to prevent the very small amount of flex that I'm seeing in the stage mounting bar. If I can't solve those issues with carbon filament construction, two further options are available: 1) moving the mounting point of the pivot shaft back up to the top of the bracket, or B) aluminum construction in one or more parts of the bracket.
- Wall projection will be difficult to achieve without making further adjustments to the head. I would have to make a new shaft for the upper negative stage adjustment knob that would relocate it to the right side of the head, and I would have to redesign the locking lever/latch of the 23C carriage to accommodate the geometry of the conversion bracket and 45 head.
- It's impossible to see in the picture of the fully-assembled 45 head on the 23C chassis, but in that image the carriage lock is fully disengaged. That is a very important piece of information because it means that the factory counterbalance springs are adequate to suspend the weight of the 45 condenser head. The carriage will also stay in place if the head is removed and only the weight of the condenser and negative stages remain, but it will all race upwards upon being bumped or jostled too severely. Movement of the carriage both upwards and downwards is smooth with the full weight of the head in place, but movement downwards is slightly easier; I think this means that the factory springs are only off by a pound or three, if that. If I design this entire thing correctly, I may not have to swap the springs out.
- At the lowest extent of the carriage travel, the lens stage is about 8.5" over the baseboard. At the highest, it's around 37.5" or so, because...wait, really? 37???
Pictured: Yes, really.
Alright...so there's room for a chassis brace at the top, if such is even needed. That's a question for Future Me, though, because I actually need to do a bit of thinking and planning before I waste too much more plastic and/or machining time. As such, I have a couple of questions for anyone that might even be remotely interested in this conversion kit, or whom wishes to contribute for any other reason:
- How important is wall projection? As mentioned, it's not really a happening thing with the current arrangement and I, myself, will basically never use it...but I may not be the only person that's using this kind of setup in the future. I have some ideas - move the shaft, create a locking bar, move the catchment latch, etc. - but unless that's a feature that a lot of people might want, I may not make it a huge priority right now.
- How much head/carriage travel is actually needed? Right now there's literally 29", which is over 30% more travel than the 45 chassis allows; that much travel might allow for additional chassis bracing at the top of the rails, albeit at the expense of overall height.
- How important is a print-it-yourself version of the conversion parts? I'm a big fan of sharing info so that people can build things for themselves if they want to do so, but since any printed parts are increasingly looking like they'll be made out of filaments that have special requirements for printers (as of early 2025) this may not be a feasible thing for some folks...and since material choice absolutely drives the design, I have to think about this pretty early in the process. Also, there may be some parts that simply can't be printed at-home, so I have to think about that as well.
- How important is back-conversion? Once the conversion parts are installed, how important is it to be able to remove them and use either the head or the chassis in their original configurations?
- Would you be willing to drill a couple of holes? Nothing major, obvious, difficult or otherwise-problematic; just a hole or two.
- What am I not thinking about, here? What looks perfectly obvious that I'm not seeing, so far? Let me know if something stands out.
Okay...that's pretty much the sum of it for now: Abby is hanging out in her barely-stitched-together glory and I'm working on a better way to handle the pivot shaft - maybe make the carriage the structural part, instead of the stage mounting bar..? - and vaguely realizing that all I've eaten today is coffee. So yeah, gotta go fix that. Stay tuned: it's finally getting interesting.