DIY: 20x24 build: re-iteration

[SergeiR]

So I scrapped my old hobo- version of 20x24 (saved back and bellows, of course) and rebuilt it, after few trials.

Your basic plywood, aluminum, cabinet hardware, stain, some nuts and bolts.

https://farm2.staticflickr.com/1686/26537959896_4afaa79bde_c.jpg (https://flic.kr/p/Gr4YUG)20x24 v2.5 (https://flic.kr/p/Gr4YUG) by Sergei Rodionov (https://www.flickr.com/photos/sergeistudio/), on Flickr

https://farm2.staticflickr.com/1582/26563967605_43600944c4_c.jpg (https://flic.kr/p/Gtnh6t)20x24 v2.5 (https://flic.kr/p/Gtnh6t) by Sergei Rodionov (https://www.flickr.com/photos/sergeistudio/), on Flickr

Now i am trying to figure out decent way to control focusing and back tilt movement :(

Any good links on rack/pinion style control? Or anyone can spare parts?

[Bernard_L]

Congratulations! Looks like mahogany. Also notable is the clever use of what seems to be drawer or tablet rails.
But maybe the front frame should be held by some triangulated structure (diagonal braces); as it is, it must be quite susceptible to swing front-back. Just a suggestion.

[Peter De Smidt]

Would something like this work? http://www.ebay.com/itm/T8-800mm-Stainless-Steel-Lead-Screw-coupling-shaft-mounting-support-/361533609589?hash=item542d151675:g:Kr8AAOSw~gRV5Xzb

[SergeiR]

Would something like this work? http://www.ebay.com/itm/T8-800mm-Stainless-Steel-Lead-Screw-coupling-shaft-mounting-support-/361533609589?hash=item542d151675:g:Kr8AAOSw~gRV5Xzb
thanks Peter, yeah it would work , i was pondering on Amazon for a slightly different set up. I have tried longer leading shaft

https://farm2.staticflickr.com/1480/26551885196_25b8fc24df_c.jpg (https://flic.kr/p/Gsimq5)tests with hack focusing shaft (https://flic.kr/p/Gsimq5) by Sergei Rodionov (https://www.flickr.com/photos/sergeistudio/), on Flickr

but it turns out they are more of hindrance than help - you never truly get past about 10 inches, specially if its more than few rotations per inch. Plus original friction mounting didn't help - it was touch to move front standard..
But now that i have decent sliding system it doesn't need to be as pushy - may be all i need is just another T-nut to match thread i already have laying around. Hmm... That would certainly work for focusing. Rear tilts seems to be more tricky b/c mount should be few inches off axis (judging by old studio 8x10 i have laying around - i am almost tempted to just steal hardware from it ..)

[SergeiR]

Congratulations! Looks like mahogany. Also notable is the clever use of what seems to be drawer or tablet rails.
But maybe the front frame should be held by some triangulated structure (diagonal braces); as it is, it must be quite susceptible to swing front-back. Just a suggestion.

Hm, thanks. These are actually heaviest cabinet rails i could have find :) I tested it yesterday with heaviest lens i got - 36inch Cooke, it didn't seem to go funny much, but it could be b/c my bellows just didn't go as far ( i do have plans to add intermediate frame to allow for more than 37" extension - whole thing can extend to about 48-52" as far as hardware
But i get what you saying - i was thinking about making extra layer on the bottom to make center to be more sturdy anyway - adding extra extendable rails under the base, might be an idea there. Got to think on prototype..

For a moment though - there is always Alex T. solution with Bogen's extendable support for heavy lenses ;)

[SergeiR]

Another concept i am toying with is to allow camera to be foldable. I started from there, but i couldn't source good hardware in nearby stores (except for hinges of course) to allow camera to be unfolded and staying firm in place. So for now rear standard doesn't fold. Which kind of sucks, b/c whole camera is not super heave and i would love to get it back in the field to shoot outdoors (as i did with original version)

[MartinP]

Thinking about my sliding-box, baseboard style camera I decided that a simple screwed rod would be slow to use, heavy and difficult to fold up. On the table-vice there is a sprung half-nut for sliding the movable jaw prior to tightening it with the handle - did anyone ever try a half-nut for the last adjustments on a friction-fit sliding lens-standard or back?

The device I am describing as a 'half-nut' is a threaded half-cylinder female portion which can be lifted off the threaded rod (by means of a small lever, working against a spring) to allow coarse manual adjustment by sliding, prior to letting the half-nut spring back on to the rod for final adjustment. Under the half-nut location would be an un-threaded half-cylinder bearing to support the spring force of the half-nut.

[SergeiR]

That's acme thread :)

[Dan Dozer]

When I made my 8 x 20, I put a rack and pinion on the front assembly for focusing, but found out that it's was too difficult reaching around the back frame to focus it that way. The back rail also slides forward and backward and I found that focusing is pretty easy just sliding it with your fingers. I have a screw in the side of it that I just tighten up to lock it in place.

Also, mine doesn't fold up, it comes apart in pieces.

Hope this helps.

Dan

[mdarnton]

You'd have to get help from someone who knows something (not me) but it seems like this would be perfect for this job:
http://www.nookindustries.com/Product/ProductName/102230/PowerAC%201/4%22-3%20RA
1/4" rod, 3 turns per inch, quadruple helix, like in a focus mount.

That would move fast, and with precision.

[mdarnton]

As soon as I post that about helical multiple-thread lead screws, ads start showing up in my browser because of my search. This one sounds particularly interesting. It sounds like it's 8mm travel per turn, just the right length, price is right:
http://www.banggood.com/3D-Printer-300mm-Lead-Screw-Z-Axis-8mm-Screw-Pitch-p-980650.htm
or, longer:
http://www.banggood.com/900mm-Lead-Screw-8mm-Thread-Stainless-Steel-Lead-Screw-with-Flange-Brass-Nut-p-993963.html

Apparently they're used with stepper motors in CNC type machines.

[Bernard_L]

Hm, thanks. These are actually heaviest cabinet rails i could have find :) I tested it yesterday with heaviest lens i got - 36inch Cooke, it didn't seem to go funny much, but it could be b/c my bellows just didn't go as far ( i do have plans to add intermediate frame to allow for more than 37" extension - whole thing can extend to about 48-52" as far as hardware
But i get what you saying - i was thinking about making extra layer on the bottom to make center to be more sturdy anyway - adding extra extendable rails under the base, might be an idea there. Got to think on prototype..

For a moment though - there is always Alex T. solution with Bogen's extendable support for heavy lenses ;)
Sorry I wasn't clear. I do not question the rigidity of your horizontal bed. My concern is with the front standard (vertical), more precisely, the mechanical linkage that should ensure that it's perpendicular to the camera bed. That linkage is made by two pieces of plywood held together by two pairs of rather small metal angle brackets. You might of course make these more massive, but you will gain a lot more rigidity with a pair of diagonal bars running from the mid-height point of your front standard to the camera bad; inclined at maybe 30° from vertical. It's a basic principle of mechanical design that a triangulated structure is more rigid mass-for-mass. Other view cameras are often built that way, and you would benefit even if you do not want to implement fron tilt (which would be an easy fringe benefit).

Again, congratulations.

[SergeiR]

Ah! :) Front standard itself. Yeah. that one is a bit questionable, you absolutely right. Additional angled support indeed would help. Need to find good place for slotted aluminum (i tried to do it myself, and failed miserably.. :) makes me miss days of middle school, when i had access to all the milling/lathe machinery..)

[SergeiR]

As soon as I post that about helical multiple-thread lead screws, ads start showing up in my browser because of my search. This one sounds particularly interesting. It sounds like it's 8mm travel per turn, just the right length, price is right:
http://www.banggood.com/3D-Printer-300mm-Lead-Screw-Z-Axis-8mm-Screw-Pitch-p-980650.htm
or, longer:
http://www.banggood.com/900mm-Lead-Screw-8mm-Thread-Stainless-Steel-Lead-Screw-with-Flange-Brass-Nut-p-993963.html

Apparently they're used with stepper motors in CNC type machines.


Thank you for links!.

Yep, i got one of those cool acme-threaded (i know official name, thanks Randy M :)) for me New Year present. Unfortunately i don't have secondary support for it, or secondary nut :( And local stores.. well.. no help, at least all the usual hardware places i checked.

[mdarnton]

It evades me why you would need two nuts, but if you do, you could buy a 6" threaded rod+nut from the same source, for about six dollars, and throw away the second rod. But it seems like you only have one thing to move here--the front standard--and the front and back ends of the rod would be the anchor points that don't move. So at most you'd need a machinist to grind a neck on either end for the fixed bearings at either end--one longer to stick through the back for the knob attachment, to use this type of rod, then hook the floating nut to the front standard.

Acme is only that particular square thread shape--that description doesn't include the multiple-thread/high pitch speed attributes of the rod.

[Tin Can]

Seems a few of us are building cameras.

I am trying to build an 11x14 with only hand circular saw, jigsaw and hand drill.

I am going to worry about the fine focus adjustment last.

I have little to show now, but expect real progress in 2 weeks when parts come.

Code name 'Tinkertoy Camera' as it will be modular construction that can be easily changed and have very little wood.

The second iteration will have no wood.

Maybe :)

[Lachlan 717]

As soon as I post that about helical multiple-thread lead screws...

Look for 4 and 5 start screws.

The higher the number of "starts", the greater the lead travel.

[Tin Can]

Look for 4 and 5 start screws.

The higher the number of "starts", the greater the lead travel.

Exactly. I also think we need a way to use it for a short distance, by the 1/2 nut or something, so we hand move approximate focus and then shift to fine focus.

[Lachlan 717]

Exactly. I also think we need a way to use it for a short distance, by the 1/2 nut or something, so we hand move approximate focus and then shift to fine focus.

Building that design now on 8x10" and 7x17" cameras!

[Tin Can]

Building that design now on 8x10" and 7x17" cameras!

And?

I will show mine in a couple weeks.

[Lachlan 717]

And?

I will show mine in a couple weeks.

Soon.... soon....

[stawastawa]

how about a friction drive, like on a monorail cambo.
use the wheel to roll a rod or square rail towards you and have that rail attached to the standard you want to move.

[SergeiR]

Didn't get done squat this weekend :( house stuff and playing with vandyke printing took its tolls (and now yes, i need to build damn UV box and printing frame).

I think i figured out all the controls and how to mount them. Off to order one more rod from amazon.

[mdarnton]

Now you have me thinking how to turn some of the extra Cambo bits I have hanging around into a ULF camera, and I don't even want a ULF camera!

[Tin Can]

Yes you do. :)

I am now considering wood strip layers with fancy tape to build ULF holders.

But later.

[Peter De Smidt]

You know, when I say things like, "Now you have me thinking of how to turn some of the extra Cambo bits I have hanging around into an ULF camera..." my wife immediately asks, "What does Randy have to do with this?"

[mdarnton]

Yeah, Randy's what they call a good influence. . . or a bad influence. Something like that; I can't remember how to tell the difference.

[Tin Can]

Good we have a thread we can laugh in and about.

LOL

[el french]

Precision nuts are pretty easy to make if you have a torch and a vise: http://bbs.homeshopmachinist.net/threads/43645-Making-Acetal-leadscrew-nuts-the-easy-way

Actually a heat gun works better than a torch.