Metals used in LF cameras

[nick mulder]

If youd care to join me I'd like to discuss the metals used in large format camera design, specifically the metals used in the actual form/frame/bulk of the camera ...

Couple of quick questions:

Why not so much aluminium around ?
Titanium, workable for a home build ?
Why brass ?

thats it for now

 

[Ian Grant]

There are Aluminium (or alloy) bodied cameras around, rather a lot actually, MPP, Linhof, part of Pacemaker Speed/Crown Graphics, Super Graphics etc.

Titanium is harder to work with.

Brass, because the first cameras where made by cabinet makers and instrument makers who had long been using brass as it's the easiest metal to work with, and looks good with wood

Ian

 

[Rick A]

Chief reason for brass, is it is machinable with basic woodworking tools. Its is easy to work with hand tools, and as Ian stated, looks good with wood. Metals technology in the 19th and early 20th centuries didn't have alloys we are accustomed to in these modern times, and it became the tradition to continue to use them.

 

[David A. Goldfarb]

I know someone who makes titanium bicycles and bicycle parts, and he once told me the cost and difficulty of working with titanium mostly have to do with the wear it puts on tools and cutting blades and bits.

 

[Martin Aislabie]

Brass is fairly inert (doesn't corrode) and is easy to work with. It can also be welded (silver soldered) together. Most local machine shops will be able to machine and weld brass parts for you.

Titanium will be a serious challenge to anyone working with at home - unless you have access to Laser Cutters, Laser Welding and heavy duty CNC machines - its stronger than high grade alloy steels, so will be very difficult to work with. However, if you have contacts in the high end Race Car Engineering and Aerospace Industry, they should have experience of using it, F1 Teams use it a lot and its pretty standard issue in military fighter aircraft.
On the other hand it is much lighter than steel, its is stronger than steel, is reasonably inert to corrosion and has an attractive colour (it looks great on my Ebony)

Aluminium is easy to cut and machine but difficult to weld (but easier than Titanium). It also doesn't work well in sliding joints. It suffers from a problem called "pick-up" - where two smooth surfaces rub together and become rough and don't slide past each other easily.

Have you considered Stainless Steel (but its heavy and can be difficult to weld - but not as difficult as Aluminium or Titanium).

Another alternative is to use Carbon Fibre in parts of your construction - it is both very light and very strong

You will have to choose one metal and stick to it throughout almost the entire camera - otherwise you suffer problems with bimetallic thermal expansion issues - do you might adjust your camera to work smoothly in cool ambients only to find it either very sloppy or very very stiff to operate in the sunshine on warm/hot days or visa versa.

Good luck

Martin

 

[Mark Fisher]

I've done a lot of metal fabricating, but never for cameras (I'm a design engineer). I suspect that brass is used for historical reasons. Back before World War 1, aluminum was insanely expensive and probably out of range of the camera producers.....plus it isn't particularly strong without proper alloying. Today, modern alloys are strong and easy to work. I'm not sure why someone would use brass today except for the beautiful way it looks.

Titanium isn't a home project. That said, I think that if you can make 2D drawings on the computer (CAD, or even something like Corel Draw), it can be water jet cut pretty easily. That is the approach I'd take. There are quite a few companies who could do that for you. I think you might be able to bend it with the right equipment, but I'm not sure. In case you can't tell, this is on my (long) list of things to do...

 

[Wade D]

Titanium is easily cut by water jet or laser. Forming or bending is very difficult without
the proper heat treating and annealing. It has a memory and when bent will go back to the original form. A case in point are the frames for glasses. They were expensive but I've smashed them flat numerous times and they spring right back without breaking. The company I retired from used exotic metals in the fabrication of turbine engines for industry.

 

[Q.G.]

I'm not sure why someone would use brass today except for the beautiful way it looks.

And it is still cheap, very easy to machine and work in other ways, very easy to achieve a high grade of finish, and strong enough for the job.

 

[nick mulder]

I was thinking titanium and/or alu ...

Titanium I read isn't necessarily 'stronger' (I really need to read up on the technical terms pertaining to metal characteristics) than all steels, but much lighter per 'strength thingy' rolleyes.

I have read that it is its low thermal conductivity that causes issues with machining, without ample coolant or feed rate (which in turn determines cutting speed and bit size) the part will heat up and do something bad like work harden which will ruin the tool, which will ruin the ... and so on. So basically you're looking at carbide bits instead of HSS and you're looking at throwing them away before they dull. I guess the cost would have to be be factored in with the weight savings and gravitas of having made your own Ebony clone, and/or compared with a bit of CADCAM at the local CNC/water/pla$ma joint...

I understand that Aluminium would results in larger profiles to account for the loss in strength, but it would be made up for in stiffness at least (?) any sliding parts could be made of wood or HDPE (?) - I don't need to build a Canham clone

Once your part is machined in Alu or titanium is there any process it can undergo to harden it or otherwise make it er... better ?

 

[nick mulder]

Titanium is easily cut by water jet or laser. Forming or bending is very difficult without
the proper heat treating and annealing. It has a memory and when bent will go back to the original form. A case in point are the frames for glasses. They were expensive but I've smashed them flat numerous times and they spring right back without breaking. The company I retired from used exotic metals in the fabrication of turbine engines for industry.

You've reminded me of Nitinol - I have some wire here I got ages ago for a robotics project - I wonder if it could be used in photography ?

 

[Mark Fisher]

Aluminum is easier to machine "pre-hardened" so it isn't usually post-hardened. 6061-T6 or 2024-T4 are reasonably common and are already heat treated. It is usually anodized after machining for corrosion protection. It can be dyed after anodizing to get some color rather than silver. It can also be "hard anodized". Hard anodized parts are more wear resistant and lower friction than standard anodization. It isn't too hard to anodize parts and dye them at home. If you are up for machining parts, anodizing shouldn't be too difficult. In the US, there are kits available to do home anodizing. There are references on the 'net too.

Nitinol is a nickel-titanium alloy. We were trying to design a "super spring" for a medical device at work and had a bunch of it. It is crazy how much it can deform and spring back. I suppose if you wanted to have a spring back that would fit a roll film back under it, Nitinol wire might be a good choice for the springs.

 

[photomc]

Might also consider that Richard Ritter opted for carbon fiber for much of his cameras rather than stell/alum. etc. Good strong cameras and still have the wooden camera look to them. Can see it working for a home build project.

 

[alanrockwood]

About titanium, I have been told by a machinist that it his hard to machine because it tends to weld itself to the cutting tool, thereby grabbing the tool and then breaking it.

 

[Q.G.]

Nitinol is a nickel-titanium alloy. We were trying to design a "super spring" for a medical device at work and had a bunch of it. It is crazy how much it can deform and spring back. I suppose if you wanted to have a spring back that would fit a roll film back under it, Nitinol wire might be a good choice for the springs.

Wouldn't it be much too 'bendy', offer too little resistance to deformation, be too weak to be of use as a spring?

 

[Mark Fisher]

Wouldn't it be much too 'bendy', offer too little resistance to deformation, be too weak to be of use as a spring?

Actually, that is one of the cool things about nitinol. It is a little stiffer than aluminum, and about 40% less stiff than brass; but the strength is roughly 2x either one and comparable to high strength stainless. This means it can take huge deformations and spring back. The biggest use for Nitinol is as spring material in stents because it can be compressed so much it can be delivered through a narrow catheter and sprung into place in the blood vessel.

Sorry, I am a bit of a material geek (with many other bits of geek-ness mixed in).

 

[Sirius Glass]

Actually, that is one of the cool things about nitinol. It is a little stiffer than aluminum, and about 40% less stiff than brass; but the strength is roughly 2x either one and comparable to high strength stainless. This means it can take huge deformations and spring back. The biggest use for Nitinol is as spring material in stents because it can be compressed so much it can be delivered through a narrow catheter and sprung into place in the blood vessel.

Sorry, I am a bit of a material geek (with many other bits of geek-ness mixed in).

That means one can build a metal camera that when dropped does not have to go to an auto body mechanic to straighten the body. If we then coat it with rubber will the camera bounce and not deform?

Steve

 

[Mark Fisher]

That means one can build a metal camera that when dropped does not have to go to an auto body mechanic to straighten the body. If we then coat it with rubber will the camera bounce and not deform?

Steve

Unfortunately, the properties that make Nitinol so cool are the same properties that make it hard to form. I've only used wire and I've only seen it as wire and strip...):

 

[ic-racer]

I would think the problem with an aluminum camera would be the casting of the large components. I wouldn't think that the lifespan of a cutting or milling or dirll bit would be a concern making a single camera.

 

[nick mulder]

I'm interested foremost in making my own camera but see no need to work in brass, perhaps for the aesthetics I could and also in the case there is something I cant build myself and therefore have to buy off the shelf in brass I dont want to mix and match metals ...

I have:

A large enough mill/drill with a rotary table that can modified to have indexed divisions (no gear cutting bits nor arbors/slitting saws/sliding dovetail cutter etc.. yet either)
An Emco lathe - the smallest one, I forget the name

I'd like to play with titanium for a try, but see myself making something more akin to a Canham, but with wooden frames, inlay metal bracketing for strength - I guess taking the best of both Ebony and Canham - in ULF ...

Actually - I'm just assuming Canham use Alu - if so, its been through CNC ? what sort of finish and what grade alloy ? Also, how do they deal with surface to surface friction and gearing ?

 

[lxdude]

I would think the problem with an aluminum camera would be the casting of the large components. I wouldn't think that the lifespan of a cutting or milling or dirll bit would be a concern making a single camera.

The components would be made from plate or bar. With aluminum the bits would last just fine. With titanium they can be destroyed quite rapidly without proper technique.

 

[lxdude]

Actually - I'm just assuming Canham use Alu - if so, its been through CNC ? what sort of finish and what grade alloy ? Also, how do they deal with surface to surface friction and gearing ?

CNC is great-but not necessary with the right tools and some skill.

Mark mentioned a couple of alloys which will work really well.

For higher rigidity, meaning you could make it a little lighter, 7075 T6 would be best, but the weight savings aren't huge. Its corrosion resistance is not high by comparison to say, 6061. Anodizing would help a lot with that, and if you're not in a harsh environment it won't matter anyway. It's often used for rear sprockets for dirt bikes, which gives you an idea of how tough and abrasion resistant it is. Its composition and physical properties make it somewhat more difficult to machine than the others, but with a rigid setup, not bad.

6061 T6 is very widely used, and would work fine, though I have had problems with gumminess at times, due to normal tolerances in its manufacture. That makes turned finishes and fine threads difficult to make without some tearing. If you run into that problem, hand tapping helps, and some 400 or 600 grit wet-or-dry paper or industrial Scotch-Brite will smooth out the finish nicely.

Material hardness and anodizing will help a lot to resist galling. There are several dry lubes which can be used which won't attract crud. A stainless or brass shim or insert between aluminum parts would eliminate galling, but add complexity.

If you want to use gearing it's best to just buy it from a supplier like McMaster-Carr. Brass has natural lubricity, not expensive but heavier than steel or nylon. Oil sintered nylon is light with great lubricity but not so pretty. Stainless is a little lighter than brass, pretty if you polish it, but very expensive.

 

[Mark Fisher]

I have:

A large enough mill/drill with a rotary table that can modified to have indexed divisions (no gear cutting bits nor arbors/slitting saws/sliding dovetail cutter etc.. yet either)
An Emco lathe - the smallest one, I forget the name

I'd like to play with titanium for a try, but see myself making something more akin to a Canham, but with wooden frames, inlay metal bracketing for strength - I guess taking the best of both Ebony and Canham - in ULF ...

Actually - I'm just assuming Canham use Alu - if so, its been through CNC ? what sort of finish and what grade alloy ? Also, how do they deal with surface to surface friction and gearing ?

Damn, I'm jealous. I've wanted a little mini-mill to to what you are doing. Please keep us all posted!

Canham definitely uses aluminum and I'm sure it is CNCed (no production shop uses manual mills to any great extent anymore). I thought that they used a standard gear rack screwed to the aluminum bits. It's been awhile since I saw it, though.

 

[nick mulder]

If you want to use gearing it's best to just buy it from a supplier like McMaster-Carr. Brass has natural lubricity, not expensive but heavier than steel or nylon. Oil sintered nylon is light with great lubricity but not so pretty. Stainless is a little lighter than brass, pretty if you polish it, but very expensive.

I'm keen to give it a crack one day soon (gear cutting) - I'm always bodging projects in other ways or not even starting them for lack of gears !

'oil sintered' nylon ??

google hasn't been helpful on that one ...

But yes, nylon doesn't exactly have the same look as brass and mahogany, but say if you made a rack out of it, it could be hidden, and it wouldn't look too out of place with anodised aluminium... Just got to switch off aesthetic expectations for a while huh - as I've said in other threads, I'm no slave to period technique or look ... Just whatever is best for the job or probably more whatever happens to interest me at the time For whatever reason carbon fibre has never done so - too alien/slick - reminds me of those twats on bicycles that ride 4 abreast on Sunday mornings heading out for a latte in their underwear :rolleyes:

 

[lxdude]

I should have just said "oil incorporated nylon" as it I'm not sure if the oil is incorporated by sintering or some other method. Regular nylon would also work but would wear more. I think there's also nylon that has a solid lubricant like graphite or molybdenum disulphide incorporated. Not sure offhand, though.

 

[lxdude]

^^^D'oh! I should have said regular nylon will wear more unless you put a little light grease on it.^^^