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How to cut a clean circle on a rear Fujifilm lens cap?

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Pansottin

Pansottin

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Hi everyone, I need your advice for a small DIY job.
I want to cut a Fujifilm Fujinon GF lens rear cap (GFX system) so that I can then make a small hood when I use these lenses in reverse mode. These caps are made from a tough polymer; on the inside of the cap it says ">PC<". I assume it's polycarbonate, but I'm not into these industry acronyms.
What's the best way to cut a nice, clean circle on one of these Fujifilm back caps?
Thanks a lot.
 
I’ve never had occasion to drill out a rear lens cap but I’ve holed body caps for pinholes.


For the larger hole use a Forstner bit and a drill press. A hand drill will work too, but requires more care to assure the hole is centered. A hole saw could also work. Use what you have available. The drill speed should be moderately fast, and you’ll want to use water to cool the workpiece as you go You want to remove the plastic, not melt it

A file and/or sandpaper will clean up the cut and remove any spurl.
 
jaberg said:
I’ve never had occasion to drill out a rear lens cap but I’ve holed body caps for pinholes.

For the larger hole use a Forstner bit and a drill press. A hand drill will work too, but requires more care to assure the hole is centered. A hole saw could also work. Use what you have available. The drill speed should be moderately fast, and you’ll want to use water to cool the workpiece as you go You want to remove the plastic, not melt it

A file and/or sandpaper will clean up the cut and remove any spurl.
Click to expand...
 
If you can’t find a Forstner bit…



Carefully drill a series of holes around the inner perimeter of your desired cut out. You could use a single hole but the more holes you drill, and the more accurately you place them, the easier the next step will be. Thread the blade of a coping saw, or jewelers saw, through one of the holes. Cut your circle from hole to hole. Again, finish with a file or sand paper.
 
Thanks for the suggestions .-)
 
You've had some good suggestions about how to cut the cap, but you might consider creating a rectangular hole (the same aspect ratio as the image format) rather than a round one... it might be easier to cut, too.
 
Heritage Cameras said:
creating a rectangular hole
Click to expand...
If you go this route, drill the four corners and “connect the dots” using a small saw. A power scroll saw would make quick work of it. If you can clamp the cap tight enough you could use a hand-held jig saw — but a table-top scroll saw or manual handsaw are probably best.

All of my suggestions in this thread make the assumption you don’t have access to a milling machine. 😉 (If you did, you wouldn’t need to ask “how?”.)
 
Heritage Cameras said:
You've had some good suggestions about how to cut the cap, but you might consider creating a rectangular hole (the same aspect ratio as the image format) rather than a round one... it might be easier to cut, too.
Click to expand...
 
Pansottin said:
Pansottin wrote:
I want to cut a Fujifilm Fujinon GF lens rear cap (GFX system) so that I can then make a small hood when I use these lenses in reverse mode. These caps are made from a tough polymer; on the inside of the cap it says ">PC<". I assume it's polycarbonate, but I'm not into these industry acronyms.
What's the best way to cut a nice, clean circle on one of these Fujifilm back caps?
Click to expand...
A drill press with a hole saw is a pretty good approach.

However, the plastics used are generally a type that melts with heat and you'd be surprised how quickly a blade gets hot. The result is often a gooey mess at the cut edge. The basic trick is to cut a little, then back off to let the blade cool before cutting a little more. The second trick is to make sure the cap has something behind it supporting it as you cut through it -- or, even better, cut halfway through, flip the cap, then cut the rest from the other side.

Of course, I'd just design and 3D print a hood...
 
ProfHankD said:
ProfHankD said:
Pansottin wrote:
I want to cut a Fujifilm Fujinon GF lens rear cap (GFX system) so that I can then make a small hood when I use these lenses in reverse mode. These caps are made from a tough polymer; on the inside of the cap it says ">PC<". I assume it's polycarbonate, but I'm not into these industry acronyms.
What's the best way to cut a nice, clean circle on one of these Fujifilm back caps?
Click to expand...
A drill press with a hole saw is a pretty good approach.

However, the plastics used are generally a type that melts with heat and you'd be surprised how quickly a blade gets hot. The result is often a gooey mess at the cut edge. The basic trick is to cut a little, then back off to let the blade cool before cutting a little more. The second trick is to make sure the cap has something behind it supporting it as you cut through it -- or, even better, cut halfway through, flip the cap, then cut the rest from the other side.

Of course, I'd just design and 3D print a hood...
Click to expand...
Thanks a lot. Is there any free available designs online for type of pieces?
 
Pansottin said:
ProfHankD said:
Pansottin said:
Pansottin wrote:
I want to cut a Fujifilm Fujinon GF lens rear cap (GFX system) so that I can then make a small hood when I use these lenses in reverse mode. These caps are made from a tough polymer; on the inside of the cap it says ">PC<". I assume it's polycarbonate, but I'm not into these industry acronyms.
What's the best way to cut a nice, clean circle on one of these Fujifilm back caps?
Click to expand...
A drill press with a hole saw is a pretty good approach.

However, the plastics used are generally a type that melts with heat and you'd be surprised how quickly a blade gets hot. The result is often a gooey mess at the cut edge. The basic trick is to cut a little, then back off to let the blade cool before cutting a little more. The second trick is to make sure the cap has something behind it supporting it as you cut through it -- or, even better, cut halfway through, flip the cap, then cut the rest from the other side.

Of course, I'd just design and 3D print a hood...
Click to expand...
Thanks a lot. Is there any free available designs online for type of pieces?
Click to expand...
Well, there's a GFX cap that you could modify at:


You might do something a little sneaky like putting a filter thread on the cap so you can use standard screw-in filters as well as a screw-in hood. Most filters are 0.75mm pitch threads; for example, here's my customizer script for making screw-in lenscaps:

www.thingiverse.com

3D-Printed Screw-In Front Lenscaps With Optional QR Code by profhankd

My thing http://www.thingiverse.com/thing:414556 was a really quick and easy 3D-printable screw-in front lenscap design, set-up as a customizer application. Less than $0.15 worth of materials are used to make a typical size lenscap, yet they work well and can even double as color references...
www.thingiverse.com www.thingiverse.com
 
ProfHankD said:
Pansottin said:
ProfHankD said:
ProfHankD said:
Pansottin wrote:
I want to cut a Fujifilm Fujinon GF lens rear cap (GFX system) so that I can then make a small hood when I use these lenses in reverse mode. These caps are made from a tough polymer; on the inside of the cap it says ">PC<". I assume it's polycarbonate, but I'm not into these industry acronyms.
What's the best way to cut a nice, clean circle on one of these Fujifilm back caps?
Click to expand...
A drill press with a hole saw is a pretty good approach.

However, the plastics used are generally a type that melts with heat and you'd be surprised how quickly a blade gets hot. The result is often a gooey mess at the cut edge. The basic trick is to cut a little, then back off to let the blade cool before cutting a little more. The second trick is to make sure the cap has something behind it supporting it as you cut through it -- or, even better, cut halfway through, flip the cap, then cut the rest from the other side.

Of course, I'd just design and 3D print a hood...
Click to expand...
Thanks a lot. Is there any free available designs online for type of pieces?
Click to expand...
Well, there's a GFX cap that you could modify at:

https://www.printables.com/model/718112-fujifilm-gfx-lens-cap

You might do something a little sneaky like putting a filter thread on the cap so you can use standard screw-in filters as well as a screw-in hood. Most filters are 0.75mm pitch threads; for example, here's my customizer script for making screw-in lenscaps:

https://www.thingiverse.com/thing:1563812
Click to expand...
Hello, thank you very much for your response and for sharing the files. I will consider this possibility.

Can these 3D printed objects be painted, for example with Musou Black?
 
Pansottin said:
Pansottin wrote:.

Can these 3D printed objects be painted, for example with Musou Black?
Click to expand...
Both PLA and ABS can be painted. Krylon makes a one-step, self-priming spray paint specifically for plastic. (As do other companies — but Krylon is what I get locally.)

However, I often start with a coat or two of self-leveling auto body primer which helps to fill in the layer lines on printed objects I don’t want to spend a lot of time finish sanding. Once primed, you can use any paint you want. However, if you use a water-based acrylic — not a paint I’d use for a body cap, but I do use it on figures — you’ll want to use a sealing clear coat on anything that’s going to be handled.

And as much as I appreciate and respect the Prof’s approach here, this is a project I’m more likely to machine than model. I would expect it to take me no more than 15 minutes to produce a working hood starting from an existing rear cap. That being said, it is a cool project, and I might undertake it to improve my modeling skills — after I have the machined prototype in the bag.
 
Last edited:
jaberg said:
jaberg said:
Pansottin wrote:.

Can these 3D printed objects be painted, for example with Musou Black?
Click to expand...
Both PLA and ABS can be painted. Krylon makes a one-step, self-priming spray paint specifically for plastic. (As do other companies — but Krylon is what I get locally.)

However, I often start with a coat or two of self-leveling auto body primer which helps to fill in the layer lines on printed objects I don’t want to spend a lot of time finish sanding. Once primed, you can use any paint you want. However, if you use a water-based acrylic — not a paint I’d use for a body cap, but I do use it on figures — you’ll want to use a sealing clear coat on anything that’s going to be handled.
Click to expand...
Most paints hold to FDM 3D-printed objects fairly well because of the roughness of the layer structure. The Krylon paints designed for use of plastic bond particularly well, but there isn't a great black. I generally use Black 2.0 to get really low-reflection black, but there's now 4.0.
jaberg said:
And as much as I appreciate and respect the Prof’s approach here, this is a project I’m more likely to machine than model. I would expect it to take me no more than 15 minutes to produce a working hood starting from an existing rear cap. That being said, it is a cool project, and I might undertake it to improve my modeling skills — after I have the machined prototype in the bag.
Click to expand...
You're right -- making a 3D model takes time, and hoods have a lot of tweakable parameters, so you'll probably end up making prints of several versions (i.e., 3D printing is for rapid prototyping). However, sticking a standard filter thread on the cap design is really quick and easy...
 
ProfHankD said:
I generally use Black 2.0 to get really low-reflection black, but there's now 4.0.
Click to expand...
I hear it’s the absolute snizzle. I’ve considered ordering a can for my lighting modifiers and photo-related projects, though the cost (plus shipping) gives me pause. I’m not doing science — I don’t need perfect. However, if I ever see it locally at the art supply it will be in my cart without question.
 
Thank you for your answers about finishing and painting the 3D parts.
I'm in Europe and Musou paint being expensive is "purchasable".-) It depends on whether we value its impact on these projects.
 
Pansottin said:
Thank you for your answers about finishing and painting the 3D parts.
I'm in Europe and Musou paint being expensive is "purchasable".-) It depends on whether we value its impact on these projects.
Click to expand...
if I were printing one I’d use black filiment, prime it, spray with matte barbecue black and call it done. However, the Musou will likely absorb more light. We can get the Musou paint here too. Spendy, but available. Cost aside, I’d be concerned that it’s a water based acrylic that will likely require a sealing or fixative coat.

(I do wonder, in an acedemic way, who wins the battle of “Blackest Black” between Musou and Black 4.0.)
 
Last edited:
jaberg said:
Pansottin said:
Thank you for your answers about finishing and painting the 3D parts.
I'm in Europe and Musou paint being expensive is "purchasable".-) It depends on whether we value its impact on these projects.
Click to expand...
if I were printing one I’d use black filiment, prime it, spray with matte barbecue black and call it done. However, the Musou will likely absorb more light. We can get the Musou paint here too. Spendy, but available. My concern about it is more that it’s a water based acrylic and will likely require a sealing or fixative coat.

(I do wonder, in an acedemic way, who wins the battle of “Blackest Black” between Musou and Black 4.0.)
Click to expand...
I don't know Musou, and I've actually stuck with Black 2.0 after Black 3.0 came out because Black 2.0 is significantly more durable.

Here's a long, but worthwhile, video comparing Black 3.0, Musou, and Black 4.0.

To make a long story short, I might stay with Black 2.0. It's quite black, very pleasant to use, and quite durable. The Musou was blacker (despite some measurements giving Black 4.0 the edge), but it's nasty stuff to use with a terrible and somewhat persistent odor -- and that means it probably outgasses, which is an absolute no-no for painting camera parts.
 
3fc9d2fcd04848ef85e9794466acfc74.jpg




The best way to get a clean hole is to use a chassis punch.

The type I am talking about has 3 steel parts.

The first part is a bolt.

The second part is a round punch with a threaded in the middle for the bolt to screw into.

The third part is a round receiving cup with hole in the middle for the bolt to go through.

You drill a hole in the center of the cap for the bolt to go into and assemble the punch then tighten the bolt.

Here’s what one looks like!




--
Will T.
“FACTS ARE NO MATCH FOR BELIEF” Robert Kenner Cralle
"Galleries don't hang DxO charts" David Hull
 
ProfHankD said:
ProfHankD said:
Pansottin wrote:
I want to cut a Fujifilm Fujinon GF lens rear cap (GFX system) so that I can then make a small hood when I use these lenses in reverse mode. These caps are made from a tough polymer; on the inside of the cap it says ">PC<". I assume it's polycarbonate, but I'm not into these industry acronyms.
What's the best way to cut a nice, clean circle on one of these Fujifilm back caps?
Click to expand...
A drill press with a hole saw is a pretty good approach.

However, the plastics used are generally a type that melts with heat and you'd be surprised how quickly a blade gets hot. The result is often a gooey mess at the cut edge. The basic trick is to cut a little, then back off to let the blade cool before cutting a little more. The second trick is to make sure the cap has something behind it supporting it as you cut through it -- or, even better, cut halfway through, flip the cap, then cut the rest from the other side.
Click to expand...
And, don't generate fine plastic chips, or plastic dust.

Remember, freshly cut plastic chips or dust have tons of recently broken bonds and are eager to form new bonds. This can include with your lung tissue and fluids, so when cutting in a way that produces fine chips instead of melted messes, or when grinding or sanding the plastic, add some cutting oil or a water spray...

And when you do make a melted mess, remember that the melted plastic may be producing toxic fumes.
ProfHankD said:
Of course, I'd just design and 3D print a hood...
Click to expand...
Yep, safest way, especially if you've got good ventilation, air filtration, and are using the more "lung friendly" plastics.
 
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