Nikon PB-4 Bellows with Stepper motor

I was long playing with the idea of adding a stepper motor directly to a Nikon PB-4 Bellows to allow macro photography and stacking photos for a deeper depth of field. The Nikon PB-4 is a very sturdy designed bellows from the 1960’s. It has 4 linear tracks. The bellows can be moved to increase magnification. Once that is set, the whole bellows, including the camera can be moved by a third knob. This makes the PB-4 ideal to be modified. I could have gone the easy way: buy a track, mount the PB-4 onto the track and finished. That works, however I wanted to make also something nice.

The concept is relatively simple: Create a base plate. Fix a stepper motor onto the base plate. Connect the stepper motor shaft to the shaft of the bellows. Add a controller and trigger for the camera. The result should do the following: program the increments and numbers of pictures to be taken. Run the software: Stepper motor will move, stop, trigger camera, move, stop, trigger camera. With special software you can stack all photo’s and that should give you a picture with a very high DOF. (take into account this is Macro photography)

Let’s Start:

For the base plate I took a 100x100mm aluminium plate, 12 mm thick. The first thing I did was milling 3mm deep slot in the contour shape of the PB-4 base. 1/4″ hole was drilled at correct position. The PB-4 will sit precisely in this slot and with a 1/4″ bolt the PB-4 can be mounted onto the base plate. Front and back sides of the base plate I milled 2 deep slots of 16x6mm: this will be used to mount the base plate onto a T-track with 2 clamp down knobs.

Stepper motor and gear. Nema 17 plate with 2 M4 holes added, base plate and tripod mount. Nikon PB-4 with exposed shaft.

On the bottom side of the base plate I drilled 1×3/8″ hole. A 1/4″ conversion screw is situated into this hole. This to protect the screw-thread. This 1/4″ screw hole gives me the possibility to mount a Tripod plate, incase I want to use the rig outdoors.

On the side, where the PB-4 shaft is located, I drilled 4 holes: 2xM3 and 2xM4. M4 bolts are used to mount a Nema plate to the base plate. This must be very sturdy to avoid play. The M3 holes are used for 2 of the 4 rods that hold the stepper motor in place.

Once I finished all milling and drilling, I gave the base plate a wrinkle paint coating. It is the same as Nikon used on the PB-4 metal parts. The base plate sits on a wooden base with a T track. It allows for quick adjustment of the whole rig.

The stepper motor is connected to a gear box with a 5:1 ratio. The M3 rods hold the stepper motor and gear box. The bottom two rods are screwed all the way into the base plate. The top 2 rods are secured with two M3 bolts onto the Nema plate. (Nema 17 and equal stepper motor) The shaft of the PB-4 is connected to the stepper motor via a flexible shaft coupling: the PB-4 has a 6 mm shaft once you removed the aluminium knob.

Base plate painted in wrinkle paint, Stepper motor mounted. Wooden base plate with T rails.

The baseplate with bellows sits onto a wooden base plate with the T track.

The controller for stepper motor and triggering the camera I had to outsource. I am sure that with an Arduino and some software know-how this can be done very cost effective. To stack photos I used HeliconFocus.

The first results are promising. With shorter days and current Covid situation this is a nice project to discover the world of Macro Photography. All materials can be found on auction sites or at OpenBuilds.

A 2mm End Mill

If you have questions: please contact me.

4 thoughts on “Nikon PB-4 Bellows with Stepper motor

  1. Hi Marcel many thanks for this interesting article. Question – as I understand from this the tripod thread in the base of the PB-4 is 1/4″ (1/4-20) as opposed to 3/8″ (3/8-16). I’m exploring getting a PB-4 and haven’t been able to find this spec anywhere!

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    1. Hi Mark, it is 1/4 on the base of a PB 4. You have 1/4 to 3/8 adaptors but the PB 4 won’t sit flush on the tripod plate.

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  2. Interesting! Still in the works?
    Just popping in to say hello and slip in my email.
    By the way Marcel, Nikon’s wrinkle paint you mentioned, is it available somewhere? It looks somewhat Hammerite-ish to me. I am using an ever evolving (very) Black Grainy Matte based on a Tamiya commercial spray. I didn’t realise the wrinkle paint is available, or is it?
    Anyway, ciao for now,
    Teddy
    Teddy.cool.be@gmail.com

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    1. Hi Teddy, Thank you for reaching out.
      The wrinkle paint is VHT Wrinkle plus high temperature paint. You need to apply 2-4 coats and the sequence is something you need to practice. It also needs a curing process at a higher temperature to get the best effect. Hairdryer could do. Again please test first.
      The paint is forgiving but the effect can turn out differently. I love the paint as it gives this nostalgic effect of the ’60’s on parts. Aluminium needs rough sanding. First a very light coat just to get more tack. (the aluminium can still mostly be seen.)
      Once this layer is sufficient dry it will help to bond the next layer. The high temperature during drying in between creates the effect.
      Try it. Good luck.

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