1:8 Shaft With Sheared Off Pin...

[Don H Marks]

I'm currently repairing a Bolex H8 non-Rex with sheared off pin on the 1:8 shaft. Not sure how a prior owner did it but the shaft was smooth all the way around, at first I could not even tell where the pin was. Only with 25x loupe could I make out where I could press to get the pin remnant out. 

Anyway,  the original washers were long gone, but I had some metric washers that appear to be the correct size. A washer on top, a wavy washer and a washer on the bottom from what appears in the 1961 service manual.

Problem is, after re-assembly  with the new pin, there is no friction between the shaft and the knob to rotate the counter. I wonder if I'm missing something or just need a stiffer wavy washer. It is not clear to me what causes the friction between the rotating shaft and the knob to turn to knob to advance the frame counter. 

 

[Don H Marks]

 It is not clear to me what causes the friction between the rotating shaft and the knob to turn to knob to advance the frame counter. 

Error above, should read..."It is not clear to me what causes the friction between the rotating shaft and the knob so that the knob will advance the frame counter."

[Dom Jaeger]

Yes, the wave spring washer sandwiched between flat washers, should exert some pressure to create friction. Make sure to grease the assembly.
Bolex had a special tool to press down on the washer while pushing in or out the pin. 

[Don H Marks]

These are the parts I have found. I might need a better wavy washer. 

[Don H Marks]

Remains of the sheared pin. Measured diameter 1.25mm. 

(H8 Non-rex SN132921)

[Don H Marks]

Friction grease and a thicker wavy washer and success! Nice firm friction on the knob. Counts all the frames!

 

[Don H Marks]

New pin was cut to about 7mm from some 1.25mm rod. 

[Simon Wyss]

The original pins were made by Spirol. A couple years ago I inquired with Spirol about manufacture of these. The answer was minimum order 200,000.

[Bill Hunt]

On 3/17/2024 at 11:38 AM, Don H Marks said:

Remains of the sheared pin. Measured diameter 1.25mm. 

(H8 Non-rex SN132921)

Don,

I have this very problem. I wonder if you could let me know where you found the replacement pin—and how tight a fit the new one was?

[Simon Wyss]

The bore is 1,25 mm into which centre groove pins are driven that measure 1,27 mm or 0.05" over the ridges.

An alternative are rolled sheets, some call them roll pins although they’re not pins. The 1 mm size, 6 mm long, fits relatively well and is available.

[Bill Hunt]

9 hours ago, Simon Wyss said:

The bore is 1,25 mm into which centre groove pins are driven that measure 1,27 mm or 0.05" over the ridges.

An alternative are rolled sheets, some call them roll pins although they’re not pins. The 1 mm size, 6 mm long, fits relatively well and is available.

I would guess this pin was substituted by a previous owner. It doesn’t have the raised middle section to hold it in place.

Luckily, this made it quite easy to remove.

The original pins seem to be only available in the U.S. so I’ll look for a rolled sheet.

Thanks Simon, and Don for the original post.

[Steve Switaj]

In the States, you can find 3/64" roll pins, which are 1.19mm

   https://www.mcmaster.com/products/pins/spring-pins~/diameter~3-64/

Don't know if they're available down under

[Bill Hunt]

2 hours ago, Steve Switaj said:

In the States, you can find 3/64" roll pins, which are 1.19mm

   https://www.mcmaster.com/products/pins/spring-pins~/diameter~3-64/

Don't know if they're available down under

Thanks Steve, I found a place that seems to have a good range, so for anyone else down my way: www.smallparts.com.au

I bought a range of sizes, I’ll go with the best fit that won’t require the Alcoa to get it snug.

I noticed Don went with 7mm length. I think I’ll go with that for safety.

Thanks again all.

P.S. The reason for all this is I got my hands onto an MCE-17b that was sold “as-is” without any description or cables—I didn’t even know the model. It didn’t take long to figure out how to wire it up and… it works beautifully.

[Don H Marks]

 

I cut my pin from a spring steel clip below. The wavy washer, pressing on the pin, keeps it in place. I have hundereds of these clips and it was the correct metric diameter. 

https://www.amainhobbies.com/tamiya-6mm-body-clip-10-tam9805702/p140105

Edited January 1 by Don H Marks

[Bill Hunt]

4 hours ago, Don H Marks said:

 

I cut my pin from a spring steel clip below. The wavy washer, pressing on the pin, keeps it in place. I have hundereds of these clips and it was the correct metric diameter. 

https://www.amainhobbies.com/tamiya-6mm-body-clip-10-tam9805702/p140105

Ahh… thanks Don, I think I know where to get these out my way.

[Brian Drysdale]

On 12/30/2024 at 11:51 PM, Bill Hunt said:

Thanks Steve, I found a place that seems to have a good range, so for anyone else down my way: www.smallparts.com.au

I bought a range of sizes, I’ll go with the best fit that won’t require the Alcoa to get it snug.

I noticed Don went with 7mm length. I think I’ll go with that for safety.

Thanks again all.

P.S. The reason for all this is I got my hands onto an MCE-17b that was sold “as-is” without any description or cables—I didn’t even know the model. It didn’t take long to figure out how to wire it up and… it works beautifully.

I had access to a Bolex H16 Reflex that intermittent problems with that shaft when an MCE-17b was fitted, it caused flickering. It appeared after the camera had fallen, but kept reoccurring even after being sent for repairs a number of times.

[Bill Hunt]

4 hours ago, Brian Drysdale said:

I had access to a Bolex H16 Reflex that intermittent problems with that shaft when an MCE-17b was fitted, it caused flickering. It appeared after the camera had fallen, but kept reoccurring even after being sent for repairs a number of times.

Thanks Brian, I’ll make sure I give it a good run.

The camera is pretty fresh from a service still so I’m hoping for the best.

[Simon Wyss]

Wild motors need to be braked to the desired speed by the mechanical governor of the camera. Different from the MST or ESM motors where we free the governor by setting the speed dial to 32 or 48 or 64 the MC-17 calls for a governor tempo. Then no flicker occurs unless the shutter is loose on its shaft or you have interference between shutter angle, speed, and an electric light source.

[Bill Hunt]

8 hours ago, Simon Wyss said:

Wild motors need to be braked to the desired speed by the mechanical governor of the camera. Different from the MST or ESM motors where we free the governor by setting the speed dial to 32 or 48 or 64 the MC-17 calls for a governor tempo. Then no flicker occurs unless the shutter is loose on its shaft or you have interference between shutter angle, speed, and an electric light source.

Thanks Simon,

Is this because the MC-17 when supplied with the correct voltage is merely taking the place of the spring?

I wondered about this when I read that the motor used a “friction drive”. Is this also why you can leave the motor powered on but still control the camera with the front or cable release (manual release mode)?

Sorry for all the questions Simon, but I’m intrigued by the workings of the drive motor and how the friction drive actually works—mainly because I don’t want to break it now I have one.

[Simon Wyss]

13 hours ago, Bill Hunt said:

Is this because the MC-17 when supplied with the correct voltage is merely taking the place of the spring?

Precisely.

There’s a friction clutch or safety friction, if you want, between the rotor and the coupling. After the many years these motors have been lying around I advise that a technician cleans out the old grease, lubricates everything freshly, and adjusts the force from the spring washers. The clutch is mostly way too hard so that in case of a stall either the internal worm gear gets damaged or the pin in the camera’s drive shaft sheared off.

Fun thing about the MC-17 is that it runs on AC as well as on DC.

[Bill Hunt]

10 hours ago, Simon Wyss said:

Precisely.

There’s a friction clutch or safety friction, if you want, between the rotor and the coupling. After the many years these motors have been lying around I advise that a technician cleans out the old grease, lubricates everything freshly, and adjusts the force from the spring washers. The clutch is mostly way too hard so that in case of a stall either the internal worm gear gets damaged or the pin in the camera’s drive shaft sheared off.

Fun thing about the MC-17 is that it runs on AC as well as on DC.

I’d be interested to hear more on the AC power Simon, although this one will be running on a lithium 24v (when it arrives).

When I tested the motor initially I only had a 12v battery running at 16fps.

My natural inquisitiveness got the better of me Simon, and I’ve opened the case yesterday to find a fairly simple clutch and drive assembly that I feel quite confident in sorting out.

There was a small amount of surface rust on the locking/adjustment rings, clutch spring and main gear. No grease or other lubricant in evidence at all, hence the rust.

Also I was interested to find the number “849” written in pencil on the inner face of the casing. I find these little traces of the human hand fascinating.

The ultrasonic vinegar bath has taken care of the corrosion, however there is a pin that goes through the inner locking ring, and also through the clutch spring that’s got me stumped.

I’m going to think about it over breakfast, but any hints are more than welcome—in addition to suggestions on proper lubricant for the worm drive etc.

 

[Bill Hunt]

49 minutes ago, Bill Hunt said:

I’d be interested to hear more on the AC power Simon, although this one will be running on a lithium 24v (when it arrives).

When I tested the motor initially I only had a 12v battery running at 16fps.

My natural inquisitiveness got the better of me Simon, and I’ve opened the case yesterday to find a fairly simple clutch and drive assembly that I feel quite confident in sorting out.

There was a small amount of surface rust on the locking/adjustment rings, clutch spring and main gear. No grease or other lubricant in evidence at all, hence the rust.

Also I was interested to find the number “849” written in pencil on the inner face of the casing. I find these little traces of the human hand fascinating.

The ultrasonic vinegar bath has taken care of the corrosion, however there is a pin that goes through the inner locking ring, and also through the clutch spring that’s got me stumped.

I’m going to think about it over breakfast, but any hints are more than welcome—in addition to suggestions on proper lubricant for the worm drive etc.

 

Is it possible that what I’ve been calling the spring/clutch mechanism is actually more of a shock absorber?

[Bill Hunt]

An exploding diagram (as Neddy Seagoon would say) of the MC-17 gearbox after cleaning and a little light oil.

The main gear assembly (centre) consists of the toothed gear itself then several very fine wavy spring washer/tensioners followed by two rings; the first to adjust tension on the spring washers, the second to lock the first in position.

At first I thought this was a type of clutch mechanism, but upon inspection I noticed there was a pin which goes through the first (tensioning) ring, the wavy washers and the gear, which in effect locks them together—stopping them from turning independently of each other.

When the shaft is inserted through the gear assembly the two screws (pictured) lock the gear to the shaft.

The whole assembly it driven as one by the worm gear (right) and held in place by brass bushes.

So, my guess is… that while the pin that locks the gear, springs and tensioner in place stops them from spinning independently, it does allow some lateral movement along the shaft (depending on the tensioner setting. This, I assume is meant to act as a shock absorber between the worm drive and the in-camera drive shaft and pin.

What I found when I first disassembled the gearbox was the gear had seized on the shaft thereby reducing the action of the shock absorber to zero. This perhaps contributed to the bending of my drive pin on the H16.

Of course I could be completely wrong—in which case I blame too many episodes of Inspector Morse…

[David Bendiksen]

Bill, I wanted to say 'thank you' for posting these photos. I had 3 of these M-17 motors that I wanted to be sure were in good shape before I sent them out with students, and your post gave me enough courage to open them. Real easy.

In addition to lubricating the worm gear and putting a dab of grease in that end cup that acts as a bearing, I also wanted to note for posterity: under the i/sec reference plate you can access the bearing on the tiny other end of the worm gear and give it a little oil. And for the curious, there is very little under the plastic switch cover except the switch itself and this capacitor. If I'm reading the color bands correctly (brown/green/yellow/white/red?), then it would be .15µF +-10%, 250V max. Someone let me know if that's incorrect and I'll edit this for reference.

[Bill Hunt]

On 3/12/2025 at 5:27 AM, David Bendiksen said:

Bill, I wanted to say 'thank you' for posting these photos. I had 3 of these M-17 motors that I wanted to be sure were in good shape before I sent them out with students, and your post gave me enough courage to open them. Real easy.

In addition to lubricating the worm gear and putting a dab of grease in that end cup that acts as a bearing, I also wanted to note for posterity: under the i/sec reference plate you can access the bearing on the tiny other end of the worm gear and give it a little oil. And for the curious, there is very little under the plastic switch cover except the switch itself and this capacitor. If I'm reading the color bands correctly (brown/green/yellow/white/red?), then it would be .15µF +-10%, 250V max. Someone let me know if that's incorrect and I'll edit this for reference.

Thank you David,

I was quite reluctant the break mine open at first, and surprised at how simple the mechanism was once I did.

I’m glad my post was of some use.

B