This is topic Bolex 521 in forum 16mm Forum at 8mm Forum.

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Posted by Paul Mason (Member # 4015) on September 04, 2015, 01:36 PM:
Has anyone experience of the Bolex 521 (or 511, 501)? Does it have a three or four prong claw?
Posted by Paul Mason (Member # 4015) on September 05, 2015, 03:10 AM:
I understand that the Bolex 521 was made in Italy, possibly by Microtechnica, for Bolex International from 1977 to sometime in the 80s.
Posted by Terry Sills (Member # 3309) on September 05, 2015, 04:01 AM:
The 521 is the updated version of the 321 but the build quality is a far cry from the 321. Very plasticy unlike the solid and high precision of the Swiss manufactured machines.. Built down to a price most probably and I believe not to the comprehensive spec as the 321. If you are interested I have an almost mint example available.
Posted by Paul Mason (Member # 4015) on September 05, 2015, 08:14 AM:
Thanks Terry,
The weight of the older Bolexes has always put me off but I expect that's the price of the build quality. There is a 521 for sale close to me so I was intrigued as to whether it was sensible choice over a contemporary Bell & Howell. Many of my films are damaged and shrunk so I have found Elfs tend to jump with the frame restorer operating.
Posted by Terry Sills (Member # 3309) on September 05, 2015, 09:04 AM:
Yes Paul they are very heavy but magnificent beasts. The B&H's are very good at handling damaged film, but for me it has to be the Debrie D16 with V gate. As I'm sure you know, 3 toothed claw and no contact with emulsion through the gate and because the film is gripped only on the extreme edges of the film it handles damaged and shrunken film very well. The downside is the bulk and weight unless you can keep it permanently assembled. I think all projectors have compromises of one sort or another. If you go for the 521 you'll have to let us know how it performs.
Posted by Paul Mason (Member # 4015) on September 07, 2015, 03:15 AM:
Absolutely agree that every projector design is a compromise even if it's great weight or size. A permanent installation is ideal but most of us have to use portable projectors I suspect. I'd like to have a Debrie one day. I will post my experiences with the Bolex if I get it but it's an auction and the price looks like going too high. [Frown]
Posted by Josef Grassmann (Member # 378) on September 19, 2015, 10:37 AM:
Bolex 221, 421, 521 are projectors we see for repair every year.
I believe 421 and 521 have 3 pin claws.
Similar to 16mm Bell & Howell ALL Bolex 421 and Bolex 521 suffer from multipe cracks in worm gear!
Nowadays very often they have electronic defects.
They are difficult to repair.
If your Bolex is in working order, I would strongly recommend not to use the STOP button and no rewinding of film on those devices.

Posted by Paul Mason (Member # 4015) on September 20, 2015, 02:39 AM:
Thanks Josef. That is very interesting. Your comments certainly discourage me from buying one to use. The Bolex 521 I saw on Ebay UK sold for £166 to someone else. [Smile]
Posted by Terry Sills (Member # 3309) on September 20, 2015, 11:16 AM:
Well I knew that they were nowhere near the build quality of the 321 but I didn't know that they were that bad!
Posted by Paul Mason (Member # 4015) on September 20, 2015, 12:23 PM:
Well Terry,
I suppose our perspective from 40 years on is these are projectors that are not built to last for 40 years but I suppose an industrial or educational buyer in 1975 would be quite happy if the Bolex lasted 10 years with 1000 hours of useage. He or she got a lot of fancy features at the time. It was expensive certainly but a classic? NO.
Posted by Terry Sills (Member # 3309) on September 22, 2015, 05:12 AM:
Totally agree with that Paul. With the exception of a few I think that was the way of amateur guage projectors after the 60's/70's.
Posted by Josef Grassmann (Member # 378) on September 24, 2015, 04:36 PM:
Bolex 421 and Bolex 521 are very nice looking machines - if they are in working condition - and have features difficult to find on other brands, e.g. buttons for 16,66 - 18 - 24 - 25fps, Stop and for single frame projection!!
If you are watching films at 24fps, then you won´t need all those features.
Bolex,CH can´t supply worm gears since many years now.
We carry out a repair to stabilize worm gear, split gaps become smaller but still remain. Now projector runs much quieter. So customers can use their Bolex for further years.
There are four pcb´s each size = half post card (beside amp-board and ...). They are stacked from bottom to top. Some have 4- or 6-pin connectors on pcb plus 4 to 9 single pin connectors. There are no marks were to connect green, red, brown,violet, yellow wire. If somebody has already reconnected the single pin connectors in his "own" order, than it is difficult to find the right connection.
I don´t know, why they did not use one 15-pin connector on each printed circuit bord. Life could be much easier.

Similar to B & H they are nice projectors if the worm gear got fixed and other parts are in good working condition.
Posted by Edwin van Eck (Member # 4690) on May 23, 2018, 09:34 AM:
The good news is that these wormgears are available again!

We fabricate these again:


Posted by Stefan Voglsinger (Member # 6537) on July 31, 2018, 05:49 AM:
hey, i have a bolex 421 and need to change my wormgear. i unscrewed the old one but it doesn't go off that easily since it's stuck to the metal part in the front when i try to peel it off. my question, has anybody done that exchange and can tell me which parts i have to remove or loosen to get the old wormgear off?
Posted by Edwin van Eck (Member # 4690) on August 14, 2018, 01:06 PM:
You need to "pull" the axis a bit to the front, so there is space to replace the gear. You need to loose up several screws. See here a picture. Maybe I missed some screws in the drawing.


If someone has better info, please let me know so that I can make a guide to do this. Even better is a short instruction video!
Posted by Stefan Voglsinger (Member # 6537) on July 15, 2019, 02:57 PM:
Great thanks, I exchanged the wormgear.

There are two more issues with that Projector...
First it runs slower than it should - I measured the speed with an RPM meter and it's always a few frames below. I tried to fine adjust it with the Potentiometer under the Motor without success. When I put the voltage to 220V instead of 240V it reaches the right speed but I don't know if that's a good idea to stress the projector with more voltage.

Second, the sound is very low - not enough to drive the speaker. I found a damaged elko so I exchanged all the caps on the amplifier board but yet without success.

Any suggestions? Similar Issues with the Bolex 421?

[ July 16, 2019, 05:12 AM: Message edited by: Stefan Voglsinger ]

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