Reawakening Brenkert BX-80

[Stu Wenschlag]

I'm happy to report to the forum that I now own a Brenkert BX-80 and plan to restore it for operation - I've been lugging the beast around for some time but it wasn't officially mine til today

I am expecting to run into a lot of hurdles on this journey, but nothing ventured nothing gained, right?! For study I have a copy of James R. Cameron's Motion Picture Projection, from 1952, and the operation manuals for the Brenkert BX80 and RCA MI-1040 soundhead (kindly provided here in the forum 'Warehouse'). However, my greatest resource may actually be you folks here in the forum. I have been reading posts here and in the old forum for a few years, and have learned a great deal.

So far my improvements have been mostly cosmetic with a little painting, and some disassembly, cleaning and greasing of moving parts. The next step I'd like to accomplish is to prepare and test the motor before powering up - it will need to be opened up and serviced. With some good advice here and there I might actually get it running. After that it we shall see if it likes eating film or has other nasty behaviors...

Stu

[Stu Wenschlag]

[Dave Macaulay]

The RCA soundhead is a tank, it's hard to kill one. It will die pretty quick if the gearbox goes dry though... keep the gear oil filled.
There were a few motors used but I think they all come apart easily. Be careful at the end opposite the shaft, the start switch or centrifugal actuator can be damaged in disassembly. Or reassembly.
If it's original it will likely have open ball bearings with a greasing path from capped holes in the end bells. If they're OK just clean them out and regrease, they will last pretty much forever in hobby use. When I used to rebuild them for cinemas I replaced the old bearings with 2RS type sealed ones which would cost you maybe $20.00 for both.
Your biggest problem will be aligning the motor with the soundhead input shaft when remounting it. This has to be pretty exact.
You can open the gearbox if you want but the gaskets are not available anywhere I know of. If it turns freely with little backlash, probably leave it closed up. I would at least drain it and look for metal grains in the oil, flush it with kerosene or diesel fuel, and fill with the correct gear oil. If the old oil is full of brass dust, it's been run dry for a while. Still... gears and gaskets are NLA so there's not much you can do except run it as is unless the gears are so worn they skip.
Sprockets and other parts are also NLA - maybe someone here has a stash though?
For the Brenkert, once again parts are not available except for any in private hands. Keith Stata in Canada probably has a few BX projectors stored away but I don't know if he's selling stuff now.

[John Eickhof]

hello, take the cover off the oil sight in the projector and clean the small filter screen, replace the o-ring seal, also clean out and inspect! the soundhead gearbox! this is essential, brenkert heads have an unusual hard startbup load and that is why rca developed the 9050 soundhead as it used the lower gear to drive the projector thus insuring better lubrication.be very careful of the alignment on the shutter driven gear and make sure all sub-assemblies are seated correct;y on their alignment dowells before tightening in place, i have thousands of rca and brenkert parts in stock, if you should need anything, especially gaskets. have fun and good luck! note that the 1040 soundhead is a fast starter so make sure the start resistor is in good condition (inside the j-box where the motor on-off switch is) or it will continually tear up shear pins on the projector drive gear!

[Mark Gulbrandsen]

That projector is a heavy load on ANY sound head gear box! I recommend you run Mobil-1 Synthetic gear lube in the gear box. Back when I serviced theaters around Chicago it was pretty much all Brenkerts and I replaced lots of bronze gears and pinons. But after I switched to the synthetic stuff I never had another bronze gear fail again.

[Gordon McLeod]

I was using APG90 Outboard gear oil in them (same as Motiograph AAA intermitent lube) and never had issues. Also the alignment with a reverse scan reader is difficult to get stable

[Stu Wenschlag]

My head is exploding here! This is great advice that I really needed.

So, Dave, the motor is Robbins & Myers ¼ HP, type 3951, SN M12928MK (see pics - figures 1 & 2, below). I'll be sure to be mindful of the centrifugal actuator area.
Once I open it up I think your other comments regarding the bearings will be more clear to me as I need a visual for it to all sink in. I will probably snap & share a couple pictures before getting rolling.

You say its best to leave the gearbox closed up, but John was stressing the importance of really making sure that area is inspected carefully. I think I'll start by doing the recommended flush-out and look for the brass filings for now and report back after that. You said to check the "backlash" so I am assuming you are talking about rotating the framing wheel (centred in figure 5, below) and feeling for play - is that correct? Knowing how it is supposed to feel is tricky for me since I don't have the experience you guys have - but when I turn it now it there is no tugging or uneven resistance.
Finally, Dave, good to know about Keith Stata as I too am in Canada (Vancouver).

John, many thanks. Good call on cleaning the filter screen, replacing the o-ring seal and doing the thorough inspection of the sound head gearbox. As for the start resistor, I'll have a look at it and see what shape its in.

Thanks, Mark and Gordon, about the lubrication advice. Well taken. There's also a great discussion in one of the old forum posts about this topic http://www.film-tech.com/cgi-bin/ubb...c;f=1;t=008140 I think I can easily get my hands on some of the Mobil-1 Synthetic Gear Lube locally.
Stu

[John Eickhof]

a couple more things...the 1040 gearbox is integral to the main frame, thus you seperate the case from the frame, it does not come out as a unit like the 90 series. with this said, you basically rebuild it in the soundhead...anyway, under the knurled inching knob between the motor and the gearbox is a flexible coupling, chances are it is shot...i have new couplings also as well as case gasdkets, they are a prescribed thickness to provide proper bearing and shaft pre-load. when re-assemblng, motor alignment is critical for vibration free operation a simple way to align the motor vertically is to set the motor on the cradle bracket, use a 1/2" i.d. tube slipped over the motor shaft and align it with the gearbox, then tighten the bolts on the cradle bracket against the soundhead, then assemble the coupling and inching knob and run the motor then slide it across the cradle bracket until no vibration or noise is felt then tighten down the motor cradle to the bracket. it takes some practice! have fun

[Will Kutler]

RCA 1040s are built like tanks and are pretty straight forward.

Paint and Finish: The gloss black finish is Pontypool Black Japanning Asphaltum as used on vintage industrial equipment and the likes of antique typewriters and sewing machines. The interior is an off-white and was specified in one of the RCA or Simplex books. After much heartache and experimentation, I finally found a brand of white high-temp paint that does not turn brown when exposed to heat, has excellent adhesion and abrasion resistance, is solvent resistant and very easy to keep spotless! The formulation of modern paints is drastically different from those of yesteryear. White is a tricky paint to lay and I have developed my own very effective process.

Beware that refinishing is a very, very labor and time-consuming project that can take at least a month or more of daily work. The majority of this work involves specific processes needed to clean and purge castings of all oil and contaminants, which is required for both paint and powder coating. This includes masking all machined surfaces with a very expensive (powder coating) tape that also withstands sandblasting. Multiple cycles of sandblasting, oven baking and washing with phosphoric acid is required until all residual oil is purged from the castings.

Gear Cover: 1040’s were known for oil leakage from the gearbox! Hence the stuffing of tampons under the gearbox and a cooking sheet covered with kitty litter on the floor. My suggestion is to Prussian Blue the gear box cover against the main casting and address any high/low spots accordingly! Please pay close attention to John’s advice regarding gasket thickness and spacing!!

Pay attention to the 1040 book loaded in the F.T Warehouse. The 1040’s were modified by RCA to use shielded bearings on the sound drum, pinion and sprocket shafts. These bearings are all the same. The gearbox originally used non-shielded bearings, hence the need for the oil slingers! With the shielded bearings, the oil is primarily needed for the gears.

Slit Lens: Make sure that your slit lens is not filled with oil! I have rebuilt several, which has included the use of an optical clean room and ultrasonic cleaner.

Motor: I have rebuilt both Robbins and Myers and Hoover motors used with Century projectors. I would suggest visiting a local electric motor shop for assistance. Additionally, there are several reputable companies focusing on the restoration of vintage ceiling and desk fans. With the Robbins and Myers, the end bells can be powder coated. On the Robbins and Myers the exterior stator casing is integral to the stator…so sand it down with wet-and dry and repaint with a good gloss appliance epoxy. Replace the cloth covered wire with UL high-temp, chemical resistant. The motor shop has special tools needed to pull and install new roller bearing. They also have special tools to align the end bells, which is critical to vibration reduction! They will also be able to balance the rotor if required. New rubber clamp/cradle bushings will also be needed. Clean motor with electric motor cleaner. Varnish on stator winding may need to be touched up. Also replace oil wicks with new! As previously stated, make sure that the shunt resistor is good. This permits the motor to gradually ramp up to speed.

Door Glass: Original RCA logo is a decal. I have reproduced the logo and cut new glass. My logo is sand-blast etched instead of decal. Please let me know if you are interested.

Fittings: hinges and door handles are nickel plated and can be re-plated by a reputable plating shop.

[Dave Macaulay]

OK, maybe I'm missing something. Are you reviving this machine to use it occasionally for nostalgia nights, or doing a museum quality restoration? I assumed the former.
Regarding the motor, there's no such thing as critical end bell alignment for any small motor I have ever encountered. The end bells fit tight in the stator section and only require alignment close enough that the through bolt holes line up fairly well. If the bearings have self aligning mounting, that's what happens: a sharp rap on the shaft after assembly will take care of rough alignment and the bearings will find the best alignment themselves after some running. If they are solidly mounted then there's no further alignment possible or required. I do suggest installing double shielded bearings once the thing has been disassembled but if the original ones are really good you can just reuse them after cleaning and regreasing.
Since your motor mounts the way it does - if you undo the clamps and lift it out, the shaft alignment to the gearbox should be maintained and that job is done for you. If you unbolt the motor cradle then you will need to realign the motor. New rubbers in the mounting might change the alignment slightly but the flex coupling (looks like the riveted rubber/leather type to me) should manage that. If the coupling flexes much when the motor is hand turned you should try and shift the motor to minimize that misalignment.
Repainting one of these old girls is not a fun job. I believe Brenkerts have a crinkle finish which is about the most impossible paint finish to recreate for a home gamer. And oil soaked cases are horribly difficult to clean well enough for paint to stick to.
The backlash I meant is in the gearbox: the motor shaft should turn only very slightly when the sprocket shafts are held still. The shaft that drives the projector is always the most worn of course. No problem opening the case if you want to... but the gasket is hard to find but you can get some sheet gasket and cut your own. Avoid using silicon or "form-a-gasket" goop on a projector.
The gearbox bearings, if you do take it apart, are a very common and inexpensive size and using double sealed ones will reduce the oil dribbling considerably (but nothing eliminates it). The bearing cover gaskets are important and again hard to find but can be made from sheet gasket (telephone books are rare now but the covers were pretty good for cutting simple gaskets from).
The sound drum roller is a fairly complicated bit of work. Take care to document the order and direstion of the roller, spring, washers, etc. if you take that apart. New rubber rollers are also not easy to find. The really early ones were compressed felt, and are very rare indeed now.
For the projector, avoid disassembling the intermittent. Nothing good can come of that: if it's working OK leave it alone.
It's been decades since I had a BX apart and I forget pretty much everything about them. If the sprocket shafts get oil from splashes through a wick like XLs and others, that wick is very important.

[Stu Wenschlag]

Thanks for all the incredible feedback - I'm still parsing out the details of the conversation so far and cross-referencing all that with the manuals before I take my next steps and respond.

Dave to answer your question about the purpose of the restoration, here's a bit of my story, I have a large collection of both 16mm and 35mm short films (mostly cartoons) and a lot of analogue editing, projection and animation production equipment in various states of condition (mostly in rough shape) all of which I acquired from an estate. Its really an overwhelming lot of stuff to deal with for one guy, but I am managing. I have a background in traditional animation and have some experience working with film, plus I am quite handy. I plan to mobilize all of the variety of resources and equipment in a few ways: provide local artists and filmmakers access to the vast library of books and films in the collection; provide some traditional analogue animation production services including editing, vintage equipment rental (film productions) and film projection. Most items would be classified as 'in storage' now. I will gradually bring items out of storage when there are opportunities to generate revenue - that's where the Brenkert comes in. Its kind of the star of the show and a means by which all these films can be shown ... basically, all paths lead to the Brenkert! I want to build some dolly's, crates and a gantry/winch set-up to facilitate moving with relative ease (by myself) between a variety small venues with some 16mm projectors in tow.

I need to be somewhat pragmatic about the quality of the restoration and keep costs low. The Brenkert won't initially see heavy use, but depending on the success of the business venture I will scale up the level of service to the projector both functionally and cosmetically. Quite honestly, at this stage I just want to see it running and know that I'm not grinding up the brass gears, or wearing down other irreplaceable parts like bearings and shafts. As for the lamphouse, I don't have one yet so its a bridge I will have to cross at some point soon. For now I rigged up an old slide projector with a 500 watt lamp and it will have to do!

[Jesse Crooks]

This might be obvious, but make sure you're using the right oil for the projector head. Brenkert oil is extremely thin, far thinner than most projector oil. It's so thin that if you rub it between your fingers you can still feel the texture of your skin. Perhaps someone on this forum can recommend an available equivalent. If you're lucky maybe you could find some NOS from Wolk that's still good.

[Mark Gulbrandsen]

You may want to pull the movement out and check the rubber seal thats at he movement casting to intermittent housing. A friend is rebuilding 8 Brenkerts for various theater as I type this anbd he found that rubber ring had disintegrated in all 8 machines. If it is the intermittent won't hold any oil and may seize up.

[Mark Gulbrandsen]

Stu, Here is what happens to those seals.

[Stu Wenschlag]

That's great intel - thank you Mark! Chances seem pretty likely my rubber seal will be gone too.

I've had to push the pause button on the project for a bit but will get back to it soon with my updates.