18 replies to this topic

[opticsguy]

Who uses the Byers 812 mount and what are your experiences and modifications??

Any owners manuals or copies available?

What is the controller that goes with this unit?

Thanks!!!

[hottr6]

Experience: Excellent!
Hotrodding: Strip/clean/blueprint/variable drive power supply/scopebuggy
Proposed hotrodding: Losmandy digital drive
Manual here:
Controller: There is an on/off switch in front of the sector drive.

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[Bowmoreman]

Interesting. Thanks for posting that picture, Shane...

Am I wrong, or does that bear a MORE than passing resemblance to my Mountain Instruments MI-250?

They could be cousins, or maybe (more likely) Father -> Son ???

curious!

[George N]

Interesting. Thanks for posting that picture, Shane...

Am I wrong, or does that bear a MORE than passing resemblance to my Mountain Instruments MI-250?

They could be cousins, or maybe (more likely) Father -> Son ???

curious!

I owned a Byres 812 many years ago (and a Byres 58 for a while) and I currently own a MI-250. The resemblance results from both mounts being based on the GEM designs of Russell W. Porter (the fellow who started Stellafane, etc). Porter advised using cone shaped axis on GEMs, and published drawings similar to both mounts. That’s the only real connection between these two.

The 812 has a sector RA drive “gear”, not a complete gear, so the RA drive has to be re-set about once an hour. This is not much of a problem, except you need to re-acquire an object after each re-set if imaging.

The mount uses mechanical setting circles that are quite accurate, but are of course pre-1990’s tech.

The drive controller and motor wiring for this mount, like all old Byres mounts, is unique to Byres and of course no longer made. Therefore you can’t just order an old drive corrector from someplace like JMI that would work with other 1980’s era mounts. I also once owned a Byres 58 mount, and I warned the person I sold the mount to that he might have a problem if the drive corrector ever died. Sure enough about two years later I saw him advertizing on A’mart for a Byres controller or info on updating the mount’s motors.

Byres will no longer support the 812 (or 58) mount. They didn’t even have the mechanical drawings for the 58 anymore when I asked for a copy.

Bottom line: they are great mounts, but you will be on your own with updating to modern motors or encoders, etc.

[hottr6]

The sector drive needs to be reset every 2 hours.

According to the advertising literature of the day, the Vista series of drive controllers will work with the 812 and presumably 58. I've not seen any on the used market.

I use a Vogel Enterprises Digitrak drive controller which works well. This unit has the added advantage of having two on-board 6V 5Ah rechargeable batteries and inverter, so it operates as a self-contained unit. The batteries last for many tens of hours between recharging. It also has an extra 12V port for powering other accessories. The only downside to this unit is that RA slewing is kinda slow, about 0.5x. I bought my unit on the other site for $125, and it just needed fresh batteries (another $20).

Both Vista and VE controllers are NLA.

I've crunched the numbers on the gearing of the Losmandy Digital Drive and motors, and it seems they should work. I have a complete DD unit sitting in a box awaiting mounting, but it requires a 12V battery and that is sitting in my bike. Its riding season, so the DD will have to wait until next winter.

The Byers 812 is awesome for visual work, I prefer it to my driven CG5. The 812 has prodigious payload (a CNer uses an 812 to carry a 9" Clark which has to weigh more than 200 lbs), and I often find myself leaning my full bodyweight against it for balance. I can pound on it hard and the minimal vibrations damp within 1 second. The quality of workmanship is evident; billet aluminum, welded steel and of course, the famous Byers gears. I replaced the bearings with sealed Timkens, and the whole RA assembly, OTA and counter-weight moves as if weightless. I'd say one would have to look to MI and Paramount for equivalent platforms today.

[rzep8]

I've had one of these since about '82.

Pros: Solid, extremely well made. Very good carrying capacity (easily 80 lbs). Good tracking ~ 5 arc second based on some tests I've done. Difficult to replace with a modern type mount for less then $6K or so. You can add encoders to this mount: www.briankidwell.com. Brian supplied me with custom devices for it.

Cons:As it uses a sector gear for the RA and tangent arm for the DEC, it cannot be made into a GOTO type mount. Uses Hurst 115 VAC synchronous motors for both RA and DEC control (although I long ago replaced the DEC motor with a 12VDC Cramer gear motor). Because of this, you have to use older "frequency chopper" type driver correctors (like the original Orion Accutrak or JMI). These still show up on various sites. There is also little documentation (although I do have an owners manual if someone needs a scan).

That being said, it is not impossible to convert the mount to auto-guiding. I've modified my dual axis Accutrak controller to accept relay inputs from a Shoestring GPUSB board. The relay module takes the place of push button hand controllers. I'm using a standard webcam and PHD software to do the control and have had (what I consider) good results. In this method, you have to manually acquire and center the target, engage the drives and then you're ready. Longest exposures are limited by the sector gear.

Conclusion: If you are mainly visual, there isn't a mount better for the money. Period. For CCD imaging, don't expect ultra high end sub pixel guiding as you would with an AP1200 or Paramount, but if your using a DSLR type (as I am) you can get some very good results.

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[rzep8]

Just to show what the mount can do via autoguiding:
M-13
AstroTech 6" RC @ F/9 piggyback.
Modified (Hap Griffin) Digital Rebel XT (8 MB)
23 4 minute exposures @ 1600 ASA
10 Darks
5 Flats
Shot in good ole light polluted suburban NJ

Guided using a Phillips 840 ToUcam at prime focus of the 12" f/10 Meade using PHD Guiding software.

Sorry for the amp glow in the corner but that's a hot Canon for you

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[opticsguy]

Thanks for everyones postings. I mounted up a 12" f/4 on the Byers 812 seesm to be ok, not sure how well this is going to work, every nght it clouds up here and every day is perfectly clear. What I dont seem to have is any of the controllers/wires to make the unit run. Will see what i can come up with.

Any idea how long the unti will run under a 12V conversion and a car battery?

[Lew Chilton]

Is this the Byer's 812 mount? That's Ed Byers next to his top-of-the-line model at the Riverside Telescope Makers' Conference, Big Bear, California, in 1980.

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[Bowmoreman]

OMG... that is beautiful...

[rzep8]

That's not the 812. It looks like a prototype for his Series II research mounts. Now THOSE things could hold a tank.

[rzep8]

The synchronous motor on the 812 draws about 3 watts @ 115 VAC. You'll be able to run all night with just the drive motor and a car battery. It's the dew-zappers and other accessories that can really suck the batteries dry.

[hottr6]

What I dont seem to have is any of the controllers/wires to make the unit run. Will see what i can come up with.

Any idea how long the unti will run under a 12V conversion and a car battery?

As I stated earlier, the 812 does not come with any controllers or "wires". Do you see any ports for controllers to plug into? Nope, none there. What you will find (if you look) is an on/off power switch for the RA motor. That's it. If you are missing these minimalist power switch, motor and reed switchs to cut the power at the end of the sector-drive run, you have work ahead of you before you even consider a drive controller. That said, I and another poster provided information on synchronous drive controllers that vary the rate of the power supply frequency.

Finally, if you had read my post, I gave quantitative information on current draw, yet you ask a question for which the answer was already given. Sheesh. :bangbangbang:

[hottr6]

I've had one of these since about '82.

Great summary, great rig, great mods and great image!

[rzep8]

Thanx! For your rig, I've always wondered how those wheeled rigs work. You move the scope to the desired location and then... what? The rubber tires looks they would bounce or could even change inflation pressure during a cold night. Is there a mechanism that lifts all three wheels off the ground to stabilize everything after you've set the mount in place? Can you put this on grass or dirt and still level it?

I finally had to built my permanent assembly (only after convincing the wife it wouldn't require a new mount) because I got ultra-tired of the setup and teardowns...

[hottr6]

As you can see in the attached picture, the ScopeBuggy comes with leveling screws. The stock screws are junk with little plastic handles. I replaced them with longer S/S screws with machinists self-leveling feet, and motorized them with an battery-powered drill.

The pneumatic tires do develop a flat spot if left, so I always store the rig elevated. Set up requires that I lower the rig, pull it out of the shop to my observing spot in the dirt driveway. I have permanently positioned surveyors marks that locate the leveling screws. First I lower one screw, then rotate the whole rig in azimuth until the other two screws are over their respective surveyors marks, and then elevate the rig. Set up takes less than 2 minutes, honest! I spend more time carting my EP case, chair, table, atlas', and other assorted junk.

Orientation of the rig may not be acceptable for AP, but great for visual. Tracking keeps an object in the field of view at 130x for over an hour.

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[seryddwr]

Are there any of the smaller Byers mounts (like the 812 or 58) that have a full worm on the RA?

Edit:(I know the 812 has a sector drive)

[George N]

Are there any of the smaller Byers mounts (like the 812 or 58) that have a full worm on the RA?

Edit:(I know the 812 has a sector drive)

Years ago I used an 812 for about 2 years. I later owned a 58 for about 8 years. The 58 is a fine mount, but much smaller and lower in carry capacity compared to an 812. I sold my 58 (and bought an MI-250) to get increased weight capacity. …..and to answer your question, the 58 has full diameter RA and Dec gears – no re-sets like the 812. I also had a nice polar scope for my 58 that really worked well, as did the setting circles.

[maknewtnut]

I've owned 2. Superb for payload capacity capabilities for those that don't have need for GOTO.