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Dob Base Question

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#1 mattalan

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Posted 13 August 2019 - 02:27 AM

Greetings all, 

 

Just a quick inquiry into the quality/durability of Orion Dobsonian bases. Can anyone comment on their experiences with them or how well they hold up? I know they are made from MDF board or something similar, I was just curious to know how durable they are. Orion Dobs seem to have great reputations, especially the OTAs, but I have read a few minor gripes about the bases cracking. Also, does anyone know of any custom aftermarket bases for them? Especially the goto XTg versions? It seems like a simple undertaking, however, my carpentry skills are not so savvy. 

 

Thanks for your time! 

 

 


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#2 stargazer193857

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Posted 13 August 2019 - 03:02 AM

I had a particle board base of Orion's. I don't know what moisture it was ever exposed to, but it held up. Just the extreme edges had worn off 1/4". I suspect plywood would not have worn but only scratched.

As for go-to, if you have the motors, there are people like Dennis Steel at Dobstuff who can duplicate any particle board base you want in plywood. There are others, who will be listed soon.

#3 kfiscus

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Posted 13 August 2019 - 01:38 PM

The base will last a long time if you are careful to keep it dry or get it dried off right after use.  The areas of concern are the edges and around the vinyl edging that covers the edges.


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#4 Eddgie

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Posted 13 August 2019 - 02:34 PM

My 12" has been stored outside on my covered patio for six years. 

 

Once, I set it up in the sun several hours before sunset and the sun and heat (it is 104 degrees in Austin today) caused the black covering on the particle board to wrinkle and shrink very slightly, but it did not delaminate.

 

Twice, the base has been submerged in 10" of water when my back yard flooded. This completely submerged the bottom electronics. The MDF did not swell anywhere that was submerged and after cleaning, the drive worked fine.

 

Now, after six years, it does not look pretty, but other than the cosmetics, the base solid and free of any sign of saggind, swelling or splitting. 

 

So, while you can inflict cosmetic damage on it (I would not let it sit in the sun) the base appears to be quite durable and capable of withstanding a lot of neglect.  (and this might seem like a bad reflection on me, but I would not own this telescope if I had to baby it. When I bought it, it was with the intention of keeping it outside.  I can be observing in 2 minutes and that is worth the price of having a dirty and dingy looking scope.)


Edited by Eddgie, 13 August 2019 - 02:36 PM.

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#5 havasman

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Posted 13 August 2019 - 03:29 PM

My XT10i is at least 3rd- and probably 4th- hand and I've had it for 7 years or so. Our dark site is subject to heavy dew and frost conditions 80% of the time and here at home maybe only 60%. The scope has regularly had water dripping off both the tube and base at the end of a session. I very seldom dry it off but just let it evaporate in the vehicle on the way home or in the garage. The base looks fine with ZERO swelling or splits along the seams. I've read the stories but my experience is completely different. I think they're close to bulletproof.



#6 aeajr

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Posted 13 August 2019 - 03:43 PM

My experience is that they are extremely durable.  Just don't take them swimming or leave them out in the rain.  ;)



#7 tomykay12

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Posted 13 August 2019 - 05:50 PM

They are not MDF, but arguably the cheapest, ugliest chip board core on the planet with a Melamine finish and cheap vinyl "t" moulding. Some are edge taped. Maybe Ikea furniture and cabinetry is worse, IDK. Melamine is not an exterior material, but I understand why they use it.

 

If you want one of these dobs, accept the base for what it is, and when it becomes an issue, just deal with it.


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#8 Solar Ken

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Posted 13 August 2019 - 11:51 PM

I had an Orion XX12i before I upgraded to a 12.5 Obsession. It was a very good scope. The mirror seemed good, even got compliments from more experienced observers on the view. The base held up well, although the material on the edge lifted in a couple of places. A bit of glue fixed that.



#9 Jon Isaacs

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Posted 14 August 2019 - 04:40 AM

They are not MDF, but arguably the cheapest, ugliest chip board core on the planet with a Melamine finish and cheap vinyl "t" moulding. Some are edge taped. Maybe Ikea furniture and cabinetry is worse, IDK. Melamine is not an exterior material, but I understand why they use it.

 

If you want one of these dobs, accept the base for what it is, and when it becomes an issue, just deal with it.

My 10 inch GSO Dob is 17 years old. It was one year old when I bought it and it had been out in the rain at least once.  The edge tape had come loose already but the base was always functional and never delaminated.  

 

Last year, Tomykay12 decided it was time to redo my base.  He removed all the edge taping, retaped it with some much better quality edge tape, painted it with heavy duty hammertone paint and reassembled it with glue.  It's now much better than it ever was, looks better than it ever did and will probably outlive me.

 

GSO Dob Base refinished.jpg
 
Jon

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#10 lakland5

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Posted 14 August 2019 - 06:16 AM

Interesting replies, thanks to everyone.
My XT10's base is cosmetically and structurally fine, even though I am at least the third owner. However, despite routine cleaning and Jon's-trick-soaping the az surfaces (pads and rocker box underside), the az motions continue to be quite stiff. I'm considering putting laminate on the base underside. Anyone got experience with that kind of mod on these?
Thanks--
RicA

#11 KerryR

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Posted 14 August 2019 - 08:48 AM

Interesting replies, thanks to everyone.
My XT10's base is cosmetically and structurally fine, even though I am at least the third owner. However, despite routine cleaning and Jon's-trick-soaping the az surfaces (pads and rocker box underside), the az motions continue to be quite stiff. I'm considering putting laminate on the base underside. Anyone got experience with that kind of mod on these?
Thanks--
RicA

I added Ebony Star laminate to my XT8, though this was many years ago. It helped a lot. On my 10" Dob, I used the knobbly fiberglass wall-board that's used for covering wet-prone surfaces. This worked extremely well, better, IMO, than the Ebony Star I tried first. It's worth a try if you can't find a good laminate (Classic Ebony Star is very difficult to find, and is no longer made, apparently). Building material re-sale stores often have smaller chunks of this stuff for pennies. It's said to work better on heavier scopes, less so on lighter scopes.

Have you tried adding a stack of "milk-jug" washers to the pivot bolt to reduce the weight on the AZ pads? I find this mod very useful for costomizing AZ friction...


Edited by KerryR, 14 August 2019 - 08:48 AM.


#12 lakland5

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Posted 14 August 2019 - 09:26 AM

...

Have you tried adding a stack of "milk-jug" washers to the pivot bolt to reduce the weight on the AZ pads? I find this mod very useful for costomizing AZ friction...

Thanks KerryR!

Yes, I have tinkered a lot with the milk jug washers, and it helps, but "buttery smooth" most certainly eludes me.   A buddy in the trades referred me to his countertop makers to see about a sink-cutout remnant of laminate, which is what prompted my query.

Best

RicA



#13 tomykay12

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Posted 14 August 2019 - 11:39 AM

My xt10i base underside was worn pretty much completely smooth, resulting in a very sticky azimuth motion. I got a scrap of Formica 909-42, roughly equivalent to Wilsonart Ebony star, and laminated it to the base. Easy fix.


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#14 mjulihn

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Posted 14 August 2019 - 12:05 PM

My Z8 has a roller bearing turntable in the base that creates incredibly smooth azimuth movement. Could your Orion base be retrofitted with one? Better yet, why doesn't Orion use this simple, no-maintenance solution as well? 


Edited by mjulihn, 14 August 2019 - 12:08 PM.


#15 KerryR

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Posted 14 August 2019 - 12:55 PM

My Z8 has a roller bearing turntable in the base that creates incredibly smooth azimuth movement. Could your Orion base be retrofitted with one? Better yet, why doesn't Orion use this simple, no-maintenance solution as well? 

One issue with the 'lazy susan bearing mod' is that it can make the AZ motions too frictionless-- making them move too easily, rather than 'buttery'. The mod works well if ways of adding and controlling friction are in place without adding excessive stick-slip uppon movement initiation, but many folks miss this critical aspect, and their AZ movements almost blow in the breeze. (Similar roller bearing mods can be done in ALT, with the same caveats.)

Ideally, both ALT and AZ will have the same level of friction, with neither requiring excessive pressure followed by drastic reduction in pressure to avoid over-shooting the target (stick/slip). It's fine if both movements require effort, or are otherwise stiff. What's really critical is that the force required to initiate movement is as close as possible to the force required to maintain movement-- that's really the critical element in the classic 'buttery smooth' movements of a well executed Dob mount, and it's what makes a good Dob avoid over-shoot or balance over-sensitivity.


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#16 kfiscus

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Posted 14 August 2019 - 08:45 PM

Consider using FRP and Teflon for your azimuth bearing.  The trick is to use slightly larger Teflon blocks (1.5"x1.5") and bevel the blocks' edges to 45 degrees.  FRP is Fiber Reinforced Plastic, the bumpy stuff that lines restaurant kitchen walls.  It is cheap and very easily cut and sanded.  I buy mine at Home Depot for $23 for a 4x8 sheet.


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#17 Jon Isaacs

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Posted 15 August 2019 - 07:45 AM

Greetings all, 

 

Just a quick inquiry into the quality/durability of Orion Dobsonian bases. Can anyone comment on their experiences with them or how well they hold up? I know they are made from MDF board or something similar, I was just curious to know how durable they are. Orion Dobs seem to have great reputations, especially the OTAs, but I have read a few minor gripes about the bases cracking. Also, does anyone know of any custom aftermarket bases for them? Especially the goto XTg versions? It seems like a simple undertaking, however, my carpentry skills are not so savvy. 

 

Thanks for your time! 

 

Hi:

 

Regarding someone who makes custom bases for Orion Dobs:

 

The previous poster, Ken Fiscus, is, by day, a nationally recognized high school science teacher. But on those cloudy nights when he's not outside with a telescope, he builds high quality replacement bases for Orion and other "commercial Dobs."  I don't know if he builds bases for the GOTO Dobs or not..

 

https://m.albertleat...-moon-and-back/

 

Jon


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#18 mjulihn

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Posted 15 August 2019 - 11:05 AM

One issue with the 'lazy susan bearing mod' is that it can make the AZ motions too frictionless-- making them move too easily, rather than 'buttery'. The mod works well if ways of adding and controlling friction are in place without adding excessive stick-slip uppon movement initiation, but many folks miss this critical aspect, and their AZ movements almost blow in the breeze. (Similar roller bearing mods can be done in ALT, with the same caveats.)

Ideally, both ALT and AZ will have the same level of friction, with neither requiring excessive pressure followed by drastic reduction in pressure to avoid over-shooting the target (stick/slip). It's fine if both movements require effort, or are otherwise stiff. What's really critical is that the force required to initiate movement is as close as possible to the force required to maintain movement-- that's really the critical element in the classic 'buttery smooth' movements of a well executed Dob mount, and it's what makes a good Dob avoid over-shoot or balance over-sensitivity.

I totally agree. Roller bearings do allow for very low friction movement. Zhumell uses a threaded knob on the AZ pivot to adjust the amount of friction, which seems to work well. 

 

NOTE:

This threaded knob gets replaced with a simple bolt when installing the Romer Push-To kit, but you can still snug the bolt down to get the desireable amount of friction on the bearings.


Edited by mjulihn, 15 August 2019 - 03:57 PM.


#19 junomike

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Posted 15 August 2019 - 05:45 PM

No complaints from me regarding my xx16g and AT12 (riding on a SW 12 Base).




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