12" Dob Choice...

[johninderby]

I have just the thing. An RC Tiger tank chassis which would easily handle the weight of a 12” dob. Must get back to the build soon. 😁 

Downside is you could buy a new small car for the price of the tank. 😁

Edited October 4, 2021 by johninderby

[Ian McCallum]

I recently sold my late mum's mobility scooter.  She had an outside, lockable storage box for it.  It could easily accommodate a large Dobsonian, outside.  My main concern would be damp getting into the wooden rocker base...

[johninderby]

The mdf (or chipboard) dob bases do indeed suffer if they get wet but the dampness inside covered storage shouldn’t be a problem and should last for years. Best thing is to build a marine ply dob base which will last indefinitely but proper ply isn’t cheap nowadays.

Edited October 5, 2021 by johninderby

[Ian McCallum]

1 hour ago, johninderby said:

The mdf dob bases do indeed suffer if they get wet but the dampness inside covered storage shouldn’t be a problem and should last for years. Best thing is to build a marine ply dob base which will last indefinitely but proper ply isn’t cheap nowadays.

One thing I've came across recently and slightly related is, spray on yacht varnish (aerosol). 

[johninderby]

Sealing the edges will help as that’s where the moisture gets in. 

[John]

1 hour ago, johninderby said:

The mdf dob bases do indeed suffer if they get wet but the dampness inside covered storage shouldn’t be a problem and should last for years. Best thing is to build a marine ply dob base which will last indefinitely but proper ply isn’t cheap nowadays.

This sort of mount is highly recommended by me

Quality plywood is an excellent material plus it weighs quite a bit less than the MDF used in the stock mounts. The mount on my 12 inch dob is baltic plywood and weighs around 10kg:

 

[Ian McCallum]

1 hour ago, John said:

The mount on my 12 inch dob is baltic plywood

 

 

Does that mean it get's cold quicker?🤔😂

[Louis D]

13 minutes ago, Ian McCallum said:

Does that mean it get's cold quicker?🤔😂

Does Baltic plywood ever get dark enough to use in the summer? 😉

[Peter Drew]

Which Dobsonians use MDF?  All my commercial Dobsonians, Orion USA and Skywatcher are chipboard covered with a sort of melamine coating.

[Nyctimene]

6 hours ago, Ian McCallum said:

My main concern would be damp getting into the wooden rocker base...

You could substitute the MDF base for this metal one:

https://www.teleskop-express.de/shop/product_info.php/info/p5637_Orion-UK-Dobsonian-mount-for-300mm-aperture-Newtonian-Telescopes.html

13 kgs, so much lighter than a MDF base.

Stephan

[John]

1 hour ago, Peter Drew said:

Which Dobsonians use MDF?  All my commercial Dobsonians, Orion USA and Skywatcher are chipboard covered with a sort of melamine coating.

My mistake - I thought that material was MDF. I now realise that MDF is fibreboard, rather than chipboard.

The material that the commercial dobs use is heavy though.

 

 

[Second Time Around]

2 hours ago, Nyctimene said:

You could substitute the MDF base for this metal one:

https://www.teleskop-express.de/shop/product_info.php/info/p5637_Orion-UK-Dobsonian-mount-for-300mm-aperture-Newtonian-Telescopes.html

13 kgs, so much lighter than a MDF base.

Stephan

I have that Orion Optics UK (OOUK) base for both my 8 and 10 inch Dobs.  They're expensive but superb!

However, if you buy one do make sure you also order the variable friction brake that comes as an accessory.

You also need to be aware that these mounts are made for OOUK's own Dobs that have smaller tubes than mass market scopes.  However, they'll make any size you want to order.  You'd almost certainly have to wait for a standard size one anyway.  Do be aware though that they have a reputation for quoting optimistic delivery times.

Not only are these Dob mounts lighter, they're also smaller in size, which makes them even easier to carry.  As a result I found that I could carry a scope one size up compared with one with a wooden base.  Talking of carrying, it's a great help to get OOUK to put on a couple of handles near the top of the base.

The other great thing is that they're exceptionally smooth.  I compared them with several mass market Dob mounts, and the only one that even came anywhere near close was the Bresser.

Edited October 4, 2021 by Second Time Around

[Louis D]

3 hours ago, Peter Drew said:

Which Dobsonians use MDF?  All my commercial Dobsonians, Orion USA and Skywatcher are chipboard covered with a sort of melamine coating.

When did this changeover from MDF to OSB occur?  20 years ago, MDF was the go-to wood product for Chinese made scope bases, at least as sold in the US.

[Peter Drew]

I can't say that I've ever seen an MDF based commercial Dobsonian ???.   My self built 30" Dobsonian is definitely MDF.     🙂 

[John]

I think I caused this confusion by picking the wrong name for the material used in commercial dobs. Sorry about that

Thinking back to the last one that I owned (Meade Lightbridge 12 inch) I recall that the mount was made from chipboard with a white laminate coating. The Skywatcher and GSO dobs that I've owned in the past have mounts made of the same material.

I think MDF (Medium Density Fibreboard as I now know it to be) might have been used by Coulter Optical for the dobsonians that they marketed back in the 1980's but I'm not 100% sure.

 

[Ian McCallum]

It's kind of academic now, as the Sky-Watcher 300p from FLO has been sold, so is out of stock... 🙄

[Dave scutt]

On 04/10/2021 at 12:48, johninderby said:

I have just the thing. An RC Tiger tank chassis which would easily handle the weight of a 12” dob. Must get back to the build soon. 😁 

Downside is you could buy a new small car for the price of the tank. 😁

Dam wish I thought of that would look so much better 

[LondonNeil]

Ooo that looks decent as it is.  I've struck a deal for the classic skywatcher but not collected it yet due to the fuel issue.  I intend to keep it in the garage so it's not far from the garden.  I have a sack barrow too.

[Ian McCallum]

I did a bit more research and discovered that the base diameter on both versions I mentioned above, would be very tight going through my front door.☹️  I can see that being a problem, even using some type of dolly or platform with wheels.🙄

[Louis D]

How narrow is your front door?  Most construction codes dictate a minimum 32 inch wide front door; however, most are 36" wide.

[Ian McCallum]

6 hours ago, Louis D said:

How narrow is your front door?  Most construction codes dictate a minimum 32 inch wide front door; however, most are 36" wide.

28 inches, but the base of the dob is 25.5 inches. I'm in the UK, so US building codes don't apply. 

[John]

Another advantage of my bespoke dob mount.

 

 

[Louis D]

4 hours ago, Ian McCallum said:

28 inches, but the base of the dob is 25.5 inches. I'm in the UK, so US building codes don't apply. 

I'm guessing there's no ADA (Americans with Disabilities Act) equivalent in the UK dictating such things nationwide.  Getting a wheelchair through a 28 inch doorway would be a serious challenge.  Getting a washer/dryer set through that door would also be tight.

[johninderby]

The gov in the UK is finally getting around to legislating disability access for landloards ( The National Disability Strategy ). Minimum legal front door clear opening in the UK is 775mm but older houses may not be up to standard.

[Louis D]

1 hour ago, johninderby said:

The gov in the UK is finally getting around to legislating disability access for landloards ( The National Disability Strategy ). Minimum legal front door clear opening in the UK is 775mm but older houses may not be up to standard.

And I'm sure the UK has a LOT more older houses and multifamily dwellings (apartment buildings in US English) than the US to be grandfathered. 😉

However, if you do a major remodel (gutting interior walls, moving entrance doors, etc.), you may have to meet ADA guidelines during the permitting process of the redesign.

In the US under ADA guidelines, businesses have to make accommodations unless they can get protected historical status (like old basement pubs).

There was a lot of grumbling when the ADA was signed into law 31 years ago, but now it's just accepted as the current normal.  Things like office building ramps have turned out to be a boon for delivery folks with heavy pallets, so it's had unforeseen benefits.  Ample handicap accessible parking has been welcomed by the aging Boomer generation as well.