28 replies to this topic

[Mak2007]

Hello,
I have seen occasionally photos of long refractors mounted on dobsonian wooden mounts ( (for example here) .
Do you know if there is a book or website that shows how to make one? Or is there somebody that makes them?
Thanks!

[beatlejuice]

Build Your Own Telescope by Richard Berry. This is where I first saw this type of mount. Good read even if you are not planning to build anything.

Eric

[schang]

Hello,
I have seen occasionally photos of long refractors mounted on dobsonian wooden mounts ( (for example here) .
Do you know if there is a book or website that shows how to make one? Or is there somebody that makes them?
Thanks!

Yes, that somebody is me:cool:
You do not see many DIYers making this kind of mount now a day. Most just buy goto or tracking mounts. Let alone tripod. Here is a pic of my crutch tripod finished recently

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[schang]

Here is a pic of a Dobsonian mount on crutch tripod

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[schang]

Here is a pic of the mount minus the scope

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[schang]

If you have rings on your refractor, you will need to look carefully what your ring configuration is, and adapt accordingly to connect your rings to the side boards/bearing and rocker cradle. Since each scope comes with different ring configuration, so building this dob mount is basically a custom made project, and requires a little more planning before you start. You do need skills in woodworking and tools to make the job easier. Good luck.

[TONGKW]

I have built one with a Meade AR5 refractor OTA (5” f/9.5) for the kids to look at the moon and search other sky objects themselves.
This mount does not require counterweight and is made from surplus wood particle board, wood pieces, plastic disc, and Teflon pads etc.
In actual use, I find it is rather difficult to track at high magnification without slow motion control by nudging the OTA.

K W TONG
C8+CG5 GT, TSA102+HEQ5 PRO, MK67+Voyager, NexStar 6SE, C5+Mizar K, WO ZS80FD+Kenko NES, Megrez 72FD+Kenko KDS, Mini Borg 50, PST

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[schang]

The mount as built this way is quite stable and behaves just like a dobsonian. Here is a link that describes its use.

http://www.cloudynig...php?item_id=851

I originally used furniture leg pads for the altitude bearing, and no pads for the azimuth bearing. The operation is not as smooth at high mags. Later I put HDPE pads on the azimuth and altitude rocker cradle, the issues were gone. It is now very smooth at high mags. I think the keys are large azimuth base (8" diameter) and altitude bearing (5" diameter) in my case.

[pogobbler]

I just completed one of these types of mounts, myself, for use with a Celestron 100mm f/9.8 achro and Orion 120mm f/5 achro. I'm a pretty inexperienced woodworker and managed to do a credible job without any plans other than what I drew up after looking at pictures of several different mounts of this type, including the one in the Berry book mention, a book which I have and recommend, as well.

It's really not a hard mount to make... I got it right on only my second try. :-) On my first, both bearings were really too small, so I rebuilt what I needed to with larger diameter bearings; I can't recall the exact size, but they're somewhere between 8" and 10", I think. They were the smallest size I could easily do with my router, so I went with that. The altitude bearings are half circles of that same diameter. I got some teflon in the mail that I'd ordered, so I replaced the furniture gliders I was using before with that. A trial last night proved it to be a superb mount, with good damping characteristics, only a small amount of movement when focusing, and smooth, easy motion even at high power.

I should note that I just made the upper part of the mount, the "Dob" part of it. I already had a good, adjustable, heavy duty, wood surveyors-type tripod I got years ago that's nice and sturdy.

Unlike some, I didn't use tube rings with mine. One less thing to spend money on, I figured. Instead I just basically built a box with felt lined holes at either end to stick the telescope tube through, attached the altitude bearings on the sides, and put a handle on top to carry it. I just move the scope forward or back to balance with a medium weight eyepiece and I'm good to go. I have each scope mounted in its own box, ready to put on the mount at a moment's notice. The whole thing is made of 1/2" plywood, so is pretty lightweight. Very "grab and go".

[schang]

I am glad to hear that there are still some die hard souls out there who would take the challenge of building obsolete things like this (but very effective for its intended purpose)

Both rings and box configurations work fine...with rings it take more effort to get it fit right. The rings came with the scope when I bought it used recently, so it makes sense to do it that way.

[Jon Isaacs]

I have built one with a Meade AR5 refractor OTA (5” f/9.5) for the kids to look at the moon and search other sky objects themselves.
This mount does not require counterweight and is made from surplus wood particle board, wood pieces, plastic disc, and Teflon pads etc.
In actual use, I find it is rather difficult to track at high magnification without slow motion control by nudging the OTA.

K W TONG
C8+CG5 GT, TSA102+HEQ5 PRO, MK67+Voyager, NexStar 6SE, C5+Mizar K, WO ZS80FD+Kenko NES, Megrez 72FD+Kenko KDS, Mini Borg 50, PST

Interesting build. The footprint looks quite narrow to me and it seems like a good bump could topple it over? With a refractor mount, I like the tripod to have a large footprint in relation to it's height.

Jon

[eklf]

I built a dobsonian style mount for my 8" SCT which can also accommodate 80mm f5, 102mm f10, 127mm f6.5 refractors as well as 20x80 binoculars (all on vixen dovetails). Works very well. I also built one that looks similar to TONGKW mount (will post picture later today).

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[TONGKW]

I have built one with a Meade AR5 refractor OTA ...........
......................

Interesting build. The footprint looks quite narrow to me and it seems like a good bump could topple it over? With a refractor mount, I like the tripod to have a large footprint in relation to it's height.
Jon

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The tripod is quite substantial using 2” x 2” hard wood.
The set up is working all right so far as we always have a club member guiding the school children in their effort to point the OTA to a sky object.
To lessen the chance of the set up toppling over, I shall undertake to increase the footprint of the tripod a bit.

[Mak2007]

Thank you everybody.
I love them, I love the color of the wood. Where can I find instructions to make one mount like this?

[Zoomit]

It's hard to call a refractor with large altitude trunnions on a tripod a "Dobsonian-style" mount. That alt/az arrangement predates the late John Dobson.

Here's a picture of a temporary setup that matched my AP130GT with an XT8 rocker box. This is probably as close as you can get to a "Dobsonian" refractor...without putting the lens cell in a Sonotube and making a PVC pipe focuser.

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[schang]

Thank you everybody.
I love them, I love the color of the wood. Where can I find instructions to make one mount like this?

Thanks. I built mine without instructions, just by simply eyeballing the pics on the Internet. I do not have the habits of documenting mine either. It was more like planning/building with whatever materials I have or can buy at local stores. Trust me, it is not complicated, just take time and measurements and you will get there.

The altitude bearing is about 5" diameter PVC pipe connector that I found at HD (~ $4) that I cut it into two pieces. If you want to make a crutch tripod which you already have, then the azimuth base plate is 8" diameter, 3/4" or 1" plywood. If you do not have crutches, you can go to the local Goodwill store, sometime they carry them for about $2 a set. Craglist also has them but cost more. Each scope is different, so just use your creativity and imagination, then measure, cut, and fit.

[opticsguy]

Here is mine based on Berry's book.

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[Zoomit]

Go Ducks!

[schang]

Here is mine based on Berry's book.

That is a great looking mount and tripod. I saw that you are using a stick (solar?) finder on your scope? I have thought about that, but chose to use a PVC pipe finder on top of my C102AZ (see my earlier photo).

[Mak2007]

That is a unique and beautiful scope.

[opticsguy]

The "stick" you see is actually a rod for sliding the small weights used for balance.

[schang]

The "stick" you see is actually a rod for sliding the small weights used for balance.

Okay... The rod position is rather in the back section, which prevents me from thinking that it is for the weight balancing function...I am thinking doing that as well. Usually it is when I use a heavy eyepiece the balance of the scope would be affected. I can adjust it by loosening the ring nuts and push the OTA up... but it is not convenient. I'd rather use a magnet moving along a thin strip of steel attached to the middle-upper part of the OTA (via double sided tape) for counter balance. Not an elaborate solution but simpler and easier, I think.

[opticsguy]

The JD scope rarely needs balancing unless I use two extremely different weighted eyepieces. Perfect balance would require a similar amount of weight on the opposite side of the OTA, but not needed for this setup.

[schang]

The JD scope rarely needs balancing unless I use two extremely different weighted eyepieces. Perfect balance would require a similar amount of weight on the opposite side of the OTA, but not needed for this setup.

If I change eyepieces between Plossls, I do not have balancing problem. However, with that ES 4.7mm 82 degrees eyepiece, the scope would tend to tip backward slightly. I can imagine an even heavier eyepiece can become a problem which requires adjustment...

[eklf]

Here is my 102/f9.8 refractor on a dob-style mount.

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