300p dobs project

[Stephen Greenfield]

Well the 300mm skywatcher OTA arrived :-), its big , bigger than i thought, and still cant get my head around the 2 ich eyepieces.

I am going to build a Dobsonian base for it.

NOw it comes with 2 mount rings and these have threads which would be ameniable to attaching two circular bits of thick marine ply instead of making a box for the tube

Just wondering regarding the bearings , any resources in the UK

and what about the base bearing , on the 4.5 inch dobs i made i used upturned castor wheels but would like to hear what others have done

[joner]

I'm sure you will have great fun with it, Enjoy .

[Polar Bear]

Well the 300mm skywatcher OTA arrived :-), its big , bigger than i thought, and still cant get my head around the 2 ich eyepieces.

I am going to build a Dobsonian base for it.

NOw it comes with 2 mount rings and these have threads which would be ameniable to attaching two circular bits of thick marine ply instead of making a box for the tube

Just wondering regarding the bearings , any resources in the UK

and what about the base bearing , on the 4.5 inch dobs i made i used upturned castor wheels but would like to hear what others have done

From my experiences with such things I would consider MDF (HDF if you can find it)

It is easier to cut , work and finish than Plywood

Kitchen suppliers sell bearings that are in a circular plastic shell and ideal for Dob bases have a trawl of the web

I have used large thrust bearings and nylon drawer sliders for the base.

keep us updated , have fun

Paul

[Trull]

Search online for etched teflon sheet - then cut to suit, and glue with two part epoxy. This will make a great bearing - the other side can be formica, or (my favourite) aluminium sheet, cut and bend to suit your needs.

Have fun.

[yesyes]

How about something like that for bearings?

Roller Balls 1" - pkg of 6

[yesyes]

Don't know if the balls in these roll easily enough. If they do, they would be good bearings for a dob base I think.

10 X BRASS BODY ROLLER BALL DOOR CATCH 13MM + SCREWS on eBay (end time 27-Dec-10 08:54:50 GMT)

[Stephen Greenfield]

Well making a start.

Got two 4cm thick circular wooden bread boards to attach to the scope rings for ALT bearings and will cover the edges in worktop edging.

Bought some hockey pucks for the feet

One have the bread boards attacked will make the base.

Now some say use marine ply and others say mdf ok. What do people thick , was going to use 18mm thickness, is this sturdy enough for a 12 inch OTA (full metal tube)

Teflon for bearings.

Now , as a 'way down the line' thing , but would like to make sure can accomodate it, what about tracking , is it possible ? I saw an equatorial platform but it was £400 !!!!!!

[Stephen Greenfield]

Well, finally had some time to myself and so got on with the project. Used mixture of 18mm mdf and ply for the construction. Used round 4cm thick boards for the alt bearings attached to the scope rings then they were wrapped in laminate strip ( had some surface texture) on Teflon sheet. Base bearing made from an LP record and Teflon furniture moving pads. Then used 3 ice hockey pucks for the feet. Few bits and pieces like handles left but for the most part done , it's ugly , it's big and heavy bit its mne and looking forward to seeing through the scope, so no doubt cloudy for a month

[yesyes]

pictures please!

[paul mc c]

We love pictures !!!!!

[Stephen Greenfield]

Pics will be posted when made less ugly lol. Added an eyepiece holder and canding some of the bolts and needs a paint. BUt none the less, managed to get first light last night and despite a nearly full moon and its proximity to orion was able to get some views of the orion nebula and make out detail. also managed to get some views of jupiter and was very impressed. As much as it pains me to say it as a man , size does matter .

Still some minor balance problems when switching from a 2 inch to a 1 1/4 inch eye piece , however have invested in some heavy magnets to use on the OTA to remedy this.

Also successfuly collimated for the first time and easier than i thought

now have to sort out the focuser to smooth it out .