In another thread I have a few pics of my 1870 pillow block mount. A beautiful bit of Victorian engineering of Brass and Cast Iron. With the exception of the RA Setting Circle, RA gear and worm and Tangent arm the mount is complete. Today I bit the bullet and bought a sheet of Brass 220 x 660 x 6mm with intention of cutting 2 8" circles, glueing them together (somehow) and engraving them with the hours. Photo's to come in the morning of this plus other bits for the tangent arm. Will be asking a few questions…. Matt
I know Mike, I must be slightly out of my mind....but it has to be done
Here is a shot of the mount with an extension to the dovetail. I needed to add a couple of tube clamps (until I get a pair of Parallax 155's)
The longer dovetail will be one part of the tangent arm.
Here is the rest of the bits a' before' photo.
And a photo of the Dec setting circle that is complete. Hopefully you can see the recessed groove in the middle...going to replicate this on the RA...
Also to be replaced is the slightly suspect counterweight rod, although this one works as is!
In the second picture is a 360 tooth gear and matching worm (not shown) I'll need to machine a 1 1/8" hole for the RA shaft and design and build a friction clutch. Other bits....Brakes on RA and Dec shafts.
A brass bush for the 360 tooth gear to sit on the RA shaft and that's it. At least it's on the RA shaft. I swing between this and the Dec tangent arm as the inspiration takes me, it's going to be a while before either is finished….
I realised when friends were looking through this scope and mount that it's OK for me to use as is, but for everyone else it isn't. How do I explain how to grab the scope and move it by hand….very difficult.
Progress!! So far I have managed to make two brass 8" circles 6mm thick each and a 3mm thick aluminium slightly smaller circle. The aluminium one will be spay painted gold to match (hopefully) polished brass. I was going to cut 2mm out from each brass disc but chickened out as I had no confidence that it would work. These disc's need to be JB welded together and have centre shaft hole cut and engraved....the tricky bit. All this has been done by hand with my drill press and jigsaw, somewhere around 25hrs of work/enjoyment. I know it's a bit mad to do it by hand instead of going to a machine shop, but that is my idea of DIY....Do It Yourself
Here is a bit more. So far I have been madly producing huge amounts of aluminium shavings....this stuff gets everywhere! I have still to engrave the circles but they have been joined by the RA 360 tooth gear and some aluminium discs which are all part of a friction clutch. More to come. The counterweight shaft is new too, an improvement over the old bit of plumbing. A question for anyone who can answer. I presume there won't be too much trouble with scope movement via the worm and friction clutch as the scope ,when balanced didn't move from where it was pointing. So what to use on the discs that provide enough friction but still movable via the clutch? I'm thinking chopping board ie white HTPE stuff? or Teflon? Matt
That's my' man cave' Mike...every bloke should have one! All 3 of my scopes live out there. It's where I have built the 6" f12 and now doing the mount parts, just my trusty and slightly dodgy drill press and bench vise and a couple of other tools like jigsaw and power drill. Here is some more...on a roll with this so I just keep at it while the inspiration is there.
The friction clutch is pretty much together ,and it works, not that I ever thought it wouldn't Next on the menu is the mounting plate for the worm gear. Still need to make the worm block too.
Some more pics
The new counterweight bar with three Skywatcher weights. These are going to painted 'Gaunt' gloss black.
Hi Mike, All brass is cut with a jigsaw and finished off with a cutting tool in the drill press, the edges are cleaned up with a paint removing tool. Just takes lots of time constantly checking etc The smaller aluminium discs are cut with bimetal hole saws which is dead easy! Improvising as I go along.....nothing dangerous (I need my hands, eyes and fingers) I have done a small redesign and replaced 12mm aluminium discs with 6mm thick brass ones. I'm limited with this mount in the length of shaft on the RA to play with. There are more bolts now grabbing onto the RA shaft too. Lastly have bolted on a worm mounting plate using existing bolt holes. A picture is worth a thousand words so here are three more pics. I had no idea of what it would look like when I started but this is taking on a very 'Steam Punk' look which I like a lot!
All this will be a visual use only so I hope that it will work....I'll find out when the worm block is done.
That is a really sophisticated solution to the problem you were faced with. Doubt if I could have conjured up something that good in a month of Sundays! Looking forward to pictures of the completed instrument.
Phoenix 204 WFT Black Beauty 150/750 R50 Semi APO in Skylight Telescopes custom build
Thanks Ian. It's grown bigger than I thought or ever imagined. The simple thing would have been to have the gear with a simple bolt to bind it to the shaft and undo the bolt to move the scope, but..... Just to show my process here is the worm block mocked up in wood, so much easier to cut bits off to get it to fit. Then it's on to making it out of aluminium...what fun and frustration that will be! The good news..it works!!! Have turned the mount in RA and have moved it with the friction clutch doing it's job...so happy.