Pillow Block Mount Build

[MattT]

Now I have finished the Gaunt it's time to get on with a new project.

This one is a 2" Pillow Block Mount. What is involved in building an EQ mount?

Just a bunch of bits bolted together....just has to be the right bits

Opticraft in the US have a number of designs. I chose to do a copy of the Gaunt for this project. The mount needs:
1. To hold 40+kgs of scope...just a random figure I picked.
2. Adjustable in Alt and Az as much as possible.
3. Have a RA slipclutch and motor drive.
4. Tangent arm on the Dec...cause I like this more than gear and worm.

Tools used....low tech again. Drill press, Hand held Jigsaw, Bench Vice and Files. Lastly...time and lots of it.

The build so far....

I started in March this year buy buying 4 Pillow Block bearings of ebay. These came from Boltons in the UK and cost $35 each.
A pair of SFQD bushes from Sprokets in Yarraville. The qd bushes are the essential joiner between 2" shafts and aluminium plates, expensive things that cost $200 for the pair.
A pair of 500mm long Stainless Steel Precision shafts. Precision shafts are need as I don't have a lathe and are perfectly round and straight, they also weigh a lot of kg's. $250 each...
A bunch of bolts and washers from Metro bolts in Richmond.
A visit to the Aluminium Trade Centre for various amounts of Aluminium flat bar and sheet, then to George White for some Brass rod and 1.6mm flat sheet.

Also have bought a 10" slipclutch and worm with 12V stepper motor from Ed Byers in the US. To drive the gear a simple driver and hand control box that can slew up to 20x from AWRtech in the UK. Lastly Gary from Wildcard Inovations has supplied the encoders, cables and gearing for Argo Navis.

All that has been involved so far is cutting the aluminium to the correct size, drilling holes for the bearings and attaching the QD bushes. The hard part is designing what I want...lots of fun though.

The sides are 18mm thick made up of 3x6mm sheet JB'welded together with machine screws for added strength. Cutting 6mm sheet is easy with a jigsaw. Lots of fileing to smooth the edges.

Design is Steampunk...what else So the finishes will be Black and Brass.

Eventually it will sit on a pier in an Obs. The pier I'd like to make from a Victorian street light base, I see these things all round the place in Melbourne.

Some photos to start with. This is still in the building phase, here is what I have done so far.

L to R it starts with Aluminium and Brass Flat bar and Sheet. The counterweight section is still under construction.
Two views of the mount so far.

To be continued....couterweight section, that is a CW bar, next.

[Kunama]

Looks good Matt, Well Done so far !!!
Re the Victorian streetlight base, be careful you don't get hit by cars when 'obtaining' one

I am going to make a 1:5 scale version of the Gaunt Mount for my bookshelf !!!

[codemonkey (Lee)]

That looks awesome so far, congrats! I'd love to make my own mount.

What's the advantages of a slipclutch RA and a tangent arm DEC? I ask this question without knowing what the hell a slipclutch or tangent arm is ;-)

I wanted to learn a bit more about this kind of stuff and look at building a mount with harmonic drives... way, way out of my area of expertise, but it seems like a fun project.

[MattT]

Matt, I thought I'd be OK wearing one of those Hi Vis jackets....no? Actually a renovation Yard, like Steptoes here in Melbourne, might have what I want.

Lee, A slipclutch is in the photo below. The central part is bolted to the shaft and the slipping part is controled by the bolts and springs which press a teflon lined plate onto the bigger outer part with the teeth on it. There is a point when there is enough friction applied, via the springs and bolts, for the worm with motor attached to rotate the gear and scope at sideral rate. When you want to move the scope by hand that is possible too while the motor is still engaged....sounds harder than it is. A Tangent arm has a couple of parts, one attached to the telescope and the other bolted to the mount. The mount part needs to have a lock/unlock clamp of some description so you can move the scope in Declination and lock it in place. The design I used on the Gaunt has a threaded rod that has limited travel of 20º either side of a central position.
The Tangent is an old way of telscope control when gears were expensive and hard to make with accuracy. I still might just add a worm and gear on the Dec axis instead as it is possible to turn it into a GoTo mount with the right electrics. My idea is Argo Navis as the digital setting circles (DSC's) so GoTo isn't really needed, just tracking with a bit of slow slewing to centre objects.

Advantages of slipclutch...no noisy motors, other than that I dunno.
Advantages of Tangent....no motors at all, cheap to build, more threaded brass rod and gears visible and I love the control rods hanging off the end of a scope, in this case an 8" f10 R50 Refractor coming out from Istar next year.

I could have just gone out and bought an EQ8 or something like that but I'd rather build my own....

[mswhin63 (Malcolm)]

This is so very close to what i want to build for a larger scope. Very nice. I have some stainless steel rods 20mm diameter that I will be using for counterbalance rods.

[codemonkey (Lee)]

Awesome, thanks for the explanation Matt :-) I'll be following this thread.

[nebulosity. (Jo)]

This is an amazing build Matt, I am very inspired by your constructions!

I have had big ideas of building something like what you are, but so far have only got the shaft.

Will be keen to view your progress.

Cheers
Jo

[MattT]

Have been beavering away on the counterweight section...but first.
Malcolm, any plans etc...love to see more of this stuff here. Thanks Jo, your creations are first class...if you build a focuser this is easy(ish).

As this mount is for a refractor I have seen lots of 19th Century mounts. The first photo is where I got ideas from for the CW shaft. I could have done a 1" thick SS shaft but that is not really what I wanted and have built this. Made up of aluminium with the usual pile of bolts holding it all together. An SFQD bush will be bolted to the 2" shaft. The central shaft is 20mm thick and bolted at both ends. 5/16th brass threaded rod on the outside to stiffen the contraption up. Inside up to five Skywatcher 5 kg weights fit beautifully, don't think I'll ever need five.
Eventually the central shaft will be SS or perhaps Brass. I have a Brass rod that is .5mm too thick for the CW holes, so a lathe might just be around the corner...
Now this is together, is it too over the top I wonder? A 1" SS shaft might still be the go....

I weighed the mount...tips the scales at 44.3kgs so far

In the pipeline....Tangent arm...some kind of dovetail arrangement...RA gear assembly...Az adjustment....some form of plate to attach to a pier/tripod.

[MattT]

Originally Posted by Kunama

I am going to make a 1:5 scale version of the Gaunt Mount for my bookshelf !!!

First there was the Gaunt....then Mega Gaunt .....now baby Gaunt

You going to put a 50mm f12 refractor on it?

[Kunama]

Originally Posted by MattT

First there was the Gaunt....then Mega Gaunt .....now baby Gaunt

You going to put a 50mm f12 refractor on it?

I have a spare brass refractor 40mm f15

Re the counterweight shaft: bore out the counterweight rather than turning down the shaft.

[MattT]

Thanks Matt....your right. Now sporting a nice Brass shaft. Paint the rest of this satin black Have drilled out and threaded two 5/16th UNC grub screws in the qd bush, should hold it.

40mm f15 brass....nice. How old?

[AlexN]

This is looking sensational.

[MattT]

The tangent arm starts to take shape. Cut out with my Jigsaw and 102mm hole saw. This part of the tangent is being made with two 6mm thick pieces of aluminium with a 1.6mm thick sheet brass sandwiched inbetween....naturally the aluminium will be black and the brass polished, the lot being bolted together on both sides. This took about an hour of cutting.

[MattT]

Several hours later....two 6mm parts with 1.6mm brass sandwiched together. One half of my clamp assembly is in place, made up from 6-12-12mm aluminium JBed and bolted to the arm with 3x 5/16th bolts. The other half of the clamp is nearly finished, and like the Gaunt mount will slide up on 40x40mm blocks bolted to the wings on the outside. As I don't have a scope for this mount the other half of the tangent is part of the saddle plate.

[codemonkey (Lee)]

Looking good, Matt!

I've been thinking about building my own mount again lately. I think I'm going to have a crack at making a friction drive mount. Originally I was thinking of some ways that I could design the axes which required more machining done, but then I remembered this thread... I think the pillow block approach will be perfect!

Now I just have top stop spending all my money on filters and focusers so that I can start putting it towards a DIY mount.

Was there any particular reason why you went with the bushings that you did, and why they they were so expensive? Was it just because of the shaft size?

[MattT]

Hi Lee,
I know there are cheaper PB bearings out there. I chose these for the compact size as well as the 50mm shaft size. There wasn't a lot of choice at the 2" shaft size. 2" is massive in real life The bearings with bolts on the outsiude were all wider than the standard 160mm Aluminium flat bar I used, which is why I went for compact. I didn't expect the SS shafts or the qd bushes to cost as much as they did either Cest la vie

1.5" would have been cheaper but was too close to the 1 1/8" size of the Gaunt mount.

Will have a few photos soon of the tangent arm, which is nearing completion....slowly. Lots of drilling and tapping of the clamping section going on...I'm waiting on the RA electrics from AWR Tech in the UK before deciding how to attach the worm, gear and motor. It should be shipped next week I hope.

[MattT]

Here is progress to date...a lot of drilling and tapping for this part which is the clamping section to the Dec axis. Just like the Gaunt only everything is bigger. The Gaunt has 5/16 bolts and threaded rod with 8mm brass rods. This mount has m12 bolts m12 threaded rods and couplers and eventually 12mm brass rods. There will be a central m12 lock bit on this mount too to help keep it in place. Up front I added a small brass counterweight. Solid as and weighing quite a lot more than it did before. One more part to build and then the tangent is done....sometimes I think it would have been easier to get a 7" Byers drive for the Dec...

[MattT]

The tangent so far. This part is so simple on paper but so fiddly to build.
Not the prettiest part, steampunkig happening later The cylinder block is a 40x40mm Aluminium block with a 20mm cylinder and in that a 12mm cylinder threaded for 5/16th brass rod. Both cylinders move... up and down for the 12mm and back and forth for the 20mm which allows the rod to stay straight

A pair of brass bevel gears will have a brass rod for slomo hand control to the back of the scope. Only taken about 10 hrs in the shed to get this right I must be nuts. Lottas fun though

Quite a bit of range in Dec with this...maybe 20º either side of centre.

The RA electrics, hand control and stepper motor driver, from AWRtech in the UK has been built and is in the post.

[MattT]

The tangent now works. Made a knob for the side...an experimental knob that I like. The control rods for the clamp and slomo hand knob...which is an old one from Matti that came with the Gaunt...are going to be held in place with brackets on the top plate of the tangent and move with the tangent arm as it travels across. All possible with double universal joints in the photos

The three rods will be brass 8mm for the slomo and 12mm for both sides of the clamp. The movement is nice and smooth...not bad for a drill press.

[Kunama]

Have you organized a crane to lift it onto a pier Matt?

I think a 220mm F15 Istar will sit nicely on that mount...... I know where there is one which is still awaiting a mount to be restored.