1948 12.5 Reflector

Unknown ATM’s 1948 12.5″ Reflector & GEM

Completed Tasks

  • 06/15/19 Freed up & Replaced Rotator Frame to GEM mounting bolts – OTA is now removable. Grinder and gentle 2 lb. hammer.
  • 06/15/19 Have good understanding, I feel, of what is original ATM work, what is later work, and what needs to be done. Much staring and thinking (really). It helps that there are clearly visible levels of ‘craftsmanship and intent’. Somewhere out there are two or three fellows who deserve a smack in the gob, in my book, for their efforts.

The recent story:

Changed departure time from 0200hrs on 14th to 2000hrs on 13th. Good call traffic and temperature wise. Travelled uneventfully from Page to Victorville / AppleValley, plus or minus some construction in St. George, Virgin River Valley, Las Vegas via I15. Traffic was light. Arrived VV/AV 0330hrs. Slept 0400 to 0800hrs. Called Spupchoochoo & Mrs. Spupchoochoo about 0840 – they are wonderful – very nice, down-home folks. Got scope loaded with wives as loadmasters, Spup and I as labour. 

Left the SV80 Access and LX-70 with him and he had a big grin. Made it a trade because I could – Spup gave the 1948 freely – absolutely free – a gift; I just thought a little reciprocity was appropriate.

Departed VV/AV 1109 hrs. Returned via I40 to avoid traffic and construction areas during daytime. Uneventful – traffic light-moderate w/ good drivers on road (really), so trip back was uneventful. Pulled into Page, shut engine off dead-nuts on 2100hrs of the 14th. Light unload, took a couple pix – I looked like hell – Mountain Dew bloat, seat bloat, allergy-eyes for 90% of trip. That watch band makes me look fat.

We loaded properly – Scope travelled well, arrived safely. Optics were cushioned and strapped on back seat. Need to upgrade cardboard box to proper box soon. Primary and Sec recoated 2017 – Have paperwork.

He offered me two large herschel wedges – Oh Wow!! But, I’m not doing anything ‘Herschel-Wedgy’ at the moment, so I suggested he contact folks in CN ‘Classics’ – because Herschels seem to be rather valuable of late and he should retain or sell. That was a good answer =)


Was wornout today, but productive. Climbed over scope and here’s my impression:

Original ATM was intelligent; good design, excellent work. Built in 1948 and was probably mounted on a wedge at first.

Supposition #1: Wedge was mounted on diff base (legs) than the current – pier, tripod, pyramid. No, I don’t know for certain that there ever was a wedge, but the structure on the bottom side of what remains of the RA Axis Bearing Block frame suggests it to me. You don’t need a pin / rod down there, I believe, unless you plan on using it as an rotational axis, as in a wedge assembly.

Supposition #2: Looks like owners between the ATM and Spup got rid of original wedge & base, removed parts (side rails) of the RA axis bearing frame – which included the drive worm gear for the worm wheel that is still mounted on the shaft! Where there should be two side rails of the RA Bearing Blocks frame there is nothing, except empty bolt holes! Aagghh! Just ‘removed’! The legs, trailer frame and RA shaft provide the rest of the structure to maintain the RA bearing positions. I’m not a mount designer, but even I know severely wrong when I see it. 

RA worm wheel is 10~10.5″, haven’t measured pitch / counted teeth – may do that later – it’s a nice cool night with 90% cloud cover), has slight helicity(?) to teeth. If I can find my can of mold-making silicone, I’ll take an impression soon or order more.

I think it is obvious that the original ATM didn’t do this – this is crap work.

Supposition #3: Can’t see in these photos, but each end of that rod has holes for cotter pins; I think the rod served as a pivot and joined the GEM to a wedge or similar base, with a now missing chunk of structure to set and lock the tilt – I believe that would have been sort of ‘standard’ even back then. Gut feeling is after ATM, at least hodge-podgers scruffulated this area – removing original structure and eventually changing current leg config at least twice – it’s just def not original ATM quality.

Rough List

  • Replace missing RA Axis Bearing Block Frame Side Plates.
  • Drop counterweights and check shaft, verify necessity of all the spacer-clamps, remount. The ‘heads’ on those clamping bolts are 1/2″ square.
  • Fix broken Setting Circle & remount.
  • Replace all (rusted) bolts, nuts, washers.
  • Refurb split-bushing clamp assemblies, thrust bearing assemblies, etc.
  • Strip and repaint as we go.
  • At least design Thrust and Centering Bearings for OTA in Rotator Frame – install only if needed.
  • Design Drive Worm & Motor Carrier Assembly for RA.
  • Design easily removeable Primary.
  • Design a new wedge.
  • Design new frame / tripod / pyramid.
  • Probably reuse Model A frame if true; maybe design new trailer frame, low, steerable if not.
  • Mount new F/T/P to trailer frame
  • Mount new Wedge to frame
  • Mount GEM and OTA

So, current priority is to replace side plates / rails – rebuild RA brg block frame. The legs are not sacred and will be upgraded or replaced. The trailer frame is ‘pretty okay’ for re-use, but requires jink around to fit a new axle &  wheel assembly in or around this frame. A new frame with new axle and wheels would save time and frustration. Something along the lines of: a steerable 3 or 4 wheel trailer with a dismountable pier, tripod, or pyramid  and wedge-base.

We can now dismount the OTA and Rotator Frame – which has three geared rings and no actual bearings supporting the OTA in the frame – the 1/2″ ratchet wrench driven pinions for the middle manage to float it a bit while driving rotation. The rings fore and aft of the middle are attached to the ‘tube’ slats and just kinda clamped between the ends of the rotator frame structure, providing unguided friction fit thrust bearing functionality. This friction fit helps keep the tube from rotating on it’s own.

Spupchoochoo’s 1948…

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.