NightTimber

8-inch · timber mount · shop plans

63 7/8 in zenith38 in footprint3× 8 ft~$384

NightTimber — Homemade pipe alt-az

8" f/6 Newtonian · Landscape timber 3×4

NightTimber — 8-inch telescope Homemade pipe alt-az
8" f/6 Newtonian on Landscape timber 3×4

CUT LIST
  3× Tripod leg — 36 in  (3×4 landscape) — Top bevel 22° so the end sits flat under the hub. Bottom sits on a pad.
  3× Foot pad — 8 in  (3×4 landscape) — Grain running across the foot. Optional ⅜ in spike from below for grass.
  3× Spreader bar — 23 in  (3×4 landscape) — Bolts through the leg at 12.0 in above grade. Forms a rigid triangle.

From 3 × 8 ft 3×4 landscape
  Timber 1: Tripod leg 1 36 in + Tripod leg 2 36 in + Spreader bar 1 23 in  (waste 0 3/4 in)
  Timber 2: Tripod leg 3 36 in + Spreader bar 2 23 in + Spreader bar 3 23 in + Foot pad 1 8 in  (waste 5 1/2 in)
  Timber 3: Foot pad 2 8 in + Foot pad 3 8 in  (waste 79 7/8 in)

PLYWOOD
  ¾ in sanded pine, 24×24 in project panel
  Hub top plate: 16 in × 16 in × 0.75 in
  Leg gusset: 8 in × 7 in × 0.75 in
  Accessory tray: 16 in × 14 in × 0.75 in
  Cradle side: 14 in × 11 in × 0.75 in
  Tube ring blank: 12 in × 12 in × 0.75 in

HARDWARE
  6  ½-13 × 5 in carriage bolt, galv. or SS
  6 each  ½-13 nyloc nut + fender washer
  6  ⅜-16 × 4 in carriage bolt, galv.
  1 kit  ⅜-16 × 2½ in hex bolt + 2 fender washers + nyloc
  1 lb box  Exterior structural screws 2½ in (#9)
  16 oz  Titebond III or exterior PU glue
  1 qt  Water-based outdoor sealer (clear)
  3  Rubber furniture cups or ⅜ in lawn spikes
  1  1½ in galvanized floor flange
  1  1½ in × 10 in galvanized nipple
  1  1½ in galvanized tee
  1  1 in × 18 in black steel pipe (altitude axle)
  2  1 in floor flange (clutch knobs)
  2  1 in to 1¼ in HDPE / furniture-grade PVC bushing
  1 roll  PTFE thread tape

Eyepiece zenith 63 7/8 in (Standing)
Eyepiece horizon 52 in (High stool)
Footprint 38 in dia.   Hub height 36 3/8 in
Estimated shop cost $384

Build

1. Square and cut the legs

Cut three legs at 36.0 in from 3×4 landscape. Cut the top of each at 22° so the full section bears on the hub plate. Mark a centerline down the 3½ in face — that face points radially (in the splay plane).

2. Pads and spreader bars

Cut three 8 in foot pads and three spreader bars at 23.0 in. The pads take the end grain off the dirt and give you a place for a rubber cup or a ⅜ in spike.

3. Laminate the hub

Saw a 16 in disk from ¾ in plywood (or a 16 in hex if you would rather not jigsaw a circle). Cut three 8×7 in gussets. ⅜ in hole dead-center for the mount bolt. Seal all plywood edges before assembly — plywood edge is where water starts.

4. Bolt the legs

Lay the disk upside down on sawhorses. Clamp each leg at 22° with the bevel tight to the plate. Screw a gusset to the plate and the inner face of the leg, then bore two ½ in holes through gusset and leg and fit carriage bolts, washers, nylocs. Snug, then stand it up and equalize the splay before final torque.

5. Fit the spreader

At 12.0 in above grade, bore ⅜ in through each leg and bolt the three bars into a triangle. A plywood accessory tray screws to the top of that triangle — eyepieces live there, not in your pockets.

6. Assemble the pipe head

Bolt the 1½ in floor flange to the hub with four ¼-20 or 5/16 in bolts on a circle. Thread the 10 in nipple, then the tee, with PTFE tape. Slide the 1 in × 18 in black pipe through the tee as the altitude axle. 1 in floor flanges jam against the cradle sides as clutches.

7. Make the cradle and rings

Two 14×11 in plywood sides, bored for the 1 in axle. Two 12 in ring blanks with a 9.25 in inside cutout (jigsaw, then rasp to fit). Felt the ID. The rings bolt to a ¾ in spine that joins the two sides, forming a U that rotates on the axle.

8. Balance, clutch, first light

Slide the tube in the rings until it stays at any altitude with the clutches just kissing. Azimuth is the flange on the plywood — a felt washer under the tee gives a nicer drag. Collimate, then pick a first-quarter Moon.