The following pages detail the complete set of plans for an 18" Dobsonian based uponDave Kriege and Richard Berry’s excellent book.
Page 2 - Book p117 - Mirror Flotation System and Cell.Page 3 - Book p123 - Detail of Flotation System Triangles and Bars.Page 4 - Book p157 - Secondary Cage AssemblyPage 5 - Book p221 - Split-Blocks.Page 6 - Book p243 - Side View of Rocker Box, Ground Board and Side Bearings.Page 7 - Completed Telescope.
Page 1
Plans for building an 18inch f4.4 Dobsonian Telescope.More information can be found online, see url/qr code below.
http://www.ngc891.com/
18”(457mm)Mirror
Mirror Flotation System and Cell, p11718inch Mirror Tailgate is made of three mild-stell bars 25mm x 25mm (502mm long), and 2 mild-steel bars 6.5mm x 32mm (397mm long).Collimation holes are 10mm, tapped at 8mm - Split bolt hole size 10mm - Side pin hole size 10mm.Mounting hole sizes 8mm, 4 along each side rail, 2 along top rung.
Page 2
514mm502mm
251mm
397mm
194mm
141mm
13mm
41mm
6mm
25mm
25mm
25mm
6mm
Page 3
121mm
117m
m43
mm
148mm173mm
25m
m
Detail of Flotation System Triangles and Bars, p123Thickness of triangle 1/8" (3mm).Thickness of bars 3/16" (5mm).6 Triangles, 3 bars all in stainless steel.
Page 4
89mm
102mm
6mm
51m
m
41mm
36mm
46mm
22mm
521mm
479mm41mm 41mm16mm 279mm 16mm
562m
m52
1mm
479m
m41
mm
41m
m
Secondary Cage Assembly, p157Use low profile focusor on focus board. Also use extra wood to strengthen board see p168. Place focusor and board as close to tube as possible, allowing enough space for the full travel of the focusor.Use kydex on inside of tube. Tubes are 1" OD 0.871" ID 0.056" wall thickness (25mm OD 22.14mm ID 1.43mm wall thickness)MARK AND DRILL ALL HOLES BEFORE CUTTING RINGS! MAKE THIS AS LIGHT AS POSSIBLE, IT WILL REDUCE OVERALL WEIGHT AND EYEPIECE HEIGHT.
22mm
Page 5
89m
m
83mm
70mm 13mm
25mm
25mm
44mm38
mm
51m
m
Split-Blocks, p2218 required, 4 left-handed and 4 right-handed (i.e. mirror images of each other).
Page 6
25m
m 210mm410mm
420mm545mm
394m
m
320m
m
610mm
545mm76mm
15m
m15m
m
500m
m
76m
m32
mm
32m
m
127m
m
15mm 15mm
Side View of Rocker Box, Ground Board and Side Bearings.Height of rocker box (and therefore end board height) depend on balance and side of mirror box!Make feet and gap between rocker board and ground board as low as possible.Teflon pads should be between 65 and 70 degrees apart, depending on friction calculations, see chapter 9 p243 and section 10.3.
Page 7
25mm
210mm
410mm
420mm
545mm
394mm
320mm
610mm
1512mm
1512mm
1397mm 16mm
279mm
16mm
562m
m
521m
m
479m
m
41m
m
41m
m
Top Related