Ronja Twibright Labs

Building Ronja 10M 90mm Tubular Optical Head

Building Ronja 10M 90mm Tubular Optical Head

Cut (115mm+focus) long piece from the 100mm smoke pipe using a hand saw
Technical drawing of slide cover Cut and drill two slide covers
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Technical drawing of one hood Cut and drill the hood. Bend the tin intoGallery[56e]this shape.
Technical drawing of one drilled profile for the heel Drill out the steel sections for the heel
How to mark coordinates on the cylinder Mark the wider end of the pipe as front and the narrower one as back. In the next, we will describe coordinates on a cylinder - by angle and length from one edge. Angle is in grads - 400 grads form complete circle.
How to place paper on the pipe and mark positions of holes Use a sheet of paper wrapped around to measure the angle. Wrap the paper around and make a circumference mark where the edge is. Then put the paper on desk and divide the circumference by 400 using a calculator and make marks at 25, 75, 125, 175, 225, 275, 325, and 375 times this distance. Mark them 25grad, 75grad, 125grad, 175grad, 225grad, 275grad, 325grad, and 375grad. Wrap the paper around the pipe again, the seam of the paper on the seam of the tube, and copy the marks from the paper onto the tube as necessary.
Mark and drill these holes on the pipe:
AngleAxial OffsetHole diameterPurpose of the hole
75grad11mm from front4.3mmHolds front cap
175grad11mm from front4.3mmHolds front cap
275grad11mm from front4.3mmHolds front cap
375grad11mm from front4.3mmHolds front cap
75grad11mm from backself-cutting screw predrill diameterHolds rear cap
175grad11mm from backself-cutting screw predrill diameterHolds rear cap
275grad11mm from backself-cutting screw predrill diameterHolds rear cap
375grad11mm from backself-cutting screw predrill diameterHolds rear cap
125grad(focus-20mm) from front4.1mmslide path
325grad(focus-20mm) from front4.1mmSlide path
125grad,focus from front4.1mmSlide path
325gradfocus from front4.1mmSlide path
125grad(focus+20mm) from front4.1mmSlide path
325grad(focus+20mm) from front4.1mmSlide path
125grad(focus+31mm) from front4.1mmSlide path
325grad(focus+31mm) from front4.1mmSlide path
125grad(focus+51mm) from front4.1mmSlide path
325grad(focus+51mm) from front4.1mmSlide path
125grad(focus+71mm) from front4.1mmSlide path
325grad(focus+71mm) from front4.1mmSlide path
25grad55mm from front7.0mmheel
25grad125mm from front7.0mmheel
25grad195mm from front7.0mmheel
25grad265mm from front7.0mmheel
225grad40mm from front4.3mmhood
225grad80mm from front4.3mmhood
How to file through the slide paths Connect holes in each group of three holes marked for future sliding path together to form a sliding path for the screws. Use a tiny file or fret-saw to accomplish this. You can also horizontally vice an iron bar or pipe, and chisel the paths out against it.
Two rear and two front caps In the next steps, we will manufacture these two caps: front and rear.
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Drilling front cap rim

  • Take one cap and mark it as front.
  • Insert it into the front of the pipe, cap seam at 200 grad. If it won't go, cut V-shaped slits into the rim at 25, 125, 225, 325 grad.
  • Drill through one 4.3mm hole with 4.3mm bit. Insert some M4 bolt and drill the hole on the opposite side. Do the remaining three holes and always insert a bolt.
  • Mark which side of the front cap is down (at the heel) with a permanent marker. Remove the bolts and the front cap.
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Drilling rear cap rim

  • Take the other cap and mark it as rear.
  • Insert it into the rear of the pipe, cap seam at 200 grad. If it won't go, cut V-shaped slits into the rim at 25grad, 125grad, 225grad, 325grad.
  • Drill through one self-cutting screw predrill hole and insert some pin or nail to keep it in place. Do the remaining three holes, inserting a pin or nail every time.
  • Mark a bottom mark on the cap at the heel holes.
  • Remove the pins/nails and the rear cap.
  • Drill through the four holes at the rear of the pipe with self-cutting screw through-hole diameter.
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Front cap, cut-out front cap and future thermal shield

Cutting out front cap: Option 1 (handwork)

Take the front cap. Make a mark in the center of the outer side using the hard stylus and hammer. Measure exactly the lens diameter with slide gauge. Set pair of compasses to (lens diameter/2)-1.5mm. Draw a circle. Make the circle more visible by redrawing it using the marker pen. Put a block of wood vertically into a vice and the cap over it, the rim down. Use cold chisel and hammer to chisel out the curve. Then the round piece will fall out. Collect it, it will be the so called thermal shield. Use the hammer to repair the face of the cut on the wooden block.

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Cutting out front cap: option 2 (mechanized)

Take the front caps and mark the inside center of them with a marker. Take a nail and with a slight strike mark the center with it (you may even drill there a 2-3mm hole). Set the pair of compasses to (lens diameter/2)-1.5mm and draw a circle. Mount a jig saw on the underside of a wooden board, so the blade would come out of the top of it. Take the cap and drill 3 to 5 holes (depending on your blade dimension) on the circumference of drawn circle. Put the cap on the board so the blade would poke through drilled holes. Adjust the position of the cap, so its marked center would be ortogonal to the natural path of the jig saw on the beginning of the blade. Now take a nail and hammer it through the center of cap deep into the wooden board. Nip off the nail header, so you can remove the cutting (future thermal shield) easily. Turn the saw on and pivot the cap. When the hole for the lense is complete, clean the impurities with a hand file.
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Rear cap drawing

Finishing rear cap drilling

Place a 8-terminal wire nut on outer surface of the rear cap in position shown shown in the drawing. Drill a 3.1mm hole between terminals 1 and 2, insert an M3 bolt, drill a 3.1mm hole between terminals 7 and 8, insert a bolt, and do another two holes between terminals 2 and 3 and terminals 4 and 5. Drill one 8.5mm hole above the wire nut and four 10.5mm under the wire nut.

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Postscript / PDF / EPS / BIG png / DXF (qcad)

Making thermal shield

Drill out the thermal shield as in the drawing.
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Postscript / PDF / EPS / BIG png / DXF (qcad)

Silicagel boxes

  • Print out these 8 templates and Cut out 4 of them. Glue them on 67x46mm boxes lids (leave lids on boxes).
  • Punch all unmarked holes with an awl and drill out the 4.3mm holes

Parts to be washed

  • Pipes
  • Caps (front, rear)
  • Heel, heel flange
  • Thermal shield
  • Slide covers
  • Hoods
  • Lenses


  • Fill a bucket with hot water and add detergent, for dosage see the bottle label
  • Throw all pieces with templates into the bucket and let the templates soak off.
  • Use emery paper to remove noncohesive rust from pieces where templates weren't used.
  • Wash parts to be washed plus parts already in water in the bucket using a brush or sponge to get rid of all grease
  • Place everything wet on a rag and dry with hairdrier while turning around.
  • Now remove noncohesive rust from pieces where templates were used.
Placement of silicon sealant

Preparing sealant for the lens

Place a fair amount of the sealant inside front cap into the corner but not on the edge on which the lens will sit.
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Sealed lens

Sealing lens

Put the lens into the place from inside the cap and shape and finish the sealant in many gentle circular motions with your little finger so that it becomes smooth and flawless. Take a great care not to smudge the lens. If you have smudged the lens and decreased clear aperture, wait until the sealant partly solidifies and then remove it mechanically and clean the remaining haze with a rag and acetone. Removing the hardened selalant is not easy and must be done using a razor blade, without scratching the lens.
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Photo of rear cap from inside

Sealing the soft grommets

Put the soft grommets into the holes in rear caps: 6mm grommets into 8mm holes and 8mm grommets into 10mm holes. Seal them all against the cap from both sides with the sillicone sealant.
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If you don't seal the optical head properly, water will probably get inside. The link may stop working and the electronics may be irreparably destroyed. See a video.

Heating network drawing

Installing heating network

Wait until the sealant solidifies on front cap. Cut four small pieces of PCB blank and cut the copper on one side of one piece into two pieces insulated by a gap. Solder these pieces regularly on the outer rim of the lens, on the tin. Solder the 8.2-ohm resistors there as specified in the drawing, connecting them to the rim with pieces of thin bare wire. Check that there is no short circuit between the network and the metallic cap itself using a multimeter. Wash the cap again with detergent, warm water and dry them into the clean dry rag. Cut two pieces of two-conductor 1.5mm^2 insulated cord, 0.41m long. Solder two one-inch pieces of 4mm^2 hard copper wire on one end of the cable and insulate the solder joints with duct tape. Solder the other end of the cord one on the terminals of the heating network.


Failure to paint the optical heads correctly can result in peeling of the paint under the silicon sealant and water getting into the pipe, which will render the link inoperable and destroy the electronics. See a video.

Painting with primer

Paint with water-soluble primer. Paint only those parts of the specified list which are able to corrode, i. e. they are from raw steel or iron and are not galvanized nor tin-plated. Paint caps, pipes (including inner surface), hoods, slide covers, and thermal shields with water-soluble primer. Adhere to Amanufacturer's datasheet for recommended procedure.

Painting black

Paint with water-soluble matte black top coat. Paint inner sides of the tubes, inner sides of the caps, inner sides of the hoods, and the thermal shield. Adhere to manufacturer's datasheet for recommended procedure.

Painting white

Paint all remaining surfaces that are not already black (including those that do not corrode) with the water soluble white (matte or glossy) top coat. Paint caps, pipes, hoods, and slide covers. Adhere to manufacturer's datasheet for recommended procedure.

Removing paint from holes

Prick out paint from all holes.

Rear cap photo from inside

Installing wire nut

Screw the 8-terminal wire nuts into itsn apropriate places using the M3x15 screws, M3 nuts, and M3 washers.
Drawing of joint between pipe and heel

Attaching heel

Attach heel to the pipe using 4 M6x14 bolts, 4 M6 (6.2mm) toothed spring washers and 4 M6 nuts. Tighten firmly. Seal with silicone sealant: around bolt heads, around the 20x4mm flange, around the heel and also cover the nuts, spring washers and bolt tips.
Drawing of joint between pipe
and front cap

Mounting front cap

Screw the front cap in using 4 M4x8 bolts, 8 M4 (4.2mm) washers and 4 M4 nuts. Seal the joints from outside with silicone sealant. Seal the gap between the pipe and the cap with silicone sealant from outside.
Drawing of joint between center of the
hood and the pipe

Attaching centre of the hood

Mount the hood's central two holes on two holes on the top of the pipe using 2 M4x15 bolts, 8 M4 (4.2mm) washers, and 6 M4 nuts. Tighten firmly. Seal the joints from inner side carefully with silicone sealant. Press the hood against the pipe firmly and drill through the remaining holes on the hood with 4.3mm bi.
Drawing of joint between hood side and
the pipe

Attaching hood sides

Mount the hood sides using 4 M4x8 bolts, 8 M4 (4.2mm) washers, and 4 M4 nuts. Tighten firmly. Seal the joints both from inner and outer side with silicone sealant. Put also some sealant between the tins before you assemble them together.

Preparing silica gel

  • Put the silica gel into the two boxes (200g fits into two 92x67 boxes and 100g into two 67x46 boxes). Screw up using M4x25 countersink head bolts and double M4 nut. Tighten the nuts one against the other.
  • If the silicagel is not 100% dry (usually shipped in airtight containers), put the bag into oven (at minimum heat) for two hours. Gas oven to minimum setting, electric to 150degC. Do not use microwave oven. If you were so stupid you bought the blue one, be sure not to do that in a kitchenware and destroy the vessel safely after usage because it will be contaminated by the cancerogenous dust. Store the dry silica gel boxes in airtight jars or plastic bags.
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Grinding paint off positioning-critical joints

Use emery paper to grind off paint around the six holes on the heel.

Postscript / PDF / EPS / BIG png / SVG (Inkscape)

To save

Save the slide covers, 4 self-cutting screws, and 4 M4 washers for mounting electronics inside and closing the rear cap. The washers should be put under heads of the screws.

An expected information missing here?