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Last modified by Tadd - Mar 8 2018

Box7 - 2018 Node Box Mod Stack

This box is custom made for expandable TARPN Nodes and is one of several designs for TARPN created by Fin, NC4FG in Raleigh. It is called the “Mod” box because you can start with just two and add as many more as you need. Also, the Base box (containing the power supply, Raspberry-Pi, fuse box, ground block, and PowerMan board) and the radio box (containing radio and TNC-Pi) are only different in small ways. This design is currently the 7th box design and the 4th by NC4FG. It is the result of many steps of trial and error, so deviate at your own peril. Note that in these instructions, all directions are from the perspective of looking at the box from the front.

Two Parts to the Instructions

Most builders of the Mod Stack will get a set of pre-cut wood and will only need to follow the drilling, gluing, nailing and sanding parts of the instructions The first part of these instructions will be addressing the gluing and nailing. Any person handy with a speed drill, with our JIGs set, and with $400 worth of hand-held power tools, could build the kit. The second part of the instructions (Kitting the 2018 TARPN Node Mod-Box) will describe the process of preparing the parts kit from 4x8 sheets of plywood. This second part is addressed to an experienced shop operator using a table saw and scroll saw.

Purpose of the Node Box Mod Stack

The cabinet set is intended to

Description of the Node Box Mod Stack

The system consists of a base box and one or more radio boxes.
Each base box has support for
  • main power supply
  • Fuse box for power distribution
  • Ground bus for power distribution.
  • Raspberry PI
  • Oscilloscope for readout of TNC-PI input audio
  • Audio amplifier for TNC-PI audible monitoring
  • 5v USB supply for Raspberry PI
  • 9v supply for Oscilloscope
  • backup battery
  • backup supply switchover circuit
  • speaker for TNC-PI/radio monitoring
  • speaker for Raspberry PI output, used for incoming connection announcements and other features

Each radio box has support for
  • large mobile transceiver
  • TNC-PI

Details of the Node Box Mod Stack

There are components which have become popular in the TARPN design but which are not specific to the intent and purpose of the TARPN. The only parts which are specific to the intent and purpose are the Raspberry PI and that there are multiple radio/TNC sets. The rest of the parts are those things which are cheap and available today. The node stack box is designed to allow easy placement and access to the parts which are cheap and available today, as well as supporting the Raspberry PI.
Parts which are in vogue in early 2018 and to which the Node Box Mod Stack has been optimised:

There are several major parts of the boxes

Left chassis
Slide In Pan
The Left chassis is 8-1/2″ wide. The primary feature of the left chassis is an 8-1/2″ wide slide-in pan which is of one of two depths. The slide-in pan is placed into the left chassis from the rear and is slid up under the rails until it strikes the front-pan-stopper. For the radio version of the mod box, the radio-pan is 3″ deep and has a radio-block on top onto which a radio is Velcroed. For the Base-Box version of the mod box, the o-scope-pan is 9″ deep and has a plate in the front onto which the DSO138 oscilloscope is mounted. The 9″ o-scope-pan is perfect for mounting power supplies, fuse distribution, and other peripherals. Both pans are removable and are held in by Velcroed accessories located toward the rear of the box, and which keep the pan from sliding backwards. mod-box_left_side_x400
Right chassisThe Right chassis is 4-3/4″ wide. On the front of the box a plate presents the Raspberry PI or a TNC-PI. The ribbon cable from these units goes up and down the stack of boxes through a cut notch in the front top and bottom edges of the box. The cable from the TNC-PI to the radio exits to the left across the front of the radio box. A ribbon cable runs up and down from the Raspberry PI to each of the TNC-PI. The plate for mounting the board is across the middle of the space leaving room above and below for both airflow, and access for running wires to the Raspberry PI and to the PWRMAN board which may be plugged into the Raspberry PI as a daughter/shield card. A fan may be located near the rear of the right chassis, blowing forward. If the mod box was placed against a wall blocking the rear, the Center Divider would permit air blown through the fan to be drawn over the radio or power supply, providing excellent cooling. right_side_highlightedx300
Center-dividerA structural member is located between the left and right chassis and runs from near the front of the mod-box to near the rear. The center-divider serves as a mount for the Raspberry PI/TNC-PI plate, as structure to hold the roof of the box up, and also as an air-flow guide. center_divider_highlighted_x300
Top PanelThis is a rectangular piece of 3/16" plywood on top of each box. The box which sits above this Top Panel will fit perfectly such that it won't slide off. The footpads on the bottom of each box fit perfectly around the Top Panel of the box below. We may be able to get the TARPN logo etched into the Top Panel which will look really great. top_panel_with_nailer_x400

This document discusses building the 2018 TARPN Node Mod-Box node stack units from a kit.

Kitting the 2018 TARPN Node Mod-Box discusses creating the kit from raw lumber.

Assembly Materials List -- included in wood kit

15 pieces of 1/2″ plywood
ABox-Roof14-3/4″ wide x 11-3/4″ deep The Box-Roof and Box-Bottom parts are nearly identical.
Both parts have marks to assist in placement of the Top-Panel (P).
In the case of the Box Bottom, the marks are for temporary placement of the Top-Panel to aid in proper placement of the Footpads (Q).
BBox-Bottom14-3/4″ wide x 11-3/4″ deep The difference between Box-Bottom and Box-Roof are that the notches are on opposite ends of the piece relative to the lighter-side and darker-side. Box-Bottom has the bigger notch on the right if the white-side is down. Box-Roof has the notch on the right if the white-site is up.
CBox-Right-Side5-1/4″ high x 11-3/4″ deep The Box-Right-Side and Box-Left-Side parts are identical.
DBox-Left-Side5-1/4″ high x 11-3/4″ deep The Box-Right-Side and Box-Left-Side sit on the box-bottom.
ECenter-Support5-1/4″ high x 6-3/4″ deep Center-Support runs front to back near the middle of the box. A drill spot is marked on this board. Later during one of the assembly steps you'll be asked to drill out this spot.
FCeiling-Brace4-3/4″ wide x 3″ deep Across the top of the right side of the box. This is used to enforce the spacing between Center-Support and Box-Right-Side
GFloor-Brace4-3/4″ wide x 7″ deep Across the bottom of the right side of the box. This is used to enforce the spacing between Center-Support and Box-Right-Side
HFront-Right-Panel-Brace5-1/4″ high x 3/4″ deep This supports the right hand side of the Circuit-Board-Panel
IO-Scope-Panel-Brace5-1/4″ wide x 3/4″ deep This piece adds structure to the Scope-Panel where it glues to the O-Scope-Pan
JO-Scope-Pan8-1/2″ wide x 9″ deep This piece supports the DSO138 oscilloscope, main power supply, fuse block, and other peripherals. The pan slides into the left side of the box from the rear.
KBack-Pan-Stopper2″ high x 1″ deep
LRadio-Block5-1/4″ wide x 3″ deep Velcro on top of this piece holds down the front of the radio.
MRadio-Pan8-1/2″ wide x 3″ deep This piece supports the Radio-Block. The pan slides into the left side of the box from the rear.
2 of these
1″ wide x 6″ deep These pieces get glued together and are used to support the back of the radio under the heat sink.
14 pieces of 3/16″ plywood
OCircuit-Board-Panel5-1/4″ wide x 2-1/2″ high The Raspberry PI or TNC-PI mounts to this panel. Four spots are marked on this panel which will be drilled out in an assembly step.
PTop-Panel10-3/4″ wide x 7-3/4″ deep This odd shaped piece sits on top of the mod-box and if another mod-box is placed on top of this one, the feet fit around this pattern perfectly.
This piece is marked on the edges to match the marks on the Box-Roof (A).
QFootpads, 8 of them1-1/4″ x 1-1/4″ These are on the bottom of the box. Four are in the corners of the bottom, and four are located so they exactly fit on the outside of the top-panel for the mod-box this box is sitting on top of.
2 of them
1/2″ high x 6″ deep These secure the O-Scope-Pan or Radio-Pan so it won't rock up or fall out when the box is moved or bumped. The pan slides under these rails.
SFront-Pan-Stopper5-1/4″ wide x 1-1/4″ deep This piece blocks the pan from sliding out the front of the box. It could also be a good place to put a label or sticker or maybe the wood could be etched with the node-name or the name of the neighbor node this radio talks to?
TScope-Panel5-14″ wide x 4″ high The DSO138 scope mounts to this panel. Five holes are marked in this panel which will be drilled out during one of the assembly steps.
Hardware and Glue (not included with kit)
TiteBond III glue or equivalent (may be called ″TiteBond III Ultimate″)
< 1003/4″ 23 gauge pin nails
< 1001/2″ 23 gauge pin nails
Base-Box hardware
(8)3/8″ 4-40 standoffsFor all hardware, zinc plated brass is cheap and adaquate
(8)1/2″ 4-40 screws
(8)4-40 nuts
Radio-Box hardware
(4)3/8″ 4-40 standoffs
(4)1/2″ 4-40 screws
(4)4-40 nuts

Assembly Tools Needed -- assemble the wooden parts


Jigs for kit building

Note: These Jigs are included in the kit but are disposed of at the end of kit building.
The Jigs are labelled and called out during the construction process.
#1Front-Edge-Jig 13-3/4″ x 1-3/4″ Used in placement of the forward edge of the pans and the Center-Support as well as to simplify placements of the Box-Left-Side and Box-Right-Side.
#2Back-Edge-Jig 13-3/4″ x 1-3/4″ Used to enforce the placement of the sides of the box and for sanity testing the Floor-Brace.
#3Board-panel-sizer-Jig 6″ x 7/8″ Used in placement of the Circuit-Board-Panel (which holds the TNC-PI or Raspberry PI)

Instructions for building the 2018 TARPN Node Mod box

Assembly Step 1: Check Inventory

Check the count of parts against the parts list. You should have parts A through T and Jigs 1, 2 and 3. Watch for quantities, 2 part N and R and 8 part Q.

Assembly Step 2: Drilling some holes

1 Find Center-Support (E).
Drill a 1/2″ hole through the Center-Support (E) where marked. This is a wire pass-thru hole..
 2018feb_fin8608x600  2018feb_fin8609x600
2 Find the Scope-Panel (T). Drill a 1/2″ hole through the Scope-Panel where marked. It would be better if you placed the Scope-Panel over a piece of scrap wood (you can use one end of Jig 1) so the hole comes through neater. 2018mar07IMG_4350
3 Drill four 1/8″ hole through the Scope-Panel where marked. 2018mar07IMG_4351
4 Locate Circuit-Board-Panel (O).
Drill four 1/8″ hole through the Circuit-Board-Panel where marked.

Assembly Step 3: Main Box Assembly (all pins are 23 gauge 3/4″)

When you change pin size in your nail gun, make sure the first pin is also cleared out.
1Place Box-Bottom (b) on your table such that the white-side of the board is down and the larger of the two notches is facing forward. 2018_03_06_Box_bottom_4321
2Place Front-Edge-Jig (#1) on the front edge of the Box-Bottom so it is flush with the front edge and centered along that front edge. 2018_03_06_place_jig1_on_box_bottom_4323
3Place Back-Edge-Jig (#2) on the back edge of the Box-Bottom so it is flush with the back edge and centered along that back edge.
4Locate Front-Right-Panel-Brace (H), Box-Right-Side (C), Floor-Brace (G).
Note that the pieces marked H and I can be confused since a sideways H looks like an I. However, the two pieces are the same size so it just doesn't matter.

In this step we're going to glue and pin Floor-Brace to Box-Bottom.

Temporarily place Box-Right-Side as shown with white-side facing out-right. Temporarily place Front-Right-Panel-Brace with white-side facing left, and up against Box-Right-Side as shown.
The two pieces, brace and side, are sitting on the right edge of Box-Bottom.

Run your finger up the right edge, front and back and make sure the Jig and Box-Right-Side are perfectly placed.

Note that when the parts are placed, the lettering (H), (C) and (G) are not visible.

Now glue and pin Floor-Brace (G) to the bottom such that it is immediately behind the Front-Right-Panel-Brace, making sure not to impact the placement of the Box-Right-Side and making sure the glue goes on the not-white side of Floor Brace (G).

2018_03_06_front_right_post_4322 2018feb_fin8611x600
5Glue and pin the Front-Right-Panel-Brace (H) into the inside Box-Right-Side (C).
Note: The Front-Right-Panel-Brace wiggles as you compress it into the side. Also note that the Floor-Brace and Jig have very straight edges. Squeezing the Jig against the Front-Right-Panel-Brace will keep it straight and then move to push down on the Front-Right-Panel-Brace.
6Temporarily put the Center-Support (E) in place nudged forward to the Front-Edge-Jig and against the Floor-Brace. See that the hole you drilled earlier is up and forward. Put glue on the bottom and bottom-right edge of the Center-Support and place it into the box up against the Front-Edge-Jig as shown. Pin the Center-Support on the left side, into the Floor-Brace.

Remove the Front-Jig and wipe away any glue that gets loose.

7 Move the Box-Right-Side and Front-Right-Panel-Brace assembly out of the way.

Apply glue in on the Box-Bottom on the right edge of the Bottom-Brace and in the top of the Box-Bottom where the Box-Right-Side will sit, then put the Box-Right-Side into place.

Note that the Floor-Brace will make it easy to place the Box-Right-Side correctly.

Pin into the Box-Bottom through the Box-Right-Side bottom edge as shown.

Wipe away any excess glue including under the Jigs if they are still in place.

8 The Ceiling-Brace (F) will be placed, white side down, in between the Center-Support and the Box-Right-Side, even with the top of each board, and will be located somewhere behind the front-right support. The front to back position is not so important.
Make sure the Ceiling-Brace ends up even with the top of the Center and Right Side!!!

Glue and pin the Ceiling-Brace (F) on both left and right.

Wipe away excess glue.

9 Pin the Box-Right-Side in from the bottom. 2018feb_fin8691x600
10 Locate Radio-Pan (M) and Box-Left-Side (d).

Without gluing yet, place Box-Left-Side in place on top of the left end of Box-Bottom. The white side should be facing out.

Take Radio-Pan and with it's wide direction running left and right and fit it between Center-Support and Box-Left-Side. It should barely fit. While keeping Box-Left-Side in place, move the Radio-Pan back and forth and make sure it fits.

Your goal is to glue and pin Box-Left-Side in place such that Radio-Pan does not bind and will still fit.

Place the front and back jigs along the front and back edges and put the Radio Pan (M) against the Center-Support.

Again place Box-Left-Side and hold it on the bottom edge against the jigs and Radio-Pan.

Stand the box up on most of the way onto its right side, watching that your loose parts don't come out. Put the box back down.

Put glue on a long edge of Box-Left-Side and put it in place on Box-Bottom.

Again stand the box up partially and turn it so you can get access to the bottom.

Force the bottom of Box-Left-Side against the loose parts to make it be true (90degrees) from the bottom. Use your nailer to pin through the bottom into the Box-Left-Side once near the front of the box and once near the back.

Now flip the box on its back and while pushing hard on the bottom over the Box-Left-Side, put several more nails in. If either of your first two nails are pushed partly out, hit them lightly with a hammer.

Turn the Box back over with front facing you as before. Using the Radio-Pan as a square, force the Box-Left-Side to be true.

Remove the Jigs and wipe away any excess glue.

11 Apply glue to all surfaces facing up and then place the Box-Roof (A), white side up and with the larger notch facing forward. 2018feb_fin8711x600
12 Pin the Box-Roof (A) on both top edges while putting pressure on at the points being pinned. 2018feb_fin8712x600
13 Measure 5-1/2″ from the Box-Right-Side on both top and bottom of the box. This marks the location of the Center-Support. 2018feb_fin8742x600
14Press down on the Box-Top over the Center-Support and pin the Center-Support from the top.
Make sure to pin only into the Center-Support keeping in mind that that support only 6-3/4″ of the total 11-3/4″ length of the box.
This is what a miss looks like.

To fix a miss, grab the tip of the pin with your long-nose plier and then rotate, wrapping the pin around the plier.

Eventually this will pull the nail through the wound.

15 Press down on the Box-Top near the Ceiling-Brace and pin above the Ceiling-Brace. 2018feb_fin8762x600
16 Turn the box over and pin into the Center-Support from the bottom of the box. 4343
17 Inspect the inside of the box looking for spinters and protruding pins.

Site down the corners of the box from front-to-back and look for pins. If there are any you'll need to take action to fix this lest damage or injury occur.
Pins extending into the bottom of the left part of the box will block proper sliding of the O-Scope-Pan and Radio-Pan. Use the long nose pliers to grab the tip of the pin and then roll the pliers to pull it into the box and remove.

18Now put the box aside and clear some space.

Find the O-Scope-Pan (J), the O-Scope-Panel-Brace (I), and the Scope-Panel (T).

In this step we're going to glue the O-Scope-Panel-Brace to the O-Scope-Pan.

The O-Scope-Pan is only half an inch deeper than it is wide.
Place the O-Scope-Pan, white side up, with the narrow side (front) facing you.
Align the Scope-Panel along the front edge of the O-Scope-Pan 2″ inches away from the left edge of the pan. This 2" space allows the HP DPS1200FB to fit so the supply's fan can exhaust to the front.
Place the O-Scope-Panel-Brace behind the Scope-Panel.

Glue the O-Scope-Panel-Brace to the O-Scope-Pan and pin through the O-Scope-Panel-Brace from the top but do NOT glue or pin to the thin Scope-Panel.
Clean up the excess glue. This is important. Make sure you get the glue off the bottom of the Scope-Panel and out of the area the Scope-Panel will glue into. We're not ready to glue the Scope Panel yet as it requires shorter pin nails.
Then put this assembly and the loose Scope-Panel asside for the moment.

4345 mod_stack_2018feb14_4169_hpsupply_cut
2018mar07IMG_4346 4347
19Locate Radio-Pan (M) used in a previous step and Radio-Block (L).
Center the Radio-Block, white side up, on top of the Radio-Pan, also white side up.
Apply glue to the bottom of the Radio-Block and place it in the middle of the Radio-Pan white-side.
Pin the Radio-Block from the top.
20Locate the two Rear-Radio-Support (N) pieces.
Apply glue to the non-white side of one Rear-Radio-Support and place it on the non-white side of the other Rear-Radio-Support.
Pin the two pieces together.
Put this assembly asside for later.

4354 4355 4356

Assembly Step 4: Box Finishing

1 Use the handheld router with 1/4″ rounding overbit to round all outer edges.
Exclude the inside of the slots
2 Use Sander and Sandpaper and, at your discretion, sand all surfaces and edges xx

Assembly Step 5 - Top-Panel and Footpads (all pins are 23 gauge 1/2″

When you change pin size in your nail gun, make sure the first pin is also cleared out.
The Top Panel has marks already on it. Current box tops and bottoms do too.
1Find the Top-Panel (P).
Place the box back on the bench upside down but facing front. The larger slot is on the left-front.
With high precision, place the Top-Panel on the box bottom and line up the lines on both panel and box bottom. This will require setting the light side of the Top-Panel up and the letter (P) is facing down. Don't lick the Top-Panel at this time.
2Use a tape measure to make sure the Top-Panel is exactly in the middle and square front to back and side to side.
3Place the four inner Footpads (Q) 1/16" away from the notches on the top panel. 4357
4Pin each inner Footpad
5Place the 4 outer Footpads on each box bottom corner and pin in place. 2018feb_fin8840x600
6Place the Top-Panel on the box top and line up the lines on both panel and box top.
7Use a tape measure to make sure the Top-Panel is exactly in the middle and square front to back and side to side.
Pin the Top-Panel in place

Assembly Step 6 -- Pan Rails

1Place the O-Scope-Pan in the box left-hand cavity such that the O-Scope-Brace-Panel is to the back. 4364
2Place the Front-Edge-Jig along the front of the box. Line the Jig up flush with the Box-Bottom front edge. 4365
3Place a thick piece of paper or two pieces of paper on the left edge of the O-Scope-Pan against the left wall. Place an Interior-Pan-Rail (R) on the left side and let it rest gently on the paper.
The front end of the rail should be equal with the front of the O-Scope-Pan. Pin the left Interior-Pan-Rail in place. DO NOT GLUE!! You should manage to pin it twice. With my Ryobi nailer, it was tight.
5Perform step 3 on the right side of the O-Scope-Pan.

Assembly Step 7: Attach the Circuit-Board-Panel (Using 1/2″ pin nails)

1 Turn the box on it’s back (the large slots are UP)

Place the Board-Panel-Sizer-Jig (#3)(7/8″ tall) on the top edge of the panel area.

Place the Circuit-Board-Panel (O) below the jig. The four holes are mostly to the right. The Circuit-Board-Panel letter (O) is on the back.

Pin the panel in place

Put asside the box for a moment.
5Align the Scope-Panel (T) in front of the Scope Panel support.

The large drilled hole has to be in the top right and the letter (T) is on the back.

Glue and pin the Scope-Panel from the front.

6Put the box back on the bench upside up and sitting on its bottom.
Insert the O-Scope-Pan in place under the rails and slide it back so the front edge of the pan lines up with the Center-Support.
Place the Front-Pan-Stopper (S) in front of the O-Scope-Pan so it is equidistant between the box left and center support.
9Pin the Front Pan Stopper in place.

Final Assembly/Application

There are several components which are now useable to create a radio box or a base-box. The base-box uses the O-Scope Pan assembly which you have created. A back-stop is provided in the form of the Back-Pan-Stopper (K). Get this piece and cover the darker side with a Vecro pad. Use the fuzzy loop side of the Velcro. If you are going to be using this new box as a Base-Box, containing the scope and Raspberry PI computer, put the O-Scope Pan assembly into the box from the rear, under the rails, then turn the box around.
Now place the Velcro Hooks pad to mate with the Back-Pan-Stopper up on the side of the box, to the left (right if looking into the box from the rear) of the O-Scope Pan.

Don't put the velcro on the floor of the box because that will interfere with the pan sliding out.

The pic on the right shows two boxes configured with the O-Scope Pan. The upper has the K block Vecroed in place. The lower just shows the Velcro hooks. You can see how the K block would keep the Pan from sliding backwards.


If you are going to use this box as a radio box, slide the O-Scope Pan out of the box from the rear and insert the Radio Pan assembly.

Slide the Pan assembly up to the front of the box as shown to the right. 2018feb_fin8880x600
Now turn the box around and place the Rear-Radio-Support assembly behind the Radio Pan.

Velcro the K block behind the Rear-Radio-Support assembly as shown in the pic to the right.

Put Velcro hooks on the Radio Block with a small amount of overlap onto the Rear-Radio-Support to secure the support in place. Apply Velcro loops on the radio itself. I wouldn't put the Velcro on the radio heatsync as that would reduce heat flow.


Final result

© Tadd Torborg, 2014↝2019 -- all rights reserved