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….....................................--- HandCab WiFi Throttle – Part 2 ---

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This and the following pages will be a step by step build of the throttle. Soon I'll have the print files up on my thingiverse.com account ( HERE ).

Before we begin the build a few things that might help....

There is going to be a ton of soldering in this build and if you struggle some with soldering take it easy and build on your technique (search YouTube's if needed). I use a $15 iron for all my soldering on all my projects almost exclusively. You don't need an expensive iron/soldering station. It won't make up for bad technique. I soldered everything in this build with (this iron) and had it on max heat for every solder joint. I like soldering this way as I'm on and off soldering joints very quickly. The longer you are on a joint the further the heat will go away from the joint and can start melting things and or destroying the components you are solder to (especially the push button switches). Use a good flux, a good small diameter solder (what I use) and learn to watch the solder joint for the solder to flow and then get off of it.

Above is the iron and wire I used for the build. You need good wire so make sure it is good. I like the wire above that you can find on Amazon and from China. It is very flexible with a silicone covering that won't melt or shrink back. Strongly recommend it. The build mostly uses 30 gauge but a little 22 gauge and that could probably be 30 also. Get some good wire strippers if you don't have them. I love ( These ).

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Let's get started.....

Above is the main wiring diagrams (there will also be some for the battery circuit added in the build further along). I would print it out and use it for the color coding of the wiring. It will make wiring a lot easier if you follow what I've done above and what you will see in the build. Notice that I used 5 wire colors the ones in one of the two choices of colors for the wires I've recommended.

If you are going to build this I'd print the image above to use during the build and use the same wire colors. Will save a lot of confusion. If it is hard to print that image here is a link to it alone that you should be able to print that page alone ( Image HERE ). If that doesn't work the following link is to a pdf file of the image that you can blow up and also should be easy to print ( Image HERE ).

Above are all the main parts minus three small brackets that will be shown later. The case top, middle and bottom were printed on an Ender 3 Pro filament printer with the control stand pieces printed with an AnyCubic Photon M3 resin printer. You could probably print all with either printer. I did it this way as I didn't need supports for the main case parts and using supports made the resin prints easier to setup and print. You will get tired of hearing this but for the resin prints they need to be made out with a resin that 'is not brittle' like the Siraya Tech 'Build' Sonic Gray which I used and highly recommend. It can be drilled, tapped, has great detail and isn't brittle.

I put on two coats of gray and followed that with a dull/flat clear to make the throttle easier to keep clean

I've used self tapping screws for a number of filament prints I've done with good success. On the resin ones even with the Siraya Tech the pilot hole has to be 'just right' or the print will crack.

For this build all screw holes are drilled and tapped for either 2-56 screws or #4-40 screws or 1/4-20 (one set screw). Holes as printed are very close to right for the taps needed but take an extra minute and drill them to clean them up. You might be able to find metric bits and taps that might work but since one can order metric or SAE about any place in the world along with the correct bits I'd stay with what I used if at all possible, it works..

Most of the holes in the two main parts of the control stand are tapped for 2-56 but a few, the above, are tapped for #4-40 screws. I bought the black drill bit adapter for a drill that holds very small diameter screws for a different reason than this but it works great to hold the tap and gives you very good control of the tapping process, highly recommended also. If you have a Pin Vise that should also work fine. I drill the pilot holes with a small handheld drill.

The upper housing needs to be tapped for a set screw that holds 2 bearings and a spring that make up the parts for the 9 detents on the throttle. One is throttle off and the other 8 are the 8 notches for the throttle.

As I write this I've made up three throttles and haven't had a problem drilling and threading any of them to this point. I attribute that to the resin I'm using, Siraya Tech 'Build' Sonic Gray. Most resins are too brittle to drill and tap like this so if you want to try something other than the Siraya Tech 'Build' it might or might not work for you. If it works well maybe let me know and I'll pass it on.

For the previous holes that were tapped I drilled with the correct drill bit before tapping the hole and it worked fine. I felt using a power drill here might not work so fine as it might grab the part with bad results. I moved from the smaller #10 up to the #7 which is the right bit to use before tapping. Put the bit in a vise and rotate the housing down onto it taking your time and reversing it occasionally as you go. Looks tedious but took maybe 10 minutes. When you have finished with the #7 then....

…... use the tap. Press down with some force, not a lot, to make sure it starts threading. Go slow, a half turn at the most and then back up a quarter turn to keep the chips somewhat clear of the end of the tap. About 10 turns in back all the way out and clean the chips out. Then continue a little further. The set screw won't go in much further than the head with slot about flush with the housing surface.

At this point we won't put the bearings, spring and set screw in permanently, that will come later. Still do a trial run to make sure everything fits through the hole.

Save the parts and we will come back to …..

….. this a little later after installing the pots.

Next you need to drill and tap holes in the pot shafts ….

…. with the tools above.

I start by drilling a pilot hole with a 1/16” bit. It might wander, just try and get it as close to the center as possible (not critical). Then re-drill the hole with the #50 drill before....

…. taping the hole with the 2-56 tap.

You are now ready to wire the pots.

Time to wire the pots. I used 22 gauge but the 30 gauge would probably work fine. Notice above how the positive and negative wires on the 'throttle pot' are reversed from the brake pot and reverser pot. Be sure and do this otherwise the software that is on the throttle will be confused.

I marked the pot with 'R', 'B' and 'T' to make sure I put them in the correct spot in the control stand. Follow the wire colors from the schmatic also to avoid confusion later. Also the post will be bent back almost 180 degrees next so that the pots fit into the control head.

Above the wires have been cut probably a little long (can be shortened later if needed). The have been tinned. The three posts on each pot have been bent back over the base and tinned. The throttle, brake and reverser wires have been cut and are the correct color.

Above the wires for the Reverser Pot have been soldered on.

Since most of the switches and pots are inexpensive. I like to test them before installing as it is easier at this point to replace one. On the pots first connect the meter's two test leads to the outside wires. This should show the resistance of the pot. We are using 50K to cut down on power consumption. Don't expect the pot to be exactly 50k. I set my meter on 200K and test. The one above was 46.6K which is plenty good for how these pots are used in the circuit.

Next connect one test lead to either the neg. or pos. (doesn't matter) and the other lead to the center wire. Turn the pot fully one way and the meter should go to '0'. Then fully the other way and it should go to near 50K (same reading you got before with the two outer wires)

If this checks out the pots are ready to install.

Next....

…. for the 2 push button switches and the other 5 you will install later. Solder a black wire (I used 30 gauge) to one post and the correct colored wire to the other post.

I've found these switches to be very sensitive to too much heat during the soldering of the wires. I always run my iron as hot as it goes (450C) and get on and off the post in about a second and have had no more failures of these switches doing that. Put flux (love what I use) on the post. Put the wire through up to the insulation. Put a good size drop of solder on the iron. Swipe up or down the post over the wire in one motion and the solder should flow and you are done with the joint. Check it to see if the solder joint is shiny and looks good. If you haven't done this before you will soon get the timing down on the swipe.

After soldering I check the button switch with a meter to make sure it works as shown above.

Time to move to the next step.

For the whole build of this throttle go ( HERE ).

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