Improving the Wemacro Micromate (Part 2/2)

Introduction

Part 1 can be viewed HERE (opens new tab).

In the previous article, I outlined my procedure to adapt a focusing drive made by Prior Scientific to the Wemacro Micromate controller box. The same controller box is shared among Wemacro’s focus stacking rail and the Micromate, so I will simply call it the Wemacro controller from now on.

At the end of the article, I outlined my plans to make a proper, nicer-looking adaptor cable. With all the parts from Taobao arriving, I put this plan into fruition. A lot of frustration was experienced during assembly.

Tools used

The figure above illustrates the tools I have used. A good portion can be replaced with a pair of scissors. Throughout my university studies in electrical engineering, I collected an adequate cabinet of high-quality tools. I find higher quality tools more enjoyable to use and all the time saved from fiddling with fragile toys is worth it, in my opinion. I have enlisted everything below, the highlighted ones are crucial.

  1. Clamp
  2. Preassembled cable
  3. DB9 female plug
  4. GX16 aviation plug
  5. DB plug housing
  6. Heavy-duty scissors
  7. Automatic wire stripper
  8. Wirecutter
  9. Solder wire (flux core, 20% lead, none of that lead-free rubbish)
  10. Tweezers
  11. Scissors
  12. Philips PH00 and PH01 screwdrivers, ESD Safe
  13. Heatshrink cable
  14. Plug housing retainer

Wemacro uses the GX16 aviation plug, which comes in male and female components. The male component is needed. Mating the male component with the shroud of the female component is recommended, this allows one to retain the threading for secure mounting. I prefer soldering material with a little bit of lead, but that is probably no longer legal. All the wire cutting and stripping duties can be done with your teeth, that was how I started at the age of 12. I do not recommend it though.

Procedure: Creating the adaptor cable

Make sure the plug you have purchased comes with these slots, this makes soldering a lot easier. Mine was the straight pins type, the seller sent the wrong component and refunded me. Soldering that was just a nightmare. I do not have any “helping hands” tools to assist with soldering, I never liked them. I regret not purchasing one now.

It is essential to add heat shrink cable before soldering and make sure the job is quickly done, or else the temperature will cause the cable to shrink, as it is designed to. I use a hairdryer to shrink the cables.

From my previous article, the figure above illustrates the pinout of the focusing drive. 1 and 6 are Phase A and Phase A’, whereas 2 and 7 are Phase B and Phase B’, respectively. For the GX16 aviation plug utilised by Wemacro, Pins 1 and 2 represent one phase couple, pins 3 and 4 represent the other. Messing these up will cause the motor to vibrate and overheat. It will not damage the controller of the motor unless one keeps it running for some reason.

Pins 1 and 6 of the DB9 plug are connected to pins 1 and 2 of the GX16 plug.

Pins 2 and 7 of the DB9 plug are connected to pins 3 and 4 of the GX16 plug.

The procedure is very simple, I do not think it is necessary to document every step. I will briefly summarise.

  1. Cut the cable and solder the four leads arbitrarily to the GX16 male plug, make sure the heat shrink cable is added before soldering and shrunk down after. Do this one by one if you are not confident in your soldering skills. If you are, I think you can skip all of this.
  2. Make sure you jolt down the pin numbers from above, corresponding to the colour coded cables. I did mine in a text document.
  3. Map the wires to the appropriate pins on the DB9 female plug. Remember, it is mirrored. A simple method is connecting it to the focusing drive and use a marker to paint over the 4 needed pins.
  4. Repeat Step 1 for the DB9 plug.
  5. Add the housing with the appropriate retainer, illustrated in the “Tools” figure, as #14.
  6. Test it, if the motor throws a noisy tantrum without vibrating, you messed up the wiring.
  7. Secure the housing with the Philips screwdriver, I clamped it down first.
  8. Finished!

Since my microscope stage is coupled with a digital indicator, verifying the focus drive’s functionality was easy. If the wiring is correct, the motor should be making a calm “woooooo…” robotic noise.

Procedure: Wemacro Controller modification

I will not show the controller board here. To do this, simply unscrew the only 4 screws on the controller box with all cables disconnected. The controller board will slide out easily.

Remove the two resistors, R19 and R20. This is important, previously I claimed the motor heated up but was not too bad. I was wrong, the motor housing became so hot, it was untouchable after just one hour of focus stacking work. To remove the resistors, heat up the pads with your soldering iron and use a solder pump, I recommend the original “Soldapullt”, do not buy those cheap knockoffs, they are horrible. I used a combination of pump and desoldering wick. If you have a desoldering gun, then you know what to do already.

With resistors R19 and R20 removed, I ran the motor for four hours without an issue. The current output is lowered significantly. Driving a 1.2A rated motor with 2.5A is not a good idea. This procedure can be reversed easily, it is even possible to add a potentiometer that allows the output current to be modulated.

Be careful with desoldering. I accidentally burnt a crevice into one of the relays, which are housed in plastic. This did not matter, but it was pretty stupid of me and I choked on a puff of plastic fumes.

There are four unpopulated through-holes on the controller’s PCB. They can be connected to a limiter switch which will halt the rail’s translation when it is triggered. I might write an article on adding a limiter switch to my Wemacro rail which is still unused.

Oh, doing all this probably voids your warranty. 😃

Result

Everything assembled, the adaptor cable looks very nice. There is one more component to add, two threads that allow the Prior focus drive’s DB9 plug to be screwed onto the adaptor can be soldered on. I will update the article when they fly in. One of the many of China’s made-up capitalism celebration festivals shopping days, “618” is approaching, Jack Ma will enjoy my minute contributions.

The new adaptor looks far nicer than the old sloppy job.

Recommendations

I recommend the Hakko FX-951 soldering station. While I do not recommend knockoffs, they are superior to the Hakko FX888 if you purchase a well-made one. A good knockoff should be compatible with the original Hakko soldering iron, allowing it to be plugged in. The soldering iron itself is not expensive, $60 I think. If that is even too much, then I recommend replacing the soldering tip with an original Hakko one.

I prefer the angled chisel tips, some like the canonical ones.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this:
search previous next tag category expand menu location phone mail time cart zoom edit close