The Tachometer

With the wiring of the KBIC out of the way, the next is to either buy or make a tachometer to display the spindle speed and also to feed Mach 3 the pulses coming out of it.  Before i know it, Terence has already completed one and generously shared it with me, all parts included.  The completed tachometer uses 7-segment LED as display.  From the case he printed, it looks good through the tinted acrylic front cover.

Next is to wired it up so that it can signal to Mach 3 via its index pin. This, I encountered lots of problem because of electrical noise in my system.  To solve this problem, Terence designed an addon board to filter out the noise so that the microcontroller is able to see the pulses without false trigger.  With the addon board design done, I asked for the files to experience milling a simple PCB on my own.

The process was straight forward enough, though I did encounter some difficulty along the way due to my inexperience milling something so small and mainly in filling up the board with components.  But I managed.  This is the board freshed out of the mill:

Fresh out of the mill

After cleaning up with sandpaper

To fill up the board with components, I've to make several purchases in term of equipments.  The cheapo soldering iron I have on hand made soldering SMD parts a terrible experience.  Since it was my birthday then, I bought myself some presents... lol. Excuses...

A Hakko FX888 soldering station

and this.... to assist my eagle eyesight when soldering the SMDs...

With the 2 bigger purchases and some little stuff like flux, I began filling up the board with components that are smaller than a grain of rice...  Under magnification, I can see that my hands tremble quite a bit when position the components.  The result, after several tries, is passable.

As the whole process was rather long, with lots of screw-ups mainly due to mistakes and stuff, I'll put the pics below and caption them as I go.  Hoover your mouse cursor over the pic for the caption.  Apologies for using this format to present the pics as I've problem selecting the many pics I've on my iphone and uploading it here.

A resistor... This pic was taken under the magnify glass I bought and with the iphone camera zooming all the way in.

The parts for the addon board. This board was the first version with the opto-isolator built in. We took it out later to keep things simple and need.

The board filled. The next step wiring the board to the main tach board gave me lots of problem. The 30 gauge wires kept breaking causing lots of frustrations. Further, I didn't realize that I shorted some of the pads during soldering.

The is the revised board. Basically the same as the earlier design but with the opto-isolator taken out.

The board added wired to the tach board. I resolder the wrapping wire so often that one of the pads on the tach board came off, together with the trace under the mask. Terence took over from here and wired up everything for me, together with another addon board he milled and filled.

With the board I made, I soldered on a set of header pins to use on the tach I'm working on, using Arduino Nano instead. It is working now but still on the breadboard. Will be milling out the PCB for it and use it on maybe my Proxxon Lathe.

The package from Terence came with some stickers for the spindle. This is pasted onto the under side of the spindle pulley. Saw this great trick to better do this job.

Sliding the sticker in.

Done!

The IR sensor is mounted to the spindle using heavy duty double sided tape.

As the index pin on the G540 may not be isolated, a opto-isolator is used. This is "cut off" from the board design in version 1.

Next is to connect it up to the tach board.

This board is easy. A tiny 68 ohm resistor and the opto-coupler. It is being wired to the tach board output on one end and G540 pin on the other. I'll be switching the connection from G540 to one of the input pins on port 2 of the USB Smoothstepper soon.

Shrink wrap it up to protect it against the environment, especially me...

Time to test it out. This and the next pic show the speed as commanded on the MDI after calibration was done. I had lots of problem between then and now just on calibration alone.

Nice... It is even better now but within 200 rpm difference is good enough for me, considering what I've been through trying to get it to work.

Finally, what I wanted few years ago came through, all because I've a good bro guiding and helping me along the way.  He guided me through several nights and helped troubleshoot over Whatsapp till 3-4am, on things like how to solder SMD, figuring out what went wrong when things didn't happen as it should.

I'll be making another tachometer using arduino, as well as making the sensor Terence did with another type of sensor.  All these will be for further learning and practicing.

I've just trammed up my wabeco mill today.  Should be starting with one of the manual machining projects which I wanted to start several years back.  This hobby kept my mind keen and not wander over negative things.  A little selfish though as I occupy of of the 3 bedrooms in my flat for it.  Both my teens are bulking together in the little room they have.  Sense of guilt?  Yes.  I need a solution to this.

I'm praying for a place with 4 bedrooms so that each of the girls can have their own room while I can still have my little cave to indulge myself in.  Lord, grant me my wish...