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Subject: Re: [Homebrew_PCBs] laminator motor one pass speed control discussion GEARS

From: Harvey Altstadter <hrconsult@...>
Date: 2016-12-18

Rob,

You could grind a flat on the shaft. Alternatively, you could, if the gear is not too hard, drill through from the outside surface to the center and tap it for a set screw. A small flat ground on the shaft would be best to keep it in place, and once properly tightened, some hi temp epoxy on top of the set screw should keep it locked in place.

You hit the nail on the head about getting metal gears. After I melted the drive gear (mine looks suspiciously similar to yours) on the Harbor Freight laminator, I realized that I could spend a lot of time and money trying to turn a sow's ear into a silk purse, when in the end I would just have an expensive sow's ear. At the same time, you gave me an idea. There is nothing sacred about the gear ratio, once we have the ability to continuously vary the speed of the motor. Any gear set that fits the shafts and the spacing between the shafts would work. I don't know how much easier this makes finding other gears, but it might. When I have some time, I will take a look at that aspect of the problem.

Harvey



On 12/18/2016 7:58 AM, Rob roomberg@... [Homebrew_PCBs] wrote:
 

GREAT!
TNX for the video.
..... looking forward to what you build.
and as gears go....

I am not the only one to run into this problem.
Something as simple as replacing nylon plastic gears with a metal gear
has proven impossible without spending $150 on custom made gears.

http://www.learnmorsecode.com/laminator/royalmods1.jpg
http://www.learnmorsecode.com/laminator/royalmods9.jpg
http://www.learnmorsecode.com/laminator/royalmodsgear1.jpg

and the other gear  issue seems to be that not all synchronous mores use a D shaft
so you can buy a $3 motor on ebay but then you have to figure out how to get a gear for its round shaft.

All these gear issues really is what pushed me to heavy metal press PCBs:
http://www.learnmorsecode.com/laminator/hotcakes.html




On 12/18/2016 09:22 AM, mosaicmerc@... [Homebrew_PCBs] wrote:
 

Hi guys:
Thx for the link to that SPWM controller board Harvey. I have ordered the board and the FETs. I will do a open source Hackaday project on it as a laminator speed control as I get time. It seems all I need to add would be the 170VDC to obtain the 120VAC (170VDC RMS). I plan to do that by using an old PC PSU  to supply the 170VDC (internal tap) and the 5VDC & 12VDC.

As a project I may do a dedicated PIC microcontroller speed control with everything integrated (including a voltage doubler for 220/240VAC motors) as a 'safe' kit to build to deliver the 200mA capability to handle a wide variety of small synchronous motors. Probably housed in a 4" x 2" PVC electrical can with a couple LEDs for status displays.

It seems that most AC Synch. 'spare part'  motors come in the 220V variety.

As I consult for a CNC machine shop company that makes gears, I can inquire as to making a batch of gears, standard size for l aminators and such with set screws. Maybe 6061 aluminum would be durable enough, but certainly mild steel is doable. Oil impregnated bronze might be available.

These two link,below,  on youtube help demo the board and demo how a micro does the job as well..including theory, BASIC code & wiring.

Demo of the sine wave PWM inverter board
https://www.youtube.com/watch?v=gtmYnbtcPVg

Use a micro to create the sine wave PWM to drive an H bridge
How to implement an sPWM on arduino/atmel (sinusoidal PWM code and explanation)