What Did You Do Today (2016)

[Ed DuffnerParticipant @edduffner79357]

Yesterday had a go at etching a PCB for a rotary encoder to attach to my Vertex rotary table.

It didn't come out as I would have liked so I'll be making a second batch of one more. The board seems to have etched more in some places, severing a couple of traces and not enough etching elsewhere leaving a few copper remnants in between traces.

I have a CNC motor already with a controller coming in the post, but I noticed today that the spec for the motor mentions 2.52V which I thought was a bit low for a Nema 23? I have emailed the seller for more info.

Also today I've been looking at my Powertank 17 which powers my telescope. The lead-acid battery hasn't been charged in years so I'm looking into rejuvenating it if possible. I'd really like to replace it with some modern battery technology.

Ed.

Edited By Ed Duffner on 22/04/2016 22:34:49

[Danny M2ZParticipant @dannym2z]

Posted by John Stevenson on 21/04/2016 21:42:43:

First job is to dig out and get a heated slab in for the workshop to stand on and be nice and toasty in the winter months. I'm quite looking forward to having a blank canvas and not being rushed to move in which is what normally happens.

Hi John, Neil may have anticipated your workshop heating endeavours – check out MEW 237 (January) page 46

* Danny M *

[John Stevenson 1Participant @johnstevenson1]

LOL, Yes remember seeing that.

[Rod NeepParticipant @rodneep80388]

A big step for the beginner…. I have never done milling before. I have a vertical slide attachment for my Warco WM-240, and this is my first attempt at milling. (And also setting up the vertical slide and the work piece using an indicator).

First I milled the base of this standard for the Stuart V-Twin Oscillator, then skimmed the four edges of the base, and now just completed milling the first side for the steam connections and valve surfaces.

OK… I did take it very steadily with fine cuts, as one of the problems for a rank beginner is figuring out how much of a cut to make at a time. But I did it! Next step will be to come out 5/32" and mill the end of the crankshaft bearing, then flip it over and do the other side.

Rod

[Russell EberhardtParticipant @russelleberhardt48058]

Ed, do your pcb tracks really nee to be that narrow? If you over etch they will always get a bit narrower. I use a Mungolux photopolymer film resist and about three seconds exposure to the sun (no UV lightbox) with an inkjet printed master and get good results.

Russell

[MuzzerParticipant @muzzer]

Posted by Ed Duffner on 22/04/2016 22:30:43:

The board seems to have etched more in some places, severing a couple of traces and not enough etching elsewhere leaving a few copper remnants in between traces.

You have to be meticulously careful with cleaning / degreasing the bare board. Looks more like contamination than overetching. Was the board good and clean / unmarked beforehand?

The motor voltage is what you get if you drive the rated current through the coil resistance (V=IR etc). There are many levels of control sophistication for steppers. The most basic ones simply switch the full supply voltage between windings. Ideally you will be using a slightly smarter driver that will control (or at least back off) the current rather than simply maintain the full supply voltage across the motor. If you have positional feedback you can even go all the way up to vector control but you pay a bit more for that.

Murray

[Ian S CParticipant @iansc]

I use an aquarium pump to agitate my etching bath, I get more even etching that way.

Ian S C

[Neil WyattModerator @neilwyatt]

Hi Ed,

I agree with making those thin tracks wider, even where they pass between pins. It looks crisp so I assume it's a photo-etch, if so you can go incredibly thin for tracks or gaps – but only do so where you need to.

Neil.

Edit – one other thing that can result in broken thin tracks – the positive film not being fully in contact. I always put a big weight on the back of the PCB during exposure (when I remember!)

Edited By Neil Wyatt on 23/04/2016 17:21:50

[EmgeeParticipant @emgee]

Ed

I use the same stepper on a 24v supply via a controller of course.

Emgee

[Ed DuffnerParticipant @edduffner79357]

Ta very much for all the hints and tips guys, much appreciated.

I think on reflection the broken track problem was possibly due to not expelling all air between the photo resist film and the board plus a bit of over etching. Cleaning of the board was with Scotch-brite, airbrush cleaner, then 99% IPA. I'll need to get a laminator if I do any future pcb's I think. I will also be making the traces wider in CorelDraw for a second attempt.

The board was sandwiched in a picture frame with a glass front and exposed to a weak sun (kind of overcast) for about 30 seconds and I suppose not ideal as a controlled environment. I saw a video on YouTube where a guy in India exposes this type of film to the sun for 7 minutes!!

The one I'm building is the controller by Steve Ward (hope it's ok to quote names here) so is a proven design and I love soldering. The motor controller for the indexer will be an upgraded TB6600.

I've also splashed out on a Mach 3 controller as a first stage in converting the WM-16 to CNC. I can then use my RT as a standalone, on the lathe, or with the mill as a fourth axis.

Ian SC, I think I have an old Whisper 500 fish tank pump hiding somewhere.

Emgee, thank you for the motor info/confirmation.

Muzzer, say what? Stepper motors are confusing and I used to be an electrician . I think about motors as having a supply voltage and the current drawn is a combination of the load on the motor shaft + any internal winding resistance/current …oh and the start-current of course. Lots of reading up to do.

Cheers,
Ed.

[Boiler BriParticipant @boilerbri]

 

As part of my retirement plan I finished building this- 

 

So that I can fit a bigger one of these-

 

And then enjoy the view while making models

I am a bit tired now after moving all the granite. I will be worth it though. I just need to get a shed strong enough to stand the south westerlies in the winter. When that's done I can return to model engineering

 

 

Edited By Boiler Bri on 24/04/2016 07:42:37

[ianjParticipant @ians]

Ed.

Steve Ward sells the PCB's for just £6 + p & p which I think is very reasonable for a professionally produced PCB with component values/number printed on it.

Ian

[David lawrence 3Participant @davidlawrence3]

I bought Steve wards stepper motor controller for my rotary table fully built and tested for around £ 60.00. it works well, good value. I could have built it myself and saved £ 10 – £ 15.00 but why bother. As to making your own pcb to save pennies is daft. I have all the pcb making gear, UV light box, etch tanks. high speed drill but its not worth the bother. my only problem with the controller is that the keyboard is turned 90' to normal which means sticking on labels on the keys, could look better.

[Les Jones 1Participant @lesjones1]

Hi David,
Can't you just change the wiring to the keyboard. Swap over the X and the Y axis ?

Les.

[Neil WyattModerator @neilwyatt]

On stepper motor voltages and currents, they don't apply with most modern controllers as they use current sensing that means a higher voltage (one that would easily burn out the windings if applied continuously) can be used.

Often the controller has a preset or other arrangement to set the maximum current.

Neil

[ianjParticipant @ians]

David.

With the latest version of firmware (v2.21 I think) if you hold digit 2 pressed and turn on it configures the keypad

Extract from Steve's manual:_

"Keypad Orientation
Note that the keypad orientation can be automatically configured on first power up for
non-standard keypads.
To do this press and hold button [2] whilst powering the unit on and continue holding
the button until the message “Keypad Orientation” appears.
The button can now be released and the unit will store the orientation in non-volatile
memory for future use so there is no need to repeat this step.
The rest of the text under “Keypad Orientation” is for information only and will only
be displayed for a short time before normal operation commences."

 

Ian

Edited By ian j on 24/04/2016 13:07:04

[David lawrence 3Participant @davidlawrence3]

Thanks ian j, that will help a lot, shame I have just glued the keypad to the case 90' lop sided but hey, I will start again. many thanks, I can now start making the wheels for my clock.

[Neil WyattModerator @neilwyatt]

Had a filling fitted.

That stuff they use as glue and for making white fillings that is set with a UV torch is phenomenal stuff. Must have 101 uses in the workshop – is there a cheap source of it?

[martin perman 1Participant @martinperman1]

Neil,

Google the words UV activated glue and the list is endless for allsorts of aplications.

Martin P

[Clive HartlandParticipant @clivehartland94829]

Yes, they glue optics together with it now, instead of Balsam. There was an optical cement that replaced Balsam but you still had to work hot. Now of course its cold and UV light for a few seconds.

[Neil WyattModerator @neilwyatt]

Yes I found some in the end – it seems to be most popular with fly-tiers!

Not cheap!

Neil

[davebParticipant @daveb17630]

Nicked my ear shaving, when I looked around ( I tend to shave from memory, saves having to open my eyes) bathroom was like a murder scene, shower, bath, toilet,basin and floor liberally coated, all from a tiny nick. Why can't they make paint that covers like that?

Dave

[john carruthersParticipant @johncarruthers46255]

Yesterday I got an old 8 day mantle clock going. I've had it in the cupboard for 20 years or more and finally gotaroundtuit.
It needed a new pendulum suspension which I made from a 10 thou" feeler blade.

New brass hands are in the post (£1.89, can't be bad)

Edited By john carruthers on 27/04/2016 08:21:50

[Ian S CParticipant @iansc]

Loctite do a UV glue for aquariums, to set in strong sun light about 10 to 20 seconds, on a dull day up to 2 minutes. Loctite Glass Bond comes in a 3 ml plastic tube.

Ian S C

[roy entwistleParticipant @royentwistle24699]

John Carruthers I personally would only use 4 thou on a mantle clock 8 thou on a long case I have just measured six different commercial suspensions they varied between 3 thou and 5 thou But if 10 thou works for you fair enough

Roy

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