Pictures of the rebuilt Bertha now a CNC

Note Big Berthas PSU's and microstepping controllers are on the shelf under bertha thought I would get Bertha working before going bigger.

I'm having trouble with the Z end stop / home using EMC2 on Ubuntu 8.04 with emc 2.3.0

When trying to home the Z Axis I get a problem with this message "home switch inactive before start of backoff move"

I first tried to use EMC on this little 3 stage machine http://bodgeitquicktools.blogspot.com/2009/05/tools-for-solar-powered-workshop.html

I put this project to one side thinking it had a faulty embedded micro switch.
For Bertha I decided to use infrared opto end stops as used on a reprap 3D printer.



Picture of all 3 Opto endstops Z then Y and X at the bottom note the fully shielded USB cable going to Z.
X and Y home exactly as expected on the bigger machine as the did on the tiny machine however Z will only some time home mainly giving the fault condition message "home switch inactive before start of backoff move"

I re wired the opto swich with Shielded cable ( an old USB lead) as I suspected stepper motor noise could be giving false readings I also decoupled the supply with high an low value capacitors for high and low frequency noise.

Neither of these fixes solved this problem Im not quite sure where to investigate next.

The Linux is Ubunto 8.04 from the CNC install CD from this site so the EMC version is 2.3.0 the mother board is an ITX Gigabyte Atom as it has a parallel port.

All ideas and suggestions welcome.

Is there a file that you can adjust the sensitivity of the hysterise on the home switch?

Is this a known issue with the mother board Im using.. ?

Is there a way to de-bounce the Z home switch in SW?

A picture of the Works in side the top box..



I get 30mm/s travel on Bertha using a 10mm 2mm pitch trapezodial drive shaft if I run it faster which it can do I get a tolerance / friction vibration from the Nylon corner blocks on the 8mm bar.

A front view or contol pannel view



Yes it is tuly amazing the things I can build in Migdes Kitchen.. and get away with..

Solar power for the solar powered workshop

Having an hour spare today I though I would test one of the Solar arrays that has been sitting in its box waiting for me to get some time to put it up.

The solar arrays came from Maplin in March when they had them reduced by £100 each making the price £3.80 a watt. Each solar array kit contains a charge controller with heavy duty plastic pipe frame. Any way here is a couple of pictures of the basic system.



As Im not sure what size of battery array I will need I have only bought one 220AH Solar battery. Now I have one of the Solar arrays connected and set up my next task is to use one of my collection of ATMEGA controllers to do some data logging. I am also looking at making a MMPT solar charge controller making use of the ATMEGA PWM outputs to do this.

From Blogger Pictures

The Solar Arrays will be fitted to the Solar Shed roof. The solar power is not only required to be environmently friendly it was also required as it will be located around 20m from the house. A secondary power source will be from a brand new petrol generator that I need to convert to run on gas.



Heating for the solar shed will be from a pot belly wood burning stove that has an estimated heat output of 7Kw. This was found second hand for £100 complete with a stainless steel chimney. I did talk the guy down from £160 though.

Some esential tools for the work shop

Temperature meter with probe.

There is a need for acurate temperature measurement calibration of extruders and soldering workstations, solar heating systems etc. I found this nice little meter on deal extreme when ordering my Kapa tape around $27.




Electronic digital scales.

Here is another little gem from Deal Extreme i.e. a digital scales with a range of grams up to 45kg. It has lb and oz scales also at a price of $8.



ARNIE - The surface mount soldering plate

Surface mount soldering plate construction I bought a small hot plate for £15 inc postage.




It is thermastaticly controlled on testing its ability to remain at any given temperature was haphazard with a maximum temperature of 170c achived. Stripping the hot plate revealed that the temperature sensor was on the control knob ie in close proximity to the hot plate but not attached.

Searching ebay I located a PiD controler and SSR with K type thermocouple.



I have mounted the PID controler in an old Vero rack case big enough to put the hot plate on.




Very carefuly drilled the under side of cast iron hotplate to take the thermistor. I spring loaded the thermistor using a circlip to hold it in place wired it all to gether using a fused IEC power connector and an IEC power socket to plug the hot plate into. Added a power switch. Removed the original thermistor control circuit from the hot plate. Replaced the hot plate wire with a short 6A IEC lead with intergal plug. So I now have an acurately Temperature controlled SM heating / soldering plate.

Tools for the Solar powered workshop

After six months of planing how to spend my redundancy money effectively. I have started collecting tools for the Solar powered workshop.

We decided to visit the National Model Engineering & Modelling Exhibition in Harrogate this weekend. We took my two of my youngest Daughters who had a great time looking at all the working Models particularly the tiny working steam engines.

My other half Midge also enjoyed the show with the girls buying all sorts of bits and bobs for her airbrush set-up. The next Model Engineering show will be mid October near Warwick / Lemmington Spa. Well worth a visit. I bought a few small bits and bobs as well.

First Purchase was a Time and Precision Ltd 3 axis x 55mm/2.20inch cubed aluminium positioning stage including stepper motors a steal for £40 with 0.00125 resolution on X & Y at 200 steps or 0.000625 Resolution @ 400 steps. The ideal basis for the baby Bertha project.

Second purchase was a the small Sieg C0 Baby Lathe from www.arceurotrade.co.uk Price £165. Thus solving the frustration of trying to use pedestal drill or Afghan lathe etcetera.

Sieg C0 Baby Lathe

Specifications:
Swing Over Bed 110mm
Distance Between Centres 125mm
Hole Through Spindle 10mm
Spindle/Tail stock Bore 10mm
Spindle/Tail stock Thread M14x1mm
Spindle Speed 100-3800 r pm
Motor Output 150w DC
Cross Slide Travel 50mm
Overall Dimensions 440x270x210mm
Weight (net/gross) 13kg/22kg
Standard Equipment:
50mm 3 Jaw Chuck, Dead Centre, Tool kit



Third purchase and slightly unplanned was a Micro Mill also from www.arceurotrade.co.uk £125.

This completes the mechanical hardware required for Baby Bertha.

Sieg Model X0 Digital Micro Mill



Features:

* Digital Depth Readout (Metric & Imperial)
* Feed Depth Set-up
* Fine Feed
* Variable Speed
* Highly Accurate
* Chuck Guard

Specifications:
Drilling Capacity 6mm
End Milling Capacity 6mm
Throat 165mm
Max. Chuck to Table Distance 205mm
(with spindle extended)
Spindle Stroke 40mm
Spindle Taper JT1
Spindle Speed (Variable) High 0-5000 rpm ±10%
Low 0-3600 rpm ±10%
Motor Output 180w
Overall Dimensions 165x275x460mm
Weight (Net/Gross) 15kg/20kg

JT1-ER11 Milling Collet Chuck Set with 6 Collets

The collet set required for Milling purchased from Chester Ltd for £29