General Update On What I Have Been Doing Relating To Model Engineering In Thailand In The Last Few Days
Continuing the Makita 2107F Horizontal Bandsaw Frame Design
This is still progressing in AutoCAD. The swing arm design is complete and I have managed to achieve 120 mm capacity for round material and 180 mm square material capacity without making the arm excessively long.
I’m now drawing up the base and trying to minimise the material content and weight with compromising strength and function.
Buying And Using A SESA MMA200 Arc Welder
I knew that I would want to arc-weld the Makita bandsaw frame when I build it. I have oxy-propane equipment and have welded my steel workbench using it but it is slow, uses a lot of gas and the welds are ugly.
(Its all described with photos on the Page “Setting Up A Model Engineering Workshop In Thailand – Making A Steel Work Bench” on RetiringInThailand.net website. Also there are a few more photos showing the steel sections available at the Ying ja Luem shop in Pak Chong and a photo of the tools sections.
Also in the last few days I have started to assemble the Stuart Turner Victoria steam engine (just the main pieces that are complete or semi-complete) and want to put some holding down ugs on the base which is a piece of steel channel.
I could braze them using the gas torch but I wondered if I could weld them.
So it was a good excuse to go out to buy an arc welder.
Buying And Using the SESA MMA 200 – 200 Amp DC Inverter Arc Welder
I have started a new page SESA MMA 200 – 200 Amp DC Inverter Arc Welder Review where I’ll cover the story in more detail. I have already started the story on the previous Update page at http://modelengineeringinthailand.com/update-131215/
As I mentioned in a comment the welding glasses were too dark so I tried to find something better. I couldn’t find the automatic electronic type that George mentioned but I did buy an “auto-darkening welding” filter for 350 Baht.
I also bought some welding goggles with flip down glass and that was not so dark as the welding mask that came with the welder.
Needless to say when I got home and started to try out the new glasses:-
- The auto-darkening welding filter wouldn’t fit the welding mask nor the goggles.
- The auto-darkening welding filter instruction warned to use a polycarbonate clear shield in front of it so that weld spatter doesn’t destroy the photocell sensors.
The original welding mask didn’t have a clear glass protection filter and the dark glass was peppered with weld spatter. So I decided not to try the auto-darkening welding filter until I had the protective glass.
I was able to see a bit better with the welding goggles than with the welding mask and I produced some better – but still unacceptable – welds.
Building The Stuart Turner Victoria Steam Engine
I wanted to make some small steel lugs 15 mm square (ends would be rounded) and about 3 mm thick. Also I needed two 3 mm plates 50 mm X 100 mm to fill in the ends of the steel channel base.
I had already bought a piece of black 2.8 mm steel plate a metre square from Jing Jaleaum so decided to try out the Bosch GST 25M Jigsaw again. The first cut was to remove a long strip from one side which had been flame-cut and was both extremely rough and also hard.
To cut a long story short (and I’ll be giving more detail, photos and a movie on the “Bosch GST 25M Jigsaw Review” Page it was a struggle. With sparks literally flying from the blade it’s no wonder it went blue even though I was using plenty of oil on the cut.
I then cut of a strip just over 50 mm wide for the ends of the steam engine baseplate. This went much smoother because:-
- There was no flame-cut edge that the blade and jigsaw had to deal with
- I didn’t use a guiding fence – just followed a marked-out line by hand
- I changed to a finer blade
- I discovered the speed adjusting knob!
I made a two spare for trial welding.
For the holding down lugs I cut strips of a black steel bar and then sawed them to individual lengths using a slitting saw in the milling machine. I made a few spare for trial welding.
Except where they had been cut or machined all the parts were left with the black millscale on them. Not quite the cleanest surface for brazing!
Since my second welding practice session was not successful (third session pending the clear protective glass) I decided to gas braze the lugs and end plates on a spare section of channel I had.
I started to braze one end piece then it started to rain to I left that and went on the quickly try brazing the lug. I think I melted that.
The parts are stuck together but not very neatly. I couldn’t see what I had actually achieved because of the black flux.
I have put the parts including the unused ones in a bath of citric acid to clean them up. I’ll then see what I have achieved and the citric acid will make the other parts cleaner (and remove the black mill-scale) so that my next attempt at brazing should be an improvement.
Replies to Comments Added
Andrew’s comment: http://modelengineeringinthailand.com/#comment-106