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Re: West of Scotland Group's "Starters" Build a loco project 3

Posted: Sun May 17, 2020 2:00 am
by Stephan.wintner
Over in the US, Paasche offer a "air eraser" which is a small grit blaster. It's similar to Paasches airbrushes, but has a cup and nozzle intended for grit (hard, etc). Especially, the cup is a flow-through arrangement, not a gravity feed. So I don't know if an airbrush would properly flow the grit...

Modellers here seem to have luck blasting using common household baking soda, for styrene and brass, although Paasche also offer various aluminum oxide grits. I'm in the midst of trying it myself - but my compressor lacks the oomph needed, it needs some 45+ psi...

Stephan

Re: West of Scotland Group's "Starters" Build a loco project 3

Posted: Sun May 17, 2020 7:24 pm
by Allan Goodwillie
HI Guy, :)

To a certain extent the two do the same in that a glass fibre Brush will not just clean the surface, but it will also to a limited extent give the surface a bit of an improved grip for the paint. The Oxide does this to a greater extent and allows more tack for the paint to stick to the surface. With a good magnifier it is possible to see the difference. A cheap airbrush with an outside mix with the hopper for the oxide sitting on top would would think would be ideal as it will rely on gravity to load the material as it gets blasted out the front of the brush. I have not had one of these to try this out , but maybe someone else has. It is not often I go into theory mode - but I am sure someone out there knows.

Allan :)

Re: West of Scotland Group's "Starters" Build a loco project 3

Posted: Mon May 18, 2020 7:47 am
by Paul Townsend
Stephan.wintner wrote:Over in the US, Paasche offer a "air eraser" which is a small grit blaster. It's similar to Paasches airbrushes, but has a cup and nozzle intended for grit (hard, etc). Especially, the cup is a flow-through arrangement, not a gravity feed. So I don't know if an airbrush would properly flow the grit...

Modellers here seem to have luck blasting using common household baking soda, for styrene and brass, although Paasche also offer various aluminum oxide grits. I'm in the midst of trying it myself - but my compressor lacks the oomph needed, it needs some 45+ psi...

Stephan

Badger used to sell an air-blaster kit but it may be discontinued. I have one from many years ago.
Amazon are not the final arbiter but.....
https://www.amazon.co.uk/Badger-Mini-Sa ... B000IG2VEO

Edit:
Here it is, 4 available
https://www.ebay.co.uk/itm/BADGER-MINI- ... 0713052641

Re: West of Scotland Group's "Starters" Build a loco project 3

Posted: Mon May 18, 2020 7:57 am
by Paul Townsend
Paul Townsend wrote:
Stephan.wintner wrote:Over in the US, Paasche offer a "air eraser" which is a small grit blaster. It's similar to Paasches airbrushes, but has a cup and nozzle intended for grit (hard, etc). Especially, the cup is a flow-through arrangement, not a gravity feed. So I don't know if an airbrush would properly flow the grit...

Modellers here seem to have luck blasting using common household baking soda, for styrene and brass, although Paasche also offer various aluminum oxide grits. I'm in the midst of trying it myself - but my compressor lacks the oomph needed, it needs some 45+ psi...

Stephan

Badger used to sell an air-blaster kit but it may be discontinued. I have one from many years ago.
Amazon are not the final arbiter but.....
https://www.amazon.co.uk/Badger-Mini-Sa ... B000IG2VEO

Edit:
Here it is, 4 available
https://www.ebay.co.uk/itm/BADGER-MINI- ... 0713052641


Further to this, some points about using air blast grit.

1. The Badger needs quite a high air pressure, more like 40psi than the 20-ish we mostly use for air-brush painting. Not a problem if your compressor system is easily adjustable.
2. Aluminium Oxide ( Alox ) grit is expensive and you use quite a lot. Recycling is viable if you have used it on bare metal but I would not after use on paint as the paint chippings might block the blaster nozzle
3. I have used baking soda....cheap and Ok for gentle cleaning but less aggressive than Alox. I have been told that the finest dry sand works but I have not tried this.
4. MESS ! It goes everywhere....do it outside.

Re: West of Scotland Group's "Starters" Build a loco project 3

Posted: Mon May 18, 2020 9:27 pm
by Phil O
Richard Watson, late of this paraish used a medium sized storage box as a blasting bay, He cut a hole in one side and end and using a pair of large rubber gloves secured by disks of plywood secured the gloves to the holes such that you could put your hands into the gloves and operate the gun inside the box. A gland fitted and sealed to the box supplied the air to the gun. Put the item to be blasted into the box, fit the lid and run gaffer tap round the join to form a seal, hands in the gloves and away you go. Once finished go and have a brew before removing the lid, to allow the dust to settle.

Cheers

Phil

Re: West of Scotland Group's "Starters" Build a loco project 3

Posted: Tue May 19, 2020 8:54 pm
by Stephan.wintner
Interesting. The Paasche has a hopper on top, and flows the air up through the media, then back down to the nozzle. I suspect it'd fluidize the media a bit better than the Badger design. But I definitely needed more than 20psi - it flows media but too gently at 20 psi. Compressor ordered, it's in the mail.

https://www.amazon.co.uk/Paasche-Airbru ... ser&sr=8-1

Stephan

Re: West of Scotland Group's "Starters" Build a loco project 3

Posted: Wed May 20, 2020 7:07 pm
by jasp
I built a wee enclosure for sandblasting (article some time ago in snooze) but now somewhat lacking in storage space I have adopted Allan Goodwillie’s thick polythene bag.
It takes up virtually no space, totally contains the used powder and is very clean in use.
Thanks Allan!
Jim P

Re: West of Scotland Group's "Starters" Build a loco project 3

Posted: Wed May 20, 2020 7:42 pm
by Allan Goodwillie
Thanks Jim, :thumb

Things do not have to be complicated and it seemed a simple cheap solution to me at the time. You have the advantage of being able to see completely what you are doing at the same time. The point about re-using the grit - you can do if you have used it to clean up an unpainted surface. Particles of paint do have the potential of sticking in the airbrush.

For anyone looking for this you will find it here-

https://www.scalefour.org/forum/viewtopic.php?f=39&t=886

Allan :)