Fixture cleaning

Sandblasting doesn't work? That's some coating! I haven't seen anything yet that will hold up to sandblasting. Are you *sure*?

GWE

Burnt on gunk isn't very likely to simply dissolve. And when you're talking dissolution, you should really be thinking about dissolving only the gunk and not dissolving your fixture. So you should be posting what your fixture is made of.

My current favorite home-baked hot cleaning is Cascade dishwashing powder dissolved in water in a stainless pot, brought to a simmer. That bath rapidly dissolves paint, grease, and lots of other junk, but it isn't as dangerous to handle as lye or as hard to find as real TSP. But it will dissolve aluminum slowly, so don't use it on aluminum fixtures and above all don't do it in an aluminum pot unless you really like pinholes.

You can also try mechanical cleaning in the form of motorized wire brushes with appropriate eye, skin and hearing protection. For example, you could try a

4-1/2" angle grinder with a cup-style wire brush rated for say 13,000 rpm, or, if you have to go down into a crack, you can try the saucer-shaped knotted wire wheels on the same grinder. If you need a recommendation on a 4-1/2" grinder, post back.

GWE

Brent wrote:

--Assuming it's a flat surface you might want to consider setting up a fixture for the fixture, so to speak, to mill off the scale..

i had been using a surface grinder on the flat surface, which works fine, but the holes on the fixture are causing the problem, they are .035" diameter. Getting gunk outta there is a nightmare. I should have also stated that it is made from copper tungsten.

I was going to suggest that you make the business end of the fixture disposable, i.e. try to make up a flat plate that could be laser cut 50 at a time, then tossed in the trash when it gets gunked up.

Somehow I don't think that's going to work for you given your material, though.

There are MIG welding contact tips with .035 holes in them, they simply screw into 1/4-28 holes. Perhaps you guys might consider redesigning the fixture to accommodate MIG welding tips which are inexpensive and simple to replace. In the meantime, you might try a set of torch cleaners.

GWE

Greetings Brent, I imagine tungsten copper is pretty hard, but have never machined it. However, this may be a bonus for you. How about using a .035 reamer to remove the gunk? A regular HSS should do. Or, if this opens up the hole at all then a "D" style reamer would probably work. To make one use a piece of already hardened .035 reamer blank. Let's say your hole is .100 long. Grind the reamer blank on the surface grinder down till it measures .019-.020 thick. Make this cut about .06 long. Now looking down directly onto the flat you have ground stone the end of the flatted area at about 10 degrees, removing most material from the right side of the end. This will make it a clockwise turning tool. Now, looking at the left side, stone the end at about 3 degrees, with the material coming mostly off the bottom. This gives you the end clearance so it will cut. Finally, stone a small radius on the left hand front corner. This type of reamer will only cut at the front so it will not make the hole larger. Depending on how thick the gunk is, and whether the hole is blind, will determine if the hole can be cleaned out in one pass. Hope this helps. ERS

Please comment on the differences between Cascade and Calgon dishwasher detergent and TSP. I am particularly interested in the reaction with and attacking of aluminum.

Many engine rebuilders and mechanics use Calgon as a cleaner for engine cooling systems especially if the system has been contaminated by an exchanger or gasket failure or when cleaning and flushing the system to upgrade from standard ethylene-glycol coolant to any of the non E-G compatible long life coolants. The corrosive effects of the cleaner is of great concern since most modern engines make significant use of aluminum and particularly aluminum radiators. I have used Calgon in both newish and very old radiators and have not experienced any problems but the cleaner is not in the engine for an extended period and is flushed thoroughly. I have not done any tests and am unable to do much of an internal inspection.

TIA

I like TSP, used to use it, it also pinholes aluminum. But when it started getting hard to find (when Home Depot stopped carrying it) I switched to Cascade dishwashing powder. Never tried Calgon. Don't know squat about the insides of car engines, sorry.

GWE

I had a discussion with a chemist about dishwasher detergents and cleaning metal parts. He told me that buffers are put into the detergent to reduce the corrosion of aluminum. At the time we discussed this Cascade was gentler on aluminum than Electrosol. So electrosol was preferred by this particular chemist as an etchant/cleaner for aluminum prior to anodizing because it was a little more active than Cascade. This was for home anodizing. He was the chemist in charge of our in-house anodizing line. We did not use any dishwashing detergents for the mil-spec anodizing. Calgon may be even less corrosive than Cascade. If it was me I'd try a couple test pieces in side by side solutions. Use identical sized aluminum pieces in the solution strengths and temperatures you would use in the engines. Weigh the pieces before and after cooking in the cleaning solutions. Then you'll know which is best in your exact situation. ERS

Is this really hard ? If so, then it is the chrome from the stainless. Really nasty to grind off. It tends to be black.

Martin Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member

Brent wrote:

Any alkaline cleaner will etch and damage aluminum, it is just a matter of how fast. Alkaline solutions dissolve the oxide layer that seals and protects the aluminum, which then reacts with water to release hydrogen gas bubbles. The hotter and more basic or alkaline the solution the faster it goes. All the machine dishwashing solutions I can think off offhand are alkaline, as are TSP solutions.

Try a scrap piece of the copper and tungsten your jig is made from in a pot of simmering Calgon or Cascade and see if it survives. If it does, try your dirty jig. You could also add some lye (couple of tablespoons per gallon as a start) to the Cascade to make it even more alkaline which will help it slowly dissolve the crud.

This is Usenet, so I have to say "be careful and use proper protection".

-- Regards, Carl Ijames carl.ijames at verizon.net

To add to the nightmare - chlorine really does a number on Al - and can catch it on fire. Had a capacitor (Al covered type) drop into a tank of FeCl (copper etching tank)

- almost exploded from the gas produced and the massive heat. Martin Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member

Carl Ijames wrote:

I take it you're English?

I can't answer your question but try sci.engr.metallurgy

You might find Dr Beckmann's Rescue Oven cleaner invaluable for de-coking cylinder heads BTW. It's available in most Tesco's & Sainsbury's. It doesn't choke/burn your skin like Mr Muscle does.

Balders (a backyard VW nut)

I'd think Dawn - the blue liquid for sinks - is the best oil/grease cutter. Cascade is good stuff, but eats Al as well. More of a surface etch.

Mart> I like TSP, used to use it, it also pinholes aluminum. But when it

Dawn is way mondo good stuff for oil/grease cutting. Marvelous for cleaning old machine tools also. In fact..its great for pressure washers/steamers too. I drop my soap hose from the Hotsie into a bottle of Dawn whenever I pressure wash Stuff, truck engines, machine tools etc etc.

Gunner

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