Making non-magnetic tools

Hi everyone,

Since this is my first post, let me quickly introduce myself:

My name is Sander, I'm from the Netherlands. I've almost finished my Masters degree in Molecular Life Sciences and am starting a PhD in Nuclear Magnetic Resonance, or NMR(akin to MRI). In my spare time I like to do woodworking and some light metalworking.

So, I have a question. In NMR we make use of very strong magnetic fields. Sometimes I need use slotted screwdrivers on the equipment, which obviously need to be non- magnetic.

Just for fun, I thought it would be a nice project to make some non-magnetic slotted screwdrivers. I was thinking to use roundstock and hammer the heads to shape, to work harden them a bit. Then the final form will be made by filing, sanding and maybe using some stones. I will turn some handles on a wood lathe.

But now the question: What material to use? I was thinking about brass, titanium or bronze, but there are so many alloys of these materials. Most screws in NMR equipment will be brass,sometimes stainless steel. What material would you suggest that is a good compromise between cost and performance? Ideally the material could be hardened, by work hardening or a very simple heat treatment. I hope someone can send me in the right direction

Look at what reduced sparking tools for explosive environments are made from and take a page out of their book. You will find a lot of brass (hammer heads) and aluminum bronze tools. 7075 and 2024 aluminum might be other good materials to look at but at their best they are still only comparable to flavours of mild steel.

Edit:
As mentioned below beryllium copper is another common material

I believe a lot of non sparking tools are made from beryllium copper. I don't think any of the non sparking non magnetic tools will hold a cutting edge.

I'm sure the European commercial alloys are slightly different from the US ones, but there are several common bronzes here which would be useful. Aluminum bronze C954 (aka 9C, aka Wearite 411), silicon bronze C655, manganese bronze C863 (aka SAE 430B), and phosphor bronze C544 (aka B2) would all have ample strength and toughness for your application, and C954 and C544 definitely can be work-hardened. (I am not sure about the other two.) As you note, there are many (hundreds if not thousands) of alloys, but these four are widely available here. I did not check the magnetic permeability of these materials, and C863 (at least) has 2-4% Fe, which may be relevant in your strong magnetic fields.

Titanium (in any commercially available alloy) would be a good choice, but may be more or less convenient to buy in small quantities in your location.

While the boundary between bronzes and brasses is blurry, I would not choose any free-machining brass for this application.

Only has to be non-magnetic, use stainless.

Non-ferrous, titanium.

guest said:

Only has to be non-magnetic, use stainless.

Non-ferrous, titanium.

Click to expand...

If he cold works them as planned even 300 series stainless will pick up magnetic properties. And I sure the hell don't want to find out just how magnetic they are.

Wow thanks for all the replies! This gives me a good starting point. Indeed I would like to go non-ferrous/non-ferromagnetic. We are talking about 7-14 Tesla magnetic fields, which is quite substantial to say the least. I will check the alloy composition before ordering any. Anyway, thanks again!

As the others have said, aluminium bronze has been used for many years for non sparking and non magnetic tools. Titanium alloys are even better, but you may find them difficult to work with. They work harden to the point that they can be difficult to cut or file with hand tools. If the university has a machine shop (mechanical engineering department?) you can probably get help with milling titanium (bring beer for payment ).

Hmm, I cannot see any departments or courses at Wageningen that would have a workshop with machine tools in them. Aluminium bronze or Austenitic (316) stainless steel might be all you can use without machine tools.

Try asking some of the laboratory technicians about local schools/companies/colleges that might have a workshop that can help. A set of titanium screwdrivers would be a useful machining project for a training school if you cannot make them yourself.

If you have the machine tools, then no problem, but if you don't, then there will be someone that will thank you for the challenge!

Non magnetic Beryllium Copper tools are common and used in all application where magnetic fields or sparking is a problem. I am using a number of beryllium copper screwdrivers, wrenches, etc. when working near magnetic particle focusing elements. Beryllium copper is almost as good as an average steel tool. Here are examples of a commercial products.

5/16" x 3" Blade Non-Sparking Beryllium Copper Slotted Screwdriver
| Fastenal

218 22mm Anitmagneitc Combination Wrenches,Hand Tools,Non Sparking Tools,Beryllium Copper ,Safety Tools From Xinjijinye, $36.37 | Dhgate.Com

Is it beryllium copper that breathing the dust is hazardous? I know it is one of the non magnetic alloys that breathing the dust is a long term hazard. Using the tools is fine but even sharpening them makes enough dust to get worried.
Bill D.

On Edit

:Berylliosis - Wikipedia

Thanks for looking that up Mark Rand Indeed we do not have a mechanical engineering department. Actually the university is quite focussed on food and agriculture and only has one 'faculty' if you will. I know the head of the machine shop, but they only do paid work and it is not allowed for students/employees to use the tools themselves. At my current internship place at the Catholic University of Leuven they do have nice machine shop facilities, but I'm in the middle of finishing my report and don't have time to do the work here.

@Bill D

I have already ordered a half face respirator (I needed one anyway for grinding and welding). I don't know about the beryllium copper, but I do know that breathing titanium is supposedly not so healthy. In any case I will wear the respirator when working these materials.

I found a place that sells short sections of Grade 2 titanium for very reasonable prices. Would that be suitable? I was also looking at Grade 5/Ti Al6V4, but I found that this grade (and many of the bronzes) still contain iron, albeit less than 0.5 or 0.25 % max. Does that mean that they don't mix iron in on purpose but it can occur as an impurity?

Some manganese bronzes are actually ferromagnetic.

Bill D said:

Is it beryllium copper that breathing the dust is hazardous? I know it is one of the non magnetic alloys that breathing the dust is a long term hazard. Using the tools is fine but even sharpening them makes enough dust to get worried.
Bill D.

On Edit

:Berylliosis - Wikipedia

Click to expand...

Read the MSDS for the alloy in use, as Be-Cu alloy is in no way the same as Beryllium.

About every second year, one of our supervisors would go full bore stupid and panic at the toxicity of beryllium, without actually bothering to do as I suggest above. They would demand that we wear full taped at the seams overalls and full face masks, etc.

Keep you fingers out of your orifices, wash before eating. Don't make sparks or dust (eg: buffing, surface grinding, welding), use coolant while machining.

I would suggest that if Be-Cu alloy was gonna kill ya, it would have done so already, as there is a lot of it out there as springs in small items in general consumer use.

A typical Be-Cu alloy has under 3 percent Be, if you can make that hurt you, it'll probably be by dropping it on your foot, or cutting yourself on a sharp edge.

All that said, Al-Bronze is cheaper and easier to get, and doesn't come with a panic-inspiring name.

Good points trevj,

Benzene in itself for instance is carcinogenic, but an aromatic molecule (containing a benzene ring) can be completely harmless. Heck, if all aromatic compounds were carcinogenic, we wouldn't be writing messages on this forum. I'll check the MSDS sheets.

That said, as having a partial chemistry background, having a fancy beryllium compound sounds more fun than boring old aluminum. Just an irrational thought.

Do you have a magnetic permeability tester. When we made tools for digging up mines in Vietnam we had to use one.

I had to make copies of standard surgical instruments once, for "the Ice Man". Used CP titanium, I think.. (commercially pure)

Fine beryllium dust, as is beryllia (beryllium oxide)dust, is certainly dangerous. I have worked with both materials taking the usual precautions. I do a fair amount of work in beryllium alloys (usually alloy 3 and 25). A nice material for machining and no danger whatsoever in the chips produced - in any case all contained in the coolant. Never had to grind it: an unlikely operation for copper based alloys. In any case I do all the grinding wet as fine metal dust, beryllium and otherwise, is not pleasant or healthy to breathe.
Beryllium-copper alloy 25 can be heat treated. It is hard enough to make ball bearings and I am using those in applications where the non magnetic quality and the compatibility with the rest is essential.
And it seems to me ridiculous to start making screwdrivers and pliers when you can buy those for the same price or less than the raw material.

SanderBash said:

Wow thanks for all the replies! This gives me a good starting point. Indeed I would like to go non-ferrous/non-ferromagnetic. We are talking about 7-14 Tesla magnetic fields, which is quite substantial to say the least. I will check the alloy composition before ordering any. Anyway, thanks again!

Click to expand...

There is a website called "quickwedge" that advertises non-magnetic tools such as wrenches, chisels, screwdrivers, hammers and other tools. Sorry that I don't have a link, just Google it. Good luck.

JH

@billzweig

It was more intended to be an interesting project, not to save any money. Thanks for sharing you experience on working these materials.

Sadly, I do not have access to a magnetic permeability tester. I am thinking this project may pose more difficulties than it is worth. But I am very thankful of everyone sharing their experience, if anything this thread is educating me on non-magnetic alloys and their uses

I work on a fair number of design projects involving research MRI where people want to image parts of cadavers such a spines and knees under load. We're just completing one for loading pieces of knee condials to compress the cartilage, imaged in a 7T MRI with about a 65mm bore. Anyway we end up chickening out of using any nominally nonmagnetic fasteners and just going with all plastic. The fields are way to high to be messing around with unless you are in a physics lab not a life science research center. And I say that as a physics PhD and PEng etc. You have to think about issues like people thinking there are non-magnetic tools but then the tools get mixed with the regular tools and suddenly someone gets a huge injury. Everything has to be properly labelled and controlled which is a really hard thing to do when grad students are involved. I imagine the MRI service guys have such tools but I'm sure it's a serious and highly controlled business. In my experience life science people are sketchy around electrical and magnetic hazards and physics people are even more sketchy around chemical and biological hazards.
All-plastic is an interesting design constraint. We recently did a series of differential screw thread loaders involving a pair of ACME threads, the outer in Delrin and the inner in PEEK, to get a net translation of something like .5mm/turn but with 4 and 4.5mm threads so lots of thread surface and easy to make properly. The young woman who did the first one under my tutelage was an undergrad from eastern Canada who got herself a good co-op job out here and who, unlike some students you run across, is absolutely the real engineering deal, so that was satisfying. Various of these projects have used lobular driver or anti-rotation structures, like large Torx screw profiles. These are easy to CNC machine so you can make a lobular plastic socket that's like 1.5" in diameter and drive it with a big custom plastic wrench. You make everything large to compensate for the plastic not being strong. Fun times.