Machining Tungsten

[JasonBModerator @jasonb]

Drilling blind to say 5mm dia and silver soldering in a more user friendly metal sleeve that can then be tapped M4 would be another option, this would mean your outer ball half looks solid. I've had no problem silver soldering tungsten TIG electrodes.

Edited By JasonB on 03/09/2017 07:33:01

[Martin ConnellyParticipant @martinconnelly55370]

Do you know anyone who could try thread milling this material? I suspect that would be the way it would be done in an industrial production process.

Martin C

[Anonymous]

Based on the reported composition I've calculated the density as 17.92gm/cm³. So a bit less than pure tungsten, but much easier to machine.

I'm not beaten yet on the tapping, although I do have some alternative plans sketched out, just in case. As long as I have enough thread to hold the blank while I form the hemisphere I'll be happy. To avoid loss of density due to the tapped holes I plan to buy some tungsten/copper alloy from fleabay and make some short studs. If I use a Coventry diehead I can tweak the thread OD to be a snug fit in whatever tapped hole I manage to produce.

I've considered thread milling. Although there are a number of local machine shops in my area I expect their prices for a relatively small PITA job would be out of my budget. Anyway if I thread mill I want to do it myself. I've bought some single point cutters to have a go, but I'd like to start with larger threads in a more benign material. Thread mills for M4 cost around £80; that's a lot of wasted drinking vouchers if I break the cutter.

I now need to trim the hedge in the front garden before the rain arrives, but I'll be doing more experimenting this afternoon/evening.

Andrew

[Anonymous]

The box hedge in the front garden has now had a haircut. Unfortunately the electric cable for the hedge trimmer is now shorter than it was.

I've been beavering away in the workshop this afternoon making a practice governor ball in tungsten. I still haven't sorted the tapping issue, but everything else was straightforward:

The ball weighs 55gms versus the theoretical weight of 65gms. Obviously there are internal voids for the screw threads and the screws themselves are not tungsten. And my kitchen scales only resolve 5gms. All in all not a bad result.

Andrew

[Speedy Builder5Participant @speedybuilder5]

This stuff was used for mass balance in some aircraft components:-
Heavy metal alloys are pseudo-alloys of tungsten with a nickel-iron or nickel-copper matrix. They are produced by powder metaland sintering processes. The most outstanding property of heavy metal alloys is the high density of 17-19 g/cm³.

[Neil WyattModerator @neilwyatt]

It's not heavy metal, it's rock'n'roll.

[Anonymous]

Hmmm, this is going to be embarrassing.

Out of idle curiosity this afternoon I drilled a couple more 3.6mm holes, about 50% thread engagement for M4, in my remaining bar and tried tapping with an old set of Dormer HSS straight flute hand taps. Worked just fine! I used all three taps in sequence, and cutting fluid definitely helped. For one hole I used Rocol RTD and the other Ferrofluid, a thin oil intended for tapping tough materials like stainless steel. It's difficult to know which was best, but the oil is less messy. The taps needed noticably more torque than normal materials, but no worse than austenitic stainless steels. So much for the fancy sooper dooper taps. Sometimes you just have to reverse up and try a different path rather than press on regardless with ever more involved, and expensive, 'solutions'.

The next question is do I stick with M4 or change to M3; the original design specified 6BA? Ultimately it'll depend on the leaf spring design. But I'm inclined to stick with M4 as during manufacture the thread takes all the cutting torque generated when using the hydraulic copy unit to form the hemispheres.

I'm going to treat myself to a beer tonight.

Andrew

[Tim StevensParticipant @timstevens64731]

You might think about generating your sphere, using a cheap & cheerful carbide tipped hole saw from that well known internet auction site. It should put less load on your holding thread, perhaps?

Cheers, Tim

[Anonymous]

Thanks, the balls are actually two hemispheres screwed together so that the leaf spring can be held between them. Would that make a difference to the idea of using a hole saw?

Andrew

[David Standing 1Participant @davidstanding1]

Posted by Andrew Johnston on 02/09/2017 20:58:58:

using WD40 as a lubricant.

Andrew

'WD40' and 'lubricant' in the same sentence. There's a contradiction in terms!

[JasonBModerator @jasonb]

I would have though conventional turning with the copy attachment would put less load onto the screw than a hole saw. As you can set the depth of cut on the attachment you will have one cutting edge taking off whatever depth of cut you want rather than large "cutting" edges in contact  with less control over cut depth. Also not sure how well carbide would cut tungsten allow with no real sharp edge, more likely to try and grind it's way through.

Being hemispheres would not affect the use of a saw

Edited By JasonB on 05/09/2017 09:40:51

[JasonBModerator @jasonb]

Just another thought. If you make your arbor to take a screw from the rear rather than with a threaded spigot you could then fit two drive pins to the face of the arbor that locate in the loop holes which will take some load off the screw.

[Tim StevensParticipant @timstevens64731]

I was not meaning the 'ordinary' old fashioned type of hole saw which is made of steel with bent hacksaw-style teeth. The type I think would work is like this:

The teeth are really sharp as delivered, although when taking off small shavings you may notice that only one tooth is actually doing much. But take it steady and it works. It does for me, anyway (in steel or light alloy).

Cheers, Tim

[Anonymous]

Posted by David Standing 1 on 05/09/2017 09:16:20

'WD40' and 'lubricant' in the same sentence. There's a contradiction in terms!

Works fine for me. I've got an industrial spray bottle which makes it easy to apply. I use it mainly for deep drilling with small drills, and for milling aluminium to prevent tool clogging and poor finish. It also has the advantage of washing away fine swarf, and being clear you can see what is going on.

My Bridgeport does have conventional flood coolant, but since I don't have a coolant tray I rarely use flood coolant as most of it seems to end up on the floor.

Andrew

[Martin DowingParticipant @martindowing58466]

Posted by Neil Wyatt on 12/08/2017 19:56:39:

I've just been called by someone with professional experience of these things. In case anyone was seriously considering it, don't start machining depleted uranium.

There may be a frisson to having a DU paperweight, but any uranium dust from machining is very toxic (mostly in a heavy metal way as well as alpha radiation) and you really don't want the swarf catching alight and filling your workshop and lungs with uranium oxide dust.

Even exposure to contamination from the use of armour piercing DU rounds appears to have caused health issue.

en.wikipedia.org/wiki/Uranium#Human_exposure

I note the source above sells three pellets approximating 3g for $69 and warns:

"Caution: Use normal safety precautions (wear a filter mask/respirator and gloves) when working with Uranium metal. Accidental inhalation or ingestion of Uranium particles can be dangerous. Machining will produce particles that can spontaneously ignite producing radioactive smoke. Note: adult signature required upon delivery"

Neil

I suspect that any issues related to DU radioactivity on the battlefield, if accurate, have probably appeared because it was reprocessed reactor waste uranium, perhaps contaminated with fission products, what was actually used, even if not officially acknowledged.

Virgin uranium (not used before as reactor fuel) is only very slightly radioactive and would not be a source of radiation related health hazards.

Chemical toxicity is comparable to lead, eg not very great unless you are occupationally exposed for years.

Needless to say, it would be daft and outright stupid to attempt to work with uranium at home workshop or even only to try to acquire uranium metal.

You don't wont to spend rest of your life being observed/bulshited by beaurocrats of all sorts and possibly open yourself to legal challenges which you don't understand.

Go on and turn Platinum or gold with few % iridium alloy (which is hard, turns well and used in dentistry). It is as dense as tungsten.

Densest elements are Osmium and Iridium, machinable by grinding mainly.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Martin Dowing on 12/09/2017 16:30:40:

Posted by Neil Wyatt on 12/08/2017 19:56:39:

…

…

Virgin uranium (not used before as reactor fuel) is only very slightly radioactive and would not be a source of radiation related health hazards.

Chemical toxicity is comparable to lead, eg not very great unless you are occupationally exposed for years.

…

With respect Martin both statements underrate the dangers of Uranium. Whilst it wouldn't worry me to sit on a block of Uranium whilst typing this post, it's nasty stuff as soon as you mess with it.

My copy of 'Dangerous Properties of Industrial Materials' says Uranium metal and its chemical compounds are carcinogenic and highly toxic. It's also radiotoxic, very dangerous if particles are breathed in or swallowed. Whilst skin is thick enough to protect you from Uranium radiation, lungs and other internal organs aren't.

The metal is also a fire hazard and an explosion hazard, including a violent reaction with water.

Finally, it's also identified as a Disaster Hazard, which means special measures are necessary if Uranium is involved in a fire or other accident.

So pretty safe until you machine or process it. After that all bets are off. Lead, particularly as dust, is also quite dangerous but it's chemically less reactive than Uranium and less radioactive. (Yes a small proportion of Lead is a radioactive isotope.)

I don't suppose anyone on this forum is likely to want to machine Uranium. Though there are some clever innovators about…

Dave

[Martin DowingParticipant @martindowing58466]

Posted by SillyOldDuffer on 12/09/2017 17:27:18

My copy of 'Dangerous Properties of Industrial Materials' says Uranium metal and its chemical compounds are carcinogenic and highly toxic. It's also radiotoxic, very dangerous if particles are breathed in or swallowed. Whilst skin is thick enough to protect you from Uranium radiation, lungs and other internal organs aren't.

The metal is also a fire hazard and an explosion hazard, including a violent reaction with water.

Finally, it's also identified as a Disaster Hazard, which means special measures are necessary if Uranium is involved in a fire or other accident.

So pretty safe until you machine or process it. After that all bets are off. Lead, particularly as dust, is also quite dangerous but it's chemically less reactive than Uranium and less radioactive. (Yes a small proportion of Lead is a radioactive isotope.)

I don't suppose anyone on this forum is likely to want to machine Uranium. Though there are some clever innovators about…

Dave

These days everything is highly toxic, carcinogenic etc, that is one of reasons why manufacturing industry have left UK and moved to China and it will stay that way.

Ever worked with stainless steel?

Read how dangerous chromium or nickel are (both highly toxic and cancerogenic). OK they dont get airborne easily while machining.

Ever used hard solder with cadmium? Awful… cancer guaranteed and you are dead man walking.

It is important to realize that discussed materials are presenting mainly *occupational* hazard and an odd contact with them won't do much harm, if any.

Also if you consider Lead to be radioactive (presumably due to minute quantities of Pb-210 present in freshly mined lead), then potassium fertilizer used in gardening is even more radioactive (K-40).

It is interesting that Lead recovered 500 and more years after smelting is no longer measurably radioactive and finds uses in nuclear research. Hence lead recovered from sunk medieval ships can be very expensive. High price makes diving for it a business proposal.

Fire hazards during machining uranium are real however. Normally such a process is done under argon.

It is difficult to extingush burning Uranium. Water or CO2 is out of question. I would use powdered kitchen salt. As per radioactivity of it, it has too long half life (in excess of 4.4 billion years for main isotope, second one has also close to billion years half life) to be of concern. Uranium ores are more radioactive and dangerous due to presence small quantities of other much more radioactive elements.

[Clive HartlandParticipant @clivehartland94829]

Wasn't there a tale about the Americans machining radioactive material and the difference in weight from the virgin materiel to the machined article did not add up, eventually they found all the lost weight in the air ducts because it was sucked out of the machining casings. I wonder how many of those chaps are still alive?

Clive

[Martin DowingParticipant @martindowing58466]

That depends, what they were machining.

Even with Plutonium 239 I am not aware of anyone dead due to radiation poisoning nor exposure traceable cancer.

Plutonium-239 is 200 000 times more radioactive than uranium btw.

Energy of alpha radiation is in range few MeV, very much like in case of Uranium and half life is 200 000 times shorter than uranium. Both do not posess gamma radiation associated hazards.

You really have to work with something short living to expose yourself to severe radiation hazards. Examples are Polonium-210 (half life less than half a year), radium (1600 years), Plutonium 238 (half life 89 years, this isotope is useful in spaceship batteries but useless for weapons) or fission products (hazardous waste requiring long term storage has half life between few and a hundred years or so).

Very short living materials like I-131 even if extremely dangerous, decay fast and doesn't pose risk for long.

I believe, the most dangerous radioactive material processed in large quantities is said Pu 238 used for spacecraft batteries. Such batteries could contain few hundreds of grams of Pu-238 each. Anyone absorbing 10ug (10^-5 gram) would be dead like a dodo within months to a year, very much like Radium Girls of the past. Radium girls could absorb 0.1 – 1 miligrams radium each…

hope this helps,

Martin

Martin

Edited By Martin Dowing on 12/09/2017 21:51:46

[Martin Evans 6Participant @martinevans6]

Martin said:

"These days everything is highly toxic, carcinogenic etc, that is one of reasons why manufacturing industry have left UK and moved to China and it will stay that way.

Ever worked with stainless steel?

Read how dangerous chromium or nickel are (both highly toxic and cancerogenic). OK they dont get airborne easily while machining."

I have to agree – back in the late 70s/early 80s I worked for an American company that manufactured Nickel- and Cobalt-based hardfacing alloys. Basically Nickel or Cobalt plus 20% Chromium and a smattering of Boron and Silicon. The factory floor was a swirling mist of Nickel, Cobalt, Chromium, you name it, dust. We inhaled the stuff, ate the stuff on our sandwiches, drank it in our coffee.

The only side effects ever seen were warts – many of us grew heavy metal warts on our hands from handling the material.

I never heard of anyone being otherwise afflicted and to this day – and I still live near the factory and see old colleagues from time to time – still haven't.

Martin.

[Martin KyteParticipant @martinkyte99762]

I remember the Heavy Metal Worts, really good band.

:0)

[Colin WhittakerParticipant @colinwhittaker20544]

I've mentioned it elsewhere on this forum but you can check out the MSDS sheet for table salt, aka sodium chloride. It's apparently deserving of filter masks and goggles. The question becomes did the same lawyers who peverted the risks of working with table salt also write the safe handling requirements of uranium and other nasties? And if so then what really are the risks?

https://www.google.co.th/search?q=msds+sodium+chloride&oq=msds+sodium+chloride&aqs=chrome..69i57j0l5.7815j0j4&sourceid=chrome&ie=UTF-8

Colin

[Martin Evans 6Participant @martinevans6]

I used to write Material Safety Data Sheets for our Nickel and Cobalt alloy products.

What a joke!

The only way you could come to any harm with them is if you dropped a parcel of the product on your foot.

However, to satisfy the Gods, I had to concoct all sorts of warnings and precautionary measures so that the lawyers could sleep snugly in their beds at night.

Worse bit was that nobody, but nobody, ever took any notice of them anyway.

But the lawyers were happy.

Martin.

[Neil WyattModerator @neilwyatt]

I bought 3m of EN1a from my local stockholder the other day.

The chap insisted in carrying it to the car with the usual 'it's a bit greasy' excuse – I assumed this was less embarrassing than admitting H&S rules mean they won't trust me to carry a few KG of metal.

Sat in the boot for a few days, then I fetched it in. Left my hands in a disgusting mess.

Neil

[Martin Evans 6Participant @martinevans6]

3m?

In the boot?

Some car.

Some boot.

Martin.

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