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I have a 10 mm diameter rod of 99.5% pure tungsten that I want to drill a 0.1 mm hole in using my Grizzly G0768 lathe. The hole only needs to be between 0.1 mm and 1 mm deep and is for a 3D printer hot nozzle. I don't know if this will break the bit yet, but I will try it when the drill chuck comes in the mail. If the bit breaks, I'll move up to a 0.15 mm hole, and so on...

I can't afford a high precision mill that costs more than $1,000. Assuming my lathe can't drill such a small hole, what other options do I have to accomplish this task on a budget? When I have gone shopping I have seen no indication of the stability / precision of the tools.

I could send the pieces of tungsten off to get drilled, but I expect that might cost a fortune.

If anyone has experience making holes this tiny, I would like to know the approach you used.

I have nice $12, 0.1 mm PCB bits made in Germany from Tungsten Carbide that break if you so much as look at them. I also found some cheaper bits on eBay but they don't look like drill bits so I'm not sure if they'd even cut a hole.

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  • $\begingroup$ A lot depends on the depth of the hole. 0.1mm ID, 0.2mm deep doesn't sound too bad. 0.1mm, 2mm deep is a tough ask. $\endgroup$ – Nick Alexeev Apr 1 '16 at 1:08
  • $\begingroup$ @NickAlexeev, I guess I only need .2-1mm. I'm designing by trial-and-error. SolidWorks is expensive and I don't know enough physics to model certain pieces of the system yet. Are you saying 0.2mm is possible on a $1000 lathe? $\endgroup$ – BananaCats Category Theory App Apr 1 '16 at 1:11
  • $\begingroup$ @NickAlexeev, I guess the shallower the hole, the better, without getting too corny like .01mm deep :) Since there will be a fluid flowing through the hole, and I have to minimize the friction of the sides of the hole or the fluid will rather flow backwards behind the "piston". $\endgroup$ – BananaCats Category Theory App Apr 1 '16 at 1:15
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    $\begingroup$ Outsource it to a hole-popping shop. EDM hole popping will do what you need and will likely cost far less than all the time wasted and money spent on various drill bits, work holding setup, and ruined tungsten (when you break a carbide bit off inside it) in the end :) $\endgroup$ – CBRF23 May 10 '16 at 3:14
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    $\begingroup$ Does it need to be 0.1mm whole length? A conical tool could make a 2mm conical indentation with tip about as sharp as you like, then you cut a "slice" of the rod off, and grind the surface until you get a through to the cone. $\endgroup$ – SF. Jan 24 '17 at 19:15
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You really need to use a dial indicator to set up a 4 jaw chuck to the sort of accuracy required for this job. This is fiddly compared to a self centering chuck but has the potential to give you better accuracy for equivalent quality parts.

Similarly you need to make sure that the part you are drilling is faced off as square as possible in the chuck and don't remove it thereafter untill you are finished.

Also for small drill and high concentricity a collet holder rather than a jawed drill chuck will give you much better accuracy and for this sort of operation you need to make sure that your tailstock is properly concentric with the headstock spindle, which is a whole other question in itself but well covered in machining manuals and web forums.

This sort of setup operation can be frustrating and time consuming but it does allow you to get much better accuracy out of a relatively inexpensive machine. Production machinery has a more precision 'built in' as a trade off between capital cost and productivity.

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  • $\begingroup$ I read that part in my manual, involves cutting some round stock and measuring taper with a dial and adjusting tailstock. What is concentricity? $\endgroup$ – BananaCats Category Theory App Apr 1 '16 at 18:17
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    $\begingroup$ Concentricity is the the measure of how close the centres of two or more circles are to each other. In this case it is having the centre of your headstock and tailstock both lying on one straight line. This sort of setup often ends up taking more time than the job itself but that is very much the nature of machining. $\endgroup$ – Chris Johns Apr 1 '16 at 18:45
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99.5% pure tungsten? A lot depends on what the last 0.5% is.

Ductile tungsten is made by adding a small amount of rhenium, for example. That makes it much more machinable, and improves your chances of drilling a hole.

Even then - a 0.1 mm hole is extremely small, and I would not try to make a hole like that mechanically. You can try electrochemical machining (ECM). Problem is - if you want to drill with ECM, you really need to be able to set up a flow of electrolyte, which would require a needle. The thinnest hypodermic needle I could find online is a 34 gage (0.19 mm OD) needle; if you coat the outside of it with a very thin lacquer you might have the potential to drill a 0.25 mm hole. Bigger than 0.1 mm, but maybe good enough for a first experiment.

Attach the needle to the negative side of a battery (power supply). Attach your tungsten to the positive side, with a resistor in series (needs some experimentation to get the right value; you don't want to drain the battery too quickly if you accidentally touch the two). Immerse the tungsten in a sodium chloride (kitchen salt) solution, and lower the needle to just above the location of the hole. A current will start to flow that will etch away the tungsten. Lower the needle as the hole is formed. Try to maintain a flow of fresh electrolyte through the needle to keep the chemistry at the tip favorable for etching.

I have to admit I have not tried this - but I believe it would work. See for example this diagram (from this lecture) to get an idea of the setup:

enter image description here

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  • $\begingroup$ This answer is just awesome. $\endgroup$ – Rick Teachey Jan 24 '17 at 22:12
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I am afraid that drilling tungsten will be very tough with any available drill bit.

You could also consider laser machining (in my country, there is at least one company offering even small batches with a very affordable price, comparable to the price of a single 0.1 mm drill bit - which you would almost certainly trash anyway).

Or, you could build your own electroerosive milling machine and fit it with 100 μm tungsten wire from a light bulb; I guess that you could use it in many other cases later.

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Actually they have a machine call fine hole machine or call Superdrill machine in the market, and use a type of copper tubing with diameter 0.08mm. Or, can use copper tube 0.08mmm as electrode, machining using electrode discharge machine (EDM).

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I would rethink your design.

The cost and difficulty of producing your component with a conventional machine setup is likely outside your range of expectations.

I suggest the following approach to create a micro orifice. Instead of a conventional printer nozzle, consider using a thin piece of sheet material, perhaps 1mm thick, which has been drilled by a water jet or laser to your specified bore.

The water jet could then cut out a small piece of the drilled sheet to fit the inside of a holder that attaches to the head. This would produce a 2-piece nozzle with the conventional exterior and thread fittings, containing a small drilled disk with the orifice. The outer part of the nozzle can be produced in aluminum for example using a standard lathe setup.

2 part nozzle with tungsten micro-bore orifice enter image description here enter image description here

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  • $\begingroup$ This answer is pretty hilarious. Instead of, How to drill through Tungsten, you made a much more complicated design with the wrong materials. If he was OK with a steel nozzle, why bother with an aluminum one? He could probably drill through steel much less aluminum. But neither of them would have the thermodynamic properties he needs. $\endgroup$ – steventaitinger Nov 19 '18 at 16:51
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    $\begingroup$ @steventaitinger how would you suggest the OP produce a 0.1mm hole in tungsten and how would you manufacture the remaining nozzle system given the OP's limited facilities and experience? $\endgroup$ – Donald Gibson Nov 20 '18 at 17:31
  • $\begingroup$ I wouldn't :) Although I have created thousands of drawings for machined parts, I actually don't know nearly enough about how they are machined to give any solid advice. I just understand the design aspect more. My first comment was a bit too harsh. I think your idea was novel and it may be relevant to other people that come upon this question. 3d printing is all about heat flow and the thermal properties though. It is pretty key to get the nozzle out of the best material you can thermal wise. $\endgroup$ – steventaitinger Dec 6 '18 at 20:56
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There is an instability (wobbliness) caused by uneven chuck jaws in my G0768 lathe. I read online about it and was able to correct it by incrementally inserting standard paper pieces until the chuck was aligned enough. (OTOH, the spindle is perfectly aligned it seems, by eye - can't see any movement in it). So doing that I was able to drill a 0.25mm hole 2-3mm deep before the bit broke. So I reckon with tissue paper I can get down to 0.1mm. However, the lathe came with a 4-jaw independent chuck, so I just have to install that :)

Therefore, a new Grizzly G0768 is capable with a little effort of drilling a 0.1mm hole 1-2mm deep into a piece of 99.5% Tungsten using carbide or tungsten carbide bits.

PS. Was able to drill that 0.25mm hole with the cheap PCB drillbit sets found on ebay for 7-10 USD.

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  • $\begingroup$ A collet is called for. $\endgroup$ – Nick Alexeev Apr 1 '16 at 4:39
  • $\begingroup$ @NickAlexeev I don't understand, why is that? I tried the 4-jaw chuck and it's really hard to get it to be centered. Maybe having my drill chuck in the tailstock when it comes I can use it to align to center then just clamp down. Should I invest in a higher quality self-centering main lathe chuck? $\endgroup$ – BananaCats Category Theory App Apr 1 '16 at 5:19
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Call local machine shops, and ask them, if they have a sonic mill. It uses special bits with coolant and ocelats to make the cuts. It can cut accurately through 1/2 inch in about 45 minutes. It shouldn't be too expensive, basically it vibrates the the material.

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  • $\begingroup$ Welcome on the Engineering SE! I improved a little bit of your post. $\endgroup$ – peterh Jul 5 '18 at 20:47

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