Drilling nozzle hole

Ive made my own J-heads many times but i cant tell you how many times ive spent a half hour machining a nozzle on a manual lathe only to have to throw it away because i broke a .35mm drill off in it or drilled it off center a hair. I think the best way to drill the orifice would be to drill it from the inside since there is alrady a drill point to guide the drill to center. However i have not yet found a micro drill holder with a small enough diameter to reach into the nozzle. I plan to make something to hold the drill and try drilling from the inside. Trying to do this on a manual lathe by hand is a tedious process, especially when my eyesight doesnt seem to be as good as it used to. I can barely see these damn drill bits let alone try and center it up to the nozzle.

So i am curious what process others are using to drill the .35 and .5 holes. I also thought of drilling the hole larger and then peen the end to make the exit diameter what it should be. This could be difficult to get it exact however, but might at least leave hole to use as a center guide to re-drill to size.

Been down this road. All I can say is you need about 3000 rpm on your spindle, a magnifying glass, and the Zen state of the Dalai Lama. Drilling from the inside or drilling a pilot hole isn't ideal, but it may help. What really helps is a high spindle rate and good alignment.

Out of curiosity, where do you purchase 0.35 mm drill bits?

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Drilling 0.3 isn't that hard, you have to prime the hole using one of these

Other than that a steady hand and a lot of oil or cooling lubricant.

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There is a special technique you can use to self-center the drill by hand. You don't need a lathe or a center drill. See: Nozzle manufacturing

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Robert_Paulson
All I can say is you need about 3000 rpm on your spindle, a magnifying glass, and the Zen state of the Dalai Lama.

While it might work at 3000 RPM, I bet you'll go through quite a few broken bits at that speed. For extremely small diameter bits ideally your speed is much much higher, as in an order of magnitude higher. They'll work better at 25k and higher. Taking things to an absurd level, the bits that get used for microvias in PCB manufacturing can be as small as 75µm (.075mm) with a spindle speed of 375k rpm in order to get to the recommended SFM (surface feet per minute) for the material and bit.

Ultra machinable brass is fine at standard lathe speeds. It only breaks for me at .15mm. Even then you can get pretty reliable results. You would only need oil if you're drilling through a non leaded metal. Otherwise it's counterproductive.

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cdru
While it might work at 3000 RPM, I bet you'll go through quite a few broken bits at that speed. For extremely small diameter bits ideally your speed is much much higher, as in an order of magnitude higher. They'll work better at 25k and higher. Taking things to an absurd level, the bits that get used for microvias in PCB manufacturing can be as small as 75µm (.075mm) with a spindle speed of 375k rpm in order to get to the recommended SFM (surface feet per minute) for the material and bit.

Hit the nail in the head right there. There are some small drill chucks you can mount in a larger drill chuck that you can feed by hand.
Something like this: LINKY


Gives you more feel for a small hole. I would try to spot it with a 1/8 spot just like .005"-.007" deep to get something to get the drill to stay put.

Also are you using a chuck mounted on the cross slide, or a drill in the tail stock? Either way they need to be DEAD on. Even off by .002 that is almost 10 percent of your diameter. Imagine drilling a .250 diameter hole that is off to one side .015 (means your drill is wobbling .030 from one extreme to the other. Now your doing that with a drill bit with no strength and 1/20 the diameter.

Edited 1 time(s). Last edit at 10/20/2014 03:42PM by Scoobyvroom.

Centering the drill is key. But getting a drill, center drill, or spot drill on center by .002" on a hand lathe is not easy. I have a whole shop full of CNC machinery but i would be willing to bet that drilling with a drill that small is easier by hand, ive never tried a drill that small on a CNC. The CNC has no sense of feel. It either drills a hole perfectly or snaps it off and keeps on going.

CNC is definitely over rated for things like this. I use a manual tailstock and scrap pieces of wax paper from shipping labels to shim the tail stock into place. Drilled thousands of nozzles this way. Very effective.

I guess no one bothered to click on the Nozzle manufacturing link. If they had, they would have seen the video showing how to drill a 0.4 mm hole in a brass hot end by holding the drill in a pin vise in your hand.

You don't have to take my word for it. Perhaps Have Blue and nophead might persuade you.

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Have Blue
Watchmakers would create a tiny divot on the center of the stock with a graver, and then use a micro drill bit held in a pin vise. All by hand, no tailstock! I saw a video of this technique on youtube long ago but unfortunately cannot find it...

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nophead
The technique with a graver is called "catching the centre". I had a link to an excellent video on my blog, but for some reason the video has become private. Here is another one though:
[www.youtube.com]

No offense, but I'd be embarrassed to sell an acorn nut with a hole jammed through it. Manufacturing can provide a more precise nozzle for less than a cup of Starbucks.

I did watch that video a few days ago actually. I have a hard time getting that hair sized drill bit to find center holding it by hand. Maybe its just me. Maybe if i had something practical to hold the drill with it would be much easier. Also you can hit dead center with a drill this small and still end up with the hole off center by a large margin where it breaks through on the other side if you arent holding it dead parallel or feeding a little heavy.

Aha. I re-read your post. Aparently i missed the links to the video showing how to use a graver to center spot the part. Never seen that before. Looks simple enough, i think i will give that a try.

I think the use of a countersink has its tradeoffs. If your nozzle has a very flat shoulder, you might be ok at large orifices. You kind of lost me on the 4th video? When he put the drill bit through the nozzle and spun it around the bit. Seems like an over sized hole.

Of course by over sized I mean .05-.1 mm big, which can of course be corrected through calibration. But I think having the countersunk tip will degrade print quality.

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Robert_Paulson
You kind of lost me on the 4th video? When he put the drill bit through the nozzle and spun it around the bit. Seems like an over sized hole.

In those videos (link again for reference), I do not think the guy is actually making a nozzle for a hot end. I think he is just demonstrating the technique.

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Robert_Paulson
But I think having the countersunk tip will degrade print quality.

Certainly possible. In the acorn nut video it looks like he doesn't use a center or a graver. They make it look easy in the videos, but as GITRDUN pointed out it sounds like it is harder than it looks.

Ok guys, I'll chip in here...

The "Nozzle manufacturing" video suggested by Matt Moses is my upload and I can assure you it is very easy to do - I made a couple more just 2 days ago! All you need to know is in the video - I could make a hundred a day if I needed to - maybe I should and start selling 'em! I intended to do a follow up regarding shaping the tip to finish it off but drilling the nut was the main focus at the time. Anyone having problems can always ask here.

Cheers,
Alan

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