Drilling M6 Grubscrew for nozzle throat

It occured to me before looking at nozzle throats, that for the same cost as a heat break, I could get 10 grubscrews upto 60mm. I did google drilling grubscrews out, the methods were aimed at removal.
How to secure a screw from turning without destroying the threads. would it be too hard to drill 30mm.

You could run two or more nuts onto it and tighten them against each other. Clamp onto the nuts with a vise, drill with drill press.

I just tried m8 nuts on a bolt, I was able to turn the bolt. however using two m8 tee nuts it did lock the bolt from turning either clockwise or counter depending on which one was gripped in the vise.

The grub (set) screws should be stainless steel. It would be even less expensive to use stainless all-thread.

It's not impossible to drill 30mm deep with a 4mm drill (assuming you will be using 4mm PTFE tube), but it is very difficult to do this so the hole remains in the center. Research peck drilling and also d-bits. If you use a regular twist drill, make sure it is new or sharpened properly. You may also want to drill undersize and then ream to size.

Drilling stainless is a pain. I have recently attempted making my own just like you are.

Here is what I have accomplished so far:

Use a retangular piece of aluminum, about 1/2 thick is good. Drill (halfway through) and tap it to hold the M6 stainless all thread rod piece.
Screw the stainless rod into the aluminum.
It is helpful if you can do all of the above without moving the piece on your drill press, so you should have your vise firmly attached to the drill press table.

Once it is in, you need to center drill the end of the rod. Since we're talking about a very small hole, drilling an even smaller hole then reaming it with the larger bit is recommended because the shredded stainless will gouge the rod and maybe even break the bit. Then you need to polish the inside using lapping compound.

Or you can buy these

[www.ebay.com]

but I'm with you... I like playing with the lathe and the mill at the local maker space more than I like shopping from china.

Edited 1 time(s). Last edit at 08/04/2015 04:32PM by thetazzbot.

drilling stainless isn't actually that hard, the problem with it aside from work hardening very easily is that things like bolts, allthread and grubscrews are all made through some veriation of the forging process and cooled very quickly,

for all the grubscrews i drill i heat them up until they are red hot and let them cool in a pile on a piece of aluminum foil, i do this with both the stainless ones and black oxide ones, after that your average sharp HSS drill bit will go through it fairly easy
with "threaded rod" or "all Thread" it's almost potluck as to getting a straight piece however if the piece you need for a thermal barrier/heatbreak is around 30-35mm long the best bet is to drillout a grubscrew as they tend to be straighter and the threading on them is almost always much better

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Initially I was going to get a tungsten carbide bit, use cooling fluid during slow drilling, I dont have any tool machining experience. hardening the steel and destroying drill bits would negate any saving, on diy heatbreaks.
The Screws are A2/70 Stainless Steel, They have an indentation at the center of the hex inner, which should give me a precise start. If straight drilling is not successful I will check out heat process.
From now on I'm using 1.75mm hotends/abs only. It is recommended not to use ptfe, because it breaks down at 250deg right. a 3mm hole tapered filament side.

I did this today with a store bought 6mm bolt. It was hardened but not stainless. I broke my heat break and needed something to get buy until my new prometheus shows up. I shaped and drilled it on my Shureline jewelers lathe. It took some slow drilling with oil but was able to drill the entire length (40mm). The amazing thing is that after reassembly and install I went to reset my Z endstop and and didn't have to move it at all. What are the odds of that. I never check the length of the piece I made just dumb luck I guess.

Don´t we use stainless steel because of it´s low thermal conductivity?
How much lower is it compared to hardened steel?
-Olaf

Quote
o_lampe
Don´t we use stainless steel because of it´s low thermal conductivity?
How much lower is it compared to hardened steel?
-Olaf

yes, however i am recently questioning recently exactly how much of a difference there actually is in practice using mild steel which is only double the heat conduction compared to stainless but still heaps lower than everything else

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Maybe a professional hotend-maker chimes in to tell the difference.
Also an option would be using M5 threads.
Isn´t it enough "meat" for 1.75 filament without PTFE liner? ( and smaller cross-section for lower heat conduction, too )
-Olaf

I stand corrected. M5 inside the heaterblock, but M6 for the heatsink adaption, would be the best choice IMHO.

Edited 1 time(s). Last edit at 08/09/2015 12:09PM by o_lampe.

Well, unless you're drilling and tapping your own heater block, sticking to the standard m6 thread size is wise.

All my heater blocks have m6 threads.

This weekend i managed to make a nozzle. w00t. and it worked. w00t w00t

The hardened bolt I use is working as well as the stock heat break. The question is will it stain over time. I've got about 20 hours on it so far and no issues.

I like the hardened bolt idea. Cheaper than stainless