/diy/ - Do It Yourself

[Anonymous No.1902341]

Dear /diy/.

At start, Im sorry if this is wrong place to ask.

I started working around making my own parts for plastic models and I frequently run into problems with drilling properly aligned holes. As you can see on pic, where each hole was supposed to be in line, each time drill drifted away. I don't use electric tool, just powered by hand and I strike with nail at each point beforehand to help drill "catch" the spot.

Is there anything I do to improve the situation, aside from press which I cant use? Material in question is polystyrene, usually 1-1,5mm thick.

Thank you for help and again, sorry if this is wrong board to ask.

[Anonymous No.1902347]

>>1902341
Take your Parkinson's meds

[Anonymous No.1902348]

>>1902341
Yeah, u need to secure both the work piece and the drill.

[Anonymous No.1902350]

>>1902341
PS is soft, so:
pre-drill a wooden plank
put the plak on your plastic part
put something heavy on the plank
drill though the hole in the plank

[Anonymous No.1902351]

>>1902341
Fellow modeller here:

1. Center punch to establish the dead center.
2. Drill slowly. Hell for styrene like that, put the bit in a pin vice and drill it by hand.
3. Get a drill press.

[Anonymous No.1902355]

>>1902348

I can only secure workpiece and I do, in vice.

>>1902350

Interesting, the only problem is that vice is only way for me to hold piece in place so I will have to figure out something different to fit. But I could later use such wood part as template of some sort.

>>1902351

I do punch in center but drill keeps going off a bit. Also, since I drill with "mechanical" instead of electrical tool, I do it slowly already.

I should add that I use drills for metal. I do have some drills for woodworking, with spike at the end but those have troubles with getting through plastic.

[Anonymous No.1902367]

>>1902355
A mechanical hand drill is still to fast. Seriously, try a bit in a pin vice and drill very very slowly, by hand.

You're not wrong to use metal bits: wood bits will tear up styrene.

[Anonymous No.1902385]

>>1902367

I don't have pin vise, sadly but I used other tool to hold 2mm drill and try to use it like this and then used 3mm one to widen it. A little better I guess but it require more practice. Thank you.

[Anonymous No.1902404]

Get a better center punchy. A nail isn't a perfect contour and will cause the bit to walk to one edge.
I suggest a spring loaded punch.
You don't hit it with a hammer. You put the tip where you want and press down, the internal springs compresses then unloads and gives you a perfectly placed divot.
EBay, $5.

[Anonymous No.1902412]

>>1902404
Just realized you said polystyrene.
Spring loaded punch might deform or blow through it because of the pressure needed to compress it.

You really need a drill press.
Material is so soft that the bit wanders off no matter what you do. That's not going to change.

Pic related might be your best option.
Its an hole punch for leather.
You can line it up perfectly.
It might compress the surrounding styrene but if you slightly clamp the material with it and the "twist" the material the die might cut through cleanly like a cookie cutter.
EBay. $6
Cheaper then a press and useful for lots of things if it doesn't work out.

[Anonymous No.1902421]

>>1902341
For drilling plastics you need sharper point or brad-point drill bits.
You may also need to consider using a smaller drill bit size to widen out the center punch mark prior to using the intended final diameter drill bit. Or simply using the smaller bit to drill a pilot hole first.

[Anonymous No.1902478]

Get a drill press and a vice

[Anonymous No.1902536]

>>1902341
You can get a used drill press for $20-$50 on Marketplace.

[Anonymous No.1902582]

>>1902412
Literally had that tool and 1.5mm styrene right beside me so I tried it...did exactly what you said it would, but a sharper angle on the die and rubber on the anvil might get a cleaner cut.
But, I'd go with a pin vise. Or hell, just twist the bit by hand

[Anonymous No.1902594]

>>1902341
-Drill first, then shape the part around.
-When holes of multiple parts shall match, just drill the f trough both.

[Anonymous No.1902743]

>>1902385
Just hold it vertically lol

[Anonymous No.1902782]

>>1902582
Hey cool.
If you put the styrene in and gently clamp it and then spin the styrene back and forth as you slowly squeeze the punch does it do any better?

[Anonymous No.1902784]

>>1902347
Not the OP. Cretin.

[Anonymous No.1902789]

>>1902341
>I don't use electric tool
>I strike with nail

Found your problem

[Anonymous No.1902792]

>>1902421
For drilling plastics you need neutral or negative rake on your drills because its gummy and grabs. Sharper bits do even worse.

[Anonymous No.1902797]

>>1902412
>Just realized you said polystyrene.
>
>You really need a drill press.
>Material is so soft that the bit wanders off no matter what you do.

I am no expert on matters related to drilling. I would have thought the problem does not lie with the polystyrene being to soft rather with the drill itself wandering and flexing. The polystyrene or soft plastic will tend to mimick melting and form gooey globs rather than the neat swarf associated with cutting metals. Those globs glue the drill bit on one side which results in flexing.

So in addition to what others suggest there perhaps exists the option of using a purpose made drill bit intended for drilling of printed circuit boards. These have a very short narrow drilling portion and a thick plain shank for precise and easy gripping in chuck. This construction maximises stiffness.

[Anonymous No.1902804]

>>1902797
Different anon but
> I would have thought the problem does not lie with the polystyrene being to soft rather with the drill itself wandering and flexing
The fact that its so soft and grabby, a sharp drill bit easily bites quick and hard. It takes more load that it can handle, thats where melting and flexing and grabbing happens.

Using a manual hand drill you have little to no real control over the feed, it makes the problem 100 times worse.

Watch this video on changing the rake of a standard 118 bit and youll do a LOT better and mitigate a ton of those problems.
His demonstration doesnt show it well because he just hammers right through quickly, but a slow meticulous peck drilling with it will make things way easier for soft plastics.

The specialty bits for PCB FR4 arent for soft plastic and wont do any better.

[Anonymous No.1902805]

>>1902804
Would help if I posted the video itself.
https://www.youtube.com/watch?v=8Ri6poVpQM8

[Anonymous No.1902855]

>>1902805
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
this video literally tells you to damage (dull) your drill to get better results?!?!?!

That's insane!

This guy should learn to fasten the plastic plate properly.

>>1902797
>drilling of printed circuit boards
PCBs are nasty to drill, for they are made of fibreglass embedded in a resin, and therefore are abrasive. Hence dedicated drills.

>>1902797
>The polystyrene or soft plastic will tend to mimick melting and form gooey globs
Obviously most of the plastics melt, for it's easier to make stuff of thermoplastics.
And friction delivers sufficient temperature to melt it.
That's why when drilling / cutting / sanding you need sharp tools and low speeds.

>>1902797
>rather with the drill itself wandering and flexing
No.

>>1902792
Ordinary drills for metal do the job fine.

>>1902582
That obviously damages the edges of the hole.

[Anonymous No.1902878]

>>1902855
>>rather with the drill itself wandering and flexing
>No.

-So what's the reason?

[Anonymous No.1902965]

>>1902855
>this video literally tells you to damage (dull) your drill to get better results?!?!?!

Yes, because he is a retired machinist who ran his own shop for 40 years and understands edge geometry for different materials. He has multiple tutorials on how to hand sharpen different drills for different materials anon. You are sitting here with a hand drill and a fucking nail and cant get a straight hole.
You want negative rake, you do not want a sharp edge. Its one of the most basic principles of drilling milling or turning any brass or plastic in machining.

>>1902855
>Ordinary drills for metal do the job fine.
If they "did the job fine" you wouldnt have made this thread now would you?

From your post it sounds like you know it all, but I take solace in the fact that other non machinist anons here dont have their head up their ass and may have learned something new.

Here is one of the most popular machinists on youtubers doing the same exact thing.
https://www.youtube.com/watch?v=pAngKHIZgyA

[Anonymous No.1902966]

if your going to be doing a lot of precise placement of holes suggest to buy a small drill press, if you're going to free-hand drill mark complete pattern of holes with a precision center punchy as suggested, drill pilot hole(s) with 3x smaller small bit then chase with final diameter. the template suggest in good also to I use 1/16" alum sheet or angle stock

[Anonymous No.1902968]

>>1902966
he wont even spend $4 on a center punch anon

[Anonymous No.1903058]

>>1902968

Im just poor and would rather use whatever I might find first.

[Anonymous No.1903076]

>>1902855
>>1902965
OP might do well with this type of bit.
I've used them to drill out spot welds to separate automotive panels.
Its kind of a mini hole saw.

[Anonymous No.1903077]

>>1903076
And the more expensive version.

[Anonymous No.1903099]

>>1902965
> You want negative rake, you do not want a sharp edge. Its one of the most basic principles of drilling milling or turning any brass or plastic in machining.
1) Negative rake has nothing to do with edge sharpness.
2) Negative rake causes the machined part to heat by friction, and while this may be irrelevant when drilling brass, but is a killer for plastics.
3) The guy in the disastrous vid says to DULL the bit, not to change its geometry. And that's a bullshit.

>If they "did the job fine" you wouldnt have made this thread now would you?
You must be a fool, aren't you? I'm not OP, but a /diy/nosaur for whom drilling a precisely located clean hole in plastic with an ordinary HSS drill for metal is no trouble at all. But well, i got my tools for that.

And I definitely have enough experience to share of how to diy without exaggerating and conducting mysterious voodoo rituals on the exact rake angles when a simple tool can do its job just fine.

>>1902968
>center punch
>PS
Solid polystyrene is brittle. Good luck getting your PS scattered around.

[Anonymous No.1903353]

>>1903099
Its funny how confidently wrong you are. Your gaps in understanding are pretty apparent.

>Negative rake has nothing to do with edge sharpness
>The guy in the disastrous vid says to DULL the bit
The word sharpness and dulled are abstractions for layman who dont understand cutting edge geometry or drilling principles.
When you alter the leading edge of a drill, it looks odd to the layman. It looks like all their dulled beaten up bits. Calling it "dulled" is giving them an expectation of what it will look like. The video isnt supposed to be a dissertation on chip load, edge geometry and drilling principles.
I dont know why you are getting so hung up on this.
Lowering rake and leaving relief does make the leading edge angle larger so calling it "duller" isnt really wrong.

>Negative rake causes the machined part to heat by friction
Heat is caused by recutting chips, poor chip evacuation, and bad chipload.
You clearly dont understand the purpose of altering rake or how heat and friction work in drilling.

You match your edge geometry and chip load to the material you are working with.
The chips take heat AWAY from the part, but only if they are the correct type of chip being cut at the correct speed.
In very basic terms, you want specific size and length chips that soak the heat and then easily go up your flute away from the part.
For plastics in general optimal chipload comes from negative rake tools.
Believe it or not, plastic soaks heat differently than metal does.

These are very basic principles, calling them *mysterious voodoo rituals* just makes you look stupid.
So you used a general purpose drill and it seemed to work, that doesnt mean its the right tool for the job. It takes no effort to actually make the drill suited to plastic.
Your pic showing whatever that abomination is, isnt helping your case. You have a marked out line and we can clearly see you werent on center from here.
Maybe mediocre and offcenter is acceptable to you, idk.

[Anonymous No.1903369]

>>1902966
This is as true as possible.

Also, when you are doing a neat line of holes, you almost have to use a drill press. Clamp a fence down onto the drill press table. This will remove one degree of freedom so you only need to worry about left-right positioning. Get a pair of calipers and do some test holes until you get the fence where you want it.

I dunno what kind of rpm you need but I'd guess around 3k.