#79 Drill bit advice

G-man · Post by **G-man** » Thu Apr 21, 2011 3:56 pm

For those of you out there who have used these before.
What advice can you offer to extend the life of a #79 drill bit.

I recently started drilling out the holes for a Ds9 fiber optic model ( i went with a #79 instead of the standard #80 since the 79 lasted through a few more holes then the 80 did with me, and the size different is negligible)

anyway, I'm using your normal standard Squadron pin vice with a swivel head on top. I have no roto tool that will spin slow enough not to melt the plastic.

( I have also discovered how to place it in the pin vice in such a way that when it does inevitably break, The top of the drill bit is still long enough to be placed back in the vice and reused until broken, and the shaft will still have just a bit of a drill furling on it, so that i can use that as well basically turning each one into three bits. )

so there is it my friends. What advice can be offered to extend the life of a drill bit of this size to more then 4-5 holes before it breaks, other then what i have listed above.

Thanks.
George

USS Atlantis · Post by **USS Atlantis** » Thu Apr 21, 2011 5:25 pm

Slow down a little bit

Don't press down on the bit more than absolutely needed, let it pull it's way through - drilling plastic is way different than drilling metal or even wood

I've got a #80 that's drilled probably 3-4 DOZEN holes so far and still looks like it'll last a good deal longer

G-man · Post by **G-man** » Thu Apr 21, 2011 5:40 pm

i don't think i'm really applying any pressure other then the weight of the pin vice its self...i could be wrong, i suppose on that small of a scale its hard to say.

I know i've snapped a few of them form just sudden unconscious just random...Jerks of one hand or another while drilling, like a odd spasm.

Do you, keep the part your drilling in one hand and your pin vice in another. or do you put the part you are drilling in a vice to hold it steady....maybe that's where i am going wrong?

far as slow i think it takes me about 30 seconds to drill trough a normal hole..these are pro ably about 0.60 thick sections of plastic, i haven't tossed a micrometer on them so i don't know for sure, just guessing. does this sound about right?

G-man

USS Atlantis · Post by **USS Atlantis** » Thu Apr 21, 2011 6:06 pm

Sounds about the right amount of time

What I do is hold the piece and the drill - and if possible, rest the heel of one hand on the heel of the other - so any "jerks" are transmitted and both hands move together

If the piece is larger, I'll set it on my bench, then rest my elbow on the bench - reduces the jerking thing again by having a stable place

Takes a lot of patience - thing to do maybe is get a larger selection of one bit size and practice on scrap stock

Kylwell · Post by **Kylwell** » Thu Apr 21, 2011 6:25 pm

You seem to have it worked out. Put as little out as possible to drill the hole, slow & try not to flex it.

You may want to try getting a Tamiya Electric Handy Drill . Runs on batteries.

I've also found that when you need to do a bunch or holes, drill the starter holes first, only going a wee bit in. Then come back & finish drilling all the way through. It @ least feels like it takes less time and seems to use bits less.

southwestforests · Post by **southwestforests** » Thu Apr 21, 2011 7:00 pm

Used a lot of these things drilling HO locomotives and cars for grab irons - thing to do is find a style of pin vise which allows bit to be seated way in so only about 1/4 inch or so is exposed.

Mine are something like 20 years old but this looks to be similar - ones I have shaft is hollow which allows bit to be deeply seated. http://www.walthers.com/exec/productinfo/230-811

G-man · Post by **G-man** » Thu Apr 21, 2011 7:58 pm

I had looked at a battery powered drill by...tamiya i think it was, that is similar, pencil grip style, though is the big different, i just wasnt sure if the collett would fit a bit that small.

I have been ordering the bits now form Micromart, they sell them in packs of ten for like 2$ each, with discounts for 2+ and 12+...funny its actually cheaper to get 12 sets of them then it is to get 11 sets.

To the drilling a pilot hole part, I've actually been using my scribing pen, to make small ...marks i guess you'd say, really shallow holes, everywhere i wanted to drill a hole ( i'm not using the template that they use on the Amt FO kit, doesn't have enough lights to match the studio model by half, so I'm using as many reference images as i can find. and coming close to doubling the lights in the kit. ) anyway, the indention i make is just barely deep enough for the tip of the bit to stay in without slipping around seems to have helped alot. hasn't assisted with the issue of drilling an oval hole yet, still working on that one, and i haven't any needle files that are 1mm in diameter either so.....

I'll give the whole bracing my elbow on the table thing a try,

I had been doing it so that both hands ere toughing the piece to drill, and my fingertip resting on the "vice" part of the drill to try and keep the bit from flexing as much as possible, but this piece is awkward to hold like that...

Another issue i am going to encounter is on the inner ring ( the promenade) there are alot of windows to be drilled on upper and lower sections, and i have a hard time getting to them because my pin vice, and drill bit = longer then the gap between the inner core and the middle docking ring. hoping not to have to cut the two sections away from each other.....

thank you for the replies so far, They have given me a few extra ideas, and as well they have reinforced that i am at least going about it correctly.

and yes, the pin vice shown in the link above is very similar to the one i have.

G-man

Kylwell · Post by **Kylwell** » Thu Apr 21, 2011 8:28 pm

You much mean Widget, MicroMark is $8.65 for 6. Widget commonly gives discounts for large orders.

Park of the reason drilling a starter & then coming back helps is that you only need to have a wee tiny bit sticking out of the collet.

& try the Tamiya, or like, they'll speed things up so much you won't care about the cost.

G-man · Post by **G-man** » Thu Apr 21, 2011 9:41 pm

yes widget, sorry, had not sure why i said micro.
I'll look into getting one of the tamiya drills next payday.

i wish there was a way to get a chuck for the ertl micro drill, i have ...three of those i think, with broken bits.

G-man

Kylwell · Post by **Kylwell** » Fri Apr 22, 2011 12:41 am

I'd have to look @ one to see if there's a way to rig it with a collet. Never used one myself.

G-man · Post by **G-man** » Fri Apr 22, 2011 1:30 am

its just a simple plastic housing, for a small 3 volt electric motor, the bit is set in a plastic cylinder that sits strait on the shaft with a fairly snug fit.

G-man · Post by **G-man** » Fri Apr 22, 2011 4:51 pm

for what its worth, i just had a brain storm and tried it out and it worked perfectly.

I have been trying to fathom how i was going to drill oval holes in the upper promenade on the Ds9 kit, that were smaller then my smallest needle file. and it came to me in a stroke of genious.

Take a drill bit, smaller then i need for the hole ( after i predrilled the .5mm holes for the center of each window) and put it in my pin vice, and i can use the drill flutes on it as a file, if i gently slide it back and forth on the inside of the hole, takes time and patience, and steady hand with little to no pressure, but slowly i was able to obtain oval holes in the windows. i have 5 of them done, i think i will end up filling in and redoing one of those five. ....so that leaves 46 more of those to go!...yay..

G-man