Fixing mis-drilled holes

[Harrypotter]

Guys,

Essentially I started to drill the windows out for my 1/1000 D7 last night and had a bit of a nightmare.

2 of the holes are maybe 0.25mm out of position, which doesn't sound much until you consider the holes are 0.5mm in diameter, in which case it's a country mile.

Also I was having trouble drilling the double holes to make the slotted windows.

This is a test piece to learn how to get it right before I move onto other things (1/1000 TOS Enterprise), so before I start trying to fix it I thought I'd ask for your collective wisdom.

So please, how do I:

i) Fill in and re-drill the holes (techniques materials, tips & tricks etc.)

ii) Drill the remaining holes more accurately (I stopped once it started going arwy) - currently I was using a pin to 'centre punch' the plastic.

iii) Any other useful tips - I've tried googling it but you get lots of different answers and very little that translates to holes this small.

TIA

[SpaceRanger1]

So please, how do I:

i) Fill in and re-drill the holes (techniques materials, tips & tricks etc.)

ii) Drill the remaining holes more accurately (I stopped once it started going arwy) - currently I was using a pin to 'centre punch' the plastic.

iii) Any other useful tips - I've tried googling it but you get lots of different answers and very little that translates to holes this small.

TIA

In my experience, filling mis-drilled holes with the usual modeling putty doesn't work; the putty is too soft even when fully cured. I'd suggest filling the holes with either:

1. Plastic plastic. Take an old (but clean) paint bottle and pour in some liquid plastic cement, such as Testors. Then add some pieces of old sprue. Let the cement dissolve the sprue and add more until the goop reaches a putty-like consistency. Fill the holes with the goop and allow it to fully harden. It should be about the same density as the original kit plastic when fully cured. Sand flush, then re-drill.

Or:

2. Fill holes with talc then apply thin CA/superglue. Immediately sand it flush, then re-drill the hole. If you allow the cured CA to sit too long, it will become rock-hard and no amount of filing/sanding will smooth it.

Or:

3. Purchase some Evergreen or Plastruct styrene rods of appropriate diameter and fill holes with them using liquid cement to weld them in place. Allow them to fully dry, then trim, sand flush, then re-drill.

Aligning portholes can be a pain. If the portholes are parallel to the edge of a kit part, I use a pair of cheap draftsman's dividers to lightly scribe a line along which to drill the ports. Set the dividers to the distance from the part's edge, and holding the dividers so that one point is in constant contact with the edge, use the other point to scribe a line into the part by running the dividers down its length. Once you have the line scribed, use a needle or other pointer to establish a pilot hole for your drill. You can also use your dividers to locate pilot holes along your scribed guide line if the ports are evenly spaced. Once the holes are drilled, the scribed guide line can be filled with a light brushed application of Mr. Surfacer or even typewriter correction fluid and sanded smooth.

For ports on curved surfaces, I use Dymo tape as a guide. That's the plastic tape made for use in lettering machines. I slice it lengthwise so its more flexible. Vinyl masking tape also works as a guide.

[Kylwell]

Even when I've check, double check, measured and adjusted I've gotten holes out of center. Practice helps but sometimes you're just going to have to find or make a super fine flat file or broach and tweek the slot.

Broaches, different than brooches, are tapered shaped tools that can help finish out a shape. Not that hard to make when working with plastic.

As for filling, SR1 is correct. Most any filler is going to be harder than the surrounding material or softer. The plastic putty trick is very handy especially for small holes.

[irishtrek]

When I end up drilling a hole and it ends up needing to be moved a bit I'll finish drilling all the way through the plastic and glue a piece of Evergreen rod and once it's dried trim off the excess and sand.
As for getting the holes drilled in the right spot have you considered using the window decals provided as a template for positioning the windows or printing out some black and white copies of the decals and cutting out the windows and taping them to the hull for a template/guide for drilling???

[Harrypotter]

Thanks guys, some good advice there.

Might stretch some sprue to get the 0.5mm rods (not done that for a while).

I was using the stickers as the template, but they started to slide and move as I drilled.

Try, try and try again

[zymurgeist]

Try making your pilot holes with a hot needle. It doesn't try to skitter around like a drill. Most drills turn way too fast for plastic and melt their way through instead of cutting. The melted plastic makes the bit slide around too. Micro Mark sells a chuck for cordless screwdrivers that works pretty well.

[irishtrek]

Evergreen does make .5mm rod.
Also when drilling such tiny holes I always use a hand drill instead of a power drill, much easier to control.

[dizzyfugu]

3. Purchase some Evergreen or Plastruct styrene rods of appropriate diameter and fill holes with them using liquid cement to weld them in place. Allow them to fully dry, then trim, sand flush, then re-drill.

Second that. You can also use plastic sprues, heat the over a flame and tear a thin string from the material - as a bonus, it will be same stuff as the kit (material hardness can vary), and through the pulling process you achieve a conical shape, so that the stuff makes a perfect plug.
Just cut a generous piece of the prepared sprue off, apply some glue in the hole to be filled, and press the plug into it. Let it dry thoroughly, and then cut the surplus plastic away, sand the surface or apply (if need be, if the stuff bonds well you get a very smooth and compact result) some putty.[/quote]

[TazMan2000]

Space Ranger 1 has a good idea, but if you can't find talc, use the plastic sanding dust collected from sandpaper. Put a dab of CA into the hole and cover it with talc or dust. When it starts to harden, push it in with a sharp object. Repeat as necessary. For me this works and creates a strong plug that after redrilling, there is no soft material that will suck-in your drill bit.

TazMan2000