Drilling perfectly perpendicular holes

[Dukat, S.G.]

All,

I know this seems like a silly question, but I am in a serious rut lately and I'm struggling with some of the simplest things.

IMG_20140408_185450_409 by Brazen Jackal

I am trying to duplicate these twin "holes" on a much smaller model, but in spite of my best efforts, the holes wind up uneven when I try to drill them out with a pin vise.

Yes, I've scored the plastic in the best straight line I could with a #11. I even tried to deepen that scoring line by running the back of the blade through that cut a time or few.

Still, again and again, when it comes time to drill the holes, one is invariably higher than the other

After a VERY frustrating sequence of events that accompanied this, I'm about ready to scrap my so-called "accurized KBoP kit" forever. I grant that I am very tired and remain angry, but it's almost gotten to a point at which I'll have to acquire yet another KBoP fuselage top half to even proceed -- something my broke-a** simply can't even begin to afford at the moment.

All pointers are appreciated, but please, keep in mind that I'm not looking to replicate the angle of the holes on the studio model -- just their approximate size and spacing relative to the stupid AMT/Ertl kit. Even holes that are slightly too large in diameter, or even a bit too small, are fine by me.

Thanks, guys, and sorry for the ranting.

-S

[Andrew Gorman]

First, don't scrap the hull- fill the botched holes with some sprue or rod! A pair if dividers can really save you here, even if they are improvised from a compass. Also, a hole in a curved surface is not going to act like a hole on a flat one-
https://books.google.com/books?id=OjJLA ... ce&f=false
If you have a reference showing the holes from directly above, use that to locate your centers. Do it in pencil, and use the dividers to make sure each one is equidistant from the adjacent symmetrical features. Once you are happy with the location, mark it with a compass point from STRAIGHT above. Poke it deeply enough you have a small, vertical cup in the plastic. If you have access to any kind of drill press, even a full size on it will help but isn't really necessary to make the mark. If it is not perfect you can still make adjustments-
Here is an excellent thread on that. The point about using some kind of magnification when making the mark is a good one!
https://books.google.com/books?id=OjJLA ... ce&f=false
Then drill tiny- #70 or so- holes as perpendicular as you can. Stick a pin in them when you are done to check your work. Then slowly work up to your final size and check after each drilling. Each check gives you a chance to make a correction. Apologies on the long post and links, but I have been in your shoes!

[Kekker]

Here's a thought - drill the holes first, but oversized.

Then take some styrene tube and fit it to the holes, taking time to get them aligned. Use thick CA to give you time to move them.

Trim them down flush with the surface, putty as needed.

Kev

[Natsu-Rokka]

Here's a thought - drill the holes first, but oversized.

Then take some styrene tube and fit it to the holes, taking time to get them aligned. Use thick CA to give you time to move them.

Trim them down flush with the surface, putty as needed.

Kev

+1

You could also make a simple jig using wire or rod that fits into the tubing, joined with a bit of sheet plastic that sets the rods to the spacing you want. Slip the tubing over the rods, inert into your model, then glue in place. Hope the makes sense.

[Bellerophon]

I was going to suggest using a drill press. The bit would deflect a bit, so you'd need to peck at it, and horizontal pilot holes at the correct height might help. But Kekker's suggestion is brilliant. His must be the best way to get neat holes aligned correctly.

[Kylwell]

Star small, drill out to larger. Adjust as needed.

Or, drill over sized, insert correct size tubing and putty into place.

[Tankmodeler]

Here's a thought - drill the holes first, but oversized.

Then take some styrene tube and fit it to the holes, taking time to get them aligned. Use thick CA to give you time to move them.

Trim them down flush with the surface, putty as needed.

Kev

+1

Plus another one.

^ this is the way to do it unless you have a drill press with a translating vice and a way to secure the parts exactly right.

Small variances can be excruciatingly irritating when yuo see them as the human eye is a master at picking out partterns and differences in patterns.

Drill the hole ovesize, use the tube idea and either gel superglue or even epoxy glue to provide longer working and adjusting time. Before you add the tube and glue, get the BoP into a position where it is on a flat surface and firmly clamped level. Use a height gauge or dial caliper to get this as exactly right as you can manage. Make a rig that clamps the tubes level and in exactly the correct position you want on the BoP yet can advance the tubes into the BoP hull.

Put the tubes into the right position, apply the glue and then let everything set up. Don't attempt to use the glue to fill around the tubes, just let it be glue. Once everything is set up, trim the tubes back to just overflush with the BoP surface. Depending upon how oversize the holes are use AVES or Squadron white to fill around the tubes and let that set up. Once fully dry/cured file and sand the tubes and filler back to the BoP skin.

Paul