Masking Circular Objects

Use blue or white tack. You can also use masking fluid.

The best tape I have found for masking over bumps is Tamiya. It has a bit of stretch.  I nestle it down around the bump with the end of a toothpick, then use a fresh X-acto blade to cut out.

If you are lucky and have a hole punch the right size, you can punch out the masking tape.

It was hard to get size from that photo, but if the circle is big enough, you can cut out the circle with a compass.  I have taken brass rod the size of a pencil lead, which fits in the compass, and filed a sharp blade-like edge to the rod.  Or, use a good pencil lead, well pointed, to draw the circle with the compass on a piece of tape, and cut out on the line with an X-acto knife.

Hi Don,

The part is about the size of the palm of my hand, and the docking collar is slightly larger than the diameter of a bic pen. On the studio model the black extends along the top rounded at the front with a narrow edge of base coat surrounding it. I am attaching a picture of what it should look like. It's that rounded point at the front that's giving me fits.

Tom

It's pretty small, so you may have problems with tape wrinkling at the apex of the curve on the upper part. I would be tempted to try & get a rubbing of the curve (pencil/paper) or impression & lay it down over a sheet or broad piece of masking tape & just cut a mask for to suit.

It's a bit fiddly to do & the tape can be difficult to remove from whatever it's cut on (plate or piece of glass the best), but it can give you a perfect mask with patience.

tdwi66

Hi Don,

The part is about the size of the palm of my hand, and the docking collar is slightly larger than the diameter of a bic pen. On the studio model the black extends along the top rounded at the front with a narrow edge of base coat surrounding it. I am attaching a picture of what it should look like. It's that rounded point at the front that's giving me fits.

Tom

 

Need one more item of information.  Do you want to put masking over the black projection, or to mask the whole rest of the model, so you can paint the projecting area.

Sorry Gentlemen,

I had to take care of some personal business and was off the grid for a few days. Yes Don, what I want to do is paint black the projecting docking collar. It's the narrow part at the top that's giving me fits.

tdwi66

Sorry Gentlemen,

I had to take care of some personal business and was off the grid for a few days. Yes Don, what I want to do is paint black the projecting docking collar. It's the narrow part at the top that's giving me fits.

 

That problem is a little easier in some ways than the reverse problem than masking a single bump or projection, as you can use many pieces to mask around something, though it does use a lot more masking tape.  I keep both Tamiya tape for crisp edges, and cheap generic masking tape for the larger areas where the tape overlaps the Tamiya tape.

Also, when I start masking something, I always replace the blade in my knife so I get a really good edge to the tape when I cut.  The sharper the blade the better it follows the feel of a bump or indentation I am masking against.

I discovered Tamiya's "masking tape for curves" a few months ago. 

It's not cheap and it can't do everthing but what it does do is really terrific.

It's the white tape, and since it's not used like regular Tamiya masking tape which I also love, a roll or two is likely to last a long time. 

There is a learning curve to it,  so a little practice on an old test model will help.

Thanks a lot Wilbur! None of the Hobby shops near my house carry it unfortunately. I will likely get some online soon for future projects. I was able to solve my problem with a combination of techniques offfered to me by the great folks on the forums. I made a stencil out of decal paper because of it rigidness. I used small strips of 3M green automotive tape for the more circular lower part. Then used the stencil and a Xacto knife to cut 3M blue tape for the tapered upper part. The result worked out rather nicely. here are a couple of pictures to show the progress. Thanks to everyone for their help, I couldn't have done it without you!

Tom

The finished product.

Great!  Glad you could get it to work.