transfering bolt head positions

[wreckwriter]

The World's longest back porch rebuild project is nearing its end, just a few more sub-projects to go....

At the back side of the porch I have 2x4/4x4 framing split into 6 "windows" where the screen is going to go. In order to do the screening the way the wife wants it (flush with the outer edge of the main frame) I need to build an internal frame, within the original frame, set back 3/8" from the edge of the original frame outer edge. I'm going to use 2x2s to do it.

The question only relates to the bottom pieces, 3 in all. The 2x4s of the original frame lay flat and are lagged in to the concrete slab. In order to get my internal frame to lay flat against the original I need to countersink the 2x2s at the lag bolt heads, with either a forstner bit or a dremel tool (depending on how accurately I can mark them). What I'm looking for is the easiest way to mark the 2x2s for the bolt head position. Their not in a perfectly straight line so measuring is likely the most time consuming way.

My original idea is to put a drop of paint on each bolt head and then lay the 2x2 on top and countersink at the paint spots. Anyone have a better idea?

Thanks for any tips!

Tom

[LarryG]

The paint trick will work, or you could use carbon paper, but you probably don't even need to do that. Just lay the 2x2 into place and give it a firm tap with a hammer at each bolt head. That will make a faint yet sufficiently distinct mark by which to locate the c'sinks. (I'm guessing that your plan is to drill them slightly oversize, so that gnat's-hair accuracy is not required.)

[LCHIEN]

just thinking outside the box again.
Depending on how many bolts you are talking about...
Why not remove every bolt one at a time. Countersink the hole in the 2x4, 3/4" dia. x 1/4" deep for the head. Reinstall bolt a little deeper or install new bolt 1/4" shorter.

Another ideas is to cross -dado a 3/4", 1/4" deep slot at the approximate bolt head location. It's not critical to be a close fit over the bolt, nor to look hidden?

Larry's Idea, hit the 2x2 with a hammer to put a dent in the 2x2 at the bolt locatio is good, too.

[wreckwriter]

The paint trick will work, or you could use carbon paper, but you probably don't even need to do that. Just lay the 2x2 into place and give it a firm tap with a hammer at each bolt head. That will make a faint yet sufficiently distinct mark by which to locate the c'sinks.

Good idea. Thanks Larry!

[wreckwriter]

just thinking outside the box again.
Depending on how many bolts you are talking about...
Why not remove every bolt one at a time. Countersink the hole in the 2x4, 1/4" for the head. Reinstall bolt a little deeper or install new bolt 1/4" shorter.

Another ideas is to cross -dado a 3/4", 1/4" deep slot at the approximate bolt head location. It's not critical to be a close fit over the bolt, nor to look hidden?

If I were to do that it would require a large countersink due to washer under bolt head. Always the chance of breaking a lag too...

I am hoping to end up with everything hidden. Not critical but preferable.

[gmack5]

Use a "Thumb Tack" fastened to the Bolt head (with a small piece of double sided Tape), point sticking UP, then align your board on top of the tacks and push the piece down so that the tacks are embedded in the part at the place where you want the hole.

If you then drive the Tacks into the part, far enough that they won't drop out easily, you have a "permanent" hole locator for free, assuming you have some Thumb Tacks around the house somewhere.

[just4funsies]

Another workable method to the paint-marking theme is to use a little piece of self-stick weather stripping (the cheap foam kind) on each bolt head. Then just ink it with a stamp pad, and press your trim board in place. If your mounting of the foam is precise, your marks will be also. You won't have to figure whether the hammer imprint is the dead center of the bolt head, although if you drill a big enough countersink, accuracy really won't matter.

[wreckwriter]

Once I layed this all out in place it turned out the the heads of the bolts were right on the edge of the 2x2s. I ended up just marking the head positions with a pencil and cutting half circles on the edge of the wood, free-hand with a Forstner bit; what fun that was.

Got everything cut, shaped, primed and nailed up Saturday. Yesterday I caulked the seams and top-coated with latex paint. So far its come out very nicely.

Over the next week I'll attach the Screen-Tight base material in the evenings after work. Should be ready to lay screen by Saturday.

Thanks for the tips!