Parallel holes

[RichB]

To finish this project, I must drill parallel holes by eye. It seems only by luck that I have ever attained success. Maybe it is from pushing too hard. Just like trying to cut a 90 deree angle with a sabre saw. The top is close to perfect but the bottom is surely not.

I have a couple of cast suncor pad eyes to install on deck and the backing plates are stainless and pre-drilled.

What is a good way to get all 8 - 5/16" holes through the 2+" deck and through the backing plate...... without wallowing out the epoxy compression sleeves I have poured?

So far I have discarded the following:
1 . My old Craftsman portable drill stand is not capable of going below the base unless I find a 12" bit.
2 . Drilling from the bottom half way up may cut the error in half ????

 

[Bill Roosa]

You second solution is what I've used in the past.
Another suggestion is to start out with 8 VERY small holes and move up in size one step at a time. The first ones WILL not be perfect but you can force the next size in the right direction. The second will be pretty close and the next step up will be even closer. Once you get the holes "almost" perfect you can drill one full size and bolt on the backing plate and padeye then use the backing plate and pad eye to guide the drilling of the rest.

Which one you choose to bolt is an art as you want to get the one that provides the least error to the others. Course if there is a critical alignment issue with the padeys and something else already installed you will want to pick the hole that gives the best alignment as the first one to drill and bolt.

Good luck

 

[Rick Webb]

Start with Your Drill Using the stand

Make a guide with a 2 X 4 to make a guide and use that on the boat.

 

[Don12364]

Any toolmaker will tell you - JIG DRILL.

For a one off the jig could be just 1½" thick hardwood drilled on a drill press and using the fitting or backing plate as a template to make the jig.
This way you can drill a set of holes at any angle you like.
You may need a long series drill bit.

If necessary temporarily fasten the jig to the surface of the deck to hold it in place when drilling the deck. Double sided tape might suffice if you are not too heavy handed!

If you are a bit wobbly you might make the jig for 1/4" holes and then use your method #2 from above and below when reaming out to finished size of 5/16"

 

[RichB]

That pretty well gets me off dead center. Thanks to the three of ya. I'm off to Sears for the longer drill bits. Ace didn't have them and Harbor freight only has 5/16th in 24" length. The proximity of the hull didn't allow straight drilling from below. The pilot holes will allow for correction of the angle. Although a real toolmaker would have more confidence in his methods.
You know I could have thought of these solutions, but I didn't. This is a great forum. Again THANKS.