Drilling holes to install new coupler

[NDNick]

I have recently obtained a 14' alumnium boat "project" and am in the process of fixing it up. The trailer was pretty beat up and I decided to upgrade the coupler, winch, bunks, etc. I found a new coupler for $10 at a marine store and assume it would fit, but the old coupler (which was rusty and bent) actually had smaller holes that were closer together. I believe the old one had 3/8" holes, and the new one has 1/2" holes that are further apart. So looks like I'll be drilling regardless, but my question is whether it'd be acceptable to simply use 3/8" thru bolts with the new coupler. I own a 3/8" drill, and a 1/2" hole would require me to find/rent/buy a new drill for 4 holes. Seems a little overboard, otherwise my plan is to drill a couple new holes further apart and install the new coupler with 3/8" bolts. I'm just not sure if it'd be a huge problem if it has 1/2" holes (the head of the bolt is obviously larger than 1/2" so that wouldn't be a problem).

 

[DianneB]

Re: Drilling holes to install new coupler

Do it right, do it once.

 

[cribber]

Re: Drilling holes to install new coupler

Head down to Lowes, Sears, or Home Depot and pick up a 1/2 inch drill bit with a 3/8 inch shank. Shouldn't cost too much.

 

[NDNick]

Re: Drilling holes to install new coupler

Great thanks for the quick response. I wasn't aware of a different shank diameter but that would seem to work perfectly.

 

[marlboro180]

Re: Drilling holes to install new coupler

For oversizing a hole in relatively thin metal, I would highly recommend using a stepped drill bit. Easily found , especially at an electrical supply house or even a big box store. I even use them in 1/4 inch with a powerful hand drill. They tend not to bite in as hard as a regular bit will when the bit digs in to the burr and tries to twist your arm off. Sometimes you get lucky though. Just my.02

 

[Reel Kahuna]

Re: Drilling holes to install new coupler

Those step drills are great and can be bought at Harbor Freight relatively cheap and hold up pretty good.

 

[Utahboatnut]

Re: Drilling holes to install new coupler

If you end up using the step bit or unibit take a good marker and mark where 1/2" is all the way around so you dont go too far, otherwise you would be in the same problem you are currently in. I would just go a good reduced shank steel twist bit for metal they arent that much $ and will drill a much more precise hole. Either will work though. Also make sure you get the highest grade bolts you can no sence going to all that work only to use cheapy grade bolts, nylock nuts are perfect for that application as well.