New mast hinge - Drilling Stainless Steel

[MikeP]

You ever have one of those "I'm so clever I can hardly stand it" moments?

Background:

Last year I broke the hinge on my 53MYs aluminum mast which holds the anchor light, Sat antenna, and radar. A local guy removed it and repaired it by having a welder reweld the AL hinges. The welded hinges broke the first time we raised the mast. He was nice enough to refund the 1200+ bucks he had charged me.

This time we did it right and I had a complete hinge with the deck plate and matching plate to be bolted to the bottom of the mast fabricated from 1/2" SS. The shop did a superb job and this thing could lift the flight deck on an aircraft carrier. It fit perfectly, with all holes lining up precisely with the existing deck holes and countersunk holes in the plate to bolt to the mast. I had to drill/tap the mast for the bolts which, being AL, was not a problem at all. The charge for the complete hinge assy, which weighed 20lbs was $650.

BUT I also needed to drill three more 3/8" holes through the hinge's SS deck plate, through the FB deck and through an AL backing plate on the underside of the FB deck (roof of the back deck). I did not have the item I needed to mount when I had the plates made, otherwise the shop would have made the holes.

Drilling SS is a total PITA and the first hole took over 90 minutes and exhausted two battery packs on my drill (note to self - toss battery powered drill in the bay, buy a cord drill). The problem was that it takes a LOT of pressure and low speed. I could only apply sufficient pressure for about 20 seconds at a time - basically holding a pushup with alll my weight on the drill. Then I had to recover for several minutes. Plus the drill batts didn't last long at all. But then I had one of those ever decreasing flashes of brilliance...I could MAKE a drill press!

So I did and I drilled the two remaining holes without much effort at all except for the battery packs going south about 1/2 way through each hole. SO if I had had a drill with a power cord I could have done the other two holes in a few minutes instead of two hours. (Note to self - toss cordless drill in the bay and buy...oh right, already made that note. Actually I made that note last year and keep relearning that lesson).

Pic of drill press is below:

 

[rrrestorer]

The trick to cutting stainless is cutting oil and a fresh drill bit. Makes a big differance.

 

[DAlter]

Mike,

I could just picture the oar breaking, then you smashing your right hand on the deck, while the broaken oar handle comes up and hits you in the face...ouch!

 

[MikeP]

I had brand new cobalt bits and cutting fluid. It takes a lot of pressure/slow speed to drill SS and get those nice spirals coming up from the hole. Easy with a drill press - hard with a battery powered hand drill.

Doug - yeah I was keeping that scenario in mind...

 

[krush]

wow, metal workers charge a lot of money there.

 

[MikeP]

Maybe so - I wouldn't know. But having a well made 1/2" thick SS hinge/plate set for $650 as opposed to a crappy repair at $1200 that broke immediately seems like a heck of a deal to me!

 

[Akyla]

The best way to do that with a pistol drill (or even a real drill press) is to step up the holes from a small drill to the final diameter. It will cut the overall drilling time and not burn out your bits as well as yourself. I would not even try to do a 3/8 hole in one step even with my 1/2 corded drill.

You do need sharp bits, some cutting oil and the right speed and feed pressure. The SS can be harder to drill than mild steel but it will drill with not too much more difficulty.

 

[Walter P]

Mike,

I really like the McGiver thing with the oar. I agree with you about battery powered drills as well. They have a use in many jobs but not all of them. A corded drill is so cheap today that it pays to keep one around just in case. One more thing is that the better the grade of SS the more critical it is that you have proper cutting fluids, a sharp drill preferably of cobalt (which you had), slow speed and very important steady pressure. If the drill starts skating on the surface of the hole it instantly work hardens the SS and you will play hell from then on. I'm not really surprised that you did the job, after all you are a Hatteras owner and we all know that that alone makes you smart.

Walt

 

[jim rosenthal]

What's really impressive is that Mike drilled the hole, held the oar, AND shot the picture. Now that is a resourceful Hatteras owner...

Mike is also going to replace the back bulkhead on my 36C. He estimates that it will take him about two hours- shorter time if he uses a corded saw as opposed to the battery Sawzall he has now.

AKA, I have the same 110vac B&D drill I've had for twenty years. Still works fine, and I hardly ever use a cordless drill.

 

[krush]

Lots of difficulty in drilling harder metals with a hand drill is because it's just impossible to keep the drill motor steady. Thus the angle of the bit where it cuts is always changing.

 

[Canuck Dennis]

Can you imagine what would have happened had the drill bit bound up in the piece and the whole mast started to spin.....wow !!!!...good movie..lol...

I drilled out 4 flat 3/4" zinc plates on Fri with a drill press and cobalt bit, one bound up, man that was fun .....luckily no dmage...

Fine job there Mike..good looking hinge...

 

[REBrueckner]

Boating sure is fun!!

Is that mast supported with rigid stays fastened somewhere high on the mast??

And I hate to ask this: But with the recent threads on stainless screws supposedly corroding aluminum window frames, are you comfortable your new stainless hige and original aluminum mast will be ok together??

How does one check for that kind of compatibility? If it's just the galvanic potential scale, aluminum is pretty far away from stainless...... not good, but maybe ok out of water.

 

[MikeP]

"But with the recent threads on stainless screws supposedly corroding aluminum window frames, are you comfortable your new stainless hige and original aluminum mast will be ok together?? "

Well the mast has SS screws into various AL fittings and it's been fine since new. Maybe over more years than I will own the boat it might matter but I don't think so.

"Is that mast supported with rigid stays fastened somewhere high on the mast??"

Yes there are a pair of 1 1/4" OD SS stays that connect from the deck to the mast at the radar shelf level. With the stays bolted to the mast it is literally a structural part of the boat. The stays are mounted to the deck with four 3/8" through-bolts for each stay. A few years ago I standing on the mast's radar shelf to install a new bulb in the anchor light and nothing moves or flexes.

 

[MikeP]

Here's a couple of pics of the whole thing all together:

The base showing the plate, with the oem shock-cord counterweight system. I had to cut that shock-cord mount section out of the original mast base and through-bolt it to the new SS plate. That was the reason for drilling the 3 holes in the 1/2" SS. You can see some of the twelve 5/16" mounting screws holding the SS plate to the AL mast base.

And here's the whole thing in the down position - you can see the 1 1/4" stays that bolt to either side of the mast. I will be mounting a new radar when I decide whether I need another open array or if an enclosed dome is sufficient for our use.