MD 180 Broken Mast

[TJones]

of mast being shorter? or is this just one one the failures that comes with usage?

[ful-rac]

Originally Posted by TJones

of mast being shorter? or is this just one one the failures that comes with usage?

I would say it's a failure that comes with usage. I noticed that they have an updated version of the 180 drive that eliminates the screw and nut mechanism on the fin. Looks like they are calling it the MD180 V2. Looks like the style I have has now, since july has been discontinued.

[TheBentRod]

How many others feel this way?

"A couple weeks without my drive...? No... that will not do..."

Very resourceful! mad props!

[monstahfish]

I doubt warranty would let you go "a couple weeks" without your drive. That being said, nice work getting that out. Screw extractors are a life saver and a must have in everyone's garage.

[Mahigeer]

Are the shafts stainless steel?

If so drilling SS is very difficult.

Unless they are less grade of SS.

Regardless, good job on repairs.

[monstahfish]

Originally Posted by Mahigeer

Are the shafts stainless steel?

If so drilling SS is very difficult.

Unless they are less grade of SS.

Regardless, good job on repairs.

They are stainless but it can be drilled if done properly. Drilling stainless requires high pressure, low speed and lots of oil. If you overheat it, it will blue and break your bits.

[IN2DEEP]

Originally Posted by Mahigeer

Are the shafts stainless steel?

If so drilling SS is very difficult.

Unless they are less grade of SS.

Regardless, good job on repairs.

Def not a lesser grade stainless
The mast are made with Ph 17-4 SS which is heat treatable and is magnetic
The mast are much stiffer than 303, 304 or 316 SS of the same size.
As others have already said. Slow RPM with lots of pressure and cutting oil

[IN2DEEP]

Hobie probably thought that jumping up to .312 instead of .281 would eliminate the chance of breaking a fin mast

Good job on keeping the drill centered
I used a vice and a vertical mill to remove a broken one on a V2 drive last year

In our shop, we have better luck using square drive extractors instead of the spiral type


Tools used

[DanaPT]

Originally Posted by monstahfish

I doubt warranty would let you go "a couple weeks" without your drive. That being said, nice work getting that out. Screw extractors are a life saver and a must have in everyone's garage.

Absolutely looks like i need one of those thingamagies.

Nice work Tony... working like a surgeon.

[FISH11]

Nice work Tony, drilling out a broken bolt or stud is not easy because it's hard to drill centered and large enough to use an easy out that will bite well and hold the amount of pressure needed. In this case it helps that it's in a brass bushing and not rusted in. Even though this is a good post on a possible weak area. I wish you had told us about the nice Hali on board. I think the broken mast is because that mast had a defect other wise it would not have broken in that spot and not had stretch signs on the metal post instead of a clean break.

[ful-rac]

The mast was pretty hard, but like Shane said low speed, and also taking your time to get your drill centered as close as possible really helps. Starting with a small bit and stepping it up to a larger bit several times takes time so you have to be patient. At least it wasn't as bad as an exhaust stud...compared to one of those this one was a piece of cake...

...another thing that made this project challenging, is that the broken piece was recessed back into the sprocket about an 1" or 1 1/2...

Makes me wonder if Hobie were to score the mast an inch or so below the end of the sprocket to make a point where if the mast were to fail it would fail in a manner in which you could replace it without the use of special tools....Of course that would make a weak point...but that is the point...just a thought. It's alot cheaper replacing a mast as opposed to replacing complete spine assemblies...