Oval hole...

[Kelpie]

I've noticed a bit of play in the steering and finally took a look. It's a shaft/gear system, I believe by Whitlock.

I don't know if this is the culprit but it's certainly not good- one of the mounting holes for the final gearbox has gone oval. This gearbox turns the rotation of the shaft in to an arm movement to connect to the stub tiller. There's a lot of leverage and force on this system.

How should I go about fixing this? I think my options would be to:
a) get it drilled out to a wider bore (along with the mounting points, one of which is glassed in to the hull)
b) get a bit of weld in there to reduce the bore, then re-drill
c) get the bolt permanently welded in to place in the oval hole.

The last one sounds the most practical, to me. But I'm not a welder so I don't really know what's possible. It would run the risk of misalignment with the mounting brackets, but fortunately one of the brackets can come right off and we could use that to get the holes at the right centres.

 

[Refueler]

Forgive me if wrong ... but has that 'knuckle' been rewelded back on ? Has the hole been 'ovaled' to compensate for error when that was welded back on ??

Sorry if I'm wrong.

 

[Kelpie]

Forgive me if wrong ... but has that 'knuckle' been rewelded back on ? Has the hole been 'ovaled' to compensate for error when that was welded back on ??

Sorry if I'm wrong.

I noticed that myself after taking the photo. I think it has broken off at some point, yes. I suppose the oval hole could be deliberate, but it would be a hell of a bodge. Hopefully I can put it back together without resorting to that.

The gearbox is mounted underneath a right angle bracket, which is easily removed from the hull. A second bracket is glassed in and the oval hole lines up with that too.

We should be able to use the right angle bracket as a template to get the spacing right.

 

[Boater Sam]

Part fill the hole with metal putty, eg epoxy metal like Evostik metal epoxy putty.

 

[LadyInBed]

The two options that I would consider are to drill out and put in a sleave or weld and drill a new hole.

 

[Refueler]

It wont be first hole 'ovaled' to compensate ....

Different ball game ... but a mounting lug on one of my 15cc Model air engines snapped off in a spectacular crash ... guy who welded it back on .... before welding - said honestly - (this guy is a real master pro as well at welding - he does Areospace stuff) .. that the hole will most likely NOT line up again ..... he asked if I wanted it filled in - to be redrilled or to leave and be 'ovaled' ?? I said leave it - hoping it would line up. It was close enough in the end.

 

[Refueler]

The two options that I would consider are to drill out and put in a sleave or weld and drill a new hole.

That's my thought as well .... I don't think I would weld the bolt in ... seems a bit drastic ..

 

[Kelpie]

Hadn't thought of drilling out and sleeving. Could be a good option. I'm a bit loathe to lose any more material from the lug if possible, though.

 

[johnalison]

Bearing in mind the possibility mentioned that it may have been ovalled deliberately, you are going to want to know where the new hole should centre before making a new round hole.

 

[Kelpie]

Bearing in mind the possibility mentioned that it may have been ovalled deliberately, you are going to want to know where the new hole should centre before making a new round hole.

That's where the bracket should help out.

 

[KevinV]

Considering this misalignment I'd say the ovalling was part deliberate. I'd weld shut and redrill in the correct place and alignment

 

[Daydream believer]

Drill then ream to a round hole at least 3mm oversize so final bush retains a wall.
Insert an aluminium plug fixed with locktite. ( Check which one will glue it in place permanently )
I might use bronze but i am not sure about electrolysis, although I think it would not matter.
Put a 4mm brass pin right through to stop it rotating during the next machining operation
Then re drill to correct position.
Drill undersize & ream to correct diameter to avoid slack allowing further wear.

 

[Kelpie]

Well it's in the hands of a welder now.
Turns out the casting is aluminium. Rather than use a sleeve, he wants to fill the hole and then re-drill. I hope this turns out to be the right course of action. Certainly better than my idea of welding the bolt in place, which does feel like it would have been a bodge.

 

[LadyInBed]

Just be sure to make a template to drill the new hole in the correct position.

 

[Kelpie]

Just be sure to make a template to drill the new hole in the correct position.

The gearbox has three mounting points, and a steel bracket with three intact holes. So we're using the bracket as our template.

 

[Daydream believer]

Just be sure to make a template to drill the new hole in the correct position.

A template from what?
The old hole is oval suggesting the one originally bored was wrong & hence the wear one side.
Or the bolt was slack allowing the wear one side in the line of the pull
On another point about welding
I do not know if anyone has tried drilling, or cutting, a weld in steel, but it is always harder.
So does that apply to a weld in aluminium? The weld will be in layers ( one assumes) because the welder will not want to induce heat stress to the main body so have to do in small steps hence it will be in layers, making it more likely that the drill could wander. I might further query the long term effect of a weld at this point on the aluminium once it has been stressed by welding. Unless, of course , the whole unit is to be pre heated , which is unlikely.
Just a question as I do not know the answer. Only surmising.

Edit
Typed slower than Kelpie

 

[Kelpie]

I'm not doing the drilling, that's up to el hombre...

 

[Stemar]

Certainly better than my idea of welding the bolt in place, which does feel like it would have been a bodge.

I'd like to meet the guy who can weld a steel bolt in an aluminium hole

 

[Kelpie]

I'd like to meet the guy who can weld a steel bolt in an aluminium hole

I think realising that it was aluminium was the final straw. You could even say it put the tin lid on it.

 

[bobgarrett]

I'd like to meet the guy who can weld a steel bolt in an aluminium hole

Easy! I have a couple of steel bolts that have welded themselves into aluminium holes in my windlass!