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Old 26 February 2008, 17:16   #51
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Originally Posted by Hightower View Post
This is what I had in mind.

Excuse the wonky look of my rough sketch, it is late

Original on left modded one on right.

The reason I have designed it like this is that I can have it made seperate and fit it in an hour.
But if you don't bring the bracing forward it will still be weak where it finishes
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Old 26 February 2008, 17:34   #52
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Originally Posted by Limey Linda View Post
The case hardening process you are thinking about is used for steel with no carbon. If the steel already has carbon in it it will harden unless the temp. is lowered slowly, which is annealing. If they took it out of the zinc bath and sprayed it with water it will harden. No, it did not work harden as you would get with a skidding drill bit.
There is no such thing as steel with no carbon. Steel is a alloy of iron and carbon. Low carbon steels will not harden and case hardening is the process of adding carbon to the surface of the steel so that it contains enough carbon for the surface to be hardened. There is a general modification to this terminlogy and case hardening also appears to be used to describe surface hardening of carbon steels. For the steel to harden, it needs to be raised above its upper critical point. This varies for different steels but is generally above 700c.

Raising the temperature to just above the melting point for zinc would succeed in fully tempering a hardened steel and so reduce its hardness.

The maximum tempering heat is about 700F so maybe that is a confusion.

However, there are various ways in which a steel can become hard and one of them is work hardening. A cold rolled steel can become very resistant to drilling, especially drilling at high speed.

The other way your trailer could be a hard steel is it's made from bed irons. Those bu**ers can be really tough.
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Old 26 February 2008, 17:53   #53
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Quote:
Originally Posted by Hightower View Post
This is what I had in mind.

Original on left modded one on right.

The reason I have designed it like this is that I can have it made seperate and fit it in an hour.
I don't think you need the shorter cross bar. Your design will be much better than original because of the longer lever to the attachment point but you are still concentrating the load at those cross bolts so that is the area you need to strengthen. I see your angle but you need to take it forward a distance to stiffen up that section of the draw bar and distribute the load. It will also be better being clamped at the ends.

Your draw bar looks to me to be too flexible for that application because of its length and section and I'd bet it was a tad springy at the front until you pulled the boat down onto the snubber. My preference would be to use a section, say 120 x 60, keeping the top of it at the same level as your drawing and cut a corner out of it where it overlaps your cross member to keep the alignment level. Weld up that end to prevent crushing. This would allow the lower bolt at the front to pass through the tube. It wouldn't be the ideal dead centre but it would be sufficiently close. Any other stiffening you added there would be an advantage.
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Old 26 February 2008, 18:17   #54
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I agree with everything Jono's said about welding it

What I'd do is a bit more radical-that drawbar looks like a Friday Aftenoon Special.

I'd do it this way:-
Remove your FUBAR drawbar and the T piece.
Cut the flat plates that clamp round the drawbar off the main chassis rails.
Buy a nice big chunk of galvanised box section that's a bigger section and with more wall thickness to use as a new drawbar.
Trim the chassis rails back a bit to suit the bigger drawbar and longer thicker clamp plates-use 4 bolts instead of two in the new clamp plates.
If possible,bolt the drawbar rather than weld it to a nice shiny new T-piece.
Use a different method of U-bolting the T-piece to the main rails-those plates on one edge look like they'd support some cheese but not much more.

Obviously there'll be a bit of 'making it fit' in there-but that 2 bolt clamp,U-bolted T-piece plate and welded T-piece that Admiral made it with are (scuse the language) worthy of CAN.

The results should be a bit like the pic below.
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Old 27 February 2008, 01:22   #55
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I would take some tubes 60x40mm and 2 plates 100 x250mm and weld it as shon in the drawing . This should be fixed over the crossboow section with 4
u-bolts like a bridge to take the tension away from this single point.
Mike
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Old 27 February 2008, 02:18   #56
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Quote:
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Those bu**ers can be really "Grumpy Stuff "

..... JW
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Old 27 February 2008, 05:44   #57
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Andy,
These people suggesting you modify your trailer are not your friends
There is a much simpler solution, your trailer looks ideal for a smaller Rib, perhaps a 5.35 with a 90 hp, my trailer however is a little large for my Rib, as unlikely as it seems I would be willing to swop boats (for free )
your friend
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Old 27 February 2008, 12:37   #58
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Quote:
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Andy,
These people suggesting you modify your trailer are not your friends
There is a much simpler solution, your trailer looks ideal for a smaller Rib, perhaps a 5.35 with a 90 hp, my trailer however is a little large for my Rib, as unlikely as it seems I would be willing to swop boats (for free )
your friend
Kernow
Taking into account that Kernow's trailer has been converted form horse drawn.
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Old 28 February 2008, 12:31   #59
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Are there any trailer manufacturers in Hampshire that could manufacture a new custom draw bar?

Andy
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Old 28 February 2008, 12:38   #60
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Are there any trailer manufacturers in Hampshire that could manufacture a new custom draw bar?

Andy
You just need a firm of metal bashers and a sketch, far cheaper too
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