/ Brazing/welding iron casting?

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Deadeye 07 Nov 2019

I've acquired (another) heavy pillar drill - a Startrite Mercury.

The base has cracked at the back and the top surface has dipped a little relative to the back side wall, almost certainly from someone over-tightening through the rear bolt hole.

The drill is stable enough with the remaining 2 holes but I'd like to repair it cosmetically and preferably structurally.

For the structural I can see several options:

1. I could get some 3/16 plate and sandwich the weak spot top and bottom to spread the clamping load; I'd also prop up the lower plate with a stack of washers.  This would make it hard to get the top to look nice.

2. I could try to press out the sagged part and ask someone to weld it up.  My worry is thta the cracks will propagate during the pressing and more so when heated.

3. I could ask someone to try to braze fill the sagged part?

4. I could leave the cracking alone and use filler and paint...

I haven't learnt to weld, so it would be off to the local garage for welding/brazing... which may not be economic for the value of the drill (which is otherwise in nice shape).  Advice or other suggestions?

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deepsoup 07 Nov 2019
In reply to Deadeye:

> Advice or other suggestions?

Only to perhaps try your question(s) here: https://www.mig-welding.co.uk/forum/
(The locals are friendly and it's not all MiG.)

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Greasy Prusiks 07 Nov 2019
In reply to Deadeye:

Where abouts are you based?

Any chance of a photo of it, it's hard to say otherwise. 

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Deadeye 07 Nov 2019
In reply to Greasy Prusiks:

Based in Buckinghamshire; if you pm me I'll send a piccie

Thanks for the help

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Timmd 07 Nov 2019
In reply to Deadeye:

Have you thought about something like J&B putty to fill in the gap, before painting it? It's a steel impregnated putty with a hardener, and you mix the two together and they stick to whatever it is and (apparently) harden enough to be drilled and things. A car mechanic on youtube (Scotty something) has spoken of repairing engine casing parts with it. 

It's a funny thing with practical things like this, I find, in that I can have almost an emotional aversion to things which don't feel like 'doing it properly', when they'd be fine to do. 

Post edited at 17:18
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it624 07 Nov 2019
In reply to Deadeye:

Applying heat or force is very likely to make the crack propagate, and in cast iron it'll shoot straight across like it's glass. While it can be brazed, it's a specialist process, and involves heating the entire part up slowly and evenly, and then cooling it similarly afterwards - not a cheap business.

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spenser 07 Nov 2019
In reply to Timmd:

I have seen a well known engine manufacturer use something similar to repair heavily cavitated engine blocks used to power a fleet of trains (operator didn't add the additive packs to their coolant as it was "too expensive", wound up having to withdraw vehicles from service to pull the engine rafts off). If it stands up to the conditions inside the cylinder on a big old diesel engine like that I suspect it will survive well in a workshop environment!

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Timmd 07 Nov 2019
In reply to spenser: Fancy that, it sounds plausible that it would be. There's few people as liable to cause issues as those who don't understand engineering, making engineering decisions. I'm not so wouldn't do, I'd ask an engineer. 

https://www.jb-weld.co.uk/

Post edited at 20:32
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Greasy Prusiks 07 Nov 2019
In reply to Deadeye:

Ah OK I'm a fair way from you then, I'd offer to have a look otherwise. 

I have seen people drill holes at each end of a crack to prevent propagation but never tried it myself. 

If the drill is fine to use I'd be very tempted to let sleeping dogs lie! 

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Timmd 19:10 Sat
In reply to Deadeye:

I thought this Wurth putty looks promising as a metal repair putty. SJS Cycles are a great shop and only sell decent quality things, they've frame building experience and are pretty cautious in their approach. Their Thorn own brand bikes (and steel touring racks) have 5mm holes and bolts rather than the standard 4mm for example.

https://www.sjscycles.co.uk/tools/wurth-putty-repair-stick-steel/

If it was my drill I'd possibly buy a new small diameter drill bit and drill a hole at either end of the crack, and then fill it with this putty. 

Edit: Steel Epoxy Stick.
An epoxy based hand malleable putty with the hardener forming the core of the stick
When mixed the product rapidly hardens ensuring rapid repairs to many different components and materials.
When fully cured the material can be drilled, tapped, filed, sanded or overpainted.
Simple to use putty formulation ensures no runs or drips of product.
Adheres even in the presence of liquids e.g. underwater.

Application Areas: Cylinder-blocks, Heads, Castings, Damaged threads, Worn Shafts, Water Pipes, All steel components

Post edited at 19:19
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