Thread: Dawn Disaster

Originally Posted by Pete F

While "welding" is often used as a generic term for joining 2 metals together, it actually has a specify meaning to a welder. I'm not trying to tell you how to suck eggs, but if it were me I'd be instead leaning towards having it brazed instead of welded. If you ask the welder to deeply groove the joint, as you want to grint it back, you should be able to achieve a relatively seamless surface. I'd suggest leaving the welder to do that so they can match the parts. If you then give it a coat of flat black paint it should hide the bronzing and will be a reasonable job aesthetically. Pre-heat/cool down is no big deal by the way, and any welder should know about it. Maybe just confirm with them as to how they'll achieve it.

Pete

Thanks for the advice.

Does this help?

https://www.woodworkforums.com/f160/c...n-weld-122822/

A.

Originally Posted by AndrewOC

Does this help?

https://www.woodworkforums.com/f160/c...n-weld-122822/

A.

What happened to the after (Tomorrow never came)

Originally Posted by DSEL74

Good advice and I thought some of the same after I discovered what I suspected was the culprit. I guess it is a lesson now learned and one I should have reason to remember.

Just keep telling yourself it was already 80% broken (I have found with things like this it doesn't even have to be true, as long as you tell yourself enough)

Originally Posted by DSEL74

I found mixing the molasses with boiling water was the best

That's exactly the kind of hands on advice I was after, especially given the cold weather, I could imagine that would be just the kind of thing that would have had me scratching my head (next weeks post would have been, for best results should I have the part in the top of the bucket with the water, or the bottom with the molasses)

Cheers,

Camo

Originally Posted by Doggie

One is always left in the poo when the Dawn breaks.

Showing our age here when was what Bobby Limb woke up and found ''Crack of Dawn.''

On a serious note
Take it to a experienced welder Cig Cast craft rods. about 3 dollars each and are made to cold repair vices etc. Used then successfully many times.
Another option refit casting on to the steel post and drill and tap right through into the larger part be enough room for 2 3/8 bolts checked mine Dawn
pot Drill [still in use here old family item] crack filled with composite quick metal and smoothed and painted.
I was taught by an old Italian gent who was a crafty clever and innovative tradesman.He showed me not to grind cast iron on a break or crack but to chisel the vee by hand as grinding tends to bring up graphite from the base metal to the surface.this applies to brazing or cold welding. I have pre heated cylinder heads and old mono blocks from veteran cars and done both type of welds succesfully.
keith fenner in one of his videos lathe steady repair if i recall brazed the broken bits.Just some thoughts to the pot John.

Just did a double check on the Dawn drill [post] here.Yes you could drill tap 2 7/16 c sunk heads into shaft through casting as it is only a top mount and a locator for the shaft. Up to you if your budget is tight. John.

Mate, that casting would be a very simple repair for a competent welder. No need to use expensive Cast iron electrodes either. Low Hydrogen electrodes will do fine.
The casting would be of good quality and given its shape etc, would be free to expand and contract, (this is what causes problems when welding cast iron normally). Pre heat would be required and the casting MAY need to be machined, reamed or filed after slow cooling in dry sawdust or preferably dry lime. I would not braze it as it will be very expensive in terms of gas used and consumables.
I have done similar on many occasions. Be aware that the finished weld will be as hard as a goats forehead in the heat affected zone and will eat HSS tooling and easily chip Carbide if care is not used when machining.
If all else fails, send me a PM and I could do it for you. Unfortunately I am in Tassie, so freight both ways would be a cost.

Originally Posted by Pete F

While "welding" is often used as a generic term for joining 2 metals together, it actually has a specify meaning to a welder. I'm not trying to tell you how to suck eggs, but if it were me I'd be instead leaning towards having it brazed instead of welded. If you ask the welder to deeply groove the joint, as you want to grint it back, you should be able to achieve a relatively seamless surface. I'd suggest leaving the welder to do that so they can match the parts. If you then give it a coat of flat black paint it should hide the bronzing and will be a reasonable job aesthetically. Pre-heat/cool down is no big deal by the way, and any welder should know about it. Maybe just confirm with them as to how they'll achieve it.

Pete

Hi.
What Pete says in the above is on the money with brazing and painting. I have repaired plenty of cast iron parts with the braze. done well it is very strong. I have restored a Qualos metal lathe and brazed some of the teeth on some gears and then filed to shape. I have some parts to repair coming up. Some of the cast pieces are missing so I will fill it with braze and grind to shape. Will post photo`s when this happens.

Regards

Ross

Originally Posted by 2blast67

Hi.
What Pete says in the above is on the money with brazing and painting. I have repaired plenty of cast iron parts with the braze. done well it is very strong. I have restored a Qualos metal lathe and brazed some of the teeth on some gears and then filed to shape. I have some parts to repair coming up. Some of the cast pieces are missing so I will fill it with braze and grind to shape. Will post photo`s when this happens.

Regards

Ross

Brazing does have a place when repairing cast iron, but in this case would not be the best option due to cost of consumables and gas.
The real forte of Brazing is where there is a higher degree or restraint as it will actually stretch to some degree and give, rather than the cast cracking. Brazing is also good when a part such as a gear tooth needs rebuilding because it has excellent wear properties.
As with all metal joining processes, the trick is to use the one that best fits the application and environment.
Gas is a very expensive item these days, as are brazing consumables, particularly flux coated rods and a decent casting will eat the rods up at an alarming rate. The labour is also a major cost and therefore, the cheaper and faster arc based processes have several advantages over Brazing provided other factors do not preclude their use.

"What happened to the after (Tomorrow never came)"
I did leave that thread hanging, didn't I?!
The main part of the U prep filled up ok; appears sound, less porosity than the parent metal. Underneath there are still 'cold shuts' (cracks) that ground out at 2mm depth; need to evenly preheat the lot again and do another run.... I keep saying soon- it's winter!
AndrewOC

Out of curiosity what would the approximate difference be between brazing materials and Arc for cast iron? In relation to a job this size that is.

Cost wise, the labour rate will run somewhere around $70/Hr for a workshop to do it, more on the mainland I believe.
We generally used to cover gas/consumables within our labour rate - except when doing some cast iron repairs such was the volume of gas and consumables used.
At a very rough estimate via my crystal ball, there could be up to a $50-60 cost advantage in favour of the arc welded item. That is at full cop, nothing spared.
Many people feel they are being ripped off when quoted for a "little 5 minute job". There is no such thing. As someone who has stood on the other side of the argument for many a year I would ask everyone to consider that even a very low rate of $60/Hr equates to $1/Min. The ten to fifteen minutes spent listening to the explanation of the job by the owner is usually not charged for. Then the casting must be prepped as appropriate, (don't forget that it is cheaper for the customer to remove mud and grease than for the welder), all the while ensuring that the parts remain aligned, often some form of jig or fixture must be rigged to accomplish this. Next, the appropriate gear must be prepared such as arc, tig or brazing gear. The joint can now be filled - not all castings play nice at this point, some have a great reluctance to accept the brazing alloy due to impurities and contamination, brazing is not a fast process and you would be amazed at how long it can take to fill a joint some times. The casting must now be placed somewhere to cool slowly. Finally the job must be cleaned up and often machined/surface finished. If it must be machined then set up time for lathes and mills must be included. This is how the dreaded "5 minute job" just got quoted at $150+GST.
The last place I worked did many repair jobs in various metals and we always dreaded Fridays when other lucky buggers got RDO's and would bring their grease and mud encrusted thumpster motorbikes, chainsaws and other distasteful items in for the "5 minute job" that had to be done then and there.
We gave Fridays a special name - F-Wit Friday.
I would estimate that your casting would cost somewhere in the $50-100 range to repair by a workshop provided it does not require machining afterwards.
As regards my previous offer if you could not get it done locally. Let me be clear that I am not trying to make money from you or anyone else, just that I know many workshops are reluctant to touch cast iron. I would not charge you labour, I am only trying to help out a fellow forum member and I like old machinery too as well. Just so no one gets the wrong idea.

Karl,

Thanks for the insight and I think it is often the same with many industries people don't see the value in what people charge. Alway see it in their own industry but not in that of others. Although I still don't think your local GP can justify there fees for a 15min consultation especially when they have you wait an hour over your appointment time costing you lost business.

It is the same with photography. Travel, expensive equipment & consumables, set up time, expertise, lighting, capture, pack down, travel, post production (editing, retouching, color correction, unwanted item removal, plastic surgery), color calibration of equipment, workflow and out put, file sizing and printing. All people think is press the button done. Which is true if all you want is a "Snap Shot" but then don't come to a professional to do it.


What I was curious about though is the cost variance between brazing and arc aside from labour and commercial costs.

Originally Posted by Karl Robbers

I would estimate that your casting would cost somewhere in the $50-100 range to repair by a workshop provided it does not require machining afterwards.
As regards my previous offer if you could not get it done locally. Let me be clear that I am not trying to make money from you or anyone else, just that I know many workshops are reluctant to touch cast iron. I would not charge you labour, I am only trying to help out a fellow forum member and I like old machinery too as well. Just so no one gets the wrong idea.

In regard to your offer I appreciate it, however I think the cost of shipping return would probably be prohibitive.