Thread: Fireplace project (novice) adv needed..

Originally Posted by montiee

I've finally gotten around to looking at the actual fireplace in the house I bought. As expected due to it's age it's not exactly in good condition :lol:
I was shocked at the prices new ones go for ~$3000+ and the internals look ok so I figure it's cheaper to repair..

Pics below tell the story..

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Anyway I've been looking into perhaps getting into a bit of welding and thought this might be the job to start it. As you can see from the pics above I'll need to fab up the outside of box outside which is heavily rusted and rusted through in some parts.

I have a number of questions for the experts..
1) How powerful of a stick welder (gas bottle rental too expensive) do I need to do the job. I believe the material is just steel. I anticipate the sheet thickness is ~2mm.

Since you are only talking 2mm steel a very small one that will pull 85 to 100 amps

2) Whats the best welder I'd be able to get away with. I'm thinking of a price between $200-$300. I hear inverter models are best? Remember this welder will get minimal use and I don't need to be able to run it for hours on end without rest. I'm not a pro nor plan on going commercial.

It will be around $300 for even a small inverter welder I'd say.Check the online vendors,tools shops and so forth.Google small inverter welder
http://www.tradetoolsdirect.com/Cata...tCode=STICK200


2) What's the best/easiest way to clean the rust off to get to a weldable surface.
Given the degree of rust I would cut out the panels 1 at a time and replace the lot.

3) What would be the typical cost (m/sq) for a hobbiest to get a sheet of steel 1.5mm-2mm thick.

The same as it is to every else.Pick up the phone book and look for sheet metal shops.They can pre cut them on the guillotoine.

4) What types of rods would I need to use?
6012 in1.6mm diam .just general purpose

5) How much (ballpark figure) would this job cost to get done by a pro if you have an idea. Obviously the outer box cover needs replacing though there is no bottom to it (just 4 sides) and it needs to be welded to the vent at the top as well. I know I should ring up but figure it's easier doing it this way rather than carting around the box or trying to fax through pictures.

Several hundred bucks give or take a hundred

I'll probably think up some other questions but that's probably enough to start.

TIA!

Grahame

Thanks for the responses so far.

A few more questions.

1. Can I weld galvanised steel to steel and if so do the rod types change.?
2. How much will a rod typically weld in 2mm steel? (trying to get a feel for how many rods I should buy)
3. Which is a better general machine, an AC or DC arc welder? I know the DC is "smoother" but what do I lose functionality wise using one over the other.

Edit: After a bit more research it seems teh DC is the more versatile machine as it can do pretty much everything an AC can.

Also I think I've decided on a machine (see http://www.weldsmart.com.au/welding-...ick-mma-welder). Can you see any reason not to buy it. The price is right, it's got a good range of electrode widths, seems to have a reasonable duty cycle and is portable and a reasonable amperage for the price. I'm not a pro welder and it will get minimal use most likely after this project is over. It might become a hobby (table, gate etc) if my experiences are reasonable with the fireplace :lol:

1. Can I weld galvanised steel to steel and if so do the rod types change.?

Yes, but grind the galvo away before welding and do your weldingin a vented area ,say with a fan behind you while welding .Welding Gal has the capacity to make you very ill.

2. How much will a rod typically weld in 2mm steel? (trying to get a feel for how many rods I should buy)


You buy rods by the packet not individually. A single packet of 2.5Kg will cover you needs for the moment.
3. Which is a better general machine, an AC or DC arc welder? I know the DC is "smoother" but what do I lose functionality wise using one over the other.

For general work DC has an edge of AC as you can reverse polarity ( swap connections for some electrodes that need DC+-ie cast iron rods and stainless steel)

If the machine has spares available, after sales backup and a 12 month warranty you should be fine.

Cheers
Grahame

Just as a matter of interest, the thicker the sheet you use, the longer it will last. I bought one of those slow combustion inserts a cpl yrs ago, and the bloke who made it told me (and it makes sense) that for a fire that burns for a fair bit of the winter (as many do) you can lose up to 1mm of steel per year. I would be looking at using thicker steel than 2mm. Mine is either 5 or 6mm (i forget), and it is definitely not the top of the line.
cheers
TM

Originally Posted by TermiMonster

I would be looking at using thicker steel than 2mm. Mine is either 5 or 6mm (i forget), and it is definitely not the top of the line.
cheers
TM

Wow.. I was just going off what was already on the box. Perhaps it's to do with the design. Internally the woodheater has some significant steel and I think perhaps the outside of the box is more to do with keeping smoke in. It's a good point you raised and definitely something to think about.

I'm not convinced the woodheater is for me but I'm curious enough to try to fix it up. I guess I'll check out the costs of 2mm vs 4mm and make a choice. If I find after a few years it's rusted/burnt out again and I really like it I might do the proper 5mm job assuming the costs are significantly higher.


On the subject of galvanised steel I' starting to wonder if it's suitable for a heated application. Last thing I want is it smelling and releasing toxic fumes into the house. If anyone can comment please do. I'll be heading down to a local steel workshop later this week to check out some things.

If space permits, you may like to consider a modification I have seen made to this type of inbuilt unit.
After rebuilding the box, you can weld some rows of flat steel, say 20 x 5 on edge over the outside surfaces to increase the surface area that generates heat.
Very simple mod with obvious results.

Originally Posted by elmoticus

If space permits, you may like to consider a modification I have seen made to this type of inbuilt unit.
After rebuilding the box, you can weld some rows of flat steel, say 20 x 5 on edge over the outside surfaces to increase the surface area that generates heat.
Very simple mod with obvious results.

I guess I'm not seeing it. The unit sits inside a bicked chimney. If I weld some flat steel on the outside of the box I'll be replacing due to rust isn't that just going to increase the surface area inside the chimney area heating it more and hence venting it more outside rather than the room?

Yep, you are quite right Montiee, I just had another look at the first pic.
Where my mod would work is if there are more vents coming from the fireplace cavity above the firebox into the room as there are in various other models.

What about re sheeting the stove in an appropriate stainless steel like 409 which while expensive is a lifetime fix?

The correct grade is essential as just any old grade will cause corrosion around the welds.The 409 grade is what is used in car exhaust pipes and will withstand the heat.

Galvanized sheet in the firebox is a no no and as the fumes given off can be very harmful to people with breathing problems.Apart from that flame temperatures will break down the gal coating very quickly.

Grahame

Originally Posted by Grahame Collins

What about re sheeting the stove in an appropriate stainless steel like 409 which while expensive is a lifetime fix?

The correct grade is essential as just any old grade will cause corrosion around the welds.The 409 grade is what is used in car exhaust pipes and will withstand the heat.

I've thought about this. Trouble is I don't know if I'm really going to be using the woodheater in the long run. I'm in Sydney so access to free firewood is going to be interesting and as such I'm not sure whether in the long run I'm going to be bothered with it. I guess I'll know after a couple of winters whether it's for me or not. Until then I kind of don't want to spend more $$ than I really need to. Might be false economy of course if I find I like it and it's feasible but I guess that's the way I'll head atm.

One thing for sure is that I'm going to put some sort of cap/guard over the chimney hole to minimise the amount of water it's collecting. With the current rain I can see a small stream down the bricks.

Originally Posted by Grahame Collins

Galvanized sheet in the firebox is a no no and as the fumes given off can be very harmful to people with breathing problems.Apart from that flame temperatures will break down the gal coating very quickly.
Grahame

I had my suspiscions after what you mentioned about gal. Thanks for confirming..

Just be aware the fireplace may have asbestos in it....Asbestos is not a problem provided you don't breath it in...

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A quick question. From the picture above you can see the welds. It doesn't seem that the weld was done across the entire panel. What is the best way to "cut" through these welds so I can separate the pannels without damaging the panel below it. I picked up a hitachie 125mm grinder with a couple of cutoff discs, a grinding disc and a diamond cutting blade as part of the package. Best to use the grinding wheel or the cutoff?

Originally Posted by Grahame Collins

What about re sheeting the stove in an appropriate stainless steel like 409 which while expensive is a lifetime fix?

The correct grade is essential as just any old grade will cause corrosion around the welds.The 409 grade is what is used in car exhaust pipes and will withstand the heat.


Grahame

Most wood heaters I,ve had will start glowing red if cranked up on a cold night .Never seen a car exhaust get red though .
I dont know about 409 specifically but most stainless if heated to red seems to loose its stainless quality and rusts after a while .Like stainless pot belly flues and stainless steel fry pans and pots .

Just what I'd noticed thats all .Thought it was the same for all stainless .Once it hits dull red for a while a few times , or cherry red especially its buggered as far as not rusting goes .

Hi
A 1mm thick disc is ideal for cutting the welds.
They are stitch welds ,evenly spaced along the join- placed to minimise distortion from the welding process.

They are best cut by almost cutting edge on into the sheet. the sheet will overlap the one below,so go easy.


.As far as exhaust pipes go 409 ss is the material used in stainless steel exhausts.

I have never owned a car with stainless exhaust pipes but I have owned one with sheet metal headers and I can vouch for them glowing in the dark ( albeit -a very dull red on a very dark night) when I opened up the bonnet to investigate a noise while on a highway trip.

Yes there is a colour change because of the heat but you won't have the scaling effect ,which is the cause I metal thickness reduction.

I know that some furnaces are lined with a particular grade of stainless to avoid this same problem. Also something that has come back from my memory, is that diesel vehicles can't use stainless exhausts because of the high carbon content in their exhaust gas.

How much carbon you stove emits ( watch out -you get taxed for it -leaving carbon footprints all over the place) I can,t even guess and what the effect may be.

Grahame