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domwild
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Joined: 16/12/2005
Location: AustraliaPosts: 873 |
| Posted: 10:25pm 25 Jun 2010 |
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Hi,
Managed to get a 6m length of stainless steel tube (22.25 OD) for $20 and would like to use it in place of a 22mm mild steel rod.
Q1.: Would I lose a lot of strength this way? Anyone with a black belt in materials science out there?
Q2.: Assuming I use it and spot weld it to the 1" exhaust tube, must I use a SS rod or a mild steel rod for the stick welder?
Q3.: My friendly exhaust man can sell me exhaust tube with a 1.2 mm wall thickness, not 1.6 mm as Glenn is suggesting. The sizes compare like this then:
25.4mm OD - 2 x 1.2 wall = 23mm ID
23mm ID - 22.3mm SS = 0.7mm diff, meaning 0.35 slack on both sides and easy pushing in of tube without radius. Strength might be a problem?
Q4.: Am proud owner of cheap $110 stick welder for this windmill project. Claims to be a 120 Amp welder but I keep losing the arc at the 90-100 Amp mark. Is it my lack of skill (likely!) or is it the duty cycle letting me down as the thermal overload in the primary windings cuts the arc?? Welding then becomes a multi-point tacking.
Q5.: Like Glenn I am using a folding tower. Passing the wires thru the top-portion of the mast must be a problem then, so how is this handled?
So many questions, so little time!
Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up.
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dwyer
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Joined: 19/09/2005
Location: AustraliaPosts: 574 |
| Posted: 12:15am 26 Jun 2010 |
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Hi Domwild
There are a few problems that I have to say. You cannot weld a mild steel-welding rod onto a stainless steel material.  That is not the correct way of doing this. However a stainless steel welding rod can weld onto mild steel. This is the other way around and also you didn’t say what size or specification-welding rod. Other sad news  that your cheap welder is not a great machine reason if you see the welder fix specification label let say 120 amps at 20 volt at 15 % duty cycle if I am correct. You can weld with 3.2 mm mild steel reasonable maybe few second a time but best at 2.5 mm mild steel and also these cheap welder have low voltage range. As for my money I will take it back where you brought from and get a welder with open circuit voltage around 30 to 80 volts with as and stay away from any home hardware shop especially Bunnings Warehouse. Try to find an inverter control welder to do a better job however make sure it has open voltage higher than 130 amp with higher voltage and is best for you to weld is tig welder for thin stuff, Maybe get someone with a lot of experience at the welding shop and try have a chat with right person or look it up in a book on how to weld.
Anyway I have little porable same size of two loaf of bread $1500 Japanese made CIG inverter welder 160 amp at 60 volts for 10 years welding hard all day long everyday  I can weld 6 mm low hyrodon rod or hard facing rod with ease and trouble free. However today you can buy it cheaper than what I had to pay for.
Any question just ask ? 
Dwyer |
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VK4AYQ
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Joined: 02/12/2009
Location: AustraliaPosts: 2539 |
| Posted: 12:37am 26 Jun 2010 |
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Hi Dom
I will go through your questions.
Managed to get a 6m length of stainless steel tube (22.25 OD) for $20 and would like to use it in place of a 22mm mild steel rod.
Q1.: Would I lose a lot of strength this way? Anyone with a black belt in materials science out there?
A: Stainless Steel is a bit stronger than mild steel for the same size but not to replace rod as you suggest,
Q2.: Assuming I use it and spot weld it to the 1" exhaust tube, must I use a SS rod or a mild steel rod for the stick welder?
A: You can use single pass with mild steel rod for non critical welding however it is prone to cracking under stress the best is a dedicated SS rod but that costs a fortune.
Q3.: My friendly exhaust man can sell me exhaust tube with a 1.2 mm wall thickness, not 1.6 mm as Glenn is suggesting. The sizes compare like this then:
A: The strength would be simular but only if you use the correct rods, you will have great difficulty welding with your small stick welder if you arn't a expert welder needs to be TIG welded for full strength.
25.4mm OD - 2 x 1.2 wall = 23mm ID
23mm ID - 22.3mm SS = 0.7mm diff, meaning 0.35 slack on both sides and easy pushing in of tube without radius. Strength might be a problem?
A: If you have slack in the joint it concentrates stress at the weld, what you can do is run several welds along the outside tube for the length of the sleeve insertion this will shrink the outer tube onto the sleeve tube.
Q4.: Am proud owner of cheap $110 stick welder for this windmill project. Claims to be a 120 Amp welder but I keep losing the arc at the 90-100 Amp mark. Is it my lack of skill (likely!) or is it the duty cycle letting me down as the thermal overload in the primary windings cuts the arc?? Welding then becomes a multi-point tacking.
A: I have a simular unit with the same problems as they have alm windings You can improve them by fitting a 240 volt fan in the end of the case and disconnecting the thermal dropout switch, then don't continuous weld let it rest for about 30 seconds between rods {sticks} and only use 2.5 mm rods.
Q5.: Like Glenn I am using a folding tower. Passing the wires thru the top-portion of the mast must be a problem then, so how is this handled?
A: Make a bolt on collar and do not weld here as this is a high stress area, one small tack weld to stop the collar slipping is OK but a full weld creates a stress point, even worse if you do use the stainless.
So many questions, so little time!
All the best
Bob
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VK4AYQ
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Joined: 02/12/2009
Location: AustraliaPosts: 2539 |
| Posted: 12:46am 26 Jun 2010 |
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Hi Dom
There are some good little Inverter welder on ebay I got mine for less than $100 and it works a treat even on 3.25 rods. As Dwyer suggested if you only just got it take it back and tell them its no good.
Over the term of your project this will save you a lot of heartaches.
All the best
Bob
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dwyer
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Joined: 19/09/2005
Location: AustraliaPosts: 574 |
| Posted: 02:43am 26 Jun 2010 |
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Hi Dom and Bob
What Bob is saying "I will go through your questions" is correct Dom and I wish I could explain more and write better like Bob but I can't So Thank for writing comment to Dom 
Dwyer |
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Downwind
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Joined: 09/09/2009
Location: AustraliaPosts: 2333 |
| Posted: 02:59am 26 Jun 2010 |
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I think you would want to be a very skilled welder to weld 1.2mm wall thickness material with a stick welder.
One would expect it will look like swiss cheese when you are finished.
Personally i would not even attempt it without a mig welder, where you have some control over temperture and wire feed.
I weld SS with the mig using SS wire and standard gas for steel, it works ok but is a little splattery and the welds go blackish but works.
The correct gas is far better, but i cant justifie a bottle of gas for the odd SS weld i do.
I wouldnt mind if i did not need to pay high rental cost on a bottle sitting around 90% of the time. (gas is cheap, cylinder rental is the killer)
Pete.
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dwyer
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Joined: 19/09/2005
Location: AustraliaPosts: 574 |
| Posted: 05:36am 26 Jun 2010 |
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Hi Downwind
I have done stick welder on 1.2 mm wall thickness with special 1.6mm stainless steel welding rod many years ago. Yes and have do it very quick otherwise will end like Swiss cheese after welding is done so best use tig DC welder is more suitable for stainless work in light fabrication job in thin wall tube,sheet metal etc however still need a very good skilled welder. Large bottle of argon cost approx $200 plus high rent monthly rent fee is big killer compare the year of 1986 was $35 for bottle of argon so how come China can make Aluminium scooter and sell for $15 dollar?? Australian Gas Company are gold mine making million of dollar while metal trades industrail are struggle to survives on expenives gas are cheap to make.
Dwyer
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domwild
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Joined: 16/12/2005
Location: AustraliaPosts: 873 |
| Posted: 09:09am 26 Jun 2010 |
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Thanks for the many answers. The welds from mild steel tube to mild steel rod (or SS tube possibly in my case) are just plug welds after drilling of the outer tube and plug welding to hold the tube to the inner rod for the PVC prop as in Glenn's PVC/Alu prop suggestions. With my silly stick welder I am not trying to weld anything structural. For structural welds I normally tack it for a qualified welder.
I must explain my folding tower + cable problem better. Imagine dropping the mill head. The cable which goes from the head and passes thru the hinged upper section (pipe) of the mast is then not going to be long enough unless I disconnect the cable and let it rise as the lower hinged section while the mill head (upper hinged pipe) drops. Did I explain my problem properly? Does one need to disconnect the cable as otherwise it is not going to be long enough? Or is there a better solution, like not passing the cable thru the mast's pipes at all?
I bought the welder second-hand some time back, so I cannot give it back. I may try to sell it to some unsuspecting individual. I also had the suspicion it is the duty cycle, which stops the arc. A fan is already installed but I might just shorten out the thermal sensor. What actually is an "inverter" welder and what is the benefit? Does it rectify to DC after the transformer? If it is $100 or so second-hand I might just get one.
Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up.
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VK4AYQ
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Joined: 02/12/2009
Location: AustraliaPosts: 2539 |
| Posted: 10:03am 26 Jun 2010 |
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Hi Dom
An inverter welder is just that, an Inverter, it is transformer less and does a magic chop on 240 AC and turns it into square wave {sort of} dc much like a DC/DC down converter simply it turns 240 volts at 20 amps into 24 volt at 200 amps by its switching plus losses of course, but is more efficient than a transformer choke regulated transformer that is very lossy and so heats up quite quickly.
There are quite a few on ebay at reasonable prices and if you want to bid you can get one reasonable. Mine actually cost $55 and $20 postage, I have used it for two years now and the smoke has stayed in so far. It amazed me as it will weld a 3.2 rod on a thirty meter lead. Its also a good battery charger on 24 volts low settings 50 od amps.
I have another expensive one, a WIA with the control board dead and they wanted $250 + fitting for the new board. It still works but flat out only, one day I will fix it when I have nothing better to do.
For plug welding on the sleeves for the blades your welder would be OK as long as you use the correct rods I would recommend CIG weldall or even better WIA equivalent cant remember the name. You can get them in 500 gm pack for small jobs about $35 dollars the last lot I got. 2.5 mm rods.
All the best
BobEdited by VK4AYQ 2010-06-27
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KarlJ
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Joined: 19/05/2008
Location: AustraliaPosts: 1178 |
| Posted: 12:49pm 26 Jun 2010 |
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Holy crap...thats a lot of talk.
I take it you are using PVC or Aluminium blades and using this for the blade support
just forget the welds and bolt through the lot.
This is what Phill does and works AOK.
Karl
Luck favours the well prepared |
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dwyer
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Joined: 19/09/2005
Location: AustraliaPosts: 574 |
| Posted: 01:37pm 26 Jun 2010 |
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HI Karlj
Doesn’t matter about what we are talking to Dom about his welding problem and some good understanding advise just like to help each other member of this forum like silly old school teachers is not a Holy crap as that is normal however your mention about “Just forget the welds and bolts through the lot” is other good ideas is not a Holy crap So everyone is different
so all the best
Dwyer
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domwild
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Joined: 16/12/2005
Location: AustraliaPosts: 873 |
| Posted: 11:14pm 26 Jun 2010 |
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Thanks for the help by everyone. If I cannot get 25.4mm exhaust tubing with 1.6mm wall thickness here in WA, I seem to be able to get 25.4 OD stainless steel tube for the PVC prop.
This stainless steel outer tube together with my SS inner tube would allow plug welding with an existing SS stick I have PLUS riveting of PVC prop to the two tubes with stainless steel rivets. They will have to be long enough to go thru the prop and two tubes.
If two SS tubes are not as strong as Glenn's tube + rod suggestion and the thing fails I only have to blame myself. It will certainly be lighter and have less inertia for startup.
Thanks for the help with inverter technology. I could have "wikepidiaed" this term but old age is a terrible thing and I suggest you all try to avoid old age.
Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up.
Winston Churchill |
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KarlJ
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Joined: 19/05/2008
Location: AustraliaPosts: 1178 |
| Posted: 12:19am 27 Jun 2010 |
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dom
what a bummer you didnt ask, I'm in Perth and have a complete prop and hub sitting in the garage....
could have had it for cost less 20%. complete and ready to bolt on.
Karl
Luck favours the well prepared |
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domwild
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Joined: 16/12/2005
Location: AustraliaPosts: 873 |
| Posted: 09:44am 28 Jun 2010 |
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Karl,
Have prop and SS inner tube (instead of rod) already, but thanks for the offer. May I ask why you did not set up a mill? Is it "she who must be obeyed"?? I live in the foot hills (Orange Grove) and summer the Easterlies are extremely strong, perhaps good enough for hot water heating.
I suppose you do not want to sell the hub separately? Where did you get yours laser cut?
Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up.
Winston Churchill |
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