b14wrc
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 posted on 3/11/12 at 10:27 AM |
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Minimum ampage on welder?
Hi,
Just wanting to know what size mig welder should be used to achieve good penetrating welds on the chassis space frame?
I'm using 25mm box with a wall of 2mm. What is the lowest ampage people have been using?
Been having some issues.
Rob
20vt powered rear engined locost
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Wheels244
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| posted on 3/11/12 at 10:49 AM |
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Hi Rob
If the thickest you're going to weld is 2mm, you'll be able to get away with quite a 'small' welder.
I would buy the largest, best quality welder you can afford.
You'll find the bigger the amperage of the welder, the better it will weld at all levels up to its maximum.
I have a 210amp ERD capable of welding quite thick plate, yet if I put 0.6mm wire in it is capable of welding thin bodywork as it isn't even
trying on the thin stuff.
Hope that helps
Rob
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Wheels244
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| posted on 3/11/12 at 10:51 AM |
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If you're down this neck of the woods anytime you're welcome to try mine out.
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zilspeed
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| posted on 3/11/12 at 11:24 AM |
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You should also consider the duty cycle.
Some of the more marginal machines really on the cooling effect of the fan to give meaningful duty cycles.
It's not uncommon for a poorer manufacturer to quote an unrealistically high maximum power rating but at a low duty cycle that means you spend
most of your time waiting on the thing cooling down.
I have a very ancient and very large Clarke 160amp with no cooling fan and it can do anything I've ever needed and it never cuts out.
I'm not sure that a modern smaller machine which relies on a fan to deliver the same numbers would necessarily perform the same, so be mindful
of what you end up choosing.
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mark chandler
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| posted on 3/11/12 at 11:44 AM |
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You should be looking at around 160amp as a minimum IMHO
I have a Clarke 160 that is 20 years old, it has had new heavy duty diodes in the past and a bigger fan.
My friend was given a Clarke 100te welder, it was a complete waste of time when I tried it, full power to try and stick 2mm box together so bad that I
drove 15 miles to get mine before doing any work.
Regards Mark
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cliftyhanger
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| posted on 3/11/12 at 12:00 PM |
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I have found a clarke 90A fine for welding 3mm thick plate. Made engine mounts and all sorts with it, but low duty cycle on full powere.
My 130A SIP (horribly unreliable) managed to weld 4mm engine mounts up and lots of other fabrication. That welding was tested to destruction of the
car, and survived intact.
My "new" welder is a clarke 150, effortless on 4-5mm styuff, but a bit heavy for thin bodywork unless it is mint (so no bad thing)
2mm. I reckon a 100A will be OK, 130 better......
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Slimy38
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| posted on 3/11/12 at 12:26 PM |
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I got my 150A Mig from Aldi, it'll do 2mm on low power no problem. I worked on the premise that while it's full power duty cycle is only
about 10-20% (from memory), when it's running at it's lowest setting the duty cycle is much better.
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b14wrc
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| posted on 3/11/12 at 01:42 PM |
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I'm using a SIP105T, and have been advised it's a bit low on power, although with good skills I know the required strengh can be achieved,
my skills need to be a lot better than they currently are.
I went to BOC yesterday and been offered a good deal on a Parweld xtm 171c.... I am tempted, but do I really need it?? From what I'm hearing, I
should be getting better penetration and my life will be easier with a larger machine. Will a 170amp be significantly easier for me to get better
welds or do I save the cash and hope the 105 amper can cope? I think when I start welding with fury it will be over heating as it's on
it's top setting now.
Rob, thanks for the offer. It's hard to decide if I will see any benefits in investing in a bigger machine. 105a to 170a. The parweld is a large
machine with a proper euro torch and I've been told it's a good mid range machine. The cost is £360.... Does this upgrade sound reasonable
or am I wasting my money and not see an improvement?
I only really have experience with my little 105, so nothing to compare.
Cheers, Rob
20vt powered rear engined locost
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Wheels244
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| posted on 3/11/12 at 01:52 PM |
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Anytime Rob.
I'm sure you'll see a world of difference between the 105 and 170.
£360 seems like a fair price especially fitted with a Euro torch.
Have they got a demo one you could try ?
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daviep
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| posted on 3/11/12 at 01:56 PM |
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Out of curiosity can post a pic of the weld you cut?
I've loked at your pics and the welds look fine to me.
Cheers
Davie
“A truly great library contains something in it to offend everyone.”
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b14wrc
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| posted on 3/11/12 at 02:35 PM |
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Hi Rob, where are you based? Don't think BOC will let me test, but I think its better to buy from them, I get my gas from them and I will get
support. If I buy a cheapy off eBay, I could be into other issues. Think with this a well known name is the way to go...
Yer, it's would be bit cheaper than list price as they have given me a 20% discount and £50 back for the regulator I bought two weeks ago. Lol.
The 171c comes with a regulator as well as torch.
Davie, no problems mate regarding my cross sectioned pieces. I planned to take one more sample in to work Monday to have examined. I will post pics
all in one go. Next week if I get a chance. Hoping this last sample piece proves disproves I need to upgrade. I did the hammer test on a few of the
samples, zero penetration as the thing just snapped off. The one I want to look at on Monday stood up to the hammer with some good tube
deformation!
I thought the information would be useful as many people said my welds looked ok, but had no fusion at all. 
So if I do upgrade, the census is the 170a parweld will be well up to welding my chassis?
Rob
20vt powered rear engined locost
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jossey
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| posted on 3/11/12 at 04:33 PM |
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150 turbo n over. My 100 is sh@t
Thanks
David Johnson
Building my tiger avon slowly but surely.
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hughpinder
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| posted on 6/11/12 at 08:47 AM |
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This will let you know:
http://www.mig-welding.co.uk/calculator.htm?example=Clarke90
2 mm should be ok with 90A, if your welder is working ok. Having used quite a few different welders over the years, I've found you can
significantly "upgrade" a cheap welder by spending £1.75 on a decent earth clamp, and making sure the earth point on whatever you are
welding is clean (degrease if new steel).
Regards
Hugh
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