Chassis welding and Fibreglass patching
Discussion
OK folks, comments on DIY suitability and techniqies please!
I need to do some welding on a tubular chassis and roll cage - basically adding in a few more tubes here and there. I've had a arc welder for years and its OK for some of thre stuff I've done before - but my welds are like pidgeon sh!t with it, and I'm not sure I'd trust their strength on a chassis. Watching folks with the newer fangled MIG welders, it looks a lot easter/neater - but are they just better welders than me, or is MIG easier than arc? I've always found it a real pain to strike the arc and get it just right. At this point I'm looking at getting the welding done professionally, but I'd be interested if anyone has been a poor arc welder and was turned into a welding superstar with just a MIG kit!
Next - I need to fill holes in a fibreglass body. Typically, the are neat 'holes' a few inches in diameter where previously some wiring or pipework went. I'm guessing that simply glassing on a 'patch' at the back and filling the 'hole' would mean there's still a chance for a crack to reappear round the filler. I'm thinking maybe I have to take the bodywork aound the hole right down to zero - sort of making a 'dent' with the hole on the middle - then building the area up again with a few sheets of mat. More work than just patch and filler, but I don't want to get cracks again. Any comments or any better ideas?
WB
I need to do some welding on a tubular chassis and roll cage - basically adding in a few more tubes here and there. I've had a arc welder for years and its OK for some of thre stuff I've done before - but my welds are like pidgeon sh!t with it, and I'm not sure I'd trust their strength on a chassis. Watching folks with the newer fangled MIG welders, it looks a lot easter/neater - but are they just better welders than me, or is MIG easier than arc? I've always found it a real pain to strike the arc and get it just right. At this point I'm looking at getting the welding done professionally, but I'd be interested if anyone has been a poor arc welder and was turned into a welding superstar with just a MIG kit!
Next - I need to fill holes in a fibreglass body. Typically, the are neat 'holes' a few inches in diameter where previously some wiring or pipework went. I'm guessing that simply glassing on a 'patch' at the back and filling the 'hole' would mean there's still a chance for a crack to reappear round the filler. I'm thinking maybe I have to take the bodywork aound the hole right down to zero - sort of making a 'dent' with the hole on the middle - then building the area up again with a few sheets of mat. More work than just patch and filler, but I don't want to get cracks again. Any comments or any better ideas?
WB
I too am a crap welder with a regular stick but can produce reasonable looking welds with a little SIP MIG machine. Need to fiddle around to get power and feed rate right but once set up much easier and only way to go for welding thin wall stuff like chassis tube etc. If you have a bit of fabrication to do worth borrowing a MIG and paracticing a bit - or just take the plunge and buy, they are not that expensive.
On the fibre glass, I've previously filled similar holes just by using a patch of matting and resin on the back and a filler (P38) on face - this was painted, looked OK. Problem with cracking might occur if you want a gel coat finish, also depends if area likely to get flexing etc.
On the fibre glass, I've previously filled similar holes just by using a patch of matting and resin on the back and a filler (P38) on face - this was painted, looked OK. Problem with cracking might occur if you want a gel coat finish, also depends if area likely to get flexing etc.
My welding was crap with arc improved with mig and has improved even more with tig.
Migs are point and shoot, but you can still get terrible welds with mig if you havn't spent the time to get it setup correctly for the piece of work you are doing. You have to have the wirefeed and current set correctly - you can only do this through practice on the same thickness of material you are trying to weld. Once I find the sweetspot for a particular material I write it down (in permanent marker on top of the welder).
This are a couple of test welds i done after 20mins of practice on my dads TIG welder (with my dad watching over my shoulder)
I was more than happy with that and went out and got myself a Miller Tig Welder shortly afterwards.
>> Edited by eliot on Thursday 18th November 16:42
>> Edited by eliot on Thursday 18th November 16:42
Migs are point and shoot, but you can still get terrible welds with mig if you havn't spent the time to get it setup correctly for the piece of work you are doing. You have to have the wirefeed and current set correctly - you can only do this through practice on the same thickness of material you are trying to weld. Once I find the sweetspot for a particular material I write it down (in permanent marker on top of the welder).
This are a couple of test welds i done after 20mins of practice on my dads TIG welder (with my dad watching over my shoulder)
I was more than happy with that and went out and got myself a Miller Tig Welder shortly afterwards.
>> Edited by eliot on Thursday 18th November 16:42
>> Edited by eliot on Thursday 18th November 16:42
eliot said:
This are a couple of test welds i done after 20mins of practice on my dads TIG welder
That's more like what I want to achieve! Sooooo, a Mig or Tig welder looks a likely candidate for the shippong list
Is a Tig welder like a Mig welder with different gas, or something quite different? I've just had a look on the MachineMart website and while Mig welder seem to come with wire feed etc, Tigs seem to be classed as 'inverters' or arc/tig. Do you use a Tig welder the same as you use a Mig?
I guess more to the point, are all these neat welds done on 'proper' tube chassis and roll cages done by Mig or Tig?
Thanks
WB
Will,
with MIG you can get away with murder compared to arc so yes it is significantly easier. TIG is a whole heap of money more expensive to buy and run than MIG so most welding is mig on chassis etc.
if you need one we can get reconditioned SIP migmates at significant discount over new ones.
Drop me a line via profile if you need one, might also be worth working our maximum thickness you need to weld so we can get the right machine for the job etc.
Patrick
www.toolsnstuff.co.uk
>> Edited by dontlift on Thursday 18th November 19:41
with MIG you can get away with murder compared to arc so yes it is significantly easier. TIG is a whole heap of money more expensive to buy and run than MIG so most welding is mig on chassis etc.
if you need one we can get reconditioned SIP migmates at significant discount over new ones.
Drop me a line via profile if you need one, might also be worth working our maximum thickness you need to weld so we can get the right machine for the job etc.
Patrick
www.toolsnstuff.co.uk
>> Edited by dontlift on Thursday 18th November 19:41
Hi William,
As everyone else has said, MIG is far easier than arc welding, and also better for use on thinner metals as used on car bodies etc.
Regarding the differences between MIG and TIG, MIG stands for Metal Inert Gas and TIG for Tungsten Inert Gas and the two are fundamentally different.
With MIG you have a continous roll of wire of the appropriate metal which provides both the arc and the 'weld fill'.
With TIG the torch has a tungsten tip that is used to give the arc, with a seperate hand held rod being used to provide the 'weld fill' just like with oxy-acetylene gas welding.
In both cases the inert gas bit is due to the weld area being shielded by a flow of inert gas (such as argon) which stops the weld from oxidising. The gas flow also provides some cooling which can be very useful when welding thin metals such as car bodywork or exhaust systems.
The quick and continious nature of MIG makes it great for welding flat surfaces, but its speed can cause problems when welding smallish tubes like on car chassis.
Haven't done any myself, but TIG welding is slower so it's easier to work round small tubes and get neater welds as a result.
As for GRP repairs, one trick is to grind a chamfer around the outside edge of the hole, cover with masking tape and glass the inside with matting. When set you then remove the masking tape and cover the hole and chamfered area with fibreglass tissue, which you then sand flush and top off with filler prior to paint.
This both gives your repair strength on both sides of the panel and removes the hard edge that can sometimes show up afterwards if left.
As everyone else has said, MIG is far easier than arc welding, and also better for use on thinner metals as used on car bodies etc.
Regarding the differences between MIG and TIG, MIG stands for Metal Inert Gas and TIG for Tungsten Inert Gas and the two are fundamentally different.
With MIG you have a continous roll of wire of the appropriate metal which provides both the arc and the 'weld fill'.
With TIG the torch has a tungsten tip that is used to give the arc, with a seperate hand held rod being used to provide the 'weld fill' just like with oxy-acetylene gas welding.
In both cases the inert gas bit is due to the weld area being shielded by a flow of inert gas (such as argon) which stops the weld from oxidising. The gas flow also provides some cooling which can be very useful when welding thin metals such as car bodywork or exhaust systems.
The quick and continious nature of MIG makes it great for welding flat surfaces, but its speed can cause problems when welding smallish tubes like on car chassis.
Haven't done any myself, but TIG welding is slower so it's easier to work round small tubes and get neater welds as a result.
As for GRP repairs, one trick is to grind a chamfer around the outside edge of the hole, cover with masking tape and glass the inside with matting. When set you then remove the masking tape and cover the hole and chamfered area with fibreglass tissue, which you then sand flush and top off with filler prior to paint.
This both gives your repair strength on both sides of the panel and removes the hard edge that can sometimes show up afterwards if left.
I liken TIG welding with gas welding. The arc from the tig starts the molten pool which you then feed filler rod/wire into by hand. Does mean you can weld most anything just by picking up the right filler rod.
Takes skill though and is more expensive than you need.
Get yourself a mig but I would not go below 150amp.
Steve
Takes skill though and is more expensive than you need.
Get yourself a mig but I would not go below 150amp.
Steve
steve_D said:
Get yourself a mig but I would not go below 150amp.
Steve
Horses for courses Steve, required power is down to what you are welding for most chassis work a GOOD 130 Mig will be sufficient. Also worth remembering that power supply to the welder is also important - if possible us a 16A socket on it's own drop not a standard 13A plug on the ring main....!!! especially important if you are looking at 150 or more..
we currently has an SIP Pro 170 in recon if any is interested, it's basically as new, took a bang in transit but has been reworked and you would never know
I wanted the Tig for the detail/precise work of building headers for my project. Migs are great for speed and knocking things together.
Yes, Tigs are like gas welding (even though ive never gas welded) - get yourself a Mig and keep practicing.
Tigs need a decent power feed - (10mm2- 60A) min for mine - whereas my 195 Mig runs of a 16A feed.
For fun my dad demonstrated welding two peices of 15mm copper water pipe together using twin and earth as filler rod!
>> Edited by eliot on Thursday 18th November 22:51
Yes, Tigs are like gas welding (even though ive never gas welded) - get yourself a Mig and keep practicing.
Tigs need a decent power feed - (10mm2- 60A) min for mine - whereas my 195 Mig runs of a 16A feed.
For fun my dad demonstrated welding two peices of 15mm copper water pipe together using twin and earth as filler rod!
>> Edited by eliot on Thursday 18th November 22:51
dontlift said:
Get yourself a mig but I would not go below 150amp.
Steve
Horses for courses Steve, required power is down to what you are welding for most chassis work a GOOD 130 Mig will be sufficient. Also worth remembering that power supply to the welder is also important - if possible us a 16A socket on it's own drop not a standard 13A plug on the ring main....!!! especially important if you are looking at 150 or more..
we currently has an SIP Pro 170 in recon if any is interested, it's basically as new, took a bang in transit but has been reworked and you would never know
My reason for saying 150 was based on my experience.
I bought my MIG to do car body welding but before long ended up welding sections of angle iron to make a trailer.
Plan ahead.
Steve
The "power" of a welder isn't that important. The thing you want to look at is the duty cycle of the welder
I can't remember how the exact specs work, but my welder is only 120A but that happily welds 5/6 mm plate (I've done chassis on a regular basis not to mention boat hulls
(I think they're still floating))
I can't remember how the exact specs work, but my welder is only 120A but that happily welds 5/6 mm plate (I've done chassis on a regular basis not to mention boat hulls
(I think they're still floating))Gassing Station | Kit Cars | Top of Page | What's New | My Stuff