RUMCars Forum
General Category => Unusual Microcar Discussion => Topic started by: Bob Purton on December 26, 2014, 05:09:23 PM
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Hi fellow restorers.
Spot welding, just about the only kind of welding I havnt tried before.
Over the holiday I have been building my Bobette windscreen frame from 1mm sheet steel, its gone very well so far but I now need to weld some members to the inside of it to stiffen it all up, all that's giving it its shape right now is the windscreen its self temporarily mounted in it and the sides which I have folded.
I want to bend and weld some square rods to the inside of the curves, top and bottom, can this be done with a spot welder or are they only for sheet to sheet?
Second question, I dont want to lay out £500 to just do this job, is there a kind rumster out there with such a device that would be prepared to loan it me please? Hire shops around my way dont appear to hire them out for some reason. I know I could do plugs welds with my mig but want to keep and refinishing to a minimum. Any ideas anyone?
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ive got a spot welder but I no you can do it with a mig and some holes cut into steel ,my spot welder I think only dose upto 4mm.... I don't no where u r but mine is available if needed
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Thanks. I just finished having a chat with a professional welder chum and he is of the opinion that I would do a lot of damage trying to weld sheet onto 8mm square rod which was the original plan. Distortion and maybe blowing the sheet out altogether. He said the only way to do this with spot welding would be to weld the sheet to channel but then bending the channel to the frame profile would be a headache for me as I dont have the right tooling for that.
He suggested riveting of using one of the modern high tech bonding products now available. I see I am going to have to think this trough some more.
Thanks for the offer, I'm down in Essex though so distance alone would be a problem. Good to know forum members are willing to help.
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Can we have some pictures please Bob
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Essex ant far really lol Cambridge - peterbough - spalding / wisbech
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Steve. Have sent you an email.
Messy. No I suppose its not that far 100 miles or so but now I'm doubting that spot welding is the answer. Cheers.
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well the offer of using tooling or workshop is here if u need
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Very kind of you. I may still take up the offer. Cheers, Bob
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How about drilling a small hole and using silver solder with very low heat?
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Hi Mark. This may be a case of being divided by a common language here as silver solder in the UK means the metal has to be red hot. As soon as you apply that kind of heat the sheet metal warps. Do you mean soft solder?
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Yes silver solder is the same here. I just the other day silver soldered some studs to 1 mm steel and it did not warp on me. Maybe I was very lucky!
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Stay Brite silver solder is low melting point.
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Maybe your just better at it then I am Mark!
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Hmmm Stay brite doesnt appear to be sold over here. I wonder if there is an alternative brand with low melting point.
Andy, you appear to be clued up on modern adhesives, what's the best panel bond?
The other thing that crosses my mind are countersunk stainless pop rivets. anyone used them?
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I thought one reason for using spot welds was it deformed the sheet metal less.
Having watched Mick do it he used some rivets to get the fit correct, or the threaded thumb clamps, forget what they are called, if they will go in. With the thing located he would then weld in a way rather like tightening a cylinder head. This spread the loading along the seam. Once the spots were holding the job the rivets/clamps came off and the job was finished off, lastly filling in the original clamp/rivet holes.
Of course proper spot welders are a clamp as well. that is a problem when you cannot access one side of the weld, or the electrode energy is dispersed by being away from close proximity to the the other, on miss matched metal thickness. it can turn into a zipper, a known prob on Schmitt monocoques.
Interestingly the normal screen surround I have found on low production cars is a channel with rivets, not least as the channel is sometimes brass extrusion. It is more malleable and chrome's up nicely. Even tin bodywork is riveted onto brackets hidden under the surface. I actually have a box of Misc rivets for repairing such things. Though cheaper cars can have a panel with a hole cut in and the screen rubber mounted. This rarely looks well.
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I order from overseas all the time, no problem.
If you want an adhesive, by far the strongest are the modified acrylics. These are stronger than epoxy glues, totally waterproof and far less sensitive to contamination and have a very long shelf life (I'm still using glue about seven years old). It's also less sensitive to mixing ratios.
There are various types you can get, but I would recommend getting it from Starloc, as they're the cheapest, but the products are first class.
If you prefer a branded name then Devcon Plastic welder is a good product (don't be fooled by the name, it's not just for plastic). You can usually pick that up on ebay.
http://www.shop4glue.com/acrylic-sga-methacrylate-toughened-adhesives-66-c.asp
http://www.devcon.com/products/products.cfm?family=Plastic%20Welder%E2%84%A2
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id use pu adhesive made by stachem (who makes tack cloths ) very strong its used as a seam sealer and a panel adhesive
soft solder (lead fill) uses low heat and it bonds (tinning)
mig uses pre drilled holes and if its done very slow it wont worp
gas welding is also an option
brazing is apparently the strongest weld but u have to use heat (high heat)
spot welding is fusing metal in a spot form for bout 4 seconds
tig weld poss option but still using heat
theres just a few confusing types of welding
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Thanks Messy. How do you suck those eggs again? ;D
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I thought one reason for using spot welds was it deformed the sheet metal less.
Having watched Mick do it he used some rivets to get the fit correct, or the threaded thumb clamps, forget what they are called, if they will go in. With the thing located he would then weld in a way rather like tightening a cylinder head. This spread the loading along the seam. Once the spots were holding the job the rivets/clamps came off and the job was finished off, lastly filling in the original clamp/rivet holes.
Of course proper spot welders are a clamp as well. that is a problem when you cannot access one side of the weld, or the electrode energy is dispersed by being away from close proximity to the the other, on miss matched metal thickness. it can turn into a zipper, a known prob on Schmitt monocoques.
Interestingly the normal screen surround I have found on low production cars is a channel with rivets, not least as the channel is sometimes brass extrusion. It is more malleable and chrome's up nicely. Even tin bodywork is riveted onto brackets hidden under the surface. I actually have a box of Misc rivets for repairing such things. Though cheaper cars can have a panel with a hole cut in and the screen rubber mounted. This rarely looks well.
True Al but you still need specialist tooling to form a tight bend in brass channel. Ever tried it without?
With this project I had very little option after searching for a suitable screen for the last seven years, and no joy. I finally found a screen from a boat that has the right curvature but slightly smaller all round. Only option was the sheet steel and screen rubber route. Looking ok though!
When you say mick, are we talking about Cooperman?
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cadburys crème egg a bit of a bugger the goo inside a bit thick ,as with a normal egg well raw dosent come into my diet :P
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;D
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I would bow to folk who have actually constructed such things, rather than repaired them. Certainly sections are not easy to bend and to keep an unbent, unified look, as though no stress has been introduced. So a screen was found, good stuff.
No, it was Mick Leeson using his aircraft fitters skills. Mike Cooper is a great free hand welder. He used to weld 2CVs by sight. I think he limits welding a bit these days after years of looking at, and breathing it.
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interesting reading so far . I think I'd be tempted to braze/bronze weld the said bits - that is if there is sufficient good stuff to braze to . you could use carbon's on low amp's ??? (morgan or eagle 6mm rods preferred) .
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Well, I picked up a new co2 bottle today for the mig and decided to experiment with some scraps of metal.
First, plug welds, done a lot of these before on both the schmitt and the first Inter but always made 10mm holes in the top sheet. I just dont have the area to use 10mm on this job so tried as someone on here suggested, 5mm holes. The welds looked great but there was no penetration and they pulled apart with no effort. Then tried again with 10mm holed and they were as strong as you like. I guess the 5mm holes just dont allow enough heat through to the surface beneath. Shame I cant use 10mm plugs on this job but there we are.
Next thought of trying stitch welds with the mig along the top inner edge. This worked great and didnt perforate the 1mm sheet or distort anything so I think I will go with this method, a neat row of about 8mm long stitch welds then I can bead some panel sealant over the top to tidy it up.
At least I now have a plan. Lets see how it works out on the actual job.
Thanks for all the suggestions and input.
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I could never get on with using Co2 as a shield gas (not technically an inert gas is it, so it's actually MAG welding)
I found Argoshield gives far superior results, which is a blend of Argon, Co2 and Oxygen. I found the arc more stable very low spatter, and much better weld penetration especially when welding thinner gauge materials.
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Over the years as I have done jobs for others with the mig and in payment they have bought me bootles of gas of all makes and combinations and to be honest, I have barely noticed any difference.
Its only a SIP welder a diy jobby really so I dont expect pro results all the time. I cant get on with those gasless wires though, tried one once and is was pants! I'm actually much better with my stick welder but obviously on heavier gauge steel. Thats a SIP as well.
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I use a SIP too- Autoplus 130.
When I first used it I tried Co2, because it was cheap, and I was advised that it would be fine for the work I wanted to do. It was Mike Hurn that first switched me on to Argoshield.
I'm surprised you say you notice no difference, I personally found it made a dramatic difference to the quality of the weld.
The other big innovation for me was the introduction of self darkening visors.
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I finally found some time to finish the windscreen frame I started over the holidays. Here it is in primer. The welding method I decided upon, that of stitch welds covered by a bead of filler worked out ok.
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often wondered if you picked up the Dunkley from Jean , you never said ;) screen surround looks excellent
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Great stuff!
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often wondered if you picked up the Dunkley from Jean , you never said ;) screen surround looks excellent
I did thanks Richard though it turned out not to be a Dunkley but a Mercury Hermes, not so interesting but very rare all the same. The appeal of a Dunkley would have been the incredibly rare own four stroke motor. Yours and Jeans efforts to retrieve it for me were much appreciated all the same.
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Great stuff!
Cheers Mike. Will we be rallying with it this summer I wonder?
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Looks really good Bob
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My smug feeling was soon overturned this morning when I found flakes of primer coming off in my hands! Apparently the panel wipe I had used on the bare metal is meant to be left for at least 30 minutes before painting. Of course I'm always in a hurry and left it about five! Result is the primer pops. Spent this morning rubbing it all off again and this time used no chemical wipe down, just a scratch up with some emery and this time used an etch primer. Wont be making that mistake again.
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Perhaps you shouldn't have bought the wipes off that " tacky " website ;D
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Didnt buy any wipes, it was a 5 litre can of the fluid from Battlesbridge autojumble. The product is fine, its just the twit using it! ;D Still, the frame support pillars were successfully painted today in 2k Fiat monza rossa. Same colour as my Motobi Catria seen hear. My favorite shade of red.
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beautifull - i didnt dare but peep to see if you were clothed in the reflection :)
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Ha! Funny enough it was Barry lee who took that photo and I'm sure he was fully clothed!
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screen pillars and frame now painted. Used 1k acrylic. Now I'm going to leave it for at least two weeks to gas off and harden before fitting it.