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4 hours ago, r1lark said:

Good to see you are back on the MG Jeff!. But........more tooling for the shop is a good thing too. :)

 

SPI epoxy primer.........I just ordered some a few weeks back, but have not had a chance to spray anything yet. Any tips or tricks that you have learned?

 

I highly recommend using their water based wax and grease remover and *nothing* else.  Barry (owner of SPI) can't be anymore clear on that.  I make sure that any rust treatment, glide coat, etc, etc is throughly removed before I apply the WaG.   So...

 

1) 80 grits scratches with a DA

2) Mix epoxy primer

3) WaG.  Apply and wipe off in one direction.  The WaG is "floating" contaminates off so no rubbing "around". 

4) Wait 30 minutes for both epoxy primer to activate and the WaG be gone.

5) Shoot 2 coats.  I actually shoot a quick tack coat and immediately follow the with a wet coat.  I wait 20 minutes and do another wet coat.

6) Beer (ok, ok, yeah, that was step 1 as well).

 

I use a 1.3 tip but I think you can use a 1.5 as well.  On the last coat you can reduce it 15% and get a flatter sheen.  It has UV protection so it can be the first and last step for chassis and such. 

You can call SPI just about any time and get tech support.  Barry's cell phone is available after hours and on the weekend.  Crazy. 

 

 

 

 

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Thanks for the info Jeff. I did get the water based wax and grease remover. I've got to get a new primer gun anyway, so will look for a 1.3 tip.

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On 10/15/2019 at 6:49 PM, r1lark said:

Thanks for the info Jeff. I did get the water based wax and grease remover. I've got to get a new primer gun anyway, so will look for a 1.3 tip.

I looked at the tech sheet again and they recommend 1.5 but say you can use 1.3.  As such, you might want to get 1.5 for the primer gun.   If you use their 2K primer they recommend a 1.8 tip for it.

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 Luv2Wrench, Very nice metal work. Those fenders look great. Going to be a nice car. John

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Small update... I've been practicing welding again.  It has been quite some time since I last did any and I thought I'd get some practice in.  Got off to a rough start as both regulators wouldn't hold pressure so I had to drive across a few towns (3 hours round trip) to get them rebuilt.  There is a fantastic company, Regulator and Torch Exchange, that will rebuild your regulators while you wait.  Really great guys.  I went ahead and changed hoses, got new goggles, etc, etc.  I'm more comfortable with the setup now and the practice has gone well.  The owner suggested changing the spring in the oxygen regulator to allow finer control over lower pressures and I think that's helped a lot.  I need to get some thinner (1/16") rod in as well as I'm struggling to keep the filler rod molten with the lower heat level needed to keep from blowing a hole in the sheet metal (20ga).  Looks like it will be mid next week before that comes in so I'll have to find other things to do. 

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If I'm understanding well, you are still welding with oxygen/acetylene? I learned the process more than 50 years ag; I'm not sure if I still could!

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6 hours ago, Roger Zimmermann said:

If I'm understanding well, you are still welding with oxygen/acetylene? I learned the process more than 50 years ag; I'm not sure if I still could!

 

Yes, I've been told to start with oxy-acetylene and then get a high quality TIG system.  Since I still haven't mastered oxy-acetylene and I can't afford a high quality TIG system... I'm staying with the gas.  I really think it will serve my purposes well.  I think it is just a matter of practice and experimenting with pressures, flow rates, tip sizes and filler rod sizes.  Granted that's a lot of variables but I've got time. :)
 

Edited by Luv2Wrench (see edit history)
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I must admit that I always thought that gas welding was like riding a bike! Once mastered you could go back to it easily. During the 60's and early 70's I did a lot of gas welding, then went onto MIG welding, in the mid to late 70's. About a year ago I had something that I wanted to weld with gas and was very disappointed with the aesthetics of my end result. I would have thought I could have done a lot better. Next time I need to gas weld something I had better have a have a good practise first!

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Buy a AHP tig welder from amazon for $720 or you can buy direct from the import company direct. No need to buy an expensive one. Read the reviews and I bought one. Incredible to use and the best value I’ve found. Yes, it’s made in China but many things from China are no longer junk. My cousin is a professional welder and was amazed at how well it performed. It is the welder I used to do all the welding on my Olds running boards and fuel tank apron. You no longer have to spend a ton of money on a very good tig welder. I purchased the warranty too simply because it also covers shipping costs in the case it needed warranty repair which would be more than the warranty cost alone. Also, using tig is easy and the arc is controlled by the foot pedal. You would learn very quickly. I think you’re wasting your time with gas welding if your intentions are to progress to the tig. Of course, learning any type of welding is a benefit but I’d start tig welding now.

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5 hours ago, chistech said:

Buy a AHP tig welder from amazon for $720 or you can buy direct from the import company direct. No need to buy an expensive one. Read the reviews and I bought one. Incredible to use and the best value I’ve found. Yes, it’s made in China but many things from China are no longer junk. My cousin is a professional welder and was amazed at how well it performed. It is the welder I used to do all the welding on my Olds running boards and fuel tank apron. You no longer have to spend a ton of money on a very good tig welder. I purchased the warranty too simply because it also covers shipping costs in the case it needed warranty repair which would be more than the warranty cost alone. Also, using tig is easy and the arc is controlled by the foot pedal. You would learn very quickly. I think you’re wasting your time with gas welding if your intentions are to progress to the tig. Of course, learning any type of welding is a benefit but I’d start tig welding now.

 

I think you logic is very good.  I don't have much welding to do on the MG so my needs are not pressing right now.  Time is still my friend.  Once the MG is done and, hopefully, I have a little money in my pocket, then a TIG is probably first on the list.  I think the longer I wait the better a unit I'll be able to get, and, of course, the better my puddle skills will be. :)

 

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Got the 1/16" RG45 welding rod in today and it makes a big difference.  Now, of course, I need a different tip size.  For some reason I have a 000 and 0 but no 00 size.  Figures.  I think I'm very close now.

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I'm still struggling a bit with each end of a butt joint.  I'm now starting with some tack from the middle out and then trying to flow out to the edges.  That seems to be showing some promise.   Here's a couple of my test pieces, they look a little better in real life but they've still got a ways to go.  I'm going to take one of these and "finish" it out the primer, glazing putty and paint.  I'm curious to see how close to flat it will get.   I'm also going to try cutting a square out of a sheet and then welding it back.  After I've done a couple of those I'm going to practice a couple of actual patches on some old fenders.   I'm getting much more comfortable holding the torch and maintaining the correct angles.  Maybe another couple of weeks and I'll have it.

 

IMG_6870.thumb.jpg.201d22a808ae569a88d6742620564baf.jpgIMG_6871.thumb.jpg.037f4759348e9ee966ac0fcb2a52a3bf.jpg

Edited by Luv2Wrench (see edit history)
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When TIG welding a butt joint I put a tack at the stopping end. When you start welding, the metal gets hotter towards the end and the pieces will move if not tacked.  you would also have to reduce the heat to prevent burn threw. Can you tack the end with a MIG welder then try welding with the gas torch?  Just a thought.  I'm sure you will get it all figured out and be on your way.

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1 hour ago, Laughing Coyote said:

When TIG welding a butt joint I put a tack at the stopping end. When you start welding, the metal gets hotter towards the end and the pieces will move if not tacked.  you would also have to reduce the heat to prevent burn threw. Can you tack the end with a MIG welder then try welding with the gas torch?  Just a thought.  I'm sure you will get it all figured out and be on your way.

 

Yes, this is what I'm trying to do. The problem I'm running into is that each end of the butt joint is, in effect, a corner.  When I get the torch on those two corners they almost immediately melt and blow out.   I've been able to put a tack about 2" in from each each and then run the puddle from there out and pull the torch up as I get to the end.   The promising part is that the middle is starting to get pretty nice.  The last two I did would need very little clean up.   I'm in no hurry so I'll just keep working at it.

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I was taught to put a tack every couple of inches and work between them so the whole thing doesn't get too hot. Weld a length here, move along a couple of tacks and weld another length, and so on.

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You did nice welds. On the pictures, the heat generated is clearly visible; that's the problem with the torch. Doing that welding on a fender or other sheet metal part, you may have a severe distorsion. With a TIG welding, there is also some heat and distortion, but much less than with a torch.

During welding, you may put some wet rag near to the welding to limit the transferred heat.

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6 hours ago, Spinneyhill said:

I was taught to put a tack every couple of inches and work between them so the whole thing doesn't get too hot. Weld a length here, move along a couple of tacks and weld another length, and so on.

 

Yes, I'm doing about 3" or 4" between though I am making one pass from the middle out and reflowing the tacks.  I can try switching between the tacks.

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I would think distortion from greatest to least would be stick, gas or MiG, then Tig. I’ve found if my butt joint is tight, the metal very clean, and the tungsten very sharp, I can weld it with Zero distortion as long as I only weld short runs. I also used very little filler rod opting for just welding the two panels together. The problem is we all get impatient with welding and just want to be done with it. I’m sure there’s a bunch of us out there that start with runs of 3/8-1/2” and see no distortion so we say, I’ll just do 3/4” from now on, and then bingo, warps appear. We all have tried at one time or another to rush it. Well, at least I’m willing to admit it anyway!😃

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Forgot to say, your gas weld looks very good. It’s not my forte so god bless you!

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Been watching but not saying.  The MG TD is a beautiful design to me!  I have an unpredicted like for some aspects of design that is very "British".  My brother has a yard full of Brit stuff.  I have a pair of Alvis TA-14's.  One is a sedan and the second is  a DHC.  I also have the remains of an Alvis TA-21 which I will be massaging into my take on a British inspired Special.  Keep up the good work on the MG.

Al

Edited by alsfarms (see edit history)
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As per distortion, while I'll try to minimize it, I also plan to just deal with it.  I think the key for me will be to have a very constant pace such that the shrinkage is consistent and can be countered with a hammer and dolly. 

That's the plan anyway.  We shall see how well that works once I start on some old fenders.  Most of my plans are quickly proven flawed... 

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I took a piece of 20ga sheet metal and turned over the sides to make a mini "fender".  I cut a small rectangle out and then made a patch panel to replace it.  I welded that in and it went OK.  Some of the tacks were easy to make but in a couple of places one of the sides either raised up or sunk away such that the two pieces were too far apart to tack.   At this point I would stop the torch and use a hammer/dolly to get the edges back together, relight the torch and try again.   Eventually I got all the tacks and welded between them.  It didn't go that well so I change to a doubler aught tip (was using a triple aught) and reflowed the joint.  That went pretty well but, obviously, that's a lot more heat.  I used a hammer/dolly to expand the welded areas some to get things back to flat.  All in all it turned out OK.  I'm going to order some more sheet metal and do this several more times.  I'll be needing more oxygen soon as well.  

IMG_6877.jpg

IMG_6878.jpg

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You are getting it.  Welding simply takes practice to get it right and improve.  Are you planning to use some heat sink clay to keep your heat from welding confined to a smaller area and thus less expansion and contraction?

Al 

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1 minute ago, alsfarms said:

You are getting it.  Welding simply takes practice to get it right and improve.  Are you planning to use some heat sink clay to keep your heat from welding confined to a smaller area and thus less expansion and contraction?

Al 

 

Thanks, that's the first I've heard of using clay as a heat sink but it sounds like a great idea?  Do you have some more details on that? 

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It is not a true clay, but a heat sink material that behaves and feels like clay.  I have a can in the shop I will get some information on it and share here.  Anything you can do to minimize the affects of heat swell in your body panels is less monkey business you have to do to have a nice smooth body panel in the end without  an inch of bondo!

Al

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