Topic: Welders Thread

[tsflstb]

I would recommend TIG method first, MIG second and stick as a last resort.

Do you think one of those cheap 115V, 15A flux-cored wire feed welders could do a decent job here?  I used one several years ago putting up a small metal building.  It worked pretty well, but that was thinner metal.

[paulages]

second what steve F said--TIG is your best option. i'd at least use gas with the MIG if you can (flux cored is really messy). one of those cheapie hobby welders could work fine if you can manage to get enough heat out of it.

[rhinoracer]

+3. Although a 120V wire feed will do the job just fine. Like so many things it depends most on the person's experience than the welder itself.

I recommend instead of a long piece of bar stock you weld two bungs cut from round stock, drilled and tapped and then fishmouthed to fit the frame tube.

That way you reduce the risk of twisting the frame by laying a loong weld bead.

Also, make sure the welder is more experienced and equipped to welding thin wall tubing than heavy machinery. It's very easy to burn a hole in your frame when welding, more so with stick and MIG.

[cafebob]

i would have the steel piece machined, and then run two bolts through the piece and the frame.  no need to weld.  a job CNC shop should only charge 30-40$. 

bob

[754]

My 2 cents,

For a top notch, looks like the factory designed it look, try this.

Make 2 flanged bushings or bungs...1 for each threaded hole. Say about 1/2 or 7/16 dia for about3/4 inch then a 3/4 inch diameter flange about 3/16 or 1/4 thick. Then drilled, tapped and countersunk. I am thinking it will be 5/16 or 8mm bolt?

Then drill a thin strip about 1/2 wide to your bolt pattern, and bolt size. You will use this to transfer drilling pattern to frame and to hold the bungs while you tack them to the frame.  After you drill your 2 holes in the frame prep by removing paint around the holes. Then insert the bungs bolted to the strip, tack weld  the bungs. Check them and weld around them, try not to go over the flat edge of the flange. When it cools down run the tap thru again.

Your original strip is too thick and heavy, and will concentrate stress in that area due to the extra weight and thickness, not to mention that unless it is curved  and fitted to match frame tube it will be putting a lot of stress into the frame tube.

I have madeThousands of threaded bits for bike frames in the past.

[Steve F]

I would recommend TIG method first, MIG second and stick as a last resort.

Do you think one of those cheap 115V, 15A flux-cored wire feed welders could do a decent job here?  I used one several years ago putting up a small metal building.  It worked pretty well, but that was thinner metal.

In my opinion, flux-core sucks, and is more prone to voids and spatter.  Tried it.......didn't like it.  GMAW or Gas Metal Arc Welding is what MIG stands for (Metal Inert Gas), and flux core is basicly stick welding without the sticks.
But to change the subject, I like what the others have recommended, like making mounts aot of short pieces of tubing instead of the long solid rectangular piece.  That seems to be a more logical approach.  Only problem is getting the parts to fit the frame tube o.d. just right so you can do a good TIG welding job.

[754]

I just described the whole fixturing and alignment details for them to end up flat to each other,

The flange on the bung should contact the frame the rest is filled with weld. If the frame is not flat there make a digher shoulder on one of the bungs.

What I described could be longer and go right thrpugh the frame but that is double the work, and if you are not standing on the pegs, probably not needed.

[ekim98]

1018 or other mild/low carbon steel is fine, but 4130 should be preheated before welding or it can crack also.

[tsflstb]

Make 2 flanged bushings or bungs...1 for each threaded hole. Say about 1/2 or 7/16 dia for about3/4 inch then a 3/4 inch diameter flange about 3/16 or 1/4 thick. Then drilled, tapped and countersunk. I am thinking it will be 5/16 or 8mm bolt?

What you describe exists right up the right side of the "Y" in the frame for the rear engine mount.  Those two 6mm bolts go through the frame but rest on a small flanged bung.  We use something similar called a weld saddle for reinforcing hot taps in the pipeline industry. 

One worry was keeping them aligned during welding, but your method sounds reasonable.  Are those bungs sold ready made for the racecar industry or anything?  Sounds like to do it right I may need to visit an automotive fabrication shop and stay away from the pipeline welders.  I weigh about 190 and put all that on the pegs on occasion, so I'd rather do it right.

With my original plan, I thought about milling out the flat bar with a 1/8" relief where the rearset mount contacts it.  That would give it a little more mechanical support.

Thanks for the replies.

[turboguzzi]

hei TS

why not try this?  (see second post from top)

http://forums.sohc4.net/index.php?topic=18579

Very little welding was needed + if you fall, you bend only the cheapo ally flat bars rather than something major.

TG

[Terry in Australia]

Here's what I did mate, just like your idea, but I used 1" x 1/4" steel strap, and welded nuts onto the back. TIG is great if you've got it, but I used MIG, it was good enough for Ducati right up until the late 1990's, so plenty good enough for an old SOHC4 dinosaur! Cheers, Terry.

[Jim F]

Does anyone know what material this frames are made of?
If it is anything close to 4130/4140 your going have to anneal around your welded area
to prevent stress and also not to heat treat the area
Would use TIG method first but that requires alot of experiance
MIG would work in a pinch with GAS
stay away from STICK

To bad you dont live in the atlanta area
would be happy to do that for you
check out the thread for micro Laser welding and you can see what my company does

good luck
big-jim

[BobbyR]

Does anyone know what material this frames are made of?
If it is anything close to 4130/4140 your going have to anneal around your welded area
to prevent stress and also not to heat treat the area
Would use TIG method first but that requires alot of experiance
MIG would work in a pinch with GAS
stay away from STICK

To bad you dont live in the atlanta area
would be happy to do that for you
check out the thread for micro Laser welding and you can see what my company does

good luck
big-jim

I would say te frames are mild steel. The Japanese love mild steel since it is ductile and not prone to cracking. The rule of thumb is if you can stress a piece of steel 1M times and there is no crack, it will not crack.

[SEBNN]

I second the thinner material idea.  5/8 is over kill, 3/16 will hold enough threads on a coarse thread bolt and be smaller and easier to weld to your frame.  1/4 is even better.  Also, to line them up, you may consider a couple of long piece of all-thread and running it through both rearsets to keep them aligned.  It will cost a few dollars at the hardware store, but make it much easier to keep them both lined up.

[Terry in Australia]

That's it SEBNN, I used two pieces of 10mm threaded rod with a spirit level taped to one to get mine "square".

[oldbiker]

Even better than any form of welding would be what we in GB call brass or bronze welding. ( It is also known as hard soldering ) The temperatures used are lower and do not make the base steel brittle. The final result is more than strong enough. I have used this for the frames that I built in the past and NEVER had a failure.

[Jim F]

Old Biker has a good idea too
If you have ever seen aftermarket dirt bike expansion chambers
they are always brazed becasue they can contract and expand with the heat
But strong enough to keep it all together

again you need to practice with this method as you really need to watch your heats
and pay close attintion to your weld Pool.

Good luck

Big-jim

[Terry in Australia]

As much as I think John is a veritable font of wisdom as he's been biking longer than I've been breathing, in my case, I wouldn't trust this particular job to "brazing".

The pegs may well have to take someone's body weight, so I'd rather join the brackets to the frame permanently, than just fill the gap, as it were. Brazing is great for many things, but not supporting my 260 pounds. Cheers, Terry.

[Jim F]

Well Terry is right
If you carry around a little more than most (I am 300 plus hence Big-Jim)
then brazing is not the way to go
TIG is the answer

Big-Jim

[coyotecowboy]

TIG or MIG is the way to go, but don't dismiss brazing so quickly.  If you look at some of the vintage race bike frames, they were brazed, but I think they used rod with a higher bronze content.  Also, original GT40 upper and lower control arms were brazed because they would give in a high-stress situation whereas most steel welds would break or tear the parent metal even it the weld didn't fail.

The main reason brazing has fallen by the wayside is in a production situation brazing is incredibly time-consuming, and not just everyone can do it well enough to let your customers have the finished product.  I'm pretty good at brazing, but the old man that showed me how to do it right could lay that stuff down like butter.  He could hardsurface (studite) the same way, mine always looked like hell compared to his.  Those old fellers know quite a bit of stuff if you're willing to listen to them

[Jinxracing]

Brazing is great for many things, but not supporting my 260 pounds.

Just out of curiosity, I've been told that a brazed joint can be just as strong as a welded joint...IF the joint is designed correctly. Like the slip-joints on older bicycle frames for example. I'm interested to know because I've been considering brazing as an alternative to welding on some stuff and would like to get some other opinions.

If it's true, then that brings up the question of what would be a properly designed joint for brazing rearset mounts to a frame? I'm thinking that lots of contact area is the key...maybe a thin-wall half-round piece of tubing whose I.D. matched the frame's O.D. that was 4" long or so? Perhaps with some threaded bungs brazed on to the outer surface? Might be ugly though...

[ekim98]

Brazing is great for many things, but not supporting my 260 pounds.

Just out of curiosity, I've been told that a brazed joint can be just as strong as a welded joint...IF the joint is designed correctly. Like the slip-joints on older bicycle frames for example. I'm interested to know because I've been considering brazing as an alternative to welding on some stuff and would like to get some other opinions.

If it's true, then that brings up the question of what would be a properly designed joint for brazing rearset mounts to a frame? I'm thinking that lots of contact area is the key...maybe a thin-wall half-round piece of tubing whose I.D. matched the frame's O.D. that was 4" long or so? Perhaps with some threaded bungs brazed on to the outer surface? Might be ugly though...

Brazing will hold just as good as a mig/tig or stick weld if done properly. The biggest problem with brazing is the amount of heat you put into the metal. most people today go with mig or tig because it's easier to control the amount of heat you put into the work piece and most people can get a better looking job from those types of weld. Plus there is less slag/flux to worry about cleaning up after welding with mig or tig. Brazing and stick welding are slowly becoming a lost art, like acetalene<sp? gas welding 40 years ago. I can still remember my dad getting his torch out and a couple of metal clothes hangers and welding a patch on a rocker panel. A true lost art.

[Terry in Australia]

Brazing is not as strong as TIG/MIG or ARC, purely because it is basically a filler, designed to seal "slip fit" jointing, or sweating into pipe joints etc, and does not melt the parent metals together, like TIG/MIG and ARC welding does.

I braze stuff all the time, and it's great, but it does not have the strength to hold something like a footpeg mounting bracket in a "butt weld" application, that might be subjected to the stress off a big bloke like me or Jim standing on the pegs.

For slip-fit joints like early motorcycle or bicycle frame tubing, or GT40 wishbones etc, it's fine, same as it is for sweating joints in radiators, exhaust systems, car panel repair etc. For some interesting reading on the subject, have a look at this:www.cnczone.com/forums/archive/index.php/t-11679.html - 20k -

 Cheers, Terry.

[BobbyR]

Today we are only using Brazing for high pressure HVAC lines, since it flows like solder in a sweat joint. On structural parts by regulation it must be welded. One thing I did not realize is that grinding a weld is vital to making it stronger. 

[rbmgf7]

I'm just wondering what peoples opinions are on certain welders. I weld at school with thousand dollar TIG and MIG units (I'm not qualified nor do I have extensive knowledge of welders. I just use them for building student design projects. I can lay a decent bead on both and still get sustainable penetration) but I just want something small for at home. I prefer MIG, not flux.

I come across this  Norther Tool brand and the price is definately affordable, it is MIG, but I don't know what kind of quality smaller units make (I'm sure it also depends on the users skill atributes). Hobarts similar model costs almost $100 extra but is flux (another $100 buys you the MIG conversion kit, so by this time you could've bought they're next medel MIG). I've heard Hobarts are pretty good units since they're a subsidiary of Miller. Clarke's simliar model is $120 more (also flux but can change with a kit) then the NT but I've heard are "cheaply" made and lack quality...?

Thanks