attaching brake discs to mild steel pole.

[T0rnado69]

is this do able with Mig and mild steel wire.

or better to use Tig
and if so, best rods to use...?


cheers in advance for any advice.

 

[hotrodder]

What's it for/what sort of forces is it gonna see? The brake discs will be grey iron and MIG or TIG welds will be brittle with mild steel filler and quite likely to crack as it cools. Stainless filler sometimes sidesteps the cracking deal but you still get some properly funky metallurgy hence the nickel iron electrodes mentioned http://www.mig-welding.co.uk/welding-cast-iron.htm

Any reason why you can't weld a steel disc to the pole with some holes drilled in it to match the PCD of the disc? Or if it doesn't need to be butch use the small countersunk holes that stop the disc moving on the hub when a wheel is removed

If you really don't want to use bolts TIG brazing is another way but nickel and/or nickel iron electrodes are sometimes available in smaller packs so possibly cheaper than 1kg of CuSi3 or CuSn6 TIG brazing wire

 

[T0rnado69]

a funky little garden table.
forces..... hmmm a large glass of coke & ice or a pint of cold lager
even a few sandwitches

i have mild steel Mig wire.

and mild steel and stainless steel Tig rods.

i have a fair few old brake discs and want to use a few up

 

[Ton-up]

I've welded a couple of large discs to things in the past. They weld ok for basic things but I wouldn't use them if they are being stressed. They make a nice off-hand grinder stand base for example.

 

[zzr1200]

Cut and weld a mild steel disc to the pole then use the brake disc's mounting holes to bolt the disc to the welded disc.

 

[colnerov]

Yes, If only to remove the possibility of spilt alcohol.

 

[123hotchef]

Just make sure they aint cast discs because they wont weld with mig or normal arc

 

[Bill Edwards]

For your application I'd try it with the MIG. It'll probably work, and if it doesn't it should be immediately obvious.
It's hardly a load bearing, critical part, if it doesn't break once cooled it should be fine.

 

[T0rnado69]

I've welded a couple of large discs to things in the past. They weld ok for basic things but I wouldn't use them if they are being stressed. They make a nice off-hand grinder stand base for example.

what did you use. mig or tig ?
cheers

Cut and weld a mild steel disc to the pole then use the brake disc's mounting holes to bolt the disc to the welded disc.

yer i could do it this way, but a lot more work involved..

Just make sure they aint cast discs because they wont weld with mig or normal arc

some are rear solid discs and some are vented front discs.
no idea if cast or not.

For your application I'd try it with the MIG. It'll probably work, and if it doesn't it should be immediately obvious.
It's hardly a load bearing, critical part, if it doesn't break once cooled it should be fine.

once ive cleaned the discs and get things set up and try.

 

[Freddy0309]

I found tig with 309 filler did the job lovely with some old Landy discs I tried mild steel filler rods but not sure if it was my technique but I kept getting cracks in the weld

 

[T0rnado69]

just checked on weldequip's site.

mild steel A15
and stainless steel 316L

is what i currently have for Tig.

 

[hotrodder]

Virtually all car (solid or vented) brake discs are cast from grey iron. Even posh/spendy two piece jobbies that have a seperate aluminium mounting bell. About the only time car discs will be something other than cast grey iron is proper exotica with composite discs

309L is a disimilar filler alloy designed for welding carbon steel to stainless. It's over alloyed so that diluting stainless (lots of chromium, almost no carbon) with carbon steel (more carbon none or very little chromium) doesn't produce a brittle microstructure.
Cast irons have waaaaaaaaaaay more carbon in them than steels. The wire choices you have are wrong. 309L is also wrong. It's nothing critical so only time, consumables and maybe whatever is put on the table to waste/potentionally risk

MIG or TIG isn't gonna make much of a difference, the potential issues are metallurgical. Cast irons aren't particularly weldable for the reasons TechnicAl explained in the link i posted and the flavour of cast iron he mentioned in the link is one of the more weldable types

 

[Freddy0309]

I was welding stainless brackets onto the disc but was decorative more then functional and tbh I could have got away with glue but tigged it because I could

 

[hotrodder]

Yeah if it's decorative or a table that's never gonna have more than few beers on it then a weld that doesn't immediatly crack as it cools is good enough. If someone decides to dance on the table after drinking all the beer then might not end so well but drunk people usually bounce so might provide some comedy

Personally i'd weld tabs onto the pole (make a feature out of them or whatever) and make use of the bolt holes already in the discs. A bit more to do but guarenteed to work

 

[T0rnado69]

yer i may go that way i think, its more work, but will be more stable..

i have a large lump of 4mm plate so could make some discs from that

 

[Liquid Metal]

Get some stainless rods 309 or even better 312 and stick weld it. Will be fine. Ive made a few things like this from old brake disks before, the latest being a large ish weight made from 6 ford focus disks, and some disk offcuts of 50mm plate arpund 8" in diameter. All with a 18mm r/bar loop welded to the top to chain my pushbike up to in my back garden. Anyone tries moving it and theryre gonna make enough noise to wake up the neighbours.
Borrowed some 309 and 312 rods from work to do it with (both packs had been open for months, would have been binned otherwise), gave it a warm up with propane torch to slow down the cool rate, (put the 50mm thick disks in oven for 2hrs too just to make sure). Has stood up to a few clouts with a sledge hammer out if curiosity too