foxy99
Posted a lot
Posts: 1,380
|
|
Feb 14, 2017 23:14:18 GMT
|
|
Hi guys.
Am making up a small jig which will have dis-mountable brackets screwed to it.
I can either tap the threads in the box-sections of the jig (the walls are only about 2mm thick) or weld nuts on here and there (I've got MIG and Oxy Acetylene).
Now every time I've welded nuts on to metal in the past the threads go hard and distort. This applies to small and large nuts.
I've noticed you can buy weld nuts quite easily. What makes them different? some are on a rectangular base which must keep the weld heat away from the thread to some extent but can't see it would entirely isolate them. Some don't even had a base so what stops them being affected by the weld heat (or HAZ ?)
Also can you tap a thread in a plate which has been welded onto a workpiece?
Can you re-soften the threads on a welded on nut by heating and cooling some way?
|
| |
1974 Daimler Double-Six VDP
1965/67 Hillman Imp pick-up
1984 VW Polo breadvan
1970s Yamaha Twins (4)
1976 Honda SS50ZK1
|
|
|
|
|
|
|
Feb 15, 2017 12:31:36 GMT
|
|
Not had any problems welding nuts onto bodywork, I use very short busts of weld and clean the nut edges first with a wire wheel, I also weld with the bolt in situ so not sure if that makes any difference?
|
| |
|
|
|
|
|
Feb 15, 2017 13:36:09 GMT
|
|
welding with the bolt in has to be better, more surface area to dissipate the heat
|
| |
|
|
fad
Posted a lot
Posts: 1,781
|
|
Feb 15, 2017 13:41:40 GMT
|
|
^This.
You essentially want to more tack it around the flats, with a bolt in situ. Not too much heat, and let it cool between tacks.
|
| |
|
|
fad
Posted a lot
Posts: 1,781
|
|
Feb 15, 2017 13:42:34 GMT
|
|
Also a 2p coin with a hole drilled in to act as a washer between bolt and nut helps a lot with getting the heat out of it.
|
| |
|
|
samta22
Club Retro Rides Member
Stuck in once more...
Posts: 1,272 
Club RR Member Number: 32
|
weld nuts - talk to mesamta22
@samta22
Club Retro Rides Member 32
|
Feb 15, 2017 14:08:20 GMT
|
|
^^^^^ great tip.
|
| |
'37 Austin 7 '56 Austin A35 '58 Austin A35 '65 Triumph Herald 12/50 '69 MGB GT '74 MGB GT V8'73 TA22 Toyota Celica restoration'95 Mercedes SL320 '04 MGTF 135 'Cool Blue' (Mrs' Baby) '05 Land Rover Discovery 3 V8 '67 Abarth 595 (Mrs' runabout) '18 Disco V |
|
|
|
|
Feb 15, 2017 14:23:52 GMT
|
|
sounds like you're getting them cherry and bringing the carbon to the surface making them hard, they only need to be tacked as mentioned.
|
| |
|
|
slater
Club Retro Rides Member
Posts: 6,390
Club RR Member Number: 78
|
weld nuts - talk to meslater
@slater
Club Retro Rides Member 78
|
Feb 15, 2017 19:49:15 GMT
|
|
don't weld with a bolt in. You will still destort the thread slightly and then you won't be able to get the bolt out once things cool. (and often you will lose the temper on the bolt and it will shear off!)
Tack the nut then remove any bolt. Then Weld fully (I normally do 3 out of 6 flats) and when done run a tap through to clean. It won't go hard enough to give you much trouble tapping them.
|
| |
Last Edit: Feb 15, 2017 19:51:42 GMT by slater
|
|
fad
Posted a lot
Posts: 1,781
|
|
Feb 15, 2017 20:08:33 GMT
|
don't weld with a bolt in. You will still destort the thread slightly and then you won't be able to get the bolt out once things cool. (and often you will lose the temper on the bolt and it will shear off!) Tack the nut then remove any bolt. Then Weld fully (I normally do 3 out of 6 flats) and when done run a tap through to clean. It won't go hard enough to give you much trouble tapping them. I've never had an issue leaving the bolt in. I guess there's lots of ways to skin a cat. |
| |
|
|
foxy99
Posted a lot
Posts: 1,380
|
|
Feb 15, 2017 20:48:54 GMT
|
|
I've never tried it with the Oxy Acetylene but always happens with the MIG. Just got me wondering how the manufacturers get round this problem. Can't imagine they're faffing around with bolts and 2ps.
I've noticed on a lot of captive nuts they look square and the corners seem to be squashed down. Do they use some sort of spot-welding technique?
reason I mention Oxy Acetylene is that I've heard when you weld sheet steel with it the joint is still malleable unlike MIG which goes hard. Thought perhaps using O'A' on nuts would keep things 'soft'
|
| |
1974 Daimler Double-Six VDP
1965/67 Hillman Imp pick-up
1984 VW Polo breadvan
1970s Yamaha Twins (4)
1976 Honda SS50ZK1
|
|
|
|
|
|
|
Feb 15, 2017 21:08:42 GMT
|
|
Bolt in with copper grease on the threads . Hot welds in very short burst , you only need a few tacks really , not hot enough to get the nut glowing . The grease will stop it seizing , only a drop will do .
|
| |
|
|
|
|
|
Feb 16, 2017 10:39:23 GMT
|
The way manufacturers do it is with a projection weld nut, which is a spot-welding process as you guessed.  The spikes at the corners of the nut shown above are the "projections." To attach the nut, the spot welder melts the projections into the sheet metal with current and clamping pressure. There are many different types, but that is the basic principle. |
| |
|
|
|
|
|
Feb 16, 2017 19:44:45 GMT
|
|
Maybe a another way around it , just tack two bits of plate together , drill through both , split them and grind off the tack and then tap them = two bits of threaded plate that you can weld to without distortion . If nuts are going to be a problem thats not going to tack more than a few minutes .
|
| |
|
|
foxy99
Posted a lot
Posts: 1,380
|
|
Feb 18, 2017 13:40:02 GMT
|
|
What about brazing? That might be the answer.
It's like gluing metal together. You aren't fusing the pieces so presumably there's less heat involved.
Afaik you are heating the piece high enough to get the filler-rod to melt and it simply flows around the flux that you 'paint' on the joints you want 'glued'. In this case the bottom of the nut
|
| |
Last Edit: Feb 24, 2017 21:30:27 GMT by foxy99
1974 Daimler Double-Six VDP
1965/67 Hillman Imp pick-up
1984 VW Polo breadvan
1970s Yamaha Twins (4)
1976 Honda SS50ZK1
|
|
|
|
|
|
|
|
ive allways put a bolt though the nut and weld it on 2 flats. wait for it to cool down , whip the bolt out and runa tap thro.
this works for me with Tig and Mig...
|
| |
Take the Next slot right coming up on the left.
|
|
