remmington
Apprentice
Owns Spark Eroder
Posts: 4,971
|
Post by remmington on Jul 9, 2021 5:12:56 GMT 1
I really wish I had a spark-eroder right now! Skoda Roomster Scout, 2013MY, locking wheel-fixings....and the key has been broken by a previous owner's neighbour, who tried to help her out by getting a leaking tyre off the car to go to the nearest tyre-centre.
Some c**t has done these up with an airgun, so even with a negative 250Nm of undoing torque on my special "getting the locking fixings off" toolset, there's no movement. Impact it to 300Nm, and the blades in the tool-head sheer off flush with the recess in the locking fixing head. The fixings themselves are too hard to touch with other sorts of tools, unless you consider the tools on the Bodgit & Leggit Youtube video of such a removal process on a BMW (I think - possibly a VW).
Spark-erosion would get these out.......
MMA arc weld a short bit of 20mm x 10mm bar to it. With a 36mm accross flat hub nut welded to the other end - then beat the end with a 4lb lump hammer while hot. Then do the other wheel fixing up tighter with a breaker bar - the undo the offending bolt with super long bar.
|
|
|
Post by wightdiag on Jul 9, 2021 12:12:32 GMT 1
Subtle ! But effective
|
|
|
Post by Dragon on Jul 9, 2021 21:54:34 GMT 1
I was going to say, that sound's like you've done that before.
|
|
|
Post by valhalla on Jul 10, 2021 0:33:30 GMT 1
I usually use M16 hex-drive set-screws, but this time I have some old VW wheel fixings to-hand. I have already offered one up to see how much clearance I have for the MiG torch, and with the tapered shroud, and gas turned-up, it might just work.
Before having the special tools, I used to take them all out this way, but I found that it was getting tedious, not least the spatter was difficult to remove from the wheel afterwards.
The MiG is my only significant option, as the other welding-wets are just too crude, or too lightweight to kick-out the current I need. The MiG will do 140A on its "5" setting, and it will do that for hours on end, or until the armoured cable into the distribution box glows a dull red..... It gives the option to go up to "6" if I find I need the last bit of agression into the weld, which is a bit much for the workshop ring-circuit for more than a few minutes at a time - torch is kicking-out 160Amps at that stage.
Only 3 fixings to take out, apparently, so that makes it easy.......
|
|
remmington
Apprentice
Owns Spark Eroder
Posts: 4,971
|
Post by remmington on Jul 10, 2021 7:36:10 GMT 1
The reasons I use MMA not MIG for locking wheel extraction - is two fold.
1. Access: On a deep wheel recess hole. I can't get a big enough "meaningful" bit of metal down the hole with a MIG torch (even with the gas shroud removed). Simply put - I can get an arc welding rod where I can't get a mig torch.
2. Cracking: I struggle with weld dulution/cracking using MIG A18 wire. The ferite content of chrome plated or hardended faced locking wheel bolts. Always cause MIG A18 weld to crack when cooling. You can overlay it - after it cracks - and you will be OK with a second pass - but you need room to overlay - and room is what you are going to be short of.
This is why I always use 312 MMA rods not normal 6013's for the process. 312's will stand the ferite dilution - also a 312 electrode deposit has a higher tensile strength - about 9000psi not the 6000psi a 6013 gives you (the 60 in 6013). This does make a difference as you only need to deposit 2/3rds of you "bird poop" to get the same strength.
Also I always do this in AC - not DC. Because I have suffered "arc blow" in DC - due to magnetic wheel bearings/hubs before - 3.2mm 312 electrode in AC at 125amps 48 OCV.
Someone (a proper welder) has given me a handfull of 309L 3.2mm electrodes to try for this process (not tried them yet). 309's are far cheaper than 312's - so thus the planned experiment.
This is also why I use 20mm x 10mm mild steel bar for the job - not hardended or high tensile bolts. Access/cracking again.
1. Assess: With a flat bar you will get a "half moon" either side - this gives you room to get soom "dig" or angle with your electrode to make a fused weld.
2. Cracking: A high tensile bolt/machine screw - will snap/shear at the point of the weld - the heat/dissimilar metals and the carbon from the bolt will give you a perfect "shear line" - when you are resorting to 1" air impact wrenches and scaffolding extensions. Mild steel bar is more tolerant to this - it just bends and deforms.
It is not all weld chemistry either - the heat from the weld and the brutal force from a 4lb lump hammer - will also loosen/free off the tightest fixing threads.
|
|
|
Post by givusaclue on Jul 10, 2021 23:55:19 GMT 1
The reasons I use MMA not MIG for locking wheel extraction - is two fold. 1. Access: On a deep wheel recess hole. I can't get a big enough "meaningful" bit of metal down the hole with a MIG torch (even with the gas shroud removed). Simply put - I can get an arc welding rod where I can't get a mig torch. 2. Cracking: I struggle with weld dulution/cracking using MIG A18 wire. The ferite content of chrome plated or hardended faced locking wheel bolts. Always cause MIG A18 weld to crack when cooling. You can overlay it - after it cracks - and you will be OK with a second pass - but you need room to overlay - and room is what you are going to be short of. This is why I always use 312 MMA rods not normal 6013's for the process. 312's will stand the ferite dilution - also a 312 electrode deposit has a higher tensile strength - about 9000psi not the 6000psi a 6013 gives you (the 60 in 6013). This does make a difference as you only need to deposit 2/3rds of you "bird poop" to get the same strength.Also I always do this in AC - not DC. Because I have suffered "arc blow" in DC - due to magnetic wheel bearings/hubs before - 3.2mm 312 electrode in AC at 125amps 48 OCV. Someone (a proper welder) has given me a handfull of 309L 3.2mm electrodes to try for this process (not tried them yet). 309's are far cheaper than 312's - so thus the planned experiment. This is also why I use 20mm x 10mm mild steel bar for the job - not hardended or high tensile bolts. Access/cracking again. 1. Assess: With a flat bar you will get a "half moon" either side - this gives you room to get soom "dig" or angle with your electrode to make a fused weld. 2. Cracking: A high tensile bolt/machine screw - will snap/shear at the point of the weld - the heat/dissimilar metals and the carbon from the bolt will give you a perfect "shear line" - when you are resorting to 1" air impact wrenches and scaffolding extensions. Mild steel bar is more tolerant to this - it just bends and deforms. It is not all weld chemistry either - the heat from the weld and the brutal force from a 4lb lump hammer - will also loosen/free off the tightest fixing threads. Lot of science in that, very impressive. you probably won’t use the spark eroded loads, but when you do it’s the best tool for the job, I recently had to erode a sheared water pump bolt from a Porsche Boxster block in situ, got the job done threads intact. those Ducatos’ can be a bit of a pig to do, but the worst glow plugs for me so far is between bmw n47 & the transit custom 2.2
|
|
|
Post by valhalla on Jul 11, 2021 0:39:23 GMT 1
It is not all weld chemistry either - the heat from the weld and the brutal force from a 4lb lump hammer - will also loosen/free off the tightest fixing threads. You had already given me an idea further up the thread about the way forward here. As soon as you mentioned flat bar, I thought to myself, "Yes, that's exactly what I'm going to do - bevel the fronts of the bolts to a blunt chisel-point, so that I can use the two main access points around the fixings to get a decent run of weld". It is something I have not done before, but I think you are spot-on in this respect, as the VW spoke pattern does give a moderately good access to two sides of the bolts. I will find-out on Wednesday morning next week.
If it works, I will not covert your new spark-eroder. No, not one bit.....well, just a little bit....
|
|