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By Dave the Bass
#88774
Spark erosion, yeah, erks! That was new to me too, I was Googling last night and came across that video. Awethumne technology but I don't know anyone that happens to have one squirreled away in the shed I can borrow! :)

I'm going to have to go for an old school approach, I've some TCT tip drill bits, I fancy having a go myself at get that stud out. I've done it a successfully more than a few times before either at work on lumps of kit or at home on bikes and motorcycles... and seeing as I'm occasionally working from home for now I have a bit of free time again (whahey!). If I totally foul up it'll be my own fault I know.

Ta for the heads-upAvondale but they are a very long way from me, I'm based in Kent. We do have Motoliner Maidstone though that also come recommended.

I've noted the tip about bolting the crankcases in place Vince, ta.
User avatar
By Dave the Bass
#88775
Also, I've found out what should bolt into that hole, yey! If I'm right, a bit of that threaded portion is what I'm working on... -> Image
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By Dave the Bass
#88778
stinkwheel wrote:
Mon Mar 30, 2020 8:30 pm
Maybe worth ordering some cycle-thread taps and dies now? I 100% garauntee they will come in handy.
If I succeed I will matey, I shall, I'd have a cause to celebrate and a good reason to buy some :) The nut is 7/16'' X 26TPI says the online parts book.
User avatar
By fernf5
#88779
"Spark erosion, yeah, erks! That was new to me too, I was Googling last night and came across that video. Awethumne technology but I don't know anyone that happens to have one squirreled away in the shed I can borrow! :)"

Thought you would probably have seen the vid. Turns out it's pretty old technology...I'm late to the party as usual.
Yes, not exactly common machines around here...and definitely not in my price range!
Here is how the fellow in the 2nd youtube link makes his drilling guides:

https://www.youtube.com/watch?v=fxx5lIGesjg

and if you are good with an oxy/acetylene torch (with music):

https://www.youtube.com/watch?v=T0ZuJMiaBQs

OK I'm done...too much time on my hands. ;) Maybe I'll go to my shop and try to make a drilling guide and get away from the pc!
By vince
#88781
Hi, there was a spark eroder where I worked in the 70s. Its correct name escapes me but I seem to recall it was an Argon?metal disintegrator it was however nicknamed the Superzapatron . If I remember correctly whatever shape the electrode was ie square/star/hexagon then it cut a square/star /hexagon shaped hole. Vince.
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By fernf5
#88785
Guide1.jpg
vince wrote:Hi, there was a spark eroder where I worked in the 70s. Its correct name escapes me but I seem to recall it was an Argon?metal disintegrator it was however nicknamed the Superzapatron . If I remember correctly whatever shape the electrode was ie square/star/hexagon then it cut a square/star /hexagon shaped hole. Vince.
Superzapatron :D Love it.
The fact the spark eroders (Superzapatrons) would cut shapes was another one of the things that I found pretty amazing.

Pic is my first drill guide attempt. As per the above video. M8 Allen bolt, 1.25 thread pitch. Plan on making a few more to have when I eventually break a bolt off and need to use an extractor.
Guide2.jpg
User avatar
By OldBoy67
#88798
You have my sympathy. The same footrest on my GT was broken in exactly the same way when it was hit by a car whilst parked a while back.

Luckily there was sufficient thread exposed on the nut side to enable the stud to be wound out from that side. It was a pig of a job because the footrest stud had been distorted in the accident – application of a lot of heat was my friend.

I may be misremembering but I think the frame was threaded to accept the footrest? The nut on the other side (along with the star washer) locked it in place. If I’m correct it looks from the images that you may have destroyed the thread in the frame? Not the end of the world and it should not be an insurmountable problem.

I also see you have the typical bend in the upper frame tube!

Apart from the good folks on this forum, there is an active Facebook page dedicated to the 250cc models (Royal Enfield 250cc Owners Technical - https://www.facebook.com/groups/6160674 ... oup_header). They may also be able to provide advice during your rebuild.
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