- Thread starter Brad93
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hotponyshoes
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I'll reply to the pm tonight, I dug some out yesterday
Brad93
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Cheers, I'm meant to be repairing machine tomorrow but can put off till Friday.
Currently considering how to open up the shagged holes with a 14.75mm drill.
Will have to turn it on the lathe to make the drill a reduced shank.
I could use a piece of steel plate and mount the rotabroach as I have one hole which still has some good threads. But I'd also need to buy a chuck adapter.
Machine is irreplaceable and already been helicoiled once so needs to be cock on.
zzr1200
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hotponyshoes
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On cast iron I'd just fill with epoxy. Gaffa tape if it's a vertical surface to stop it running out.
Once it's cured locate the center, pilot drill, then a counter-sink until you've a good mm or so into metal. Drill bit should follow in ok from that.
Thin Wall m10 is a 14mm external thread, Thick Wall is m16
Brad93
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Won't last mate. This mixer does 150kg of dough at a time with a 15hp motor.
These four M10 bolts are where the bowl scraper attaches. All the power of the mixer and weight of the dough pushing against it.
hotponyshoes
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No, just use the epoxy to fill the hole so you can re-drill it.
Then tap and fit an insert.
Brad93
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Ah I see what you're saying good idea
MetalMonkey
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Might also be worth looking at E-Z Lok inserts as well, I've had good luck with using those to replace knackered helicoils.
I instantly thought of epoxy as well. Metal filled like JB Weld. Perhaps even glue in the helicolis to stop them vibrating loose.
Brad93
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Tried green loctite last time. Didn't provide a permanent solution it seems
sako243
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If you do @hotponyshoes epoxy trick can you open up the holes to say M12 and tap into new metal rather than heli-coiling? Does the mating part allow for a bigger bolt to be used instead of the M10?
Or if the cast is prone to the tapped hole breaking can you turn a steel insert that sits in a reamed hole (thinking interference fit that you could heat/freeze) and then perhaps run a little bit of weld to help glue the two bits together? Then you'd perhaps have more luck with the tapped hole. Basically a better version of a helicoil hopefully less prone to shaking loose.
Or if the cast is prone to the tapped hole breaking can you turn a steel insert that sits in a reamed hole (thinking interference fit that you could heat/freeze) and then perhaps run a little bit of weld to help glue the two bits together? Then you'd perhaps have more luck with the tapped hole. Basically a better version of a helicoil hopefully less prone to shaking loose.
8ob
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Could you get away with a stepped stud Brad and hold the bowl scraper down with nuts? You would get a lot more thread deeper into the cast iron with the studs.
premmington
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Could you get away with a stepped stud Brad and hold the bowl scraper down with nuts? You would get a lot more thread deeper into the cast iron with the studs.
That is where I am - stepped studs made on lathe - drill go bigger with thread.
Or make your own "keenserts" up on lathe - M16 or M18 outer and just loctite it all together.
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I have zero success with helicoils - I only ever use them - if there is not enuf meat around the job to go "bigger" on the thread size...
Brad93
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These helicoils have lasted two years so they do work. I just don't think they're the right tool for the job in this application. Soft cast iron with bendy stainless bolts that then shear once they've work hardened.
Cast iron is very strong, until you've got movement in the threads. Then it seems to just crumble little by little.
premmington
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Thats 3yrs... Which is enough for a new expensive car - let alone a few repair bolts in a "dough mixer"
What about filling the holes up with TIG braze and drilling and tapping them. All least if it all fails in another 3yrs - you can rework it...!
Brad93
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The casting is so large you'll never get the heat into it to TIG braze.
Thats the mixer there.
MetalMonkey
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How to tell me you are a tool tart without telling me. 
Nice loadout
Nice loadout
