Counter-clockwise Drill bits

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Re: Counter-clockwise Drill bits

Post by joe36 » Tue Aug 11, 2020 10:45 pm

From the picture showing a chip in the plug. It is a good bet that the plug is made of gray cast iron. If the boiler is steel and not cast. The plug can be shattered by placing dry ice on the plug until chilled completely then striking it with a chisel.
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Re: Counter-clockwise Drill bits

Post by RGSP » Wed Aug 12, 2020 7:17 am

Going back to the original posting and request, drill-service.co.uk do a range of specialist drill bits including left-handers. I'm doubtful whether they'll have reduced shank versions, and some lathe or grinder work may be called for if you really need that, though a reducing adapter may be easier, and you certainly used to be able to get hand braces with extra-large chucks.

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Re: Counter-clockwise Drill bits

Post by joe36 » Wed Aug 12, 2020 7:13 pm

Have you tried an air impact?
Left hand drill bits are easily found with a Goggle search, Amazon sells them.
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Re: Counter-clockwise Drill bits

Post by PeteThePen1 » Mon Aug 17, 2020 4:42 pm

Hi Joe and steamboating colleagues

Many thanks for the further thoughts. I have given up on counter-clockwise drills, although somebody on Home Workshop, where I also posted the query, found me a firm that sells them in big sizes. The only trouble is that for 20mm the price is in the region of 40GBP which is probably a very high quality product, but too much to pay for this project.

The plug is a malleable iron plug which I have always assumed is wrought iron rather than cast. However, I am sure that somebody can enlighten me further.

We have a plan which will start tomorrow (18 August).
* Use paint stripper to clear any paint lurking in the join between the plug and the mud drum.
* Apply Kroil and leave over night.
* Use the Dremel tool to square up the tapered sockets so that a standard 1/2 square drive fits well.
* Apply some force with either muscle or power through the square drive.
* Possibly apply some heat with a red hot chunk of scrap or perhaps drill right through with 1/2 drill then apply a small width flame letting the 'waste' heat enter the pressure vessel.
* If this all produces no movement then drill out with progressively larger 'normal' drills.
* Hit the residue of the plug on one side with a cold chisel to start it turning.

A full report with photos will be posted later in the week.

Regards

Pete
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Re: Counter-clockwise Drill bits

Post by Rainer » Mon Aug 17, 2020 9:54 pm

Hello Pete

one of the businesses in 'my' company is to remove broken bolts from big industrial sewage pumps. In general this patients will be operated on a big mill. By this you do not have any alignment issues of drill/mill and the tap hole.

I didn't know the idea with the counter- clockwise Drill till today...

In your case, I strongly advise you to prepare a drill sleeve. Find a suitable surface on your boiler or use the outer jacket of the protruding screw as a guide. Turn a round material as tool that matches this surface on the lathe from any material - you do not need any hardening because you will use this tool for one drill action only. You drill a 6 mm starting hole in this tool on the lathe.

Place the tool on the guide on the boiler, hold it with strong pliers in place and drill through the tool into the defective screw with the same 6 mm drill bit.

Then you take the tool back on the lathe and drill with 6.5 mm. Repeat this process until you get close to the inner thread diameter of your patient. Remove the remaining screw sleeve just mechanically.

I actually recommend that you only ever choose 0.5 mm steps so that you can drill safely in the center and at correct angle. Do it right the first time with patience. If you are living in the Imperrial Size corner of this world use adequat small steps from your ordinary drill set.

Good Luck!
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Re: Counter-clockwise Drill bits

Post by PeteThePen1 » Wed Aug 19, 2020 6:44 pm

Hi Rainer and Steamboating Colleagues

Thanks for your advice Rainer. I do like the idea of making a drill guide, though hopefully this will be the last large rusted plug project that ends up in my workshop.

Yesterday I set to work on the square sockets in the plugs with a Dremel tool. The sockets were tapered rather than parallel making it impossible to use a 1/2" square tool easily. The Dremel cutters changed the taper to a sort of parallel, but did introduce some error in the right hand plug. Once that was done the square tool fitted satisfactorily in both. They were then both regularly treated with Kroil.


Well soaked with Kroil.jpg
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Last edited by PeteThePen1 on Sat Aug 22, 2020 3:53 pm, edited 1 time in total.
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Re: Counter-clockwise Drill bits

Post by PeteThePen1 » Wed Aug 19, 2020 6:47 pm

Today Mike Rometer kindly came around to my house with his car boot loaded with equipment. We began by heating a large piece of steel round bar to red and then holding that against the plug. Two goes at that and it was felt that it was time to apply some turning force.

Setting a square tool with extension into the right hand plug and putting as much muscle power as was available into pushing was next. Result, much puffing but no movement. The same clouted with a hammer was equally ineffective. The manual hammer drive was then tried but again to no discernible effect.

It was at this point that the compressor was plugged in and set in motion. By the time the hose and the hammer drill had been sorted out the tank was up to pressure. The drill was fitted with a 1/2" square drive and applied to the task. There was plenty of noise but no movement from the plug nor from its mate which receives the same treatment.

Next the DeWalt 48v hand drills were deployed with some amusement that we both had bought the same cordless drill. A 13mm bit was used to create a centre dimple as this fitted the sockets rather better than the 1/2" bit. A pilot hole of about 6mm was made right through and then the 13mm was used to open it out. The astonishingly inexpensive, but guilt inducing, boxed set of Blacksmith drills with 1/2" shanks was then opened. Work began at 14mm and progressed slowly up to 22mm. At this point it was clear that the right hand plug was beginning to break up. The remaining bit of the plug that extended beyond the end of the mud drum was 'attacked' with a chisel and persuaded to start turning. It was then possible to knock out that half of the plug. At this point it became obvious that the Dremel work had probably moved the bottom of the socket off centre as the drilling had caused some damage to part of the threading in the drum.

As the fragments came out it was clear that there was no evidence of the presence of any of the penetrating treatments that had been tried.

Not perfectly true.jpg
Not perfectly true.jpg (116.97 KiB) Viewed 5406 times


Next the 3/4" BSP tap was applied and the existing threading cleaned up. Fortunately, the new bronze plugs are quite long so that when test fitted it appeared to be very secure.
Last edited by PeteThePen1 on Thu Aug 20, 2020 10:07 am, edited 1 time in total.
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Re: Counter-clockwise Drill bits

Post by PeteThePen1 » Wed Aug 19, 2020 6:50 pm

The same drilling procedure was then applied to the left hand plug. However, in this case the centre drilling was pretty close to perfect and it was necessary to go up to 24mm to clear the old plug. After that drilling all that remained were the bits of plug thread sitting within the threads in the drum. Very difficult to remove, but they eventually came out as thin strands of metal.

Nearly there.jpg
Nearly there.jpg (102.06 KiB) Viewed 5403 times

With them out, the 3/4" BSP tap was applied and the threads cleaned up. Finally the second plug was test fitted satisfactorily. The only thing that remained was to check that the locomotive style firebox doors would still open. Ooops! The trade name on the top of the plugs was just enough to snag. The plugs will now need that skimming off before the final fitting.
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Re: Counter-clockwise Drill bits

Post by PeteThePen1 » Wed Aug 19, 2020 6:53 pm

Completed.jpg
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With many thanks to Mike Rometer, without whose enthusiasm the job might never have been done.
Regards

Pete
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Re: Counter-clockwise Drill bits

Post by Mike Rometer » Wed Aug 19, 2020 7:51 pm

I have to say I feel that to be a slightly precised acount from Pete, I think it was probably somewhat longer winded than that. The first side definitely served as a learning curve for the second, which went much better and quicker. The air drill mentioned was actually a CP 1/2" drive Impact Wrench, no mean beast, but it certainly didn't make any useful impression on these plugs! Drilling them out was the only option.

A enjoyable day's outing, with the benefit of feeling useful (For a change. Before anyone else suggests it) Thanks Pete! Anytime!
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