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Post by Jim on Apr 8, 2016 2:47:31 GMT
You are making great progress there Julian your work really does look good and something you should be very proud of. As for tapping 16BA holes I can only say I've been very lucky so far,I too have a collection of broken BA taps created when I wasn't so lucky.
Jim
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Post by Roger on Apr 8, 2016 7:02:02 GMT
Hi Julian,
If that doesn't come out, you can drill the tap out with a carbide PCB drill, but it needs to be set very accurately to the centre, and the infeed has to be infinitesimal. You'll probably break a few, but it does work. If you don't have a fine feed on the mill, it probably won't work.
By all means come over or send it and we'll get it out on my mill.
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Post by Jim Scott on Apr 8, 2016 9:04:57 GMT
Gents A warm/hot solution of Potassium Aluminium Sulphate (Pot Alum) in water is very effective at dissolving steel. It appears to have no effect on brass, bronze, copper or aluminium so is very useful for removing the remains of broken taps in these materials. Potassium Aluminium Sulphate can be obtained in in small quantities at low cost from Ebay. Jim S. Just found this link www.tap-die.com/contents/en-uk/d296_Tip_Remove_Broken_Tap_Drill_Reamer_Tap_and_Die_Co.html |
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Post by Roger on Apr 8, 2016 9:21:56 GMT
What an interesting solution (pun intended!). I can't say I've heard of that before, but that's useful option.
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Post by vulcanbomber on Apr 8, 2016 21:11:46 GMT
Hi Julian, If that doesn't come out, you can drill the tap out with a carbide PCB drill, but it needs to be set very accurately to the centre, and the infeed has to be infinitesimal. You'll probably break a few, but it does work. If you don't have a fine feed on the mill, it probably won't work. By all means come over or send it and we'll get it out on my mill. A normal carbide end mill will do it. Touch the top of the broken tap with a stop set. Wind the table up a tad and touch it with the tool again.... Then wind the table up a tad, touch the tool and just keep going. |
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jma1009
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Post by jma1009 on Apr 8, 2016 21:48:25 GMT
Thank you so much Jim S, Roger, Jim M, and Dave for your comments.
Alum would be useful stuff to have in stock, especially as I get older and will no doubt break more taps in non-ferrous stuff on future projects.
My particular problem is/was my habit of when breaking a small tap to re-grind it for further use. I have now thrown in the bin all the small taps that had this treatment. I dont often break small taps.
I have cut up today thin sheet copper from an old domestic water tank for the inside tank and coal space for the LBSCR wagon to go behind Stepney. As this isnt strictly part of Stepney/Boxhill by Martin Evans I may resurrect the LBSCR wagon thread.
Cheers,
Julian
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johnthepump
Part of the e-furniture
Building 7 1/4"G Edward Thomas
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Post by johnthepump on Apr 9, 2016 9:36:30 GMT
Gents A warm/hot solution of Potassium Aluminium Sulphate (Pot Alum) in water is very effective at dissolving steel. It appears to have no effect on brass, bronze, copper or aluminium so is very useful for removing the remains of broken taps in these materials. Potassium Aluminium Sulphate can be obtained in in small quantities at low cost from Ebay. Jim S. Just found this link www.tap-die.com/contents/en-uk/d296_Tip_Remove_Broken_Tap_Drill_Reamer_Tap_and_Die_Co.htmlHi Jim, What an interesting link, the knowledge that can be gained from members on this site is amazing. John. |
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Post by Jim Scott on Apr 9, 2016 10:11:12 GMT
Gents A warm/hot solution of Potassium Aluminium Sulphate (Pot Alum) in water is very effective at dissolving steel. It appears to have no effect on brass, bronze, copper or aluminium so is very useful for removing the remains of broken taps in these materials. Potassium Aluminium Sulphate can be obtained in in small quantities at low cost from Ebay. Jim S. Just found this link www.tap-die.com/contents/en-uk/d296_Tip_Remove_Broken_Tap_Drill_Reamer_Tap_and_Die_Co.htmlHi Jim, What an interesting link, the knowledge that can be gained from members on this site is amazing. John. Hi John I agree entirely, you're never too old to learn and some of the less traditional processes described here are fascinating. However I'm sure the use of Pot Alum has been mentioned on this forum before so I'm only providing a reminder. Actually, I'm somewhat embarrassed to have posted a perfectly valid link as to how to do this when I remembered there is an excellent description with photos on our Club website..! My apologies Malcolm... www.tsmee.co.uk/page56.phpJim S |
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Post by Roger on Apr 9, 2016 10:31:54 GMT
That's a great article Jim, I like the detailed tips on what to expect. I'd certainly consider using it in an emergency. Would it work for a broken Stainless Steel stud I wonder?
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johnthepump
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Post by johnthepump on Apr 9, 2016 10:45:43 GMT
Thank you so much Jim S, Roger, Jim M, and Dave for your comments. Alum would be useful stuff to have in stock, especially as I get older and will no doubt break more taps in non-ferrous stuff on future projects. My particular problem is/was my habit of when breaking a small tap to re-grind it for further use. I have now thrown in the bin all the small taps that had this treatment. I dont often break small taps. Cheers, Julian Hi Julian, Three years ago Glyn a club member, pointed out that the best way to break a small tap was by hand, as the forces on the tap wrench tend to be unbalanced. What I needed was a guided system and he would bring the one he made to the Pumphouse the following Wednesday, well he did and we tried it and so I set out to make one, a simple device rather like the George Thomas's tapping and staking machine, the only real difference it is in the horizontal plain and this makes it more user friendly. Glyn also told me not to hide it away, but keep it handy on the bench. Only this Thursday I tapped 100 x m4 holes into aluminium blocks 6mm deep into an open hole. I use spiral point taps whenever possible as they push the swarf forward these work well for through holes and spiral flute taps for blind holes. I realise these may dearer and that ordinary taps are more likely in a model engineers workshop. Anyway here is the photo. Regards John.  09.04.16 by John The Pump, on Flickr The handle is adjustable to suit the size of tap and the platform is moveable to line the work up to the tap, I have made fixtures to fit in the 1/2" hole in the end plate to do special jobs, since making this I have tapped many hundreds of threads with it. |
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pault
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Post by pault on Apr 9, 2016 17:18:23 GMT
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jma1009
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Post by jma1009 on Apr 9, 2016 22:14:51 GMT
Alum is on order courtesy of Ebay, thanks to Jim Scott's excellent help and advice.
My old great friend John Salter phoned this evening to suggest that the 1mm tapping size for 12BA in my old Zeuss table is a bit too tight, so duly noted.
Apart from the rather awkward smokebox fixing for the upper lamp/disc bracket (when I broke 2 10BA taps going through part cast iron and steel) I have only broken 2 taps on Stepney. Both were 'iffy' taps I'd previously broken (8BA and 12BA) and reground.
There must be a 100 or so 10BA tapped holes on Stepney's side tanks all done successfully with no broken tap.
I am a firm advocate of the use of a small drill chuck for small taps fitted with a wooden handle. My own was made by Arthur Grimmett. Unless you are 'hamfisted' I cannot see how you can do small tapped holes (8, 10, 12BA) otherwise than be hand as any other method lacks the sensitivity for this fiddly stuff.
Just my own personal opinion of course.
Cheers,
Julian
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jma1009
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Post by jma1009 on Apr 18, 2016 19:29:15 GMT
The broken 12BA tap in the top of the L-H side tank was successfully removed thanks to Jim Scott's advice to use Pot Alum and further advice re how to use it. I am having major work done this week on the rear of the house (delayed a week due to last week's bad weather). So here is a bit of light relief! 6 x threaded 6BA bolts into the backhead regulator flange from 8BA AF Hex stainless. The 2 horizontal bolts have extended bits turned on the ends 8BA for 2 stainless nuts for the regulator rod gland. I have a bit of a thing about trying to use studded glands in miniature where they occur in fullsize, and it doesnt half make things difficult sometimes! If you asked me how the 5/16" or so 8BA threaded extension on the horizontal stainless bolts was turned down to 85 thou the short answer is "carefully!" In fullsize all the bolts on the regulator flange on the backhead (ok, in fullsize they are studding and nuts) are hidden by a brass cover which is the next 'interesting job'. On this cover are the stops for the regulator handle plus engraved 'ON' and 'OFF'. Which reminds me of a story about Herbert Jones on the Talyllyn Railway which Ed and Malcolm might have heard of or experienced at first hand, as some of the Talyllyn locos were similarly marked, and Herbert stuck a label in the middle saying 'Open too much'. Anyway a picture..  Turning up fitted bolts out of stainless for boiler fittings is one of my most hated jobs! Cheers, Julian |
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Post by Roger on Apr 18, 2016 19:38:31 GMT
What a great looking backhead that is, the gland really looks the part.
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jma1009
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Post by jma1009 on Apr 18, 2016 20:16:39 GMT
Hi Roger,
Many thanks! It wasnt till the other day I realised the bolts in the smokebox tubeplate and backhead for the regulator flanges were still the steel bolts used on the test, and need replacing with stainless bolts. I had thought I'd made all the stainless bolts required, and fitted them, but obviously not.
My Uncle Roy gave me a 4ft length of 6BA stainless hex 32 odd years ago - that is now down to less than 1ft, having been used exclusively on specially made bolts for boiler fittings.
Most of Martin Evans', and all of LBSC's designs, have threaded glands on piston rod glands, valve rod glands, and regulator glands, plus threaded flanges for the regulator on the backhead.
Cheers,
Julian
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Post by Roger on Apr 18, 2016 20:22:31 GMT
Oh well, if you eventually run out of Stainless hex, I'll knock some up for you. It sounds like that might be some time away though!
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mbrown
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Post by mbrown on Apr 19, 2016 9:50:06 GMT
I hadn't heard that story about Herbert Jones but it is entirely in character. His nephew David, now in charge of the TR locks, has a similarly low view of drivers who use more steam than necessary.
Herbert would have made the sign for No.3 Sir Haydn's regulator quadrant which has Open and Shut beautifully cast into the brass stops - a nice detail typical of the ex-Corris Falcons. No.7 Tom Rolt also has the stops marked but by stamped-in letters, and of course No.7 came after Herbert's time.
TR No.6 still carries a discrete label on the regulator sector plate dating from the 1980s. It was the favourite loco of Druver Graham White who treated it as if it was made of glass. If you open the regulator beyond a modest amount it reveals the note, "Too Fast! GW" - which remains invisible if you drive on a small regulator setting.
When your railway is 2' 3" gauge and no one else owns locos that fit the rails, you have to look after the ones you've got very carefully...
Malcolm
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jma1009
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Post by jma1009 on Apr 19, 2016 21:38:37 GMT
This is a 'what the team thinks?' moment...
I added an extra crown stay on the middle of the firebox wrapper, plus lowered the backhead regulator bush to be in the prototype position. Despite carefull measurement initially, the top of the middle girder stay is in line with the regulator rod and interferes by just under 1/16".
I have rather put off dealing with this problem, but must get to grips with it.
2 options,
1. somehow reduce the top of the middle girder crown stay to clear the regulator rod (and if so I havent the faintest idea how)
2. Put a set in the 3/16" stainless regulator to clear the middle girder stay. I have done this previously with 3.5"g locos, but 3/16" is altogether a rather more taxing job, plus very little room to achieve the offset at the rear end between regulator flange and cover with insert for the gland before the rear of the middle girder is reached.
2. seems the obvious solution on a completed boiler, but I must admit I dont have a lot of experience of bending other than small dia stainless with very tight bends, which I have always done by heating locally on the bend.
Any suggestions gratefully received please!
Cheers,
Julian
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Post by Roger on Apr 19, 2016 22:37:09 GMT
Just a thought Julian... can you make a long filing jig that locates in the regulator hole to protect that, so you can file the top off the crown stay? A round hole to suit a 6mm diameter round file ought to keep it in line so it can be persuaded to stay on top of the stay. Alternatively, use a round bush and a small square file. If it's only 1/16" too high, I can't see why you can't lower it that way. Ok, it might take an evening and a large donation to the swear box, but I think it's doable.
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jma1009
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Post by jma1009 on Apr 21, 2016 21:49:34 GMT
Sincere congratulation on HM The Queen celebrating her 90th birthday today! On a slightly lesser note, here is my attempt at dealing with that middle girder stay that is just a shade too high. Here is a homemade 1/4" cutter out of silver steel all filed up and hardened and tempered. I need to stone with a triangular oilstone the edges, and make up a sleeved bush for the regulator flange on the backhead and with a bit of luck we should have some progress on reducing that troublesome top of the middle girder stay.  Cheers, Julian |
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