The usual "ohh no"

[John Lee]

I am sorting out a boiler for a friend, a bit old, but professionally built to a very nice standard and never steamed. A stalled project that he bought.

The regulator is retained in the backhead, in the modern way, into a large phospher bronze bush with six screws.

Unfortunately the previous owner had decided to use brass slot head screws.......

I got 4 out with some effort, but the other two have sheared. Normally an extractor would be the tool of choice, but these are 8BA!! I can't stand the boiler on end, and drill and tap larger, its too long for my pillar drill, and anyway accurate support would be an issue.

So, any ideas how to get those out???

John

[the_viffer]

Can you drill it out on the lathe?

[chyvarloe]

Set up in lathe and do by hand using tailstock. that is how I have done it before.

[John Lee]

Put a boiler complete in the lathe?? Errr....no.

Perhaps I was not clear t-v; these are two tiny bolts, sheared off in the backhead of a complete boiler, in the bush of a bolt on regulator.

John

[chyvarloe]

You say "no" But I just set mine up in the cross slide no problem. I had exactly the same problem. Will do it for you if this would help you.

[the_viffer]

I was meaning just as my cousin Jacky (?) describes, John.

And if you lathe is not big enough I know someone about to sell a 5" Drummond on ebay which surely will be.

[Deleted]

Hi
You could try making up a plate with holes in it in the same positions as the backhead flange, bolt it in place using the bolts that you did get out, and then use it as a drilling jig to drill them out by hand, if you make the holes tapping size, you may be able to clean the threads up and still use 8ba, otherwise there is always the next size up.
Hope this helps
Regards
Trevor

[chyvarloe]

Good suggestion, trevortilney, probably easier than mine.Might sound silly, but I must admit that I did not even think of that. Just goes to show you don't always see the wood for the trees.

[spurley]

Hi John

I think Trevor has probably suggested the most practical solution to your dilemma. If the guide is accurately made you could drill out the screw remnants using a Dremel or similar which can be just the job for tricky jobs such as these.

Let us all know how you solve the problem please. It's good to share things like this.

Cheers

Brian

[ron]

John
Someone a long while ago posted on here about removing a broken tap from gunmetal by dissolving it in Alum, claimed it worked well.
If the worst comes to the worst what about making a new bush, boring out the old one and silver soldering the new one in?
Ron

[the_viffer]

Alum is for dissolving ferrous screws out of a non-ferrous job. Silver soldering in a new bush? Any idea for this week's lottery tickets?

[John Lee]

trevortilney said:

Hi
You could try making up a plate with holes in it in the same positions as the backhead flange, bolt it in place using the bolts that you did get out, and then use it as a drilling jig to drill them out by hand, if you make the holes tapping size, you may be able to clean the threads up and still use 8ba, otherwise there is always the next size up.
Hope this helps
Regards
Trevor

That's a good one Trevor, and yes Brian, I have a Dremel so that would be the tool of choice.

I'll give it a go thanks.

John

[Shawki Shlemon]

Hi Trevor
A brilliant idea and simple,one karma for that.

[chyvarloe]

Second suggestion. Instead of drilling out etc, could you replace fitting, turn through 30 degrees and drill 6 new holes and tap, leaving broken studs in situ.

[John Lee]

spurley said:

Let us all know how you solve the problem please. It's good to share things like this.

Cheers

Brian

Ok, did as Trevor suggested... here is the offending item



and it worked a treat. I had to go up one size to 7BA, but as I have some "one size smaller head" screws, all matches up.

These are steel,not ideal, so when time is to hand I will make 4 8BA and 2 7BA screws from pb hexagon.

Thanks for the suggestions all

John

[simonwass]

Would it be better to make some studs up, they can be loctited in and you are not stressing the threads in the bush. You can make a stepped stud for the 7ba new hole, just machine the rest to 8ba dia. and thread 8ba.
Studs are correct engineering practice

[John Lee]

Studs are indeed better practice Simon, and even easier to make than pb screws . The eagle eyed would be able to spot the 2 "foreigners" unless they were stepped as you suggest.. But of course I have had to open out the regulator flange a little to allow the 7BA to pass through with clearance.

I'll check about root depths and see if I can take them all out to 7BA.

Another one of those cases where one job turns into another, and another.....

Thank you for the suggestion

John

[simonwass]

Why would you have to open out the regulator flange for the 7ba bit? Make a stud with 1/8" (or however deep the tapped holes are) of 7ba, a bit of plain 8ba diameter topped off with an 8ba thread. Screw this into the boiler flange so the 7ba bit is flush with the bush, then the existing regulator valve box will slide over the studs as they are all now 8ba apparent diameter.
It would be less work sticking with what you now have thread size wise, you are making screws anyway, studs are easier, only the stepped one(s) are slightly more work.
Only gripe with a studded flange is making the gasket, the regulator not being flat needs the gasket part making before stud holes are cut.

[John Lee]

The Regulator base is not flat?? It is..at least flat enough for a hallite gasket ( or the old favourite brown paper and oil) to take up the slack.

I will open to 7 BA for them all if I can (enough metal permitting as I said) for 2 reasons.. its stronger... and they all match.

KISS is my watchword.. its only a small part (which went wrong) of a larger job, and its not even my boiler, I am just knocking up the fittings having a little Cowells lathe tucked away that does a precision job.. providing I am not the limiting factor.. ;D

Regards,

John

[simonwass]

The Regulator base is not flat?? It is..at least flat enough for a hallite gasket

Sorry, slightly confusing. I meant the bit that fits to the boiler bush, not flat as in a sealing face and a locating spigot fitting inside the bush. Not flat, as in stepped, I think thats what I meant