Making Safety Valves.

[Beachside_Hank]

Hi,

This is the difference between most safety valves and the semi 'pop' variety. The usual valve is on the right and the recently made 'pop' on the left. As can be seen the ball is in a cup on the pop valve and in the open on the other. The ball in the cup is a good rotating fit. When the ball fits in the hole in the valve body the edge of the cup is only a few 100ths of a mm off the valve body. It works (I think) as the steam pressure increases the ball lifts slightly and instead of going directly to atmosphere the steam acts on the inside of the cup and given this extra area opens the valve quickly with a distinct 'pop'. The valve also seems to close quicker and doesn't seem to weep as much as the usual type of safety valve.

Regards Tony.

Your theory of operation is correct as far as I know. I remember in Boilerman school while in the Navy, the seating area of the safety was designed to “pop” at a given pressure, in the case of our ship’s boiler that was 610 p.s.i. What the internal flange did was increase the surface area such that the escaping steam would hold the valve open until a lesser pressure was achieved, something like 580 p.s.i. if I recall; simple, reliable, very few moving parts.

 

[locoman]

A most informative and well presented thread. And very clear photographs! Well done.

 

[Luke]

Great instructive thread and posting Tony, Thank you very much. I'm using your guide to make several myself. One tiny question regarding the used 'ball' what can you suggest where to locate them, or just use some scrap from old ball bearings ?
Thanks,
and Best Regards,
Luc

 

[Tony Bird]

Hi Luc,

The balls are stainless steel and I get them from am model engineering suppliers here in the UK; I often use Blackgates Engineering. I don't think it would be a good idea to use steel balls I have used bronze balls which are also available but I usually use stainless steel.

Regards Tony.

 

[Buzbey2014]

Hi,
Can you tell me which ME had the info on converting safety valves you mentioned?
Thanks
Ken

 

[Luke]

Hi Luc,

The balls are stainless steel and I get them from am model engineering suppliers here in the UK; I often use Blackgates Engineering. I don't think it would be a good idea to use steel balls I have used bronze balls which are also available but I usually use stainless steel.

Regards Tony.

Tony,
Thanks for the info. I will try to get some over here.
Cheers,

 

[Tony Bird]

Hi Ken,

Can you tell me which ME had the info on converting safety valves you mentioned?

I tell fibs! It wasn't the ME that had the article but Engineering in Miniature July 2006; it was titled 'SAFETY VALVES-Some alterations in designs' by Gordon Smith.

If you cannot get a copy email me direct [email protected] and I will send you a scan.

Regards Tony.

 

[Jennifer Edwards]

Thanks for sharing this with us.

That is a really great Turret Lathe. When I actually made a living as a machinist, I loved when I had use of an accurate and powerful turret lathe for multiple part runs. It made life so much easier.

Nice job!

 

[goldstar31]

I see that ArcEurotrade still sell one at £78-ish but Lawrence Sparey writing in the Amateurs Lathe book published drawings.

I've a turret for the bed on the Myford Super 7-- but have never used it. Cost me about £45 second hand.

For those who want one, Ken Metcalf wrote details of his which fitted his ML7 in Model Engineer.

Norm

 

[fcheslop]

I made this unit with a few mods .Mainly to the locating plunger on my version it is tapered in the hope it compensates for wear n tear
http://www.projectsinmetal.com/foru...w-project-plans-for-a-lathe-tailstock-turret/
I keep thinking about using a flat seal as per small commercial safety valves but have not got round to trying it
Nice work Tony
cheers

 

[Jennifer Edwards]

Thanks Norm,

at the moment I am using an Axminster SC2, basically a 7x12, so it is quite small to fit a turret to.

But a gal can dream!

 

[goldstar31]

Thanks Norm,

at the moment I am using an Axminster SC2, basically a 7x12, so it is quite small to fit a turret to.

But a gal can dream!

Apart from the length between centres, your SC2 is not much different to his ML7.
I was hoping to remove the tailstock on my slightly larger Sieg C4 now fitted with a Vertical Mill which ----won't work. I would guess that Ken Metcalf's turret would give you more room.
Drop me a note if I can help

Regards

Norm

PS. I'm still dream at 88!

 

[Jennifer Edwards]

Apart from the length between centres, your SC2 is not much different to his ML7.
I was hoping to remove the tailstock on my slightly larger Sieg C4 now fitted with a Vertical Mill which ----won't work. I would guess that Ken Metcalf's turret would give you more room.
Drop me a note if I can help

Regards

Norm

PS. I'm still dream at 88!

orm,

I had no clue that they made one small enough for my lathe. I just had to cut four parts that required three different cutters and a die. it woud have saved me an additional 12 setups if i had one. I will see if I can suss one out. If I strike out I wil drop you a line.

Thanks again,
jen

 

[goldstar31]

I hav e macular degeneration but Metcalf- as far as I can see, made the turret out of a hexagon with sides 3.75 and the block was 1.5" thick. Again, he talked of lathes other than the mentioned Myfords.

I printed it out - in case?

N

 

[Jennifer Edwards]

I would love to read it, do you have a link?

 

[fcheslop]

Is this of any use
apologies to Tony for taking his thread of topic
http://mikesworkshop.weebly.com/tailstock-turret.html

 

[goldstar31]

Deleted- sorry!

 

[abby]

This is the ideal machine for mass producing small parts.

It's a Pultra 1750 with capstan turret and cut-off slide.
I collected the basics over a couple of years and built a bench/cabinet.
The 3 phase motor is housed in the cabinet and has inverter control.
I am looking out for a clutch to avoid switching on/off between parts which can be time consuming and not good for inverters.
A mechanical collet closure can also be obtained , along with a bar feed this becomes a serious piece of kit.
Once set up I can safely make a hundred parts without inspection which is helpful.
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These are banjo connectors for a steam loco boiler feed pump I was designing.
It is easy to get carried away though and make loads more bits than you can realistically use.
Dan.

 

[fcheslop]

deleted not relevant to thread

 

[the artfull-codger]

Hi Tony, I too have a tailstock turret,mines about 45yrs old & they're really usefull, I notice you using your "diamond" turning tool,I also bought mine from australia I have lh & rh & their parting tool all great quality, one thing puzzles me is are you using it on brass or bronze safety valves? I tried mine on brass once & it self feeded in really bad, I was tempted to grind it flat but never bothered as I have tools with no top rake for brass, nice valves & models btw.
Kind Regards
Graham.