Bolt thread pitch

[Thrashsmith]

Hi all,
Can anyone tell me what sort of thread this is? My little toothed thread pitch set tells me that 27 fits best, and the O/D of the thread is 9.5mm. So I'm guessing that's meant to be 3/8th, but what would the 27 mean?
I'm trying to find a replacement brass gas injector for a ceramic chip forge I've bought, so I can run it off LPG bottles instead of natural piped gas.
The hole size in this one is 5.5mm but according to the old manual I need 3.2mm. I have asked the original manufacturers, (FlameFast), but no joy so far.
I had a thought that I could just buy a replacement bolt in whatever size this is, then drill a hole lengthways through it.
Cheers me dears

 

[Robert Weaver]

Likely a 3/8" thread, 27 threads per inch (TPI)

 

[Agroshield]

27 tpi is the standard pitch for a 1/8" NPT thread. NPT is national pipe thread (or national pipe taper), the US-equivalent of BSP. In the context of how it is being used, a pipe thread makes sense. The OD you quote is slightly small, but it may be that the thread is tapered.

You could buy a 1/8" NPT blanking plug, try it and make a hole in that.

https://www.amazon.co.uk/Brass-Internal-Hexagonal-Blanking-Plug/dp/B078YV5JV1

 

[Mick Annick]

Swan may be able to help - https://gasforges.co.uk/

 

[Thrashsmith]

27 tpi is the standard pitch for a 1/8" NPT thread. NPT is national pipe thread (or national pipe taper), the US-equivalent of BSP. In the context of how it is being used, a pipe thread makes sense. The OD you quote is slightly small, but it may be that the thread is tapered.

You could buy a 1/8" NPT blanking plug, try it and make a hole in that.

https://www.amazon.co.uk/Brass-Internal-Hexagonal-Blanking-Plug/dp/B078YV5JV1

Thanks. All this pipe stuff is new to me. 1/8" sounds far too small for a 3/8" o.d?

 

[Brad93]

it's standard 1/8" BSP

the ⅛" refers to the bore not the thread size.

Find your local engineering supplier, auto hose place, hydraulic hose service and you'll find what you need. I've actually got that exact fitting you have in your hand in stainless in my field kit of bsp fittings

ParkerStore have branches up and down the country.

If you're near essex you won't go wrong with Advanced fluid solutions at Woodham Ferrers

 

[iNf]

This might help

 

[Agroshield]

it's standard 1/8" BSP...

...except 1/8 BSP is 28 tpi.

It is possible that the OP has measured the pitch incorrectly (especially if starting at 24 and trying each gauge in turn until something fits) but no BSP thread is 27tpi.

 

[Brad93]

...except 1/8 BSP is 28 tpi.

It is possible that the OP has measured the pitch incorrectly (especially if starting at 24 and trying each gauge in turn until something fits) but no BSP thread is 27tpi.

Yes i reckon OP has measured thread wrong.

Flamefast are a british manufacturer, i cannot see them using NPT.

Only place i see NPT is aerospace and automotive.

 

[Turbo]

Solder your existing jet up and drill a new hole.

 

[awemawson]

I found Flamefast extremely helpful when I rebuilt and re-jetted my ceramic chip forge. Have you called them?

They sent me a new jet.

 

[oldbikedavey]

Flamefast have been extremely helpful to me regarding the various bits of kit of their manufacture that I have.
Couldn't recommend them enough.

 

[Thrashsmith]

I found Flamefast extremely helpful when I rebuilt and re-jetted my ceramic chip forge. Have you called them?

They sent me a new jet.

Yeah, emailed them & waiting for a reply. What model forge do you have?

 

[awemawson]

Can’t recall the model atm but there are several threads on the Madmodder forum where I’ve been working on it.

 

[Thrashsmith]

Hi folks, I need a bit more help, please.
Thanks to your help I managed to get some 1/8 bsp brass blanking plugs from a local hydraulics supplier, which I can drill to suit.

My next job was to find a suitable regulator. I was sent the manual by FlameFast & it stated a fixed 35mbar regulator at 1.5kg/hr. I could only find 37mbar at 1.5kg/hr, so I guess that's near enough.

The regulator has a 8mm tail coming off it so I bought some 8mm bore hose. I also managed to get a 15mm compression fitting with a 8mm tail, so I can screw straight into the back of the forge unit.

Annoying I totally forgot about a flashback arrestor. It seems the threads on them are typically 3/8bsp. To make an inline one of sorts I can find online 3/8 bsp LH female to 8mm tail, but I can't find 3/8 bsp LH male to 8mm tail, which would enable me to splice a flashback arrestor into the hose.

This is becoming a bit of a merry go round. Is there a simple solution to splicing a flashback arrestor into a propane hose?
Thanks in advance

 

[Turbo]

I don't think you need a flashback arrestor on a propane only torch.

 

[northwest]

I have never, ever seen one.

 

[Brad93]

Highly unlikely to need one as you have no mixed gases

 

[Thrashsmith]

Shamone mo fos