Nut sizes imperial measurements, disorientation!

Hello,

As you can tell new to the hobby, I have always love railways and when it came time to consider building my own model railway as I did when younger the thought struck me why was I building an electric version of a steam locomotive in 00 gauge, when I could run an actual steam locomotive!

To this end I have taken the plunge and got myself a small 5" tank loco. Very old and looking forward to tinkering.

My local club is really helpful but I don't want to keep bothering them with my questions! Was wondering if I could bother all of you instead!!

I'm 35 so have grown up in a metric world. Hardest part of this so far is wrapping my head around imperial measurements (1 8th?)

My actual question is (I think) fairly simple and maybe if someone elaborates a bit on the answer the whole imperial world would make more sense to me.

I need to buy a blanking plug, this will be for a T piece that I want to inset in the water feed for a future planned tender.

The copper piping on the engine is all 3/16 OD. The threading all appears to be 32T. I was going to buy a 3/16 T piece to use.

What size brass blanking plug should I buy for the end I am not yet using. I can't seem to find any which are listed as 3/16...

Would anyone be able to offer an opinion? Sorry if this is such a basic question, and I'm sure there is a really easy obvious answer but any help appreciated! Even if I do not go ahead with the plan, understanding this a bit more would be helpful!

Thanks, Ed

I'm not sure I have ever seen a blanking plug for the typical type of pipe fittings used on model engines.

If you buy a commercially made Tee fitting for 3/16" pipework it will have make threads on the fitting to take nuts which draw a Ferrule or nipple into tapered sockets in the fitting.

Your options would be to solder a piece of 3/16 diameter brass, bronze or copper into the unused nipple rather than a piece of copper tube or if you have a lathe make a nipple without a hole in it

That's a good point thanks, I was just chatting to someone about this and they pointed out that what I would need is actually a cap fitting, not a blanking plug which is why as you mention they are not about.

The tee fitting has a male thread, and a cap would have a female thread!

Deleted post.

Edited By Weary on 23/02/2023 19:37:20

Edited By Weary on 23/02/2023 19:38:01

Edited By Weary on 23/02/2023 19:53:17

The thread is likely to be 5/16" x 32tpi which is the norm on 3/16" pipe fittings

I've seen caps but not in that size

Hi Jason,

Re: Threads:

Yep - of course. More speed = less haste (on my part) & more confusion. I've deleted my post to avoid further confusion.

Apologies all round - don't post often & now you know why not!!

Ta.

Phil

Edited By Weary on 23/02/2023 19:52:16

If the tee has nuts and olives you can put a ball bearing in instead of the olive and seal up the branch. I might have misunderstood the question of course. Use a non rusting ball obviously

Edward, for conversions from Imperial fractions, just convert the fraction to decimal inches then multiply by 25.4.

Example: for 1/8" first do 1 divided by 8, this is .125", .125 x 25.4 = 3.175 mm

I have a large poster like sheet hanging on the wall in my workshop. It came from Tracy Tools and is invaluable as one side has all the inch, imperial and metric sizes and on the other is all the usual thread sizes pitches and taping sizes etc. My one was from a exhibition where they were selling tooling, somthing like this is invaluable I don't know if they sell them perhaps worth a call.

David

Sounds like a very useful poster David, but if like me you do not have room for it, "Drills, Taps and Dies" by Tubal Cain in the Workshop Practice Series is an excellent read with an abundance of data in the appendices.

Mick

Assuming the the Tee piece has three externak threads,

Instead of a blanking plug why not put a ball bearing into a nut and screw that bontonmthe Tee piece.

This is quite a normal procedure in industry.

Howard

Hello Edward, welcome to the hobby.

I use a great thread size chart that I'm sure you'll be dead chuffed with. And it's a pdf so you don't need a big wall to pin it to.

Unfortunately the posting page here tells me it doesn't support pasting links in when I try. Worse still it doesn't tell me what it DOES support....and the pasting icons don't do it, so here's a talk through;

Go to haugfasteners.co.uk. Then click on 'bolting guides' then click on the top one ( guide to screw threads). It's a pdf so you can save yourself a copy. And; credit & thanks to Hauge for producing this chart.

Good luck, Allan

Link to above though it does not include ME threads so not much use in this case.

If you do try the ball bearing option be very careful not to strip the threads as with a 1/4" ball you don't get much more than a turn of thread engagement

It took me a little while to spot your typo Allan … but thanks for the info.

**LINK**

https://www.haguefasteners.co.uk/pdf/Screw-Threads.pdf

MichaelG.

.

Edit: __ Jason got there first.

Edited By Michael Gilligan on 24/02/2023 11:10:17

Edward , Why not check with your preferred fittings supplier that their tee pieces and elbows are fully compatible ? Initially fit an elbow , and then simply exchange it for a tee piece as and when required .

Trevor

Or buy a spare olive and solder a piece of 3/16 brass or copper into it to blank it off. Soft solder would be fine, it's on the feed side

You might consider buying some M.E taps and die's you could say tap a piece of brass to fit onto your tee piece

H

Wow thanks for the responses this is great information.

I like all the suggestions, as I'd like to get running quickly I might fit an elbow temporarily and replace later. As I'm starting to work out how to use a lathe I might try and machine a cap from some hex bar as a small project.

The ball bearing idea sounds effective, although I am still quite ham-fisted so would probably overtighten it!

Tracey Tools looks like a useful place, I will need to look up the differences between plug tap, second tap, a die CS and an HSS tap!

Edited By Edward Lewsey on 24/02/2023 20:57:50

At one worlplace, I came across UNS and UNEF.

But fuel injection pump manufactire is not for most of the population.

And you can find some unusual metric threads on pumps made by other manufacturers.

How about the left hand threads used oin vacuum cleaner motors to refain the impellers?

Howard