MoM Orifice Thread Size???

AdmiralYoda

I'm looking to further balance my steam system and I have Maid O' Mist air vents that have the interchangeable orifice's on them. I'd rather not but some additional vents just to get the orifice and I know I can get a vent with one of all the orifices.

Does anyone know the thread size of the orifice that screws into the MoM vent? I'd like to buy some plugs or short bolts that will thread into the vent and I can drill my own holes.

Much cheaper and allows me more flexibility.

ethicalpaul

It's 5/16"-32

Here's the tap and die I bought to try to make a check valve for mine. It was a perfect fit: https://www.amazon.com/gp/product/B08MZ5WZPJ/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1

I made the pieces with my mini-lathe, it was fun.

However!!! Every so often I see one with some other thread size on it. I've purchased maybe 6 vents and one of them had this other (unknown to me) size on it.

As for much cheaper, there's no way it's going to be much cheaper than the MoM prices but suit yourself

SteamingatMohawk

A hardware store (including big box stores) usually has thread gauges in the nuts and bolts aisle. Take an orifice with you and you can be sure to get it right.

If you have to take one off a working radiator, block the vent or just shut the supply valve on the radiator.

MOM now makes an adjustable vent, it's just hard to find them in stock. Don't leave it open to vent steam.

https://s3.amazonaws.com/s3.supplyhouse.com/product_files/Jacobus-JAC-ADJ-Product Overview.pdf

Jells

I measured one a few years back with the same idea, it was not a typical SAE thread, but an odd one like 5/16-28. I'd gauge it but I don't have one here. I'm amazed they don't sell them with the complete set for a buck more or something. The pros, of course, presumably travel with a sack of them.

Jells

Found one, had a bad one from HD sitting in the van to be returned, and forgot about it. Yes, it's 5/16-27 or 28 near as I can tell with a caliper and comparing it to a 3/8-27 tap. How insane is it that they make them both???

You're not likely to find screws in this size. It'll run you like $12 for a die. Take a 5/16 brass rod and thread it with the die. You could even put the die in a vise and the rod in a drill and run it through. Then cut it up for your vent orifices. Of course, a lathe would help tremendously.

ethicalpaul

Did no one see my post where I named the size and posted a link to the tap and die?? 😅

Jells

ethicalpaul said:

Did no one see my post where I named the size and posted a link to the tap and die?? 😅

Guess I missed the link. How did you determine it was 32 tpi? Not that it wouldn't work in a 27 tpi, or vice versa, for the few threads we're talking about on those orifices. I had a thread gauge once upon a time, I guess it's deep in the archives somewhere.

ethicalpaul

I measured the thread, then got the die and cut a brass rod to test it

Jells

ethicalpaul said:

I measured the thread, then got the die and cut a brass rod to test it

On the female side with an actual thread gauge? There's not enough threads on the male to gauge them accurately to within a few tpi. But like I said, for this close enough is fine. There's some SAE to metric close calls that will work fine for a nut but not a deep tapping.

ethicalpaul

I measured the male with a thread gauge. I’m not sure what the mystery is

ChrisJ

This thread was rather fun to read through.

SteamingatMohawk

What I didn't mention above is that I called MoM a couple of years ago and a very nice lady sent me a set of orifices at no cost. They aren't commercially available and may have been replaced by the adjustable vent I mentioned.

SteamingatMohawk

If you can believe the manufacturer's cut sheet for the MoM adjustable orifice (web page posted above), the thread is a 1/8-32" which is an American National thread, not a pipe thread which is 1/8-27 either tapered or straight.

I checked a Lowe's and it didn't have that size. Bolt Depot doesn't have that size threaded rod either. Good luck finding a tap or die.

Personally, I don't believe it is wise to try to engage unmatched threads.

Jells

SteamingatMohawk said:

If you can believe the manufacturer's cut sheet for the MoM adjustable orifice (web page posted above), the thread is a 1/8-32" which is an American National thread, not a pipe thread which is 1/8-27 either tapered or straight. I checked a Lowe's and it didn't have that size. Bolt Depot doesn't have that size threaded rod either. Good luck finding a tap or die. Personally, I don't believe it is wise to try to engage unmatched threads.

The OD of this thread is 5/16, much smaller than npt 1/8. It sure seems like it's not a pipe thread but a 5/16-32 machine thread.  I didn't see any threaded rod on McMaster Carr either in these sizes, which is why I suggested a die and 5/16 brass rod.

If I were to make them I'd take it as a challenge to work on my single point threading on the lathe, not something I have any skill at.

ethicalpaul

My lathe can't cut threads very well. Or I can't cut threads on it very well. Or both.

That's a very fine thread and the die is very affordable but good luck regardless

Jells

ethicalpaul said:

My lathe can't cut threads very well. Or I can't cut threads on it very well. Or both. 

That describes my situation well too, and there lies the challenge!  My Logan is 1940s era and does not have the quick change box, you need to disassemble the whole drivetrain to change the thread pitch.  Fortunately in this application, as I said, the threading does not need to be good quality...

AdmiralYoda

Thanks guys! It looks like there are two options....buy a 5/16-32 die and some rod and tap these yourself....

Or just buy a 5/16-32 bolt and drill it to the orifice size you prefer. Here is a socket head 5/16-32 screw. 3/4" long so either live with the extra length or cut it down.

$19.49 for a 5 pack, so $3.90 each. If you don't have a die already this may also be an option.

https://mcmaster.com/90044A207/

Chris_L

If you already have extra MoM orifices, you can just drill them out to the size you want. If you want to make the hole smaller, fill it with solder. Then drill it out to the smaller size.

ethicalpaul

That's an expensive screw

ChrisJ

ethicalpaul said:

That's an expensive screw

We don't talk to Paul about Mcmaster.................

SteamingatMohawk

OK, you got me. Some day I will learn to be more careful.

What does the 1/8" 32 mean in the drawing? I mistakenly assumed it mean 1/8-32 thread. I just got off the phone with a guy from Maid-O-Mist who said the thread is a 5/16-32, which is a UNEF threadform (Extra Fine).

Hopefully, I made up for my misreading of the drawing.

ethicalpaul

Huh, 5/16-32, you don't say! Who could have known that?

The 1/8" you saw I think is just referring to the thickness of the wall there, not very useful IMO. Or maybe the person who made the drawing thought it was 1/8" thread.

Jells

ethicalpaul said:

Huh, 5/16-32, you don't say! Who could have known that?

The 1/8" you saw I think is just referring to the thickness of the wall there, not very useful IMO. Or maybe the person who made the drawing thought it was 1/8" thread.

Interesting, that drawing conforms to neither screw nor pipe specification standards!

ChrisJ

Imagine that.
An inaccurate drawing.   That never happens eh @KC_Jones

KC_Jones

ChrisJ said:

Imagine that.
An inaccurate drawing.   That never happens eh @KC_Jones

Don’t get me started….

ChrisJ

KC_Jones said:

ChrisJ said:

Imagine that.
An inaccurate drawing.   That never happens eh @KC_Jones

Don’t get me started….

SteamingatMohawk

@ethicalpaul

I am embarrassed to post bad info. More than once in the recent past, I've messed up in looking at pipe dimensions vs. machine threads. I know better and still messed up. I won't bore everyone with how I saw something that didn't seem right, but ignored it.

The MoM guy confirmed the extra fine machine thread. I never got a clear explanation for the 1/8" other than speculation the same as your suggestion, which I agree is of little use.

ChrisJ

The drawing is useless and whoever did the dimensions didn't understand what they were doing.

That's pretty much it.

It happens a lot and it has nothing to do with the country the drawing was made in. This problem has no boundaries.

KC_Jones

ChrisJ said:

The drawing is useless and whoever did the dimensions didn't understand what they were doing.

That's pretty much it.

It happens a lot and it has nothing to do with the country the drawing was made in. This problem has no boundaries.

Dan's phrase about who gets to work on steam, pretty much applies to every industry.

Who gets to make drawings? Everyone!

Jells

KC_Jones said:

ChrisJ said:

The drawing is useless and whoever did the dimensions didn't understand what they were doing.

That's pretty much it.

It happens a lot and it has nothing to do with the country the drawing was made in. This problem has no boundaries.

Dan's phrase about who gets to work on steam, pretty much applies to every industry.

Who gets to make drawings? Everyone!

Don't leave out 'everyone' writing instruction sheets! It just amazes me that a company will do all the work to create and market a product and then can't be bothered to have a native English speaker proofread their instruction sheet. And then there's a whole genre of hilarious typos and misspellings in US business signs and awnings.

ChrisJ

And let's not forget those who go on a forum asking for help but then refuse to follow any and all advice given because they think they know better.

SteamingatMohawk

I'm old school and use a hard copy newspaper to do the puzzles and wake me up in the morning. It's amazing how either stupid or lazy the writers and/or editors are, including stuff from the national newspapers.

What I find most disrespectful is misspelled words in an obituary, no joke.

Jells

ChrisJ said:

And let's not forget those who go on a forum asking for help but then refuse to follow any and all advice given because they think they know better.

Yes, lets not forget you were all wrong. It was the burner not the venting or water. I did know better.

ChrisJ

Jells said:

And let's not forget those who go on a forum asking for help but then refuse to follow any and all advice given because they think they know better.

Yes, lets not forget you were all wrong. It was the burner not the venting or water. I did know better.

Ahhh the burner not venting. Or water.
Of course...


Whatever that means.

Jells

ChrisJ said:

Ahhh the burner not venting. Or water.
Of course...


Whatever that means.

Do you normally stalk people across threads just because they didn't listen to your wrong "free advice"? What next, going to stalk me across different websites like @wmgeorge ?

ChrisJ

Jells said:

Ahhh the burner not venting. Or water.
Of course...


Whatever that means.

Do you normally stalk people across threads just because they didn't listen to your wrong "free advice"? What next, going to stalk me across different websites like @wmgeorge?

Don't worry 
Stalk suggests I went out of my way to find you. I assure you that won't happen.

Jells

ChrisJ said:

Jells said:

ChrisJ said:

Ahhh the burner not venting. Or water.
Of course...


Whatever that means.

Do you normally stalk people across threads just because they didn't listen to your wrong "free advice"? What next, going to stalk me across different websites like @wmgeorge?

Don't worry
Stalk suggests I went out of my way to find you. I assure you that won't happen.



Why don't you take it a step further: if you cannot be in the same unrelated thread with me without attacking me for ignoring your incorrect advice, just ignore me and I will continue to ignore you. I have no doubt you have some expertise, but if you must be so personal, I can do without it.

wmgeorge

When you post on two related website Forums and Google finds those posts... is that Stalking?

After we finally got you to Look at the flame, you were right.

Erin Holohan Haskell

That's enough, guys. Arguing with one another doesn't help any of us. Let's move on.