Threading size problem

[powderhorn01]

I am in the process of building one of the Elmers Engines, the Grasshopper, and have run into an odball thread spec. It calls for a 3/16-40 thread, and I have not been able to find anything that is even close. I have checked Enco, McMaster, MSC, and MicroMark without any luck on finding anything close. I am thinking about a 10-32 as a replacement, but till I get the metal to size I am not sure if it will work. ???

 

[Hilmar]

powderhorn01

Yes there is such a thing

Try Coles Power Models in Texas, I don't have the address
Hilmar

 

[GailInNM]

As Hilmar says, they are available, but not very common.
In the US, a very acceptable substitute is 10-40 which although listed as a special thread in most places is quite commonly available. It's what I use. It is only 0.003 larger in diameter.
Gail in NM

 

[rleete]

Single point it; you can make any thread you have the gearing for.

 

[kvom]

If 10-40 is only .003 larger then so is 10-32, which also ought to work.

 

[Metal Butcher]

I am in the process of building one of the Elmers Engines, the Grasshopper, and have run into an odball thread spec. It calls for a 3/16-40 thread, and I have not been able to find anything that is even close. I have checked Enco, McMaster, MSC, and MicroMark without any luck on finding anything close. I am thinking about a 10-32 as a replacement, but till I get the metal to size I am not sure if it will work. ???

I got all my 3/16" 40 tpi taps and dies from PMR. They are really good quality, you won't be dispirited. (today's new word)

http://www.pmresearchinc.com/store/home.php?cat=314

-MB

 

[arnoldb]

I just used M5 for the pack nuts and gland threads for the Grasshopper.

Remember, you'll need taps and a die nut of whichever thread size you choose - unless you want to single-point turn the threads on the packing nuts.

Regards, Arnold

 

[Jasonb]

If you want to use commercial steam fittings (even in the US) then its best to stick with 3/16 x 40ME as thats the usual thread type use, all PMRs smaller fittings are threaded with ME series threads. Here in the UK its also the standard thread form for fittings upto about 1/2".

Jason

 

[tel]

Liney also have 'em, very reasonably priced.

http://www.lineymachine.com/threadtap31640tpi-p-3347.html

http://www.lineymachine.com/die31640mestraight-p-3304.html?osCsid=150938de39e1907b2ab6edecc5e33ebe

I'm sort of amazed they are not as common and widely available as they are here or in the UK.

 

[Loose nut]

If you want to use commercial steam fittings (even in the US) then its best to stick with 3/16 x 40ME as thats the usual thread type use, all PMRs smaller fittings are threaded with ME series threads. Here in the UK its also the standard thread form for fittings upto about 1/2".

Jason

If by ME threads you mean Model Engineering series then they are 55 deg Whitworth thread form, he should check and see what his fittings are.

 

[GWRdriver]

. . . you won't be dispirited. (today's new word)

;D ;D ;D Good show!

FWIW . . . I use a lot of ME 32 and 40 TPI series threads. A few years ago I bought a few 32 and 40 TPI HSS taps and dies from MSC (usual disclaimer) which were sold in the "Special threads" listings and tended to be cheaper and better than the carbon steel taps & dies from the UK, not to mention 24hr delivery. (There are reasons for using carbon steel but I prefer HSS.) I quickly discovered that the US thread form if used with British ME thread fittings will foul (ie, come to a halt when using finger tightening) after about 3 turns. The fouling is caused not by the difference in degrees but by the difference in crown and root profiles which are pointed in the US form and radiused in the British form. I still use these taps and dies regularly but if I have to mix fittings I must run a die (or tap) over (or through) one side or the other to eliminate the foul at the crown OR root which occurs at one or the other, not both.