Derby Leg Pipe Thread Size?

[William Johnson]

Hello All,

I know the leg to body is a male thread 1/2"-13 but what is the bigger outer pipe-like thread size? It appears to be a ~1/2" pipe but ~32 TPI Straight. Is this correct? What do you think?

Yep, I did get the 'Green' Derby back again. It's a very nice, very clean, not used much Green DB E9. I moved my floor pedals to the right one position - the 2nd starting position (when I got it the ABC were all the way to the left). I am shortening the legs ~ 2" and two of the leg pipe threads got damaged somehow, so I need to chase with die. I am referring to the big leg pipe threads.

Thanks,

Billy

[Ransom Beers]

The MSI200-10B from Vu is a sturdy, durable microphone stand with a low-profile, cast-iron base. "The 8-lb., circular cast-iron base has four anti-skid rubber feet on the bottom and measures 7/8" at the edge and 1 5/8" at the center. Its 7/8" and 5/8" diameter steel tubes are adjustable from 32.5" to 60.5"via the metal clutch and terminates in the industry standard 5/8" thread. This affordable microphone stand is ideal for churches, schools, clubs, conference rooms, music venues or anywhere PA systems are being used."

I found this online & it seems right,it is not a TPI or a straight pipe thrd. but a machine thread,it would be a 5/8-18 or 7/8-14.Might be a bit of a chore to find a die but were it me I'd take it to a local machine shop & have them chase the thrd.,that way you'll be sure it's right.

[William Johnson]

I do count ~ 24 TPI and diameter measures 3/4", so if I am accurate its a 3/4-24 UNF machine thread. Like you say, and I agree, it's a straight machine thread. Re-counting 1/2" of threads (~12) suggests 24 TPI. The diameter does measure 3/4" using outside calipers.

I think 3/4-24 UNF is a standard machine thread with its UNC (coarse cousin) being 18 TPI.

What do ya'll think?

Thanks,
billy

[Jerry Overstreet]

I believe the large tube threads are 7/8-27 UNS, Unified National Special thread. You can check with your local music store as the mic stand clutch, base, tube are the same size. Bit of an uncommon size thread if you've ever tried to repair one, not a NPT [national pipe] neither a national fine or coarse either.

That is if I am understanding your description correctly.

[Ransom Beers]

I think the 5/8-18 may be the small pc. that slides into the larger one.I'm not very familiar with those thrds. as my yrs. in the machine shop dealt with standard thrds. related to aircraft mfg.

[William Johnson]

Jerry and others, I think it's the 7/8-27 as well. I re-counted threads and re-measured. The legs only have 1/2" of threads so I had to count and multiply by 2 to get TPI.

Thanks for everyone's help.

Later, Billy

[Jerry Overstreet]

Billy, if your tube is not bent up, you might consider buying a thread gauge to verify the thread size then a thread file to repair them depending on expense. Or, you might have a competent machine shop do it for you.

[William Johnson]

I actually got a little lucky and used a triangular file to dress-out the damaged threads. Yea, the pipe was not bent or damaged so it all worked out great!

So now, if moving my ABC pedal starting position over 1 space helps me out, I'm ready to start playing the Green Derby again. The steel appears to have never been played much at all! Seriously, I am not sure if the case was ever loaded in a car, truck, trailer or bus, etc. It is spotless.

As some of you know, this Derby was built as a gift (Derby order was placed by an individual) to Mr. L. Green but he either, never picked it up or never played it, so it drifted to maybe 1-2 others besides myself. I did confirm this by taking it up to Derby a few years back.

Thanks for the help,

Billy