Need the help of a machinist...

[bobfowler]

I just got a Majestic head to use with my Calumet Green Monster. I have a Davis & Sanford Model C tripod which the head fits just fine, but I'd like to be able to use it on my Bogen 3036 as well. There are a couple of adapters out there (B&H will special order them) that will allow the slip on head to be used on my 3036, but I'm not crazy about the way they are made.

While I can handle woodwork and most sheet metal work, this one is beyond my current tool set. What I'd like is a single piece of steel machined as to the picture I've attached to this posting.

If you can help. please PM me with an estimate of the cost.

Thanks!

 

[Donald Qualls]

PM sent...

 

[bobfowler]

Woohoo!

Within just a few hours, I had a couple of very generous APUGers come to the rescue! Thanks guys!!!

 

[Charles Webb]

Bob,
Just read your post, not a difficult job, but it looks like everything is taken care of annd under controll now.

Charlie.............................

 

[ricksplace]

Just read the post. Easy part to make. I have a metal lathe with a milling attachment, and have made quite a few parts and adapters for photographer friends. Maybe I can help someone next time...

 

[Buster6X6]

Count me in If any one need something made that require a lathe or a mill I can help.

Greg

 

[claytume]

Can you guys with lathes cut 25tpi?

I don't have a job for you but many years ago I was asked to make adaptors for lens cells into a shutter, 25tpi.........couldn't do it and never seen a lathe that had that pitch on it.

Clayton

 

[JohnArs]

I need also one and tried several times to write emails to Adam at SK Grimes but the mails came back.
I need urgent a adapter lensboard for my Burke & James to Sinar boards any ideay whats going on with the Grimes company?

 

[bobfowler]

I need also one and tried several times to write emails to Adam at SK Grimes but the mails came back.
I need urgent a adapter lensboard for my Burke & James to Sinar boards any ideay whats going on with the Grimes company?

Are you trying to put B&J boards on a Sinar or the other way around? Lensboards and adapters are usually a piece of cake. I just came in from the shop where I was working on making an adapter to let me use the 4.5" square boards on my Toyo monorail.

 

[barryjyoung]

Hi Bob:

Let me know if things don't work out, I can help.

Barry Young
cameramaker.com

 

[barryjyoung]

Hi Clayton, yes, I an cut 25 tpi.

Can you guys with lathes cut 25tpi?

I don't have a job for you but many years ago I was asked to make adaptors for lens cells into a shutter, 25tpi.........couldn't do it and never seen a lathe that had that pitch on it.

Clayton

 

[ricksplace]

I checked my (very old) lathe. 24 and 26 tpi, no 25. Don't have the change gears to cut 25. Sorry.

 

[Donald Qualls]

Can you guys with lathes cut 25tpi?

I don't have a job for you but many years ago I was asked to make adaptors for lens cells into a shutter, 25tpi.........couldn't do it and never seen a lathe that had that pitch on it.

I'm pretty certain my lathe, with 16 TPI lead screw, can do this if I have the right gears (or order some inexpensive spares) for the change gear train. If I haven't bent my brain, I'd need 50:20 compounded to 50:80, but I don't think the original change gear set includes two 50 tooth gears. It'd be dead simple on a larger lathe with the very common 10 TPI screw, if it's got manual change gears, just a 20:50 or equivalent pair and enough no-change to complete the train.

It's very common, however, to find lathes with quick-change gearboxes for which there either doesn't exist a manual change train, or more likely the manual gears were put away years ago and no one now in the shop has ever seen them. Since 25 TPI isn't a standard thread, it's not found in most QC boxes.

The most modern of the small lathes have "electronic lead screws" using shaft encoders on the spindle, counter/divider systems, and stepper motors driving the lead screw, to cut any thread, either metric or inch, that you can specify -- right or left hand, front or rear tool post, inside or outside. Need to cut a 28.6 tpi to match some bizarre non-metric thread found on something? No problem...

 

[claytume]

The most modern of the small lathes have "electronic lead screws" using shaft encoders on the spindle, counter/divider systems, and stepper motors driving the lead screw, to cut any thread, either metric or inch, that you can specify -- right or left hand, front or rear tool post, inside or outside. Need to cut a 28.6 tpi to match some bizarre non-metric thread found on something? No problem...

Donald..........never seen or heard of these.........anywhere on the net I can see one?

Clayton

 

[claytume]

It's very common, however, to find lathes with quick-change gearboxes for which there either doesn't exist a manual change train, or more likely the manual gears were put away years ago and no one now in the shop has ever seen them. Since 25 TPI isn't a standard thread, it's not found in most QC boxes.

Yes the lathe I had access to had a QC box and no change gears. The shutter was a #5, can't remember the brand. Seemed very odd to me at the time a 25 tpi thread, never seen another one.

Clayton

 

[S.K. Grimes]

In a pinch, one could probably get away with using a 1.0 thread to fit a 25 TPI. As long as the length of the threaded section is short enough to avoid jamming and the thread was cut loose.

If you take the decimal equivilent of 25TPI (1/25 = .04), it is nearly the same as a 1.0M pitch (1.0/25.4 = .0394"). Granted, it is best to use the right thread. And as Donald pointed out, there are lathes today which use the "electronic lead screws" which make machining the right threads a dream.

Adam Dau

 

[Ed Sukach]

Can you guys with lathes cut 25tpi?
I don't have a job for you but many years ago I was asked to make adaptors for lens cells into a shutter, 25tpi.........couldn't do it and never seen a lathe that had that pitch on it.

I can't ever remember coming across a 25 T.P.I. thread. I wonder,

1) How was the pitch determined? ... by measurement or ? If someone used the folding "Thread Pitch Gages", they might well mistake a 1 millimeter pitch for ...? Then again, I can't ever remember seeing a folding thread pitch gauge (National Thread Form) with a 25 T.P.I leaf.

2) Is it possible that the thread in question had something other than a 60 degree National/ Metric form? I don't know ... but it might have been something like a Whitworth (55 degree rounded) or Lowenhertz 53 degrees, 30 minutes; or -- or Dardelet Self-Locking ... or ..... I don't know what the "standard" pitches were for those.

 

[claytume]

In a pinch, one could probably get away with using a 1.0 thread to fit a 25 TPI. As long as the length of the threaded section is short enough to avoid jamming and the thread was cut loose.

If you take the decimal equivilent of 25TPI (1/25 = .04), it is nearly the same as a 1.0M pitch (1.0/25.4 = .0394"). Granted, it is best to use the right thread. And as Donald pointed out, there are lathes today which use the "electronic lead screws" which make machining the right threads a dream.

Adam Dau

Yes I thought of that one, would work like you say if the thread was cut loose and was very short.

Clayton

 

[claytume]

I can't ever remember coming across a 25 T.P.I. thread. I wonder,

1) How was the pitch determined? ... by measurement or ? If someone used the folding "Thread Pitch Gages", they might well mistake a 1 millimeter pitch for ...? Then again, I can't ever remember seeing a folding thread pitch gauge (National Thread Form) with a 25 T.P.I leaf.

Was measured with screw pitch gauges, both metric and imperial......yep I've never seen one before either.

Clayton

 

[barryjyoung]

25 tpi is used on many old wood working tools to make the screws proprietary. The biggest offender by far was Stanley Tool Works. I made a living for a few months making replacement screws for the venerable old Stanley #45 and #55 combination planes. I suspect that this thread may be oddball for similar reasons.


I had to do the math on my change gears in order to turn 25 tpi. Almost all lathes with screwcutting ability can be used to make oddball threads that are not listed on the change gear charts. It is a matter of fractions. If you have a 16 tpi leadscrew then the fraction is 16/25 or .64 turns of the leadscrew for each turn of the spindle. Not many 16 tooth change gears out there, so multiply the fraction by two to get 32/50. Those gears I have. Engage a 32 tooth gear with the bull gear on the spindle and slap a 50 on the end of the leadscrew. Use an idler gear of any size to hook them together and you have 25tpi. You can get some really odd pitches this way. Just remember that gear ratios are merely fractions, maintain the relationship between the numerator and denominator and you will be fine. This also works with compound gearing which is where you can get some incredibly odd pitches. How about 114.6 tpi? Hmmm??? Multiply the possibilities immensely if you have a quick change gearbox on the leadscrew.

For an excellent dissertation on figuring out your own change gear combos, I recommend Using the Small Lathe by L.C. Mason. It is published by Tee Publications in England

 

[Donald Qualls]

Donald..........never seen or heard of these.........anywhere on the net I can see one?

They're the simplest form of CNC for a lathe -- look at threading setups for Taig or Sherline lathes, neither of which have change gears available to do traditional thread cutting. In their simplest form, they use an optical encoder on the spindle, and each spindle pulse is converted to some set number of lead screw stepper steps, giving a set amount of advance per revolution. Using an encoding wheel with enough teeth, combined with the response time and inertia of the stepper system, gives smooth motion.

Start here.

 

[DavidV]

I'm having a similar part made at a local machine shop here in Baltimore, since Bencher doesn't supply them in that size any longer. My local guy says $40 or so. I should get it back shortly. Then I can use my 8x10...