Motor slipping on its rod.

[Victor Lazaro]

Hi,

My M-One analog motor has this bad habit of slipping on the 15mm rod and getting disengaged from the lens now and then.

Anyone has a good trick other than tightening the living hell out of the kipp handle?

[Nick Muller]

You can put a strip of gaff around the rod where the motor should be and try clamping over that. Kinda ghetto but it's worked in a pinch.

[Sam Law]

If mine slips I generally take a bongo tie and put it around the motor and the oposite rail. I've also heard the mounting the motor so the gear engages the lens at the exact top, bottom, or either side prevents slipage. While i don't understand the physics behind it I beleive it does slip considerably less when mounted that way

[Evrim KAYA]

Hey Victor,

 

I had similar issues as well with M-one slipping a while ago. my solution was using a standart style dogbone with both ends having a tightening screws instead of badly designed m-One dogbone with a single kipp serving both. also if you use a 19 to 15 adaptor make sure that the adaptors' cutout is placed motor rod clamps' cutout. since I made these changes I had zero slippage.

 

also you might wanna end the manual calibration of BFD a liitle bit before the lens' hard stop. as the M-one is extremely powerful it will push itself of the barrel when it hits the hard stop.

 

I hope this helps.

[Victor Lazaro]

I usually end the calibration right on the last mark and not on the hard stops. It usually pops off when the Ac reports the hand unit and the motor spins quickly to the position. I will have to look into a better dog bone. Good idea for the bongo across the other Rod.

[Alan Rencher]

I always mounted a rod above the lens, and I put the motor hanging down to the lens. Gravity kept it from jumping. Otherwise, I used a bongo as Sam has said.

[brett.mayfield]

Wasnt there a triangular system created sometime ago by Hill or a similar mind?

[axel ebermann]

Often a quick and 'non-messy' fix is to just add a 15mm bridge.

What happens is that the motor torque slightly bends the rod - aka pushes it away from your lens.
Then your motor gear comes off and slips.

The longer the rod and the 'bendier' the material (aluminum and carbon fiber are worse culprits than steel)
the worse it gets.

What the 15mm bridge does is tie your motor 'host' rod to another rod. Aka it cannot bend away that easily anymore.

This usually fixes the problem for me.

[Jerry Holway]

About the "triangular" system, I made one such system for old Heden motors. It used the dual 1/2 inch rods on the front of old CP dovetails and positively pushed the motor gear into the lens gear. The system did not flex and removed a lot of the mechanical slop - and therefore the annoying backlash - that folks had with Seitz and older wireless systems. However, with today's standard 15mm and 19mm rods, the solutions offered above should work just fine.

[Alec Jarnagin SOC]

Jerry, I remember this system and it was such a great device, especially on those video ENG lenses with the fine pitch!

 

Victor, good advice above. Regarding the dog leg, skip it if you can. The M1 has a lot of reach because of the size of the motor. I used to attach its integral sliding bracket (with round knob) directly to a rod on the camera when possible. That motor mount is native 19mm so try using a different 19-15 reducer if you have one (as well as a different 15mm rod). The reality is the machining on all of these things is not as precise as "critical parts" (as Greg Bubb says "you pay a lot more for each decimal place in accuracy"). Lastly, the M1 is a very fast & strong motor, remind your AC not to "floor" it unless necessary.

[Paul Check]

On 3/14/2016 at 12:23 PM, axel ebermann said:

Often a quick and 'non-messy' fix is to just add a 15mm bridge.

What happens is that the motor torque slightly bends the rod - aka pushes it away from your lens.
Then your motor gear comes off and slips.

The longer the rod and the 'bendier' the material (aluminum and carbon fiber are worse culprits than steel)
the worse it gets.

What the 15mm bridge does is tie your motor 'host' rod to another rod. Aka it cannot bend away that easily anymore.

This usually fixes the problem for me.

I'm going for Alex's solution x 2 for good measure for my macro lens that is a bit stiff in low T stop ranges: I'll place one clamp on either side of the motor, bridging the two rods together twice, eliminating any bend in the focus motor rod.