I have a Dana Dolly, how to add drag ???? at DVinfo.net

Brent Kaplan · June 11th, 2012, 01:23 PM

I want to slow it down , any suggestions on how to add drag?

Thanks

Alastair Traill · June 11th, 2012, 10:20 PM

Hi Brent,

I am currently making a slider for my own use and one of my requirements is that I want to be able to control speed. For some applications I will want it motorized and for others I plan to experiment with fluid damping using a silicone fluid. In my current design the rollers are attached to an axle that rotates in a bearing. The axle will protrude beyond the bearing and slip into a fluid filled cylinder. As the axle rotates within the stationary cylinder there will be drag generated. The amount of drag will depend on the rate of rotation as generated by the dolly’s movement, the thickness and viscosity of the fluid film and the diameter of the axle. The success or otherwise of this approach is dependent on the friction between dolly rollers and track. An alternative is to drag the dolly with a cable connected to a fluid damped hand powered winch.

As an example of what can be done with a silicone fluid I can attach a boom to my fluid damped tripod head and with suitable balancing can obtain hands free lifts or descents at controlled rates. By hanging a chain on the descending end of the boom I can also achieve very gentle stops. All very useful.

Bill Hamell · June 11th, 2012, 11:05 PM

I have three sliders an Igus, a CineSlider and a Shuttle Pod the first two have drag control but the Shuttle Pod does not I hold it so some part of my hand drags on the rail, this way I can control the drag and speed myself.

Jacques Mersereau · June 26th, 2012, 05:03 PM

We just took delivery of a Dana dolly 'rental kit'. I set it up with 8' pipes that sit on top of Matthews lowboy rolling stands. Used a Vinten Vision 3 head and the gool ol' EX3. I love it. BUTTER SMOOTH, so I am not sure what it exactly is you are looking to do as it certainly makes the grade for me.

Brent Kaplan · June 26th, 2012, 08:45 PM

Im using it with a ex3 as well and its real smooth, Im trying to slow it down and get a consistent slide.

Alastair Traill · June 27th, 2012, 07:11 AM

Hi brent,
How slow do you want? What have you tried?
Earlier I mentioned a slider that I am developing. So far I have tested it with a motor that gives me speeds of 0.5 mm/sec to ~ 9mm /sec. - a range that I want to try for some macro work. I will also be setting up a another motor for higher speeds. As mentioned I have also added some fluid damping that gives me better manual control, this turned out to be much easier than I expected.

Jacques Mersereau · June 27th, 2012, 07:41 AM

It sounds like you want motor control, but again, I am not sure what kind of stuff you are doing.

For me, the Dana dolly is soooo smooth, I can creep it as slow as I would ever want or need for shooting something live. If you go too slow, the movement it gives the camera is defeated.
IMO, if you add drag, it will likely hiccup.

If you are looking for timelapse, then it is not the right tool without some expensive modification.

June 11th, 2012, 01:23 PM	#1
Brent Kaplan Regular Crew Join Date: Nov 2010 Location: Los Angeles,CA Posts: 166	I have a Dana Dolly, how to add drag ???? I want to slow it down , any suggestions on how to add drag? Thanks

June 11th, 2012, 10:20 PM	#2
Alastair Traill Major Player Join Date: Nov 2008 Location: Melbourne Australia Posts: 626	Re: I have a Dana Dolly, how to add drag ???? Hi Brent, I am currently making a slider for my own use and one of my requirements is that I want to be able to control speed. For some applications I will want it motorized and for others I plan to experiment with fluid damping using a silicone fluid. In my current design the rollers are attached to an axle that rotates in a bearing. The axle will protrude beyond the bearing and slip into a fluid filled cylinder. As the axle rotates within the stationary cylinder there will be drag generated. The amount of drag will depend on the rate of rotation as generated by the dolly’s movement, the thickness and viscosity of the fluid film and the diameter of the axle. The success or otherwise of this approach is dependent on the friction between dolly rollers and track. An alternative is to drag the dolly with a cable connected to a fluid damped hand powered winch. As an example of what can be done with a silicone fluid I can attach a boom to my fluid damped tripod head and with suitable balancing can obtain hands free lifts or descents at controlled rates. By hanging a chain on the descending end of the boom I can also achieve very gentle stops. All very useful.

June 11th, 2012, 11:05 PM	#3
Bill Hamell Major Player Join Date: Aug 2004 Location: Mystic Ct. Posts: 477	Re: I have a Dana Dolly, how to add drag ???? I have three sliders an Igus, a CineSlider and a Shuttle Pod the first two have drag control but the Shuttle Pod does not I hold it so some part of my hand drags on the rail, this way I can control the drag and speed myself. __________________ Cinematographers Bring Shadow To Light

June 26th, 2012, 05:03 PM	#4
Jacques Mersereau Trustee Join Date: Mar 2002 Location: Ann Arbor, MI Posts: 1,334	Re: I have a Dana Dolly, how to add drag ???? We just took delivery of a Dana dolly 'rental kit'. I set it up with 8' pipes that sit on top of Matthews lowboy rolling stands. Used a Vinten Vision 3 head and the gool ol' EX3. I love it. BUTTER SMOOTH, so I am not sure what it exactly is you are looking to do as it certainly makes the grade for me. __________________ Jacques Mersereau University of Michigan-Video Studio Manager

June 26th, 2012, 08:45 PM	#5
Brent Kaplan Regular Crew Join Date: Nov 2010 Location: Los Angeles,CA Posts: 166	Re: I have a Dana Dolly, how to add drag ???? Im using it with a ex3 as well and its real smooth, Im trying to slow it down and get a consistent slide.

June 27th, 2012, 07:11 AM	#6
Alastair Traill Major Player Join Date: Nov 2008 Location: Melbourne Australia Posts: 626	Re: I have a Dana Dolly, how to add drag ???? Hi brent, How slow do you want? What have you tried? Earlier I mentioned a slider that I am developing. So far I have tested it with a motor that gives me speeds of 0.5 mm/sec to ~ 9mm /sec. - a range that I want to try for some macro work. I will also be setting up a another motor for higher speeds. As mentioned I have also added some fluid damping that gives me better manual control, this turned out to be much easier than I expected.

June 27th, 2012, 07:41 AM	#7
Jacques Mersereau Trustee Join Date: Mar 2002 Location: Ann Arbor, MI Posts: 1,334	Re: I have a Dana Dolly, how to add drag ???? It sounds like you want motor control, but again, I am not sure what kind of stuff you are doing. For me, the Dana dolly is soooo smooth, I can creep it as slow as I would ever want or need for shooting something live. If you go too slow, the movement it gives the camera is defeated. IMO, if you add drag, it will likely hiccup. If you are looking for timelapse, then it is not the right tool without some expensive modification. __________________ Jacques Mersereau University of Michigan-Video Studio Manager