Cinematography Mailing List - CML

Laying Dolly Track


Can anyone tell me if there are any tricks to laying a dolly track so that you don't have any bumps or wobbles? Is there a "How to" website somewhere that talk about this?


Rick Tullis

>Can anyone tell me if there are any tricks to laying a dolly track so that >you don't have any bumps or wobbles? Is there a "How to" website >somewhere that talk about this?

There's a few things...

1) Use good track for starters. Film-air track is superior to Mathews track in that the connections are better.
2) Proper cribbing is next with plenty of wood depending on the
circumstance, if needed.
3) Good dolly wheels! Make sure to block the dolly up on a good set of speed wheels and don't use the stock rubber wheels.
4) Most importantly, a GOOD dolly grip will take away all wobbles.

David Suddaby

I am a UK grip with over 5 years of experience.

if you are using heavy duty track (in the UK moy or Arri/Ronford baker track) then:

I lay track using the following procedure:

1/. Roughly lay out all the track pieces
2/. If the ground is very uneven then lay the track one piece at a time
3/. On uneven ground pick the section you believe to be the highest point
4/. At one end of your chosen first piece of track level just that one end width wise
5/. At the other end of the same piece level down one side
6/. Then level across
7/. This piece should now be perfectly flat in all directions
8/. You may need some one to stand on the track at the first end when you move to the other end
9/. If this has not worked you must start again from scratch, don't try to fix it
10/. If this piece is now flat you can fill in the sleepers in between the two ends
11/. VERY IMPORTANT : you must only slide in the middle wedges until they stop, use no force to push them tight, you will only be lifting the track.
12/. Now with someone standing on the set piece connect to next track piece, don't tighten the track ties until this next piece is level

That's about it

Matt Lopez-dias

The only thing I'd add to Matt Lopez-Dias's track laying instructions are that when Matt suggests that you have someone stand on track they must stand only on the rails. Never stand or walk on the cross ties. Standing on or walking on the cross ties will bend the cross ties so that the track will never again lay flat on the floor.

Jim Forrester
Student Production Services
Point Park University

>Can anyone tell me if there are any tricks to laying a dolly track

One good trick is getting down on all four's and getting your eye right at the track. You can often get things quite straight and level just by eye.

You can also fashion caps that fit the end of track and attach a taught string to each end of the track - it is then quite obvious what is needed to put things right.

My favourite trick is hiring the best dolly grip I can get and making sure we get FilmAir track!

Those plastic door framing wedges are useful...

If you are sceptical about the quality of the track available check EVERY piece they have and pick the stuff that works best.

David Perrault, CSC

Many paths to the kingdom.

Matt's system will work beautifully...

...and here's the system I used back in the day for live action and still these days for motion control track:

1/. Determine the high point of your track run...outside this is more important than in a level room...bearing in mind that concrete floors in industrial spaces are almost never level as they are graded slightly to drain water to one end (usually the end where all the cardboard boxes are stacked)

2/. Lay out your track sections loosely, not locking the turnbuckles or camming latches yet. Sight down the run, make sure it is straight and loosely lock the sections together. DO NOT OVERTIGHTEN THE LATCHES...for now, looser is better than tighter. If The run is wavey enough in height, don't lock any sections that would force the weight of one section to bear down on the next section.

3/. Roughly level one side of the whole run longitudinally by starting at either the high end or the highest point. Don't worry about the other rail yet. Level only the track ends, not the intermittent ties yet (assuming your track is not all bent.

4/. Now go back down the line raising the other rail - using your level crosswise to the track and raising it to the levelled rail's level, again only levelling the joints of the track. Lock any loose sections and fill in the middle ties, MAKING SURE NOT TO RAISE THE TRACK while doing so.

If it is a long run, lie down and eyeball it again to make sure you are not making a slalom course.

Several notes :

1/. Get in the habit of using your level in the same direction down the track and crosswise...if your level is a bit off from being dropped while you were off the set, you are better off with a flat even slightly unlevel track than one that corrects first one way and then the other depending on which way around you used your level. That's what levelling heads on dollies are for.

2/. DO NOT OVERTIGHTEN SECTIONS! Since the buckles pull tie to tie (except on the exceptionally well designed G I extruded track which pulls rail to rail) They are obviously pulling from well below the centerline of the track. If you overtighten, you may force the track to crown right at the connection which will result in a tiny bump and a visible gap You will often find rental track that has been overtightened and then filed down by some well meaning grip-like person...causing a problem and then exacerbating it. (Many wheel designs don't even ride the top of the track, but rather on the top sides.)

If you are on a really wide lens, worry more about how the shot looks than how it feels. This takes an act of faith sometimes, but it is all about the light that hits the film, not the operator's posterior. (awaiting flames on this)

3/. If you have a piece of track that is crowned or bent down from previous abuse (often involving running a heavy jib with insufficient cribbing, you may need to run the dolly down the track to check the level with the weight of the dolly on it once you have shimmed up all the ties.

4/. Put at least a little bit of cribbing under even the highest point so that if you judged a bit wrong, you still have enough room to get a little bit of wedge under the adjacent ties

5/. If running a jib arm, especially a long one with a lot of weight in the bucket, loosely crib the track between the ties with single wedges so you don't cause # 3 above.

6/. I find two wedges in opposite directions slid together work better than stacking wedges fat end to fat end...the angle caused that way may encourage the track to shift down the ramp you have created.

7/. Shimming with the wedges parallel to the track is handy in situations where actors or clients are likely to walk near the track - crosswise wedges are more likely to be kicked out.

In the motion control world, we will often screw the wedges to the floor...obviously not a good idea on location interiors and rarely required in normal live action work.

I have levelled 100 ft runs of motion control track with a surveyors optical level and a stick... spinning lasers work too (if the ambient light is not too strong) but this is really only necessary in our twitchy world of visual effects.

Set the level on its tripod at one end and use the stick to raise or lower each joint, using the measuring stick to determine how much.) You can rent an optical level for a few bucks a day or buy one for a few hundred. If you try this on a live action set for a normal shot, you will be laughed off the set, but it is not a bad way to work if you are doing a really long run over uneven ground (assuming you have the time)

I love the GI track and a number of the aluminium extrusion tracks work well also... but if it has been abused, the ends get dinged more easily than steel track and have sometimes been poorly filed. If using speed wheels aka trays, aka skateboard wheels aka channels, you are not even riding on the top of the track but on the45 degrees away from the top on each side...if you are having problems at a joint, look where the wheels are going, not the top.

The extrusion tracks are generally stiffer in the vertical axis but
still need to be shimmed properly...since the track does not sit on the ties, but rather on the ground with the ties acting as spacers, be sure to shim the track and not just the ties...some of them (especially in rental stock) may have some slop in the hinge joint between the ties and the rails.

Practice . . . practice . . .practice

Mark Weingartner
(used to grip a bit in the olden days)
LA based VFX DP/Supervisor

As I said, this is but one path to the kingdom...

David Perrault, CSC

>>One good trick is getting down on all four's and getting your eye right at >the track. You can often get things quite straight and level just by eye.

As a former IA 52 grip in NYC that is the way we all did it . Find the "high point" of the track get down on all fours and have your second "fill in the air" with cribbage. once you get one side of the track good, you can go in with the level and match up the other side. It's really pretty easy unless you have a very uneven surface.

Nick Hoffman IA600DPnyc

The only thing I would add, is to clamp a mafer at one end of the track and a second mafer on the opposite rail, at the other end. Be sure that the pin is down and pointing at the other rail. A sand bag across the rail, in front of the mafer, acts as a soft landing for a runaway dolly and won't gauge the wheels.

I have mainly used skate wheel dollies, so when I set my marks, I start by hanging an inverted T piece of tape off the back of the dolly that hangs down and acts as the witness. My start mark is a horizontal piece of tape on the ground, or the sleeper. The end mark is an inverted V, with the point being the stopping point. The V is usually two, or three feet long and gives me enough time to feather the move.

Mark Sasahara

Your right sorry, I am used to track built by Ronford-Baker here in the UK. His track sleepers are made from inch think aluminium box section and as such are very very strong. On any other track maybe it's best to use a few sand/shot bags on the tracks themselves.

Matt Lopez-Dias

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