Hi!
Im just starting to build some kind of re-usable "stage" for my upcoming stop motion masterpieces. Im probably going to get into the whole Moco question, with stepper motors and arduinos and sliders etc.
Right now I have a slider, mounted on tripods, a few good lights... and...
An old table that I think would make the basis for a good "stage".
Before I jump right in Id like to ask a fw very simple questions to save me the heartache of finding out the long way. Hope you guys can oblige with your experience.

1) What is a good working height? Currently the table is just 40cms high and I was thing to increase it to about 1m, or 90cms. Assuming I will be sitting here for many hours leaning in and out, what would be a good ergonomic hight?

2)I have variable colour on my lights, and I may get arty (probably actually) with gels etc, but would you normally shoot tungsten or daylight colour?

3)Assuming I only have a regular slider for left/right moves, Are there any cool ways to track in and out (In the old days I used to move the whole scene (on squared paper to time to moves) towards the camera, but that was completely wrong really as the lights didnt move, so shadows would move... I didn't notice it much then, but I do now. Im think of making sliders on each side of my table that the camera slider can move on... Is this a known way? How DO you do tracks?

Im sure there will be many more questions... but maybe...

Can I ask?
Can you guys share pics of your stages, if they seem relevant to what IM try to achieve.
Maybe I can make a "build series" ? so here's my starting place...

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Impressive Simon!
Can I ask, did you buy the cogs someplace? I feel I can probably make a few custom bits, buy a few brackets and camera mount parts, but the cogs and bearings Im not so sure about. Did you copy/follow a particular design, or just design from scratch on paper?
Personally, Im pretty good and making things (im am animator, its 80% of the job) but lack the metal working tools, so am kind of looking out for parts I can re-purpose. Like pan tilt heads that can be hacked to be motorises etc,...

Hi Mark

Yes, the gears and bearings came from Servocity. If you are in the UK, they are distributed by Active Robots.

I took the same approach as you, and found I was able to source quite a lot of parts. For example, the camera mount is a Fotomate 3 (the long one) with an extra Fotomate slider mounted on it. The right angle camera platform is Arca-Swiss or similar. I have made a new, more geared down focus controller using a manual focus controller as sold for camera rigs.

I will be taking a slightly different approach for the next rig, partly as I have bought a 3D printer. So the only stepper motors that have sufficiently small backlash are the high precision ones, and you need something like 30:1 reduction on most of the axes. My new approach will be to see if I can achieve this with worm gears, as there is minimal backlash and the advantage that the gears will prevent anything moving even when the power is off. Servocity sell some nice looking worm gears.

If going down the conventional route, the gears I used were 100T servocity ones with 1" bore, driven by 30T gears on the motor (which was already geared down). I also make sure that micro-stepping is enabled on the drivers... but that's another whole ballpark. The 1" bearings and shafts from Servocity I rate highly, because a larger diameter gives greater accuracy and they have fantastic pillow blocks for mounting. You can also get an Aviation connector through the tube.

I recommend going for the Aviation connectors, and you will need quite a lot. The 4 pin version is what you need. I sourced wire cable from car suppliers.

For the track, my big rig used an aluminium ladder, and it works very well. On that I ran some scooter wheels, but we needed to remove the rubber tyres, so they are not perfect. There are some nice nylon ones available now. My track was 2m long (!), and I will be going for something just 1m long next time. You need ball bearings on everything that moves.

On top of the track is a large square dolly with two plastic discs, one attached to the dolly, one to the tower. These have 14mm ball bearings running between them, held captive by an mdf ball cage. There is a 6mm pin running in a bearing in the middle. It swings round effortlessly.

The tower was constructed from birch ply and has a thrust bearing at the top onto which the jib arm goes. The jib arm is controlled by a ballscrew operated by a motor attached to the tower. It works very nicely, better than Edu Puertas's revised arrangement for his rig, as it does not stick out but up. 

At the end of the jib arm is the pan/tilt head, which you have seen pics of. 

The electronics are controlled by an Arduino Mega 2560 with black box drivers, which I consider to be the best arrangement as they are optically isolated and you can easily select micro-stepping without fiddling around with bridges etc, I also have an Arduino Uno with CNC shield, ut have not got this working yet. I made the mistake of just using the sketch provided by DF, and it blew the Arduino. There is a thread on their forum about adapting a sketch for the CNC shield.

The smaller rig runs on a track made from 2 stainless tubes, with ball bearings on the dolly. The tubes are 200mm apart, as I consider the normal camera sliders that people adapt to have too narrow a footprint to be stable. The 3D printer will enable me to make new end pieces and utilise some 40/40 extrusions for maximum stability. I will keep to this width.

The small dolly track is belt driven, and I would consider using belts instead of gears next time. With either you have to have a tensioning mechanism or a means of meshing the gears closely so there is minimal backlash - that is your enemy, so precision everywhere is essential!

Hope this helps!

Helps? Thats fantastic.. Of course I dont understand all of it right now, IM checking out the things you are using, and already I see the Servocity site to be an immense source of stuff...
BTW, Did you mean 100T gears? You mean these?Not using the classic NEMA17´s???

Poring over all the cool bits and bobs on that site I was wondering, does anyone know whether these things are any use?


It's the hardware Im after, I'm pretty sure I can fix the motors and arduino stuff... OH! YES, and thanks for the tip that the DF sketch blew up the chip... that not good... Will try to find the thread of which you speak, cos, yes... that's exactly the way I was intending on doing it.

Mark


OK.. I pretty much see that these things despite being cheap as chips, and therefore appealed are kinda tied to using servo motors so I spose useless... Was gonna edit my stupidity, but the 15mins were just up... I guess it's out now...

Yes, for a motion control rig you need stepper motors that can move tiny increments. So most of those units would have to be cannibalised to make them work for stopmo.

Can I suggest you have a look at the black box drivers? Wiring them up to the Arduino Mega is not too difficult (instructions are in the DF Resources folder where you find the Arduino sketch - I mean they are in the sketch itself. Definitely the way for me, as they are forgiving of mistakes, can take different currents and micro steps etc. I put them all into an old desktop computer cabinet, with the connector sockets and a switch on the side.

Main thing always to remember is to turn off the power before disconnecting everything. 

Run them off 24V.

The gears are as you indicated. Not quite sure what you mean by 'not using the classic Nema 17s?' The Nema 17 geared motor is not very visible in that shot, but it is there...

You are talking about this?
https://openbuilds.com/builds/blackbox-motion-control-system.8320/
And this replaces all the little small red drivers typically found on Amazon?

No. Sorry, if only it were that easy!

This is what I am referring to

https://www.amazon.co.uk/TB6600-Stepper-Driver-Controller-Segments/...

There are a load of similar things on eBay and Amazon. They have dip switches for selecting the voltage input, and for selecting the microsteps. They are also optically isolated, which means you are less likely to burn stuff out if you accidentally disconnect.

They go between the Arduino and the stepper motor. The Arduino is powered off the computer, so at 5V, but this is nowhere near powerful enough to drive a motor, so the driver translates the step and direction signals from the Arduino into a higher voltage input to the motor. You therefore need one per motor/axis. That's why I use a desktop cabinet!

I have used stuff like the big easy driver in the past, and had nothing but grief until I realised that they were only rated to 1A, so were blowing when I put some load on a motor. I think the purple drivers sold with the shields are better, 8825 they are called. But they only cope with up to 1.5A.  The ones above can handle 4A, so you will not blow them under any circumstances.

When purchasing steppers, have a look at omc stepper online, who seem to have the biggest stock. You need 4 wire bipolar steppers, and they state their amperage and torque. To move a moco rig you need plenty of torque, which is why an ungeared motor is no good. But the standard geared ones are quite sloppy, and I have found the backlash to be unacceptable. The high precision ones are much better, irritatingly they have a non standard mount... That is why I am investigating worm drives, as they reputedly have very little backlash.

BTW all this is gold dust. It took me several years and too much money to learn it!



Simon Tytherleigh said:

BTW all this is gold dust. It took me several years and too much money to learn it!

Oh believe me I can imagine that, and appreciate it so much!
For years I've been building a modular synth, much the same rabbit hole.

Compared to that spaghetti, this is very simple!

What I am aiming to do is to come up with some 3D printable parts for a moco rig, that will utilise standard extrusions etc. It will ease the whole making by hand process, especially as my tools are really for woodworking and metalworking is a bit of a stretch.

But it does work, and using it with Dragonframe is wonderful, completely transforms what can be done with a shot.

Thanks for all your valuable advice Simon. I can see its a minefield, and I should have read every darn thread on this site before diving in.
I have already ordered the X Slider from Ratrigs, as prviously recomended, no sooner as I did, I found the link to https://openbuildspartstore.com/c-beam-linear-actuator-bundle/ which alos look awesom... Im certain a short on of them could live happily on top of another longer one...

But just one quick question Simon, when you said, "No. Sorry, if only it were that easy!" referring to this thing called Black box... whats actually wrong with that?
Its seems to be able to handle Nemo17s ok? and 4 from one box, which I would have thought was a bit of an advantage over the ones you posted...
https://docs.openbuilds.com/blackbox/#321-nema17.html
Oh Price perhaps...? Which is.. I must say... not un-important.

M

What I meant by not that easy is that I could not find any off-the-shelf options that would do what I needed, i.e. up to six axes, controllable through DF and their Arduino sketch. This was a few years ago, so things may have changed. 

My reference to 'black box' may also have been confusing; it only referred to the colour of the drivers and the fact they have a cover at all. I wsasn't previously aware of the offerings from Black Box, so will have a look.

Last post didn't seem to go up, so I have repeated a bit here... Ignore!

What I meant by not that easy is that I was unable to find something off-the-shelf that suited my needs exactly, so controlling up to 6 axes/stepper motors via the Arduino sketch and DF.

The Black Box you linked to is effectively 4 drivers in a box. That's fine, but it still needs an Arduino and a PSU, and you are limited to just the 4 drivers. So no real advantage over doing it bespoke...

Sorry if I was misleading when referring to 'black box'. I was just referring to the colour of the drivers and the fact that they have a cover at all, not to this specific product, which I was unawarre of until you mentioned it. The point about the drivers I linked to is that they are adjustable for voltage and current and are optically isolated. 

The basic truth about this is that making a moco rig is mostly off-road stuff. You need to be prepared to get all the components and make them work together. Either that or go the whole way with a supplier. If you are uncomfortable with working it out (surely not, judging by your modular synth...) then you pay for someone else to have done it for you. I am fairly ignorant of electronics, but managed to get it up and working...

I like the linear actuator. It will be very slow for travel, but nice and accurate. Depending on the width it could be a good basis for a custom rig. I used a ballscrew for my big rig (16mm dia screw) and it is quite slow. But this is not usually a massive problem for stop motion. For my small rig I used a belt, and this works well and can be much faster.

Certainly it should be possible to adapt 3D printer/CNC parts for a moco rig, except for things like the jib arm. If you go instead for a pedestal type movement, then this is more similar to printers etc.

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