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 My home made Rail/Dolly - ongoing project... 
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Joined: Thu Jul 24, 2014 4:52 am
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Post My home made Rail/Dolly - ongoing project...
Ok guys, here's a couple of pics of the rail I've made for timelapse capture.

Image

Image

It works really well for me, but I've encountered one major major flaw. Wobble when it's breezy!

The problem is that this setup has a VERY high centre of gravity as you can see from the pics, so I'm building a mk2 version where I will attempt to keep the weight of camera & lens as close to the top of the tripod legs as I can.
Will be mostly aluminium too, to save lots of weight, but may introduce a problem of flex potentially. We'll see. If that happens then it will be out with the welder and some angle iron!!

Anyway, this thing is powered by a stepper motor and arduino and takes around 20 minutes to traverse its 6ft length on the slowest speed (has a potentiometer to control speed & direction). Works great until the wind upsets it and then it wobbles something terrible, hence the need to build a better one. It struggles to pull the camera up much of a gradient due to the torque from the stepper when using micro stepping, and also because of lack of belt tension, which can cause it to slip when trying to move uphill.

I'm interested in feedback from others in terms of what has worked well, and in particular if wobble is something others have had to overcome, how they've got round the problem. If nothing else I'll be removing the battery grip from the camera, and potentially get a small ball head instead of the manfrotto joystick head on there - that should knock off a fair bit of height straight off I think.

Thanks!


Mon Jul 28, 2014 10:05 am
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Post Re: My home made Rail/Dolly - ongoing project...
Looks good. If you have a video of the thing in action shoot me the link and I will add it to my channel over at VIMEO.


Mon Jul 28, 2014 3:50 pm
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Post Re: My home made Rail/Dolly - ongoing project...
This might be suitable I guess.



Mon Jul 28, 2014 3:56 pm
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Post Re: My home made Rail/Dolly - ongoing project...
Great clip. You don happen to have a VIMEO clip do you? I can't share a YouTube clip over there.
Cheers,
Doug.


Tue Jul 29, 2014 4:50 am
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Location: Merritt Island, Florida, Estates Unitas
Post Re: My home made Rail/Dolly - ongoing project...
Looks nice! Are you sure your wobble isn't caused by the way you are resting it on natural supports like rocks? Also, have you checked how it is attached to the tripod? The rest looks pretty strong, surprised wind is creating such problems.

I can't see the motor very well in the pictures. Most people use a motor with geared speed reducer to increase the torque of the motor for going uphill carrying a load. Here is a link to one just in case you haven't already tried one.

http://www.phidgets.com/products.php?ca ... _id=3327_0


Tue Jul 29, 2014 8:11 am
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Post Re: My home made Rail/Dolly - ongoing project...
I don't have a vimeo account sorry Doug. Are you making a compilation of different DIY ones or something?

Sciencelookers - yes the wobble is definitely from the hardware itself and not the fact it's resting on different things.
I actually bought a tap & die for cutting proper tripod threads, so under the rail at each and is an aluminium plate where I screw the tripod head into.

The wobble is apparent at different points and for a few reasons, but it's essentially due to a very high centre of gravity above the tripod legs.
It especially bad with that horrible little velbon tripod as it's not meant for much weight and is mainly plastic, but even with my decent Slik tripod and manfrotto head I get it.

Don't forget that above the legs, in this order is the following:

  • Tripod head (my Slik tripod has a very solid but very tall manfrotto medium format head)
  • The wooden rail board
  • Spacers
  • The rails themselves (which are capable of a very small amount of flex
  • The platform and bearings it goes on
  • Tripod pistol grip head
  • Camera battery grip

So all of that lot puts the lens a long way above the top of the tripod legs and any bit of flex or movement is amplified horribly unfortunately.

What I'm doing now therefore is to build a new rail with the following improvements:

  • Lighter & wider version with a much lower centre of gravity hopefully.
  • For starters it will bolt directly to the tripod legs, with the legs themselves giving adjustment for angle where required - with the manfrotto head this removes about 4" of height alone!
  • The rails are directly at the height of the tripod legs next, so that removes some extra
  • The trolley sits level with the bottom of the rails, instead of being perched on top - probably another 2" saved.
  • I'm going to be using a small cheap ball head instead of the big pistol grip mount. Not as solid but much shorter!
  • I'll be removing the battery grip from the camera since it's not necessary for timelapse.

Here's what I made last night, the basic rail, and the two runners for the trolley. My bandsaw is just hacking its way through a thick ally plate for the trolley base as I write! :D

Image

Image


Tue Jul 29, 2014 11:36 am
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Post Re: My home made Rail/Dolly - ongoing project...
Thanks for the tip re' the motor by the way. I was looking at the same model yesterday oddly enough!

I've got different pulley wheels coming from ebay so I can experiment with gearing, but if I can't get it behaving how I want then I'll get one of those.
I need to experiment a bit with compromises between less microstepping and bigger delays between motor steps to hit the sweet spot.

I don't want to use a direct drive motor as I think I have better control with a stepper for when I start work on trying to integrate shutter control for night time sequences. Hopefully.... :D


Tue Jul 29, 2014 11:41 am
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Post Re: My home made Rail/Dolly - ongoing project...
Ok so the carriage/trolley is sort of made now as you can see here (please excuse the mess in my garage - I have limited space and a zillion projects on the go!!):

Image

I need to do some work on getting the clearance just perfect so it moves really smoothly.

Here it is from another angle where you can see how low the carriage plate sits:

Image


I measured on the first rail that it's roughy 14.5" in height from the top of the tripod legs just to the base of the camera, then add whatever to the centre of the lens from the bottom of the battery grip. It's a horrific amount of leverage about the fulcrum point at the top of the tripod legs. No wonder it moves so much!!

The new rail is a couple of inches wider as extra stability, although there is a downside in using angle aluminium as it inherently flexes over a length. It remains to be seen how much this is the case. Worst case scenario is that I'll have to add a piece of wood or box section underneath to prevent this. Hopefully not....

But with the new rail, the carriage is basically level with the tripod top, so a huge amount of wobble potential is removed right from the word go, before a breeze is involved.

That's the theory here at least! Time will tell, and if it still wobbles a lot then I'll analyse where/how it's happening and go back in the garage to fix it! :D


Tue Jul 29, 2014 12:44 pm
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Post Re: My home made Rail/Dolly - ongoing project...
Hey MrJoshua, love that movie by the way,
go and check my channel at VIMEO. Look at what others are doing and I assure you, you will have an idea or two about your system. My own thoughts about the system,
1) Use heavier alu for the rails. That stuff is way to light for the width and length you are going for.
2) Invert the carriage so it sits higher. more space underneath to allow for belts or other drive components.

Just a couple of suggestions.

Cheers,
Doug.

Quick question, how did you get your pics attached to your post? I am still having problems getting photos up with my posts! We all have things to learn:)

EDIT: Never apologize for a messy garage:) You should see my basement!


Wed Jul 30, 2014 7:37 am
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Post Re: My home made Rail/Dolly - ongoing project...
My garage looks the same, so probably good there. Thanks for making me think its more normal.

I agree that the aluminum angle looks pretty thin for the job. If you have any problems with it, I'd try changing the angle pieces to a thickness more like the trolley base, which looks like 1/4 inch if you live somewhere they don't understand metric.

I like the low rider trolley though. Will be interesting to see it all together with the drive mechanism in place. Some shots can be done with the camera and ballhead hanging upside down under the trolley. You just flip the image right side up in post. If there are no cross braces between the tracks to run into along the way, it would give you the low center of gravity you wanted, also gravity works to stabilize, not destabilize the camera.


Wed Jul 30, 2014 8:29 am
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Post Re: My home made Rail/Dolly - ongoing project...
Thanks guys - it's almost armed and fully operational now.

I agree about the thickness of the ally rails. Didn't have much choice unfortunately due to semi remote location where it was the best I could get without buying steel (didn't want to because of weight). They're 20 x 20mm and 1.5mm thick.

To my amazement it's actually fairly easy to keep it straight without it bending. I wasn't expecting that, but yeah, it could definitely do with being thicker.
The motor and belt arrangement is already mounted and working. No need to invert it - it's fine, and keeps things low. Will take a pic shortly.

I don't yet have the ball head I'm waiting for but I'm going to order a second one to put on the bigger tripod. I know I was going to mount the legs directly but potentially it makes it tricky to attach the legs when screwing them in, and gives a fairly high risk of stripping the thread. Seems to work ok, but I need to make up brackets or something for securing the battery pack and control box.


Wed Jul 30, 2014 11:19 am
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Post Re: My home made Rail/Dolly - ongoing project...
Ok, some pics

Image


Image

You can see here just how low the camera is in relation to the top of the tripod due to a raised bracket I made to drop the rail down lower than the tripod legs:
Image


I'm contemplating the use of the chrome tubes from the first version, bolted along the length of the angle ally pieces, as this 'ought' to stop those from twisting, and add very little weight. It'll be tricky and very expensive for me to get much more solid angle aluminium.

Thoughts on this?

And I wasn't going to try it but turns out it fits directly anyway so.....
Image :D


Wed Jul 30, 2014 11:43 am
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Post Re: My home made Rail/Dolly - ongoing project...
That looks really good, but, you are going to have more wobble issues with the new version that the first I am afraid.
I have been DIY building dollies for 12 months now and I am finally content that I have a strong solution.

I'm using Carbon fibre tubes with bearings similar to yoursImage
That is an end on view.
You can see that I have used a tri-truss arrangement of carbon fibre tubes, there is one on the bottom not drawn.

http://brocklesby.net/dolly/photo%201-3.JPG
http://brocklesby.net/dolly/photo%202-3.JPG

Those are a couple of photos of the unit in build stage.
It is now finished and working beautifully.
Rock solid, no movement with wind.

What you will find with yours is that the dolly car will be able to rotate side to side due to the alu angle being thin walled, and being unsupported over that span.

What I have done is make a truss section so that it cant twist at all.
The benefit to that is that I can, and have, run a 3m length dolly move where it was only supported at each end and it is rock solid.

I generally hike in to where Im shooting, I needed super lightweight, so my rig is designed around that as the first principal.

It is stepper motor controlled driven by a raspberry pi that is wirelessly connected to a tablet or phone, and is driven via a webpage.
Camera control is via USB, so you get full control over camera including automated focus pulls, and you can save the images to the raspberry pi instead of the camera, even see a preview on the webpage.

Im just finalising the hardware and software and will post up int h next few weeks full details, just finishing off the testing currently.

Any questions at all, please dont hesitate to contact me and Im happy to share what steps Ive taken to minimise or eliminate the issues that you are now finding.

cheers
Andrew


Thu Jul 31, 2014 4:48 pm
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Post Re: My home made Rail/Dolly - ongoing project...
Thanks Andrew - your design looks fantastic! Do you have any reasonably priced source for carbon tubes? I think that sort of thing is not something I can afford to replicate currently, but I'm certainly interested in the wireless control etc and how you've gone about that. I'm happy enough with my arduino's control in that it basically has an on/off switch, then a pot for direction/speed, but more flashy functionality is always nice to meddle with!

Re' the rigidity of my new one, I can see you're not convinced and I can appreciate why, but having taken it out in the wind I can confirm that it's vastly less wobbly than the original, but subject to a good stiff breeze it still does move a small amount. It's a massive improvement though, seriously.

Last night I was adding leftover angle section adjacent to the main pieces to further stiffen it, so it'll be interesting to see if it makes any difference...

The difference between my first and current rail is that the first had stiff rails generally, but the entire setup was inherently unstable, and horribly horrribly top heavy, which caused any minute movement to get amplified greatly, and resulted in a lot of movement at the highest point where the lens was.

The new rail on the other hand is more susceptible to flex of the rails themselves as you mentioned, but the centre of gravity means that it's much harder to actually move it in the first place because it doesn't have tons of leverage like the original had.

I'll try to illustrate when I get a sec.

But I really like your one. It's fantastic!
I'm going to have a look at your page and see more about it. Great work though. :)


Fri Aug 01, 2014 4:18 am
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Post Re: My home made Rail/Dolly - ongoing project...
WOW adavis, your dolly looks awesome! Would you mind sharing how you join the carbon fiber sections? I have a suggestion in case you haven't considered it yet. Pelican makes a case specifically to fit under an airline seat or in the overhead bin. If you can make the rails break down into sections that fit that case interior, it might make the dolly even more desirable. Another famous company made their tubes one inch too long, so they have to go in at an angle so far fewer of them fit than could. (don't be those guys) Any chance you'd sell the carbon fiber tubes with the joining devices or just the joining part? When are you planning to start selling dollies and how much do you plan to ask for them?


Fri Aug 01, 2014 7:25 am
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Post Re: My home made Rail/Dolly - ongoing project...
Was wondering the same thing actually about how the tubes had been made to join seamlessly so the carriage progresses smoothly over them.


Fri Aug 01, 2014 9:16 am
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Post Re: My home made Rail/Dolly - ongoing project...
Here's a comparison between the wind resistance of the original rail and the new one.

The first clip was used on a day with a breeze but not really windy. It's wobbly all to hell!


Here's more or less the same clip but on a much more windy day and using the new rail. Not perfect, but a massive improvement!


Sun Aug 03, 2014 4:23 am
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Post Re: My home made Rail/Dolly - ongoing project...
Thanks sciencelookers I have been working up to this system for about a year now, and I think that this is my second dolly track material, 4th arrangement of the track (makerslide, twin carbon tubes, twin carbon tubes with carbon rod stabiliser, three carbon tubes).
Once I got to the stabilised carbon tube version, I started getting steady results.

https://www.youtube.com/watch?v=xFX1RkIUcUY
That is lifts with the 3rd version of the dolly.
It works fantastic, but I wanted to get it to span greater length.

OK, so v1 of the carbon tubed dolly, I joined the tubes by milling an acrylic tube to fit tightly on the inside of the tube and bored a m10 thread through the middle.
I then made an m10 aluminium screw thread.
The acrylic pieces were glued into the tube, with one being about 20mm inside the tube and the other being 20mm outside the tube.
The aluminium rod was screwed into the first tube and loctited in so that it wouldnt spin..
The tubes could be very easily screwed together very tightly and the join was excellent, but there were downsides.

You could only have about a 2m total length.
The first 1m I made with the rails glued together with spacers. That was rock solid and light and perfect!
The next 1m screwed in, but you could only fix at the end, and that is where the dolly stopped.

This dolly worked very well and was very light, but it developed a sag in the middle when the glue gave way.
That was when I decided that I would never really get that glue to hold right and designed the next method.

I take a carbon tube that fits tightly inside the outer tube and have about 100mm or 150mm or so long.
Inside this inner tube, I press fit acrylic or acetal rod.
Drill and tap from the side, through all 3, but not out the other side.
Fit a screw and it isnt going anywhere, very strong.

I will take some pics when I get home, I dont have any handy.

I translated this design of joiner to the tri-truss carbon tube and it is unbelievably strong.

As far as tube length goes, when I had my makerslide dolly I travelled by air with it without issues but had to check it into oversided baggage.
It was 1m lengths.

The beauty of the new design is that it can whatever tube length you want, so I dont see that being an issue again.
It also easily breaks down so that it takes up very little room, as in the centre supports are totally removable, leaving you with just the tubes.


Sun Aug 03, 2014 12:22 pm
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Post Re: My home made Rail/Dolly - ongoing project...
Look forward to seeing more pics in due course. It's all very well thought out indeed!

Your footage is excellent too. I can't wait to try some dark skies timelapse soon. It's been a bit late recently in summer for the stars coming out to go out and sit for hours, then get woken by the kids at 6am, so now the evenings are getting shortly I'll be trying that before too long.

Great work though in all respects! :-)


Sun Aug 03, 2014 12:48 pm
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Post Re: My home made Rail/Dolly - ongoing project...
Thanks for the kind words, I have been spending too much time building and not shooting lately, which is very short sighted of me as this is prime Milky Way shooting time here in Australia, with the galactic core visible and very bright. I need to time it with some Friday or Saturday nights where the moon in thin, then I will get some great footage.
The other that I have real issues with is light pollution.
I have to drive 90 minutes to the Blue Mountains outside Sydney to get nice dark skies, and in winter, with some wind, the temperatures overnight get down to -10C or lower some times. There has been snow this week! So hiking out to a prime dark sky spot and sitting in -10C while you wait 3 hours for a time-lapse to shoot is a difficult task :-)


Sun Aug 03, 2014 1:03 pm
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Post Re: My home made Rail/Dolly - ongoing project...
I'm very fortunate when it comes to dark skies as I live on the Isle of Man, which is renowned for this. I can drive about 10-15 minutes from my house in the town (village) here and be in pitch black.
If I drove for 90 minutes here I'd have gone as far as I could go on the IOM and all the way back! :D

I've wanted to try some milky way shots for a while now after seeing some cracking photos by a local guy near me:
http://www.isleofman.com/photo-gallery/ ... ll-photos/


Sun Aug 03, 2014 1:15 pm
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Post Re: My home made Rail/Dolly - ongoing project...
Yeah that is definitely an advantage.
I guess that I am very lucky as my family are humouring me and we are currently in the process of selling our house and moving to the area that I currently drive to to shoot, so I will have the 5-10 minute drive from home as well :-)

I noticed that you are using the A4988 stepper driver as well.
Have you had any issues with missed steps?
I am not convinced that that is exactly what I am experiencing , but if I run my stepper continuously, I am getting a rhythmic ticking for want of a better word, where it sounds like the stepper is missing. It is probably a timing issue in the code, we are moving onto clean up mode now of the code, so it will turn up I guess. I was just wondering if it is was hardware related and if you had experienced it.

I have also designed a 3 A4988 carrier board if you are interested, as I gat sick of having it stuck into a breadboard with the fly leads everywhere.
Image

I have built the prototype board but needed to fix a few minor issues, however i just broke the last engraving bit and seemed to have killed a stepper motor on my mill. Just waiting for replacement parts to arrive then I will finish the board.


Sun Aug 03, 2014 1:28 pm
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Post Re: My home made Rail/Dolly - ongoing project...
That's impressive mate! I used to etch my own boards when I was a youngster but nothing for IC stuff beyond a 555 timer, it was just really basic stuff and I never got beyond that.
Have you done that board in Eagle? It's good anyway, but if it's not a silly question would you be able to use a RAMPS or Melzi setup for this sort of thing like reprap printers use? They basically have a bunch of A4988/Pololu drivers combined, although I guess the rest of their functionality would be a bit useless on a dolly.

Re' missed steps, the honest answer is not that I know of, but I'm not 100% sure how apparent that would be if it was just happening a bit. I've had suspicions about that with my printer when successive print layers have been ever so slightly offset occasionally across the full height of a printed item but it's hard to know. I don't get funny noises like you describe though.
I'm sure you have, but have you set up the vref accurately for the current demand of the steppers?

The code I wrote for controlling my stepper is pretty basic as it was my first attempt at writing stuff for an arduino. I get the 0-1024 val from a potentiometer, change it to a negative or positive 0-512 value and then get the square root, and refine it a little further, which then gives me both speed and direction control from a single potentiometer. It's pretty basic but it works for now.
I've got it on the smallest microstepping level too.

The speed control is far from refined so I want to re-write it at some point but it's enough that I can use it for now. I think it takes 15-20 minutes to move the length of the rail at slowest, which is ok for daylight stuff I'm currently doing.


Sun Aug 03, 2014 2:01 pm
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Post Re: My home made Rail/Dolly - ongoing project...
I made that board layout in Inkscape as I intended to mill it.
The gcode is just a path follow at 0.2mm depth, with a 0.2mm drill depth using the v mill in the centre of the drill holes to centre the 1mm drill.
I then do a bit change to the drill and it drills all the holes nicely, then change again and cut the mounting holes and the outside trim.
So, no eagle, sorry, I have tried it in the past, but it seemed very difficult to use and the gcode generator plugin seemed very very convoluted to me.
It took me about 15 minutes to draw up this in Inkscape and I can absolutely say with certainty that I would still be scratching my head a long time after that in eagle :-)

I thought of the RAMPS setup, but wasnt sure what the extra stuff would do, decided to just build this one.
I have set the stepper current, but not in any scientifically specific way, I turn the current down until the stepper stalls, then back up until it runs without stalling.
Regardless, Im seeing the same stuttering on any setting.


Sun Aug 03, 2014 2:11 pm
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Post Re: My home made Rail/Dolly - ongoing project...
What is everyone else using for batteries to power their rigs?
I have been through the full spectrum.
Car battery jump start box - very very VERY heavy but can power everything for days
SLA 'alarm' battery form factor (12v 7ah) - quite heavy, worked reasonably, but the trailing cord to the dolly has had me in trouble in couple of time so moved to on the dolly cart battery
Ebay Chinese seller "Blue Box" lithium batteries - worked fantastically for a few months then all died. Every replacement that I bought was dodgy or they lied to make the battery look bigger.
Locally sourced brand name Panasonic 18650 cells - expensive, at $15 each and I now use 8 of them, but it gives me a reliable 16v at 6.8Ah. (I rectify this down to 5v for Raspberry Pi, 7,3v for the camera and 12v for steppers)

This does work well for me as the 8 batteries in a holder can easily hand off the side of the dolly cart and all the electronics fit in the dolly cart too, it is light to carry and is about as power dense as you can get for the weight. Just after others ideas.


Sun Aug 03, 2014 2:50 pm
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Post Re: My home made Rail/Dolly - ongoing project...
At the moment I'm using 8 AA cells (alkaline) for mine, and I've had somewhere between 1-2 hours run time so far and going strong.
But that's running a single 0.4a nema17 stepper and an arduino/pololu so not a massive demand.
Once I eventually get to 3 steppers with pan & tilt I don't think that'll cut it at all. Might swap to a small 12v gel motorbike battery like my KTM uses - I forget the spec but it's pretty small.


Sun Aug 03, 2014 2:57 pm
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Post Re: My home made Rail/Dolly - ongoing project...
Yeah that will probably be a 12v 7ah.
I note that you have the stepper on the end of the rail, how do you plan on cabling from the electronics to the dolly cart?
Also, have you though of sleeping the steppers between steps to save power?

cheers
Andrew


Sun Aug 03, 2014 3:05 pm
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Post Re: My home made Rail/Dolly - ongoing project...
Think it is about 7 or 8 ah yeah. It\s barely enough for the bike even though it's bigger than the normal one!

Not even thought about sleeping them no. I think that'll become more of an issue once I start trying night time stuff to be honest. It'll be a whole new learning experience and I'm only a noob as it is :D

For cabling I was pondering on the use of one of those plastic linked track shield things. Not sure what they're called sorry, but where it's like a segmented tank track the cable sits in and it rolls along by the carriage back & forth.
Hope that makes some sense!


Sun Aug 03, 2014 3:12 pm
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Post Re: My home made Rail/Dolly - ongoing project...
Yeah Im constantly thinking about power usage and how to maximise run time :-)

A plastic cnc cable chain might work, I hadn't thought of that actually.
What are you using for the connection to the camera for shutter trigger?
I have in the past, with the Dynamic Perception MX2 that I have been using, used the remote shutter release cable, but I've now moved to USB connection as it gives me so many extra functions. Not sure on how good that would work with such a long USB cable.


Sun Aug 03, 2014 3:18 pm
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Post Re: My home made Rail/Dolly - ongoing project...
My shutter is currently just triggered either by a cheap intervalometer (it broke today finally after years of abuse so I bought a new one), or using a phone app called triggertrap, which comes with a dongle thing to hook up between the phone and the shutter release socket on the camera. Triggertrap is a clever system for the low price and I like it but today it misbehaved a bit and I'm not sure why.

I do intend controlling the shutter from the arduino for when I try night stuff (it'll have to be manual at first I guess), so that the step movements are not happening while the shutter is open obviously. I've not even started looking at the code for controlling that yet though.

Time I hit the hay anyway. After 1am and work in the morning!


Sun Aug 03, 2014 4:11 pm
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Post Re: My home made Rail/Dolly - ongoing project...
Yeah I have Triggertrap it is a really cool intervalometer!


Sun Aug 03, 2014 4:18 pm
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Post Re: My home made Rail/Dolly - ongoing project...
Ahh ok. I bought it about a year back but only really tried it yesterday properly as my normal timer broker.
What was odd was it was doing a shot every 1500ms but then began doing bursts erratically with several shots per second on & off.
Pretty sure my volume was on full. Have you had this at all?


Sun Aug 03, 2014 11:03 pm
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Post Re: My home made Rail/Dolly - ongoing project...
To be honest, I haven't used it much.
I ordered the TT dongle and a regular intervalometer at the same time and got the regular intervalometer first, so started to use it.
My idea was that the TT unit would be used for a second camera rig, but I never got around to it.

I have shot only one sequence with it, when the battery in my intervalometer was flat, and it did what it said on the tin.


Sun Aug 03, 2014 11:27 pm
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Joined: Thu May 15, 2014 5:28 pm
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Post Re: My home made Rail/Dolly - ongoing project...
Here is a shot that I took last night of the carbon fibre tube joiner.

Image

You cant really see it, but where the cross brace in joined to the tube is where the bolt goes into the tube.
A similar arrangement is used to hold the extra tube (not fitted here) in place.


Mon Aug 04, 2014 1:12 pm
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Joined: Wed Nov 11, 2009 10:45 am
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Location: Merritt Island, Florida, Estates Unitas
Post Re: My home made Rail/Dolly - ongoing project...
Thanks for the pictures. I can see how it goes together now.
I guess you made the plastic inserts that go inside the tubes by turning each one on a lathe?
It looks like the carbon tubes are made to fit inside each other with a tight clearance.
Did you buy the carbon tubes? Where did you get them?
Do they sell sets designed to fit inside each other or did you discover some which would on your own?
What sizes fit?
The triangular braces are very cool. Are they carbon or did you 3-D print them?

This is a very nice design. it packs compactly, can be extended to any length,
and looks like it is stronger than the usual two tube configuration everyone else uses.
Is this just for yourself, or do you plan on selling them?
I'll buy one if its affordable as well.


Tue Aug 05, 2014 5:30 am
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Joined: Thu May 15, 2014 5:28 pm
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Post Re: My home made Rail/Dolly - ongoing project...
The acrylic inserts are not machined, I managed to find some rod that was the exact internal dimension of the carbon tube :-)
Yes, it is a good fit between the tubes.
Generally they are made in sizes that 'telescope' so it was no magic on my part, just asking the supplier for 22mm outside diameter tubes with a 20mm internal diameter, and 20mm outside diameter with 18mm interna diameter.

I was buying the tubes locally in Australia, from someone else that imported them from China, but they were $38 AUD per 1m length.
Thad made a 1m dolly track $114 AUD for the 3 carbon tubes, plus the $20 shipping locally.
When he ran out of tubes, I went and sourced them direct from the factory in China and I'm now able to get them for $12 USD per tube.
MUCH better, although the shipping is now something like $65 USD.

The internal braces are milled out of HDPE plastic.
The one in the photo you can see has lines and looks 3D printed as I didnt have the right mill bit at that point.They are totally smooth now 8-)

The whole design was built around a few principles.
1. Light weight
2. Strong enough to stop the torsional twisting that happens mid span when you get a high centre of gravity rig on top
3. Strong enough to span a minimum of 2m without any centre support
4. Be extendable to whatever length you want.

I have been able to smash all those principles and totally exceed them.

I have a mate that is working on the control code for me, and I'm building him a dolly as thanks for the awesome coding and ideas that he has brought to the project.
When we are satisfied that we have ironed out the bugs I do intent to sell some, if just only to repay the development costs.
I do think that our software and hardware combination is totally unique though, and geared towards the time-lapse photographer only.

I spent months looking for some open source, or even commercial 3 axis dolly control software / hardware that didnt cost thousands of dollars, and came to the startling conclusion that
pretty much it doesnt exist.
Everyone, Dynamic Perception included, have gone down this complicated multi-box road that looks to be geared towards cinematographers, and not time-lapsers.
Sure it still works for time-lapsers, but it is not likely that someone is going to pack it all down into a backpack and hike into the wild country with it (which is exactly what I do)

I dont have costings totally sorted yet, but the track would cost somewhere in the ballpark of $100 a meter to buy when I am done.


Tue Aug 05, 2014 11:56 am
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Joined: Wed Nov 11, 2009 10:45 am
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Location: Merritt Island, Florida, Estates Unitas
Post Re: My home made Rail/Dolly - ongoing project...
Nice!!! PM me when you want to sell one


Tue Aug 05, 2014 4:05 pm
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Joined: Thu May 15, 2014 5:28 pm
Posts: 76
Post Re: My home made Rail/Dolly - ongoing project...
actually I missed finishing my point in the last post haha
The commercial systems that are currently available that do keyframing, as in set a start point, drive to an end point and the system will work out the moves between, or set start, set mid point, set end, pretty much exclusively build there motion systems around dragonframe or other computer based splining software, that is pretty much impossible for in the field use.
I have made sure that in the system that we have developed, you only need a smartphone or tablet in addition to the dolly system, and do entire new setups, or modify existing ones, on the fly, in the field.
Drive the dolly to the start in 3 axis, set the start, drive it to the end in 3 axis, set the end, 'Home' it, set camera settings in the software, like ISO, exposure time etc, select where you want the images saved, name the sequence, hit go.

I will make a post on this forum when I have something ready to sell, in the next 4 weeks or so, and PM whomever is interested, but keep in mind that the dolly track is only the start, and probably the cheapest bit :-)
That said, I'm happy to sell just the track if that is what people are looking for.

cheers
Andrew


Tue Aug 05, 2014 4:26 pm
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Joined: Thu Jul 24, 2014 4:52 am
Posts: 83
Post Re: My home made Rail/Dolly - ongoing project...
Thanks for the photo of yours Andrew.

My new one is coming along now - my carbon tubes should be here tomorrow hopefully. I've gone for a slightly different design whereby I have 4x 1.3m long 16mm OD tubes.
For now I'm keeping it that length as I've found so far that rail lengths between 1.2-1.8m gives a nice convenient size with pretty good results, but might make it more modular in future so I can lengthen it potentially.

I've designed brackets in sketchup, and started printing them off. It's slow going as each one takes 3 hours to print and uses a lot of ABS, but is still light as internally they print with a honeycomb structure.

Here's the printed brackets where you can see what they look like:
Image

The one on the left isn't perfect as I paused the print part way through and tightened a belt, and this affected the offset of print layers.

This is a terrible quality picture sorry but you can see the idea of how the two halves overlap then bolt together. I can choose the width I want before bolting them together with M6 bolts, due to a series of even spaced holes that align between the halves. The other holes including the large ones are just to reduce the amount of extruded plastic used, and to lighten it.

Image

One change I will make is to make actual complete holes for the lower tubes to fit into, when I next print some brackets (instead of the tubes fitting into semicircular recesses on the outer edges), as there is no requirement for bearings to run on the tube surface like there is at the top. A little oversight but this will be fine for now anyway.

I've received my linear bearings (x4 in alloy housings) and they're quite nice actually. They have 5 bearing tracks inside each bearing so I will try a carriage using these first and see how well it works.
I'm slighly concerned that it might abrade the surface of the carbon tubes but only one way to find out, and if they don't then they give a great solution for a secure and simple carriage.

I'll be adding adjustable feet at the corners for putting on unlevel ground, but also tripod mount points at either end, as per my existing one.
Not 100% sure yet how I'm doing the pan & tilt module as I've a number of options for that including a great design I saw that someone else had done, but I kind of need to finish the conversion of my milling machine to CNC before I can do good aluminium stuff like that.

I've already got code I wrote for the arduino computer that controls my existing carriage, but I'll be refining this further as it's a bit basic currently, and I need to add more functionality to it. It's not a program language I'm used to so I have to learn more about it first!

As soon as my carbon tubes arrive I'll post up a pic of how they fit in with my printed ABS brackets.


Sat Aug 09, 2014 11:30 pm
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Joined: Thu May 15, 2014 5:28 pm
Posts: 76
Post Re: My home made Rail/Dolly - ongoing project...
That is looking really good!
Im very interested to see how you go.

I got my dolly car all together and running on the new track last night.
Just a few more tests and adjustments and I'm calling it ready for a field test.

I need to make some more track to extend mine as well, and the last piece is to mill out a few tripod mounts.
The HDPE is too slippery and not strong enough to take a thread for the tripod mounts, so I have a piece of thick Delrin that I plan on using.

cheers
Andrew


Sun Aug 10, 2014 11:52 am
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