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 My home made Rail/Dolly - ongoing project... 
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Joined: Thu Jul 24, 2014 4:52 am
Posts: 83
Post Re: My home made Rail/Dolly - ongoing project...
Thanks Andrew - looking forward to seeing pics of the finished beast!

My printer has really been playing silly buggers while trying to do these brackets - I've had all manner of trouble to be honest. Each time it's been ironed out then a new problem occurs.

I ran out of ABS and had to switch to a reel of pink (I know!) PLA plastic instead which meant a ton of mucking about setting up the different temperatures etc for printing again, then the nozzle jammed, then it randomly stopped printing most of the way through doing a bracket etc (it's still useable).

Getting there though. Here's one of the 4 linear bearing blocks. It's actually pretty heavy!
Image

Have also been busy trying to make progress on my CNC conversion and it's been awkward.
I have to make a 26mm hole in two pieces of (I think it's) Delrin that I'm using for a spacer/mount, in order to fit thrust bearings.
I only have a 3 jaw chuck on my little Sieg lathe so I've had to make a faceplate/clamping plate to hold the work piece. It's fun as I haven't used the lathe for a while but why can't anything be simple?! :lol:

So here's the plate after turning and facing it a bit.

Image

I drilled & tappe the chuck to mount this. Now I need to make threaded holes in the faceplate so I can clamp the plastic down!


Sun Aug 10, 2014 12:35 pm
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Post Re: My home made Rail/Dolly - ongoing project...
Looking good!
Yeah I know what you mean about two steps forward one step back with hardware.
My CNC mill threw a stepper motor last week, then the replacement had a different length shaft, so it didnt fit the original mountings.
I had to make a temporary mount to fit it to make a proper mount :?

I dont have any photos with me, but I managed to isolation mill out my stepper controller board, and assemble it.
Very happy with it, and it works a treat.
3 axis on the one board with removable drivers, single power connector for the steppers and single power input for the drivers too.

How are you thinking that you will do for weight on your dolly, those linear bearings look heavy :D


Sun Aug 10, 2014 12:48 pm
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Post Re: My home made Rail/Dolly - ongoing project...
Similar sort of thing here Andrew as the stuff I'm making things to make is just that - temporary mounts in order to get my machine in one piece, then once it's functional I can use it to make stronger & neater hardware for itself before it does anything else. I've no experience of a CNC machine and very little even at using my mill so this is all a good learning curve and I'm sort of dreading it being finished because then I have to learn the Mach3 software and learn more about feed speeds and all that sort of thing.

Almost ready with this faceplate now....
Image

As for the bearings, yeah they are heavier than I expected. I'm sure it's too heavy for normal aluminium so I think it must be something else. Time will tell if they're any use, and if they're too much pressure on the bearings, and cause wear then I'll remove them the instant I see any visible sign of wear. I don't mind the weight in respect of carrying though since the rest of it will be so light. As long as they don't wear the tubes, and if they do they'll just wait for another project! :D


Sun Aug 10, 2014 1:34 pm
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Post Re: My home made Rail/Dolly - ongoing project...
Well, I'm very clearly a novice when it comes to machining.
I had a few summers as a general helper in a big engineering shop is high school 30 years ago that taught me a lot of the basics, then my ex father in law had a big lathe that I would build all sorts of things, but again, that was 15 years ago.

Ive only had the CNC mill for about 4 months or so, so am quite clearly still learning.
I have not used Mach3, I use LinuxCNC or EMC is the old name.

I create my objects using Inkscape, then turn them into 2.5D using Makercam.com.
Both of these pieces of software is free.
Actually LinuxCNC is as well.

The software side I find relatively easy.
it is just drawing your shapes and then working out the cut paths.
ie this inside shape should go all the through so it is -11.5mm from the top surface
this circle is a bearing mount so it should be a pocket of -4mm from the top surface
etc

My biggest issue with the Mill is that because I can easily cut stuff out I flip flop on designs too easily. :D


Sun Aug 10, 2014 1:53 pm
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Post Re: My home made Rail/Dolly - ongoing project...
I've got no real experience to speak of I'm afraid Andrew other than randomly fiddling about and trying to make things in my garage! I bought a sieg C3 minilathe (14 x 7") and sieg X2 mini mill about 9 years ago after I got about £1000 that I hadn't expected. I'd always wanted the machines but had no idea about correct use, and still just look everything up online and in a couple of books I have.
I've no-one to show me correctly, although I have a couple of DVDs on basic use.

I'm ok really with the lathe, but my milling results are usually terrible from incorrect use (wrong speeds/feed rate, too big cuts etc). I'm probably fortunate to still have all my fingers!

I'll have a look at inkscape to see what it's like though cheers.


Sun Aug 10, 2014 11:59 pm
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Post Re: My home made Rail/Dolly - ongoing project...
I'm just heading out to Scouts, but when I get back I'll offer up some nuggets of advice that I have learnt with the mill :)

#1 you need the right mill bit for the job, you will beat your head against a wall without the right bit.

cheers
Andrew


Mon Aug 11, 2014 12:21 am
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Post Re: My home made Rail/Dolly - ongoing project...
Ha ha - thanks! I've got a set of 2 flute end mills, and a set of 4 flute end mills. That's it!

Anyway - I've completed the job of making the temporary hardware so I now have a Y axis that turns freely on the new bearings with no real axial play to speak of. Result (sorry, I'm getting off topic a bit with this!).
It's by no means pretty and restricts Y travel but it'll do the job temporarily.

Image

I rang the courier company this morning as my carbon tubes were on the island according to their website, but they tell me they're actually in the UK still and won't be here until Wednesday.
That'll make it 7 days for their "2 day" express service. Hmmm....


Mon Aug 11, 2014 12:29 am
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Post Re: My home made Rail/Dolly - ongoing project...
Things that dont look pretty that do the job are fine by me :-)

I have a tonne of mill bits now.
4 flute, 2 flute and my favourite single flute.
Depends on what you are cutting obviously.

I dont know any of the science behind it, i just try them out and google if it doesn't work.
It took me ages to find why the HDPE was melting as I milled it, making a really crap edge.
Turned out to need a single flute cutter and oh boy did that make a massive difference.


Mon Aug 11, 2014 3:08 am
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Location: Merritt Island, Florida, Estates Unitas
Post Re: My home made Rail/Dolly - ongoing project...
I found these wheels on ebay. They look like they were designed to roll on the carbon tubes
some of you have been showing. (thanks for the pics)
I bought some wheels and carbon tubes because you guys seemed to be having so much fun with them.

http://www.ebay.com/itm/new-4-Wheels-fo ... RTM1562571


Mon Aug 11, 2014 6:30 am
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Post Re: My home made Rail/Dolly - ongoing project...
I wonder why the single flute mill cuts better... less friction preventing it getting as hot maybe?

Those wheels look great sciencelookers! Good find. I'll have to see if I can find some in the UK.


Mon Aug 11, 2014 9:27 am
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Post Re: My home made Rail/Dolly - ongoing project...
I have looked at those wheels previously.
My issue with them is that they are 40mm in diameter, which is huge.
Contrast that with the bearings that I am using at 22mm and you can see that I can save almost half the size.

I do have another theory.

The carbon tubes are resin finished.
If you pick up sand or dirt on the wheels, it will damage the tube over time.
If you use a shaped wheel, the surface contact area is huge, leaving a lot of room for dirt to get caught and cause harm.
With the bearings, the surface contact area is minuscule, reducing the risk.

That is my 2c worth in any case.

That being said, If I managed to find shaped wheels that were 22mm in diameter I would have bought them :-)

MrJoshua, Im sure that you could easily turn some up on the lathe, and turn a pocket to take a small bearing inside..

cheers
Andrew


Mon Aug 11, 2014 11:47 am
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Post Re: My home made Rail/Dolly - ongoing project...
Valid points about debris getting on them and causing wear potentially. I'm not sure it would cause me enough concern not to use them though - I'm tempted to get a set, but I'll see how the bearings go first.

Well, while I'm waiting for my tubes to be delivered I've been more busy with the mill still. I now have 2 out of 3 axes armed & fully operational:
[img]
http://i26.photobucket.com/albums/c113/ ... onrsbf.jpg
[/img]

Not sure how to do the vertical Z axis, but once that's done this will be such a useful tool to have!


Mon Aug 11, 2014 11:58 am
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Post Re: My home made Rail/Dolly - ongoing project...
Yeah as I said, would have definitely used them if I could have found them small enough 8-)

Holy buckets they are big steppers, what are you planning to mill? :D
There must be other that have done a z axis conversion on that mill.
Is the Z Axis moved by the handle on the right side only?

cheers
Andrew


Mon Aug 11, 2014 12:04 pm
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Post Re: My home made Rail/Dolly - ongoing project...
Interesting idea about turning some on the lathe I must admit.

The steppers are 435oz ones. Most people recommend 425 as being plenty powerful enough for these little machines but it just worked out that these were a better deal. I'd rather have a little too much power than not enough.
Yeah the handle turns the Z axis (also can be locked and a small wheel used for fine adjustment) which is a rack & pinion type arrangement rather than a leadscrew that it had for X & Y (now ballscrews instead). It did have a torsion spring to assist the weight but I upgraded it to a gas ram instead.

But yeah, there's plenty of people have coverted these machines. You can buy ready made hardware kits but I didn't have the money spare so am doing it the hard way. :lol:

This is what I have:
http://www.siegind.com/products_detail/ ... 77667.html


Mon Aug 11, 2014 12:14 pm
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Post Re: My home made Rail/Dolly - ongoing project...
yeah you are right, bigger steppers means more holding power, as well as the ability to track better.
It just looks odd to me, my steppers are nema23 size, like these.
http://www.ebay.com.au/itm/Nema-23-Step ... b45&_uhb=1

the mill looks good, I always wanted something like that.


Mon Aug 11, 2014 12:21 pm
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Post Re: My home made Rail/Dolly - ongoing project...
Thanks - was years of wanting one before I finally got one, and only then because I got a few quid I hadn't expected.

Mine are nema23 but quite long. The picture is a deceptive perspective of course and makes them look very disproportionate.

*edit* carbon tubes arriving this morning via TNT apparently...


Mon Aug 11, 2014 12:25 pm
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Post Re: My home made Rail/Dolly - ongoing project...
Ok I've got the tubes at last. Heavier than I expected for 16mm but it's because they're thick walled with 12mm ID which should make them really strong anyway. Still light enough. Each 1300mm tube is 185g for what it's worth.

First issue is they're just not going to work with those linear bearings. They won't even fit in because they're 16.2mm and I think the bearings don't tolerate that discrepancy in size. I'd have to force the tube in to get it properly in don't want to risk damage. I guess we'll never know if they would work ok or not. :(

They're not a great fit in the brackets I printed and I think the 16mm holes have come out tighter than that. I can sand them or whatever but I might just tell it to do a 17mm hole instead and print new ones.
Bit of a chore but might be best, then I can enclose the holes for the bottom tubes.


Tue Aug 12, 2014 4:24 am
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Post Re: My home made Rail/Dolly - ongoing project...
well that is a bugger!
Oh good, you got the thick walled tubes.
I was going to say that 16mm is going to be on the small side, but with the 2mm wall they should be very strong.
I used 20mm for my first two rail dolly and the tri-truss version is 22mm, but they are only 1mm wall section.

185g should be good as that is going to still be less than 750g for the 4.
My first dolly, by the way, made out of makerslide extrusion, was 1kg per Metre, so it weighed 2kg for the track alone.
I have gotten my dolly down to approx 500g per Metre now.

It is a pity that the tubes are oversized for the bearings, that would have been great to find out how it would have worked.


Tue Aug 12, 2014 11:51 am
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Post Re: My home made Rail/Dolly - ongoing project...
Yeah it's a shame about the bearings but like I say I'm sure I can use them in some future project.

I've further amended the printed brackets with a couple of refinements to reduce print time a little, lighten, use less plastic, add an adjustable foot/bolt under each corner etc.
This is the previous version, which the tubes fit perfectly!! I had to change the hole size to a 17.4mm theoretical size hole to fit the 16mm tubes as they're always a bit tighter than they're meant to be.
Image

They're not secured in place on the top mount in that pic but as I say they're very snug in the lower tube mount before they're even screwed in.

I know I could have saved a few grams with the thinner walled tube but I'd prefer the reassurance of the stronger stuff. It's probably still lighter than the ally rail I currently have, plus loads more rigid so it should be a win win.
Hopefully.....


Tue Aug 12, 2014 4:12 pm
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Post Re: My home made Rail/Dolly - ongoing project...
nice colour :lol:

That looks really good!
How are you going to fix the tube to the spacer?
When I had that sort of attachment printed, on the one that wrapped around the tube I had a gap in the ring and a lug so that I could put a bolt through to secure it tightly.
You do have to be careful to avoid torsional moments.

If you are not intending to go over the 1.3m, why not have the wrap around fitting on the top tubes as well?

cheers
Andrew


Tue Aug 12, 2014 4:22 pm
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Post Re: My home made Rail/Dolly - ongoing project...
I just have left the top section open to maximise the amount of travel the carriage will be able to get hopefully. If it doesn't work out then I can print more brackets where the top is enclosed.
On the newest variant there are flat sides on the lower clamps, for ease of fitment of bolts or screws through the rods. I'd be tempted to bond them in place as well but that would be an issue if I want to dismantle then, and since I'm very indecisive that's likely to happen!
I tend to have an approach of trial and error rather than careful planning I'm afraid. I'm too impatient to get on with things immediately to sit down & properly plan things, so I probably use 3x as much time up overall having to re-do things, but it's all fun.

As for the colour, I'd run out of ABS (waiting for more) for printing, and only had this really cheap PLA plastic. Any guesses for why it was so cheap? lol :)


Tue Aug 12, 2014 4:30 pm
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Post Re: My home made Rail/Dolly - ongoing project...
My other question I guess is that you have made the supports in two pieces so that you can adjust the width of the rails, is that for testing to determine the optimal?
Just that any adjustment means changing the dolly cart, which to me is a pain as it means making a new cart base.

here is my new dolly cart base, by the way.

Image


Tue Aug 12, 2014 4:31 pm
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Post Re: My home made Rail/Dolly - ongoing project...
I have no issues with your approach, I am exactly the same really.
I will make version after version of things, as it is easy to do with the CNC Mill.

Despite making a new rail bracket earlier this week, and cutting it out, I have redesigned it twice already before using it, and will more than likely cut out a different version tonight.
Continual refinement is good I think, as long as it doesnt stop you reaching the goal.

That dolly cart base plate is about the 10th version that I will have cut out. I milled it last night and it looks quite good.
Im not convinced that it is stiff enough though out of HDPE, I might have to mill it out some 12mm polycarbonate, but that will be heavier.
I could cut it out of 6mm ABS as that is pretty stiff, but I have run out :evil: so I will stick to the HDPE for now.

The colour means that you wont lose it at night hahah
The HDPE stock that I am using is kitchen cutting boards, so the only choice of colours that I have is;
Red, Blue, White, Brown, Green and Yellow.


Tue Aug 12, 2014 4:37 pm
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Post Re: My home made Rail/Dolly - ongoing project...
The adjustability factor is actually more a 'side effect' of the design for want of a better phrase.
My printer has a theoretical max print size of 200 x 200 x 100mm, and even then it won't really do 200 I don't think.
I wanted a wider rail base for stability, so therefore I had to do it in sections, but this then allows me to decide the width I want even after the brackets are made. I don't intend keeping on changing it though once I've made a cart for it.

The plan with this design is to allow the camera to sit pretty low, so the shorter rail length can still give a good visual impact. It'll be very stable being wide, and has built in feet.
It also will have the tripod mounts each end too, so it can be sloped, or used above more challenging surfaces.

Speaking of mills, I've ordered the bits for my Z axis conversion now. In the meantime I might attempt a 2D "engraving" type job as practise.


Tue Aug 12, 2014 4:48 pm
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Post Re: My home made Rail/Dolly - ongoing project...
By the way, that cart is a fascinating design! What's the rationale behind the layout?


Tue Aug 12, 2014 4:50 pm
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Post Re: My home made Rail/Dolly - ongoing project...
Ahh IC, I didnt think of the limitation of the printer width, good plan :D

So the cart layout.
The T sections are where the bearings go.
I decided to make them embedded into the cart so lower the centre of gravity as far as I can.
It is a t section so that I can drill the hole for the bearing bolt and have room to fit it without the bolt having to be really long.
in the bottom centre of the drawing is the camera mount ball joint.
At the top is the stepper motor mount with the bearing for the timing belt pulley and holes for the idler gears.
The holes around the outside are to bolt on a supporting 'skirt' structure that will strengthen the cart and the bearing supports.

I then just whacked in cutouts wherever looked like a good idea for weight saving.
This bottom plate is made from 11mm thick HDPE, so it does have a bit of weight to it.
I tossed up making the cutouts pockets instead of cut outs as my current cart base made from 12mm polycarbonate has a lot of pockets to save weight, but I would have had to do a tool change or wait for an hour or so for the 3.175mm bit to mill a pocket :-)

I am assembling all of this tomorrow, in its entirety, to pass on to my programmer mate that is finalising the coding, so I will take a load of pictures then.

By the way, if you are interested, I have another design that I have been tinkering with, for an LED fill light.
I have made 2 versions previously.
#1 used 4 x 24LED modules so 96 LEDs on a small board.
It worked awesome, and is brighter then the sun, but that was the issue, way way too bright.

#2 used 4 x 24LED COB Dome light replacement modules, and I fitter it with a PWM dimmer.
It is just as bright as the #1 version, but I can dim it down to 1% brightness if needed.
For some shots, that is still too bright :o and the colour balance is out as I got daylight balanced LED's

#3 I have bought 100 individual square mount Warm White LED's and I am designing a carrier board with built in PWM dimmer.
I think that I will use all 100 LED's, but design it in such a way that I have 2 switches, allowing me to have all LED's powered, and dimmable, or only 10 or so powered and dimmable.
That should see me through the full range of lighting circumstances and being warm white, should look natural.


That is a time-lapse using the #2 version, turned down to 1% brightness. (20 second exposures, f3.5, ISO1200)
That was my first go at a panning rig, made with meccano worm gears.
It was out of round as I drilled the worm to take the 5mm shaft, and you can see that it binds in places.


Tue Aug 12, 2014 5:11 pm
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Post Re: My home made Rail/Dolly - ongoing project...
Well that's another printing problem going on again now. I left it running last night after fixing it, and it completed the print but had broken again (different failure each time) at the end.
I got up at 5am when the kids awoke to go and take the finished item off and start the next, only to find it wouldn't work. The foibles of new(ish) technology eh! It's all good learning though.

So another print is going now at last.

This shows the rough fit of the parts, although the top tubes are not actually attached, and it needs another M5 bolt at the bottom. Typical that I made if for M5s then found I haven't actually got enough of the correct ones, lol!
Image

The newer version of the bracket is on the left in this pic:
Image

Note that the foot on the new version is not full width to save on plastic and has a hole for a bolt to thread in as an adjustable foot if needed:
Image


Wed Aug 13, 2014 1:03 am
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Post Re: My home made Rail/Dolly - ongoing project...
That is looking really good.
Any specify reasoning to have the bottom rails wider than the top?

Also, you might need to make some intermediate spacers to help support the rails, just clip in ones that will prevent the torsional force.


Wed Aug 13, 2014 1:43 am
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Post Re: My home made Rail/Dolly - ongoing project...
The top ones are actually the same width - they're all 30mm thick, but the section that goes to the top mount narrows partly to reduce plastic waste and print times slightly (it's really strong still), so it probably looks like it's not as wide maybe.

I'm going to test without an intermediate to see how it behaves but I'll probably have a set there sooner or later. Not sure I'll bother printing new ones or just hack about the previous prints to make them fit as it's not as critical.
There's no big reason not to have an intermediate, as I've made it so there should be adequate clearance for stuff underneath the cart as it moves.

Another thing I need to look at imminently is an attachment for each end that provides the location for the stepper, the pulley at the opposite end, tripod mounts, and figure out how I'm going to add the arduino and associated stuff like the battery pack etc.

They're currently in a project box that's badly hacked up just to fit the circuitry in, but ideally I want to find a box that will neatly house the arduino, an 8AA battery pack, up to 2 pololu circuits, plus some potentiometers/switches/LEDs.
Ultimately I hope to have an LCD that I can choose menu options from, but that's a long way off at the moment!! I've got a couple, but I've not even dabbled with code for that sort of thing yet.

It would be nice to have a nice printed label for the controls and a proper neat cutouts for the controls etc, but maybe once my CNC machine is running I could try that.


Wed Aug 13, 2014 3:23 am
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Post Re: My home made Rail/Dolly - ongoing project...
Re' your earlier post about the cart design etc - I wasn't ignoring that by the way but was half asleep when I read it very early this morning sorry!

It's a good layout from the look of it and I like the bearings being high up to keep the cart low. With my mkii rail (the current metal one) the bearings are above the bed and it makes a big difference I think so hopefully I can do something similar since I have good width to play with. This does bring issues though. If I use my manfrotto joystick head then it restricts the positions it can go if it needs to be at an angle, and if I use a small cheap ball head then it makes it slightly more awkward to lock it etc.

Not sure yet what the best solution is for a camera mount. It needs to be a ball head of some sort until I have electric pan & tilt, but one that's not a ballache to actually tighten/position/release etc.

That video of yours is great. I can't wait to try night time stuff. It'll be a little while off yet I think, but the days are (sadly) getting shorter now so it's easier to get out at reasonable times to get stars at least.


Wed Aug 13, 2014 3:32 am
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Post Re: My home made Rail/Dolly - ongoing project...
Yes, using the existing printed versions for the intermediary is a good idea and should work well.
You have hit the nail on the head about the CoG mitigation techniques and them getting in the way of the camera mount.
I luckily have a fantastic Manfrotto ball head, that I found on a Manfrotto 144 tripod in a hard rubbish collection, that is ideally suited the dolly cart camera mount.
I'm glad that I didn't have to buy it :D

It's 7am here and I'm just about to start work on the dolly cart again, I will have some photos for you in the next 3-4 hours, should be a completed dolly cart and rails.
I worked on it last night and cut out my new stepper mount.
You will see in the pics when I get to them, but I was too overzealous with the lightening cutouts on the dolly cart, I will need to come up with an alternate mounting method now, or cut out a new dolly cart base, but I would rather not.

The days are starting to get longer here, so it is getting more difficult for me.
I really enjoy shooting the Milky Way, so at the moment, it is around 1-2am that is the prime shooting time.
This month I specifically went shooting to get back into panoramas, as I have been shooting so many time-lapses, as I wanted some shots for some upcoming competitions.

http://500px.com/photo/77215445/lincoln ... er_library

At least shooting Pano's only takes 15 minutes per 12 shot pano or so, so it isn't like sitting for hours.
It was -5 that night :lol:

Arduino mounting boxes are a pain. the connectors are troublesome and mounting the board is a PITA.
Im just mounting the raspberry pi to the dolly at the moment and will come up with a milled custom cover when I get to need it.


Wed Aug 13, 2014 1:13 pm
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Post Re: My home made Rail/Dolly - ongoing project...
Well that took a lot longer than the 4 hours that I thought that it would, but I now have an operational dolly cart.

I did cut out the complex dolly cart shape and it was good, but it didn't allow me any adjustment for the bearings and the fit was too tight on the track.
So, I redesigned the cart, again, and this time have managed to do something that I haven't been able to yet, put in adjustable drag.

Image

You can now tighten the bearings closer to the track, pulling on the angled ones.
This removes any slop from the fitting, but also allows you to tighten it just a bit so that the dolly doesn't roll without pressure.

Image

I remade the truss supports as well, and went with a different design, allowing for a greater amount of space of items dragging under the cart, such as idler wheels etc.

Image

Here you can see the final mockup of the items before I screw them into place.

Image

The stepper needs to be on an angle to get the mount to fit, but I dont think that that is an issue.
I lied, Im not finished, I still have to fit the battery boxes to the sides of the dolly and make up some belt grips for the ends of the rails.
That is a job for tomorrow.

cheers
Andrew


Wed Aug 13, 2014 10:07 pm
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Post Re: My home made Rail/Dolly - ongoing project...
That's looking great Andrew and I love the cart itself. Wish I could get worm drive too for my stepper! :P

What is it that holds your rail upright? Is it attached to a tripod or something?

I'm going to start planning a cart for mine this evening. Here's how my rail currently looks though:

Image


I've got some smaller bearings to suit M6 bolts and may use those as they'll be just as smooth but take up less space than the earlier M8 ones.

The belt pulleys came from China today at last so now I have (I think) 16t ones to run from the stepper, to a 36t one I can then use to gear down the cart. Just need to have a think about how all that will be attached etc.
Plus I'll have to attempt to make a loop of the belt as it's continuous length currently, and If I'm doing this to gear it down then I will have to make a closed loop belt, and also make a tensioner of some sort I guess since I won't be able to use the normal spring tensioners that these belts use.


Thu Aug 14, 2014 11:33 am
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Joined: Thu May 15, 2014 5:28 pm
Posts: 76
Post Re: My home made Rail/Dolly - ongoing project...
that rail is looking awesome, it is going to be very very strong!

I made some tripod clamps, you can see one in a few of those last pics, the curved piece on the bottom rail.
The worm sets were really hard to find, and were what I consider to be expensive, but that set was about $30 including delivery from an Australian supplier.
I found a few Chinese and Japanese suppliers, but it was very hard to determine what was suitable and the prices including delivery ended up costing the same.

I have read quite a few people making their own worm sets however.
You have a lathe a lather so should have all the pieces to make it work.
You use a course threaded rod and turn it down on the lathe to form the worm itself, then using a tap that is the same as the threaded rod, you turn the worm gear on the lathe using an aluminium or acetal blank.
basically you slowly spin the tap against the blank and it slowly cuts the gear.



it looks really easy actually


Thu Aug 14, 2014 2:01 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 compliment :)

Ahh - I see the part you describe now for the tripod, thanks. Is it a single tripod that you use in the centre then?
My current rail is using any mix of:
[list=]No tripods
Single one (at one end)
Pair of tripods (longer one at one end)[/list]

Depending on what sort of height/slope I want, and what the surface is like that it has to be positioned above etc.
I like the flexibility this gives so will probably retain this setup. I may experiment with adding an additional tripod mount for the centre brace as I've seen a lot of rails purely supported from a central point, but I just can't convince myself that it wouldn't suffer from wobble like that. I've been wrong plenty of times before though! :lol:

I've got taps & dies for the correct size Whitworth 1/4" 20tpi tripod thread size so it's easy yo make mounts fortunately.
Can't remember if I'd previously mentioned it or not but I'm pondering (again) about the bearings (or some at least) being ever so slightly sprung in some fashion to help guarantee that if there is any flex in the rail that it cannot result in one of the bearings getting air beneath it. Not sure if I need to worry about it or if this is just unnecessary complication. I'd thought about doing this the other day then decided against it as too much hassle and just to make sure it all fitted well from the outset, but I can't help but think it might be a useful feature. I think the approach will be to build it without, but if I subsequently find any occasions when all bearings are not properly seated to then modify it accordingly.

Hadn't considered making my own worm gears - could be worth a try I guess. I'll investigate further but here are the pulley sizes I got today:

Image

So the stepper will have a small pulley and a loop belt (if I can make one!) turning the large pulley from this to gear it down. A small pulley on the same shaft as the large pulley will then turn the main belt at a slow speed compared to what it currently does, meaning approx 3x longer move times along the rail.


Thu Aug 14, 2014 2:34 pm
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Joined: Thu May 15, 2014 5:28 pm
Posts: 76
Post Re: My home made Rail/Dolly - ongoing project...
Yeah my setup is the same as yours when it comes to tripods, that bracket was just there for testing.
If you loosen off the bolts it is movable, in both sliding up and down and twisting so it would seem to be extremely flexible for mounting.
My favourite tripod positioning of late has been to run the rail nearly vertical with one tripod on the bottom, laying down for stability and the big tripod mounted half way up.

here is one of the early dollies, you can see the bend in the rails. this is why I changed design.
Tripods at either end
Image

the first maker slide dolly track, tripods at either end
Image

not a good pic, but this is the vertical setup
Image


Thu Aug 14, 2014 2:48 pm
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Joined: Thu May 15, 2014 5:28 pm
Posts: 76
Post Re: My home made Rail/Dolly - ongoing project...
you dont need a loop belt actually.
Fix the open ends to the dolly cart on either side, loop through the pulley at each end.


Thu Aug 14, 2014 2:51 pm
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Joined: Thu Jul 24, 2014 4:52 am
Posts: 83
Post Re: My home made Rail/Dolly - ongoing project...
That's how it is currently setup actually, but to gear it down with the new pulleys I received it will stay like that, but with a small additional loop going from the pulley at one end of the rail to the stepper.

Thanks for the pics. That near vertical one is very impressive!!


Thu Aug 14, 2014 4:16 pm
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Joined: Thu Jul 24, 2014 4:52 am
Posts: 83
Post Re: My home made Rail/Dolly - ongoing project...
Hopefully this might give a better idea of how I'm going to gear it:

Image


Image


Fri Aug 15, 2014 12:11 am
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Joined: Thu Jul 24, 2014 4:52 am
Posts: 83
Post Re: My home made Rail/Dolly - ongoing project...
Well I've been trying out different versions of bearing carriers today with the printer, to try and get the best solution.

So far, this is working out pretty promising so there's 3 more printing off as I type, then I can cut the ally plate for the cart and try assembling it.

Image

Image

I was having trouble getting how to arrange this to work properly due to the small space involved until the wife suggested I offset the bolts. Duh!! The stupidest thing about me not thinking of that is that my first rail had them offset like that and it still didn't occur to me! Doh!

So I've got 4 of them printed now, and have ordered a load of exact length bolts to make it neater (M6 25) and half thickness nuts to replace the washer stack on the bearing side, again for neatness and will also make them more rigid potentially than washers, although I doubt that actually matters.

Hopefully this evening I'll be able to cut out an aluminium plate for the cart. I think I've got some suitable pieces around 5 or 6mm thick or so which should do nicely.


Sat Aug 16, 2014 2:51 pm
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