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 First little steps 
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Joined: Tue Aug 23, 2016 7:07 am
Posts: 61
Location: Germany
Post First little steps
Hi there,

it took now months until my metalworker had a couple of hours to start with me building the rig.
Yesterday we spent four hours sawing and welding. Of course not much but I was so happy that there are finally the first steps.

I hope we will find time (which is the major problem now) to work continuously on the rig in the future...small steps but steps.

Unfortunately I cannot attach some pictures (causes internal server error) :-(

Greetings
rame


Sun Jan 15, 2017 4:23 am
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Joined: Tue Apr 09, 2013 6:49 pm
Posts: 175
Post Re: First little steps
Hey Rame,
can't wait to see it.


Mon Jan 16, 2017 10:40 am
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Joined: Wed Nov 11, 2009 10:45 am
Posts: 1685
Location: Merritt Island, Florida, Estates Unitas
Post Re: First little steps
Me too. Hope it works well for you. Post some pictures as it starts to take shape.


Mon Jan 16, 2017 12:01 pm
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Joined: Tue Aug 23, 2016 7:07 am
Posts: 61
Location: Germany
Post Re: First little steps
My first steps cutting steel :-)

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The base is being welded

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Base

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Part of the modular tower

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Bits and pieces waiting to be welded

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Tue Jan 17, 2017 11:37 am
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Joined: Tue Aug 23, 2016 7:07 am
Posts: 61
Location: Germany
Post Re: First little steps
Base and tower...

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Sat Feb 04, 2017 8:45 am
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Joined: Sat Apr 25, 2015 7:34 pm
Posts: 79
Post Re: First little steps
Rig for what?


Sun Feb 05, 2017 7:58 am
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Joined: Tue Aug 23, 2016 7:07 am
Posts: 61
Location: Germany
Post Re: First little steps
TIMETRAVELER wrote:
Rig for what?


A MoCo rig - or what am I getting wrong? :?:


Sun Feb 05, 2017 8:53 am
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Joined: Wed Nov 11, 2009 10:45 am
Posts: 1685
Location: Merritt Island, Florida, Estates Unitas
Post Re: First little steps
I like it! I'm assuming this is the tower for the crane support. It looks like some of the "cubes" can be added or removed to adjust the height of the tower. If so, congrats, I haven't seen that feature before, but imagine it will be really useful. Many times, the track is elevated by building up a support structure and then laying track on top of that. If this works it should save a whole lot of time building up and tearing down because track can be laid on the ground and levelled with screw-feet or other means.


Sun Feb 05, 2017 2:25 pm
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Joined: Tue Aug 23, 2016 7:07 am
Posts: 61
Location: Germany
Post Re: First little steps
That´s correct. The cubes will allow to have three different heights of the crane arm.


Sun Feb 05, 2017 3:02 pm
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Joined: Tue Aug 23, 2016 7:07 am
Posts: 61
Location: Germany
Post Re: First little steps
We´ve built the mount for the wheels today. Unfortunately the wheels haven´t been delivered this week :evil:

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Sat Feb 11, 2017 9:45 am
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Joined: Tue Aug 23, 2016 7:07 am
Posts: 61
Location: Germany
Post Re: First little steps
Now the base is (more or less) ready :-)

Time for the motor...looking for a 1000W servo with 1:25 or 1:50 planetary gear and AT10 25mm belt.


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Tue Feb 14, 2017 2:22 pm
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Joined: Wed Nov 11, 2009 10:45 am
Posts: 1685
Location: Merritt Island, Florida, Estates Unitas
Post Re: First little steps
Nice looking welds you guys make. The jig for holding down the angle pieces was interesting. I assume more track sections can be added as needed and that the nub at the end of the round part of the track is to precision-align the sections automatically. Do you have any plans to have more wheels run on the underside of the track? You were looking for some pretty fast moves when you started this project. I designed my trolley so it has wheels on top, on the sides, and under the track. Your angled wheels do the job of my wheels on top and on the sides. My bottom wheels are to reduce the possibility of the top-heavy crane lifting a set of wheels off the track, or possibly toppling the crane tower when the dolly undergoes rapid acceleration. Maybe anyone else who has experienced the need for speed can comment on this issue. Am I being too conservative and over-engineering this? Am I being over-optimistic about how much acceleration I can get out of this? I am also looking at 750 to 1,000 watt servos. Hey, go big or go home, right?


Wed Feb 15, 2017 2:58 pm
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Joined: Tue Aug 23, 2016 7:07 am
Posts: 61
Location: Germany
Post Re: First little steps
Yes, we´ve been thinking about wheels from underneath for a while, but we started now with this solution and we will build the underside version later.

The track is endless :-)

Concerning the motor we look for the following:

speed 2 m/s
total weight 100kg

1000W servo
36 teeth gear
1:10 planetary gear
AT10 25mm belt


Thu Feb 16, 2017 6:34 am
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Joined: Wed Jan 20, 2010 4:50 pm
Posts: 561
Post Re: First little steps
Hi Rame - and the track is Panther... :)

One day I hope to hear from someone who has used Bartrack from SolidGripSystems Netherlands - it was originally advertised as being good for Motion Control..

Meanwhile - you should check what rpm your servo motor is capable of. Many brushless servos top out at 3,000 rpm.

With 10:1 gear 3,000rpm -> 300rpm or 5 rev/sec. With a 36T pulley and T10 belt your theoretical maximum speed will be 1.8 m/sec.... so maybe allow for a larger pulley and ability to change it. With a smaller pulley you will have faster acceleration, so for short quick moves this can be more useful... :)

My experience with servos indicates when the motor is working at near full capacity - then it will lag more (i.e be a bit late in being where you expect it..) which means less accurate following of programmed path. In most cases this won't be noticeable, and will always be consistent, but in some cases can cause problems. Just one reason why steppers can actually be superior to servos... since they will never lag... :)


Sat Feb 18, 2017 12:15 am
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Joined: Tue Aug 23, 2016 7:07 am
Posts: 61
Location: Germany
Post Re: First little steps
Hi Gerald,

right now we have a 1000W Servo with 2500rpm as an option and a 1:4 planetary gear.

So, do you recommend closed loop steppers over servos for all parts of the rig or only specifc axes?


Sat Feb 18, 2017 1:59 am
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Joined: Wed Jan 20, 2010 4:50 pm
Posts: 561
Post Re: First little steps
It's hard to recommend. Either can be ok. With servos it's possible to tune them more tightly, but depends on the software and the amount of reserve power the motor has. Closed loop steppers are much easier to work with though, and require no tuning. Proper calculation will also take into account the acceleration rates and the weight of the rig...

Just be prepared maybe for some trial and error.. :)


Sat Feb 18, 2017 7:39 pm
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Joined: Tue Aug 23, 2016 7:07 am
Posts: 61
Location: Germany
Post Re: First little steps
I know that there will be trial and error.

Nevertheless it´d be great to have the amount of burned money as low as possible.


Sun Feb 19, 2017 2:29 pm
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Joined: Wed Jan 20, 2010 4:50 pm
Posts: 561
Post Re: First little steps
To answer your question a little more - for pan, tilt and lens drives normal steppers are quite adequate. For other axes it's less clear. As said, I quite like the closed loop steppers in terms of ease of setting up. They also make a mains voltage version with higher rpm than the standard EasyServos, though I haven't tried it myself... servos will be quieter of course - so if sound is an issue?


Sun Feb 19, 2017 3:27 pm
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