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Subtitles in videos

Posted by gerard94 
Subtitles in videos
October 22, 2009 07:29PM
Hello all,

I'm French and building a Mendel. I get some difficulties understanding explanatory videos about its construction. For foreigners, understanding oral English is, in general, more difficult than reading written texts, even in English. If someone could add English subtitles to these videos, it would be great.


Re: Subtitles in videos
October 23, 2009 04:45AM
Hi Gerard,
if you want me to write out English text for a couple of the videos in which you are particularly interested, just let me know which ones. Happy to do that. Can probably do so today, or perhaps Sunday.

I would offer ecrire in French, but you'd have plus de chance understanding the oral English!

Re: Subtitles in videos
October 23, 2009 05:48AM
Three videos look important:




If you can transcribe only one of them, do the first one.

They are the videos that appear in the Mendel building pages.

Thank you very much for what you can do. Don't worry about French. Most french people who know some computer science understand English. And if anyone asks, I can translate your text.

Merci beaucoup.

Re: Subtitles in videos
October 23, 2009 06:59AM
Hi Gerard,
here is the first transcription from the video about the ball bearings. The speech is a little difficult to distinguish on a video, partly because the chap has a lisp. But, this is the second time of watching, so I've now "got my ear in", ie I have learnt to understand the speech well. But not perfectly, as you'll find.
(I'll skip to the important bits, and [correct (most) grammar] to allow best use of translation software if need be.)

He says, "Hello, this is just a quick video.."
"to show how I designed Mendel in such a way that all of its axes can move/be constrained with just these: ball bearings. For each axis we've got 2 round bars; a pair here for the y, a pair here for the x and a pair here for the z, and I've got this fancy diagram to try [to] explain what I mean.
...there's a pair of bars for each axis and this is an end section view of one of the axes, bar 1, bar 2, and this is a plan of those bars Each axis can move in 6 degrees of freedom, along x, y and z, and about x, y and z.
... take that axis there as a kind of example. You've got the bearings [that] wrap around this bar and around this bar here. Most of the constraints are wrapped around bar number 1, which has got 3 bearings around it. I'll use this as a demonstration; this is one of the bearing sets, and it's arranged in such a way that 3 bearings sit at 120 degrees around the bar, which allows movement up and down the bar but, critically, prevents movement along the x and along the y. However, as you can see, it will be able to rotate about the y and about the x, but we solve that simply by using 2 identical sets of bearings on that bar to prevent that happening, so it can't rotate there and it can't rotate here in x and y.
So, what we've done so far with bar 1; we've constrained it along y, constrained it along x, constrained it about x and about y, we're allowing it to move up and down z. What we haven't done yet is constrained it about z, and that's all the second bar does.
We imagine that without these bearings (and this ruler represents the axis), the axis can rotate about this bar; then all these 2 bearings do is prevent the bar from rotating. We can see those 2 bearings over here on the z axis there and there.

There's a couple of notes to go with this bearing philosophy: there are obviously a lot of different ways you can constrain..." (missed this word) "... I've chosen this design specifically because it's versatile for low-precision parts. As you can see, most of the constraintrs are loaded onto 1 bar. It's really, really important because if you can't get hold of a very straight bar, or your axes are not parallel, there's a lot [lower] risk of it jamming. For example, if the bars aren't parallel and the bar moves out here, then these 2 bearings allow the bar to float within a certain range, which prevents the axis from jamming.
The second note is that while we haven't quite achieved an accuracy on RP parts yet to..." (missed the words) "...., which is what you want.."(skipped) "..for tolerances and moving things, what I've done is included an adjuster bolt so that we can get very precisely the constraint radius between the bearings, and you'll find an adjuster bolt on each bearing set around the design....." (waffle skipped)
"..We haven't had a single jam using this philosophy and [I hope] you won't either."

Re: Subtitles in videos
October 23, 2009 08:58AM
Very well. It's surprising how suddenly you understand what hou are hearing when you have the text under your eyes. Your transcription will be important for me, and for others I guess. Thank you Hazel.

Of course, if you can do the same thing for the other videos...

Re: Subtitles for Mendel's improvements over Darwin
October 23, 2009 09:48AM
You're very welcome.
Next one coming right up, same rules as before.

Transcription for (the salient parts from) Mendel's improvements over Darwin:

"the biggest change is the orientation of the axes, and there are a couple of reasons for doing this. The big change is that y is now at the bottom forming a rolling bed and one of the big advantages of that is that we don't have the x and the y sat on the top of the structure - that was very top-heavy and it needed a lot of mechanical structure to keep it stable. By moving it down, it's not top-heavy any more; we can control the weight at the bottom a lot [more easily].

The big reason was, now that the bed rolls, instead of moving up and down, the z axis isn't over-constrained any more. In Darwin we have 4 points/leadscrews driving it up and down, and that caused a lot of jamming. But now we only have 2 leadscrews, one here and one here, and, coupled with the bearing constraints, that means we don't have any jams whatsoever.

This design now caters for ball bearings...." (skipped) "...and now the axes move and are powered using NEMA-14 motors instead of NEMA-23s, which is approximately 8 times less torque..." (skipped) "... which makes the whole machine a lot more efficient.

Another feature of Mendel is that at some point we'd like to get tool-changing in to the builds, so that you guys can experiment as much as possible with different materials. The tool-changing gantry is up here; it's these 2 studding bars which are just waiting for some mechanical parts to [be added] to enable that tool-change to happen. There's a couple of advantages of the gantry being up here; firstly, this is dead space, so a good place for the tools, but, critically, by having it up here, we can take advantage of this leadscrew here, so we get a lot of mechanical advantage if we need it [actually to] do the tool-change..." (skipped) "...

The motor drives are a bit more stable. As you can see, we've got a motor, for the y, that powers the axis directly - we don't have that annoying drive-bar any more, which caused problems, specifically in the coupling and the gears. Because this is now a rolling bed, we only need one drive point of attachment.

The final note is the assembly. Apologies; Darwin wasn't the easiest thing to put together, largely because it had a lot of trapped nuts in its components. .." (skipped) "....the best way to achieve a good mechanical structure is just with studding alone, and as Zach actually put it, using the kebab-effect to have a nut on each side of the component is a much easier way of assembling .." (skipped) "..

The other thing is the [number] of bolt-types that we've used. I've tried to make the whole assembly out of only 3 types of bolt: 2 M4 and one M3."

Re: Subtitles in videos
October 23, 2009 11:47AM
Very well.
I've made a subtitle file from your first text. Could you check it, please?

open | download - How Mendel\'s axes work.srt (4.2 KB)
Re: Subtitles in videos
October 23, 2009 01:18PM
And here are the subtitles for the second video.


open | download - Mendel\'s improvements over Darwin.srt (3.9 KB)
Re: Subtitles in videos
October 23, 2009 05:00PM
Hi Gerard,
not being a computer bod (or bodess), I don't know this type of file, or how to open it to be anything meaningful.....
Re: Subtitles in videos
October 23, 2009 05:21PM
SRT files are standard subtitles files. To use them, download the video file (for that, you can use e.g. the module "DownloadHelper" in Firefox), place it in the same directory as the SRT file and give it the same name (but not the same extension, of course). Open the video file. You should see the subtitles. If not, use another video player, such as VLC, that works.


If you get problems, tell me.

Re: Subtitles in videos
July 13, 2010 05:36AM
I would like to have the subtitle of the video " How its made ball bearings" from team222badbrad.

I really appropriate If you give me the subtitle of that. I'm looking forward to recieving your help.

Thank you very much!

Re: Subtitles in videos
July 13, 2010 06:38AM
@Team222badbrad: If it's your video then I think you can create the subtitle file easier then anyone else in the known universe.
@gerard94: You should send these files to someone on the core team so they can add them to the wiki.

Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse
Re: Subtitles in videos
July 13, 2010 09:25AM
@rhmorrison: Yes, you're right, I'll do that. Thank you.

Re: Subtitles in videos
July 14, 2010 08:15PM
Anyone can register to get an account, and then add pages and files to the wiki -- there no need to be a core team member to do that. We want everyone who is involved in RepRap to be able to improve our documentation smiling smiley

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