YASV (Yet Another Scraping Video): Flaking ...

Hi!
Made another one, this time about flaking. But I'm bad at it (you'll find out by yourself <G>)
Here it is: <
http://www.youtube.com/watch?v=7yeqSjT7UBE
But still I think I earned your 5 stars rating at YouTube. :-))
Nick
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You must have had a reason for ruining that camel-back straight edge...
Is it just me that thinks flaking is ugly and frosting is beautiful?
regards Mark Rand
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Mark Rand wrote:

It simply doesn't work if it is only scraped.*) After putting on the blue, rub it on the surface you want to scrap and you'll discover that it sucks onto the surface and makes the blue on the work completely unreadable. There need to be pockets to keep the blue. After "ruining" it, it worked perfect.
Look at your tools for touching, they all do have pockets.
*) And I had to rescrap that camel back. I got it lented and had to discover that it was bent. More than 0,03 mm out of shape. I scraped it flat again to within 15 µm. 1000 mm long. Now it's a good grade 1, grade 0 would allow 8 µm
Nick
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wrote:

Hi Nick, Whilst your English is one hell of a lot better than my Deutsch I must correct you <G>
"I got it lented and had to discover that it was bent."
I think you mean "I borrowed it" (from someone else) and found it was bent. NOT that you "lent" it to someone and when it returned it was bent.
Thanks for all the info on your scraping experience.
BTW can you reply to my Yadro query sent to Yadro.de
Thanks Best Regards
Richard
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Richard Edwards wrote:

remember that.

You're welcome!

This evening. I'm right in the middle of scraping the Myford and just took a break to relieve the back-pain (part two will be named "part 2 / AKA back-pain"). Not much fun scraping bent over. :-(
Nick
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In several old engineer books I have found. that the average workheight while standing at the bench, should be set to the finger tips, keeping the lower arm horizontal and hands pointed downward as indicator. Hope this helps. Dirk
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Dirk PG1D wrote:

What a nonsense! <http://www.cncecke.de/forum/attachment.php?attachmentid 69&d36776057>
<VBG>
The best height seems to be (with the BIAX) when work is at level with the highest point of your hip's bone. With hand scraping a bit higher.
Nick
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LOL, you must have sore knees too ;-)

Yes, correct. the same height as in the old books, at least compared to my hip bone that is ;-)

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Kind of odd way to say it but it was understood. Of course I live where English is the American version ;) I'm used to oddities in language since we slurp up any word that works for us and then we mangle a few on purpose. ;)
Darn flash player is doing weird things so I'm using keepvid to download it atm.
Ah, nice vid, grabbed the hirez version. Noticed your line on tool that you index to drawn diagonals.
Wish my dsl was faster. I have 12 minutes to wait for the next vid you produced to download.
Thank you for sharing this information.
Wes
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Wes wrote:

Bought a better camera. :-) So starting with part 2, the videos should be better. I'm also trying a new software for cutting (Magix $WhatEver) that uses the video in its original format and needs no converting before (as with that damned MS Movie Maker that crashes every once and a while and is sometimes unable to export his own crap).
Anyhow. My English might be funny, but still understandable. :-)) And corrections are welcome, I'm still willing to learn. But for the vids, it's too late, they are online.
Nick
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Youtube tends to make high and low rez versions of one's uploads. I tend to believe they serve them depending on perceived bandwidth. I used keepvid to pick the better of the two.
A better camera is always good. Some day I'll have a better one than my Sony V-3. It isn't really a video camera but I've tried to use it as such. I'd like a HD video camera someday. Static pictures of engines isn't as nice as machines in motion with sound.

Your English is generally better than what is spoken where I live and work. Even if it was not, what you tend to share would be worth any effort to understand.
Wes
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Hello Nick, A couple of questions to fill out some of my (considerable) ignorance...
Am I correct in thinking you scraped the camel back in the 'normal' fashion to straighten it as you showed in the earlier video? Then this was solely a surface finishing technique which you applied afterwards.
Is the camel back wide enough to cover the whole width of the grinder bed way or do you have to slide it across? If so, how do you know whether the twist you found is 'real' and not due to the camel back rocking about its long axis? Roughly how much height in total did you remove from the hump in the middle of the grinder bed?
Looking forward to the installment about the bed vee. I'm considering having a go at my lathe bed, but am too frightened at the moment.
Rgds Richard
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Richard Shute wrote:

Yes.
Yes. As I said, it can't transfer blue if it is simply flat. The way I scrap, the pockets / valleys are about 3 µm deep. Not enough for the blue to -kind of- be smeared in when sliding across work.

Its long enough and wide (by the millimetre) enough. "Bridging" longer guides can be done, but its takes some paying attention. Depending on what tools you have it can be made accurate enough and be sped up.

Well the twist. :-) Admittedly I was stupid enough not to check the Camel Back in advance. During scraping, when the twist showed up to be serious, I checked with the level and the bed was twisted. In fact, it was twisted the other way round as the camel back. But I learned that later... When I thought that I was finished, I tried to level the grinder and found the twist again. Finally checked the camel back and ... well ... twisted 0,03 mm. So I had to scrap the straight edge (he's gonna have to pay for that <GRRRR>) and re-scraped the Myford's bed. But that didn't take that long. Checked with the level and now I do have a twist of 0,01 mm / m (this calculates with the levels geometry to about 1 µm IIRC)

It was something around 0,015 mm. Not that much.

I always say then: "It's hard to make it worse". :-)
Nick
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Mine don't :-)
The 600mm, 900mm, 1200mm Camel backs, the home-made 30-60-90 degree template, the home made squares are all as scraped, without flaking and the bed that I'm currently fitting the saddle to is as ground. The ground finish behaves differently from the scraped finish in that it is possible to wipe off nearly all of the blue on a single spotting if the workpiece is moved too far, that is not a problem since it will still mark the high points on the workpiece and the workpiece is not moved very far when spotting.
The blue needs to be completely re-applied every cycle with these tools instead of being "smoothed out" every few cycles on a granite surface plate, but they still work. Not so good for roughing with a heavy layer of blue, but perfectly good for lighter layers.
Here we are happily scraping machine tools in the "old fashioned way" in our spare time and thoroughly enjoying ourselves. Will our grandchildren come home from a busy day at the office and write C++ and Java in the "old fashioned way" for relaxation and amusement?
regards Mark Rand RTFM
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Mark Rand wrote:

Interesting!
I do know that the way the reference is scraped makes a huge difference how they "draw" the points. Roughly scraped (valleys 8 µm deep) draws a very clear pattern but doesn't make a great difference between low / middle / high spots. The shallower the valleys are, the clearer the difference, but the lighter the blue (harder to see).

So you say, that with a ground (or like ground) surface, you're moving less?

I'm always doing that. The references I have (except the granite plate) only allow 2 passes at maximum without recharging.

Interesting technique. Never tried, never heard. I'll try that. Do you have to say more about it?

My observation too. The way the camel back was before, it was better for roughing. Now the pattern needs a closer look, but is better at low/medium/high spots. But it absolutely didn't work without the halfmoons. Or at least I didn't get it to work.
Nick
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No, I end up moving the work by the same distance and wiping most of the blue off the "master" each time :-) It is not a problem, because the blue will still go to the highest points on the work, even if there are some points that get missed. Eventually, any high island will get blued and scraped, even if it gets missed one time, because next time it will be higher and will starve the other points of blue.

I find that with a scraped or ground master I have to re-blue every cycle. I don't have to put fresh blue on the roller every time, because that seems to carry enough blue for several cycles, depending on the area.

Possible misunderstanding...
I meant that the blued area on the granite does not need fresh blue applying for several hours worth of scraping instead of every cycle for a scraped or ground master. The texture of the granite holds quite a lot of blue. The blue on the granite surface plate can be made more even by using the roller without adding any extra blue from the tube or the "area for picking up new blue".
The blue gets thinner and thinner because you are not adding any more, but if the work piece is reasonably small (say 50mm x 250mm like an angle template) then the blue gets thinner as the work gets flatter, so you get thick spotting for roughing and increasingly fine spotting for finishing. All automatic :-)

Too good/flat, with the work already too good/flat? ;-)
regards Mark Rand RTFM
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Mark Rand wrote:

ACK to that "the next time it will be caught". But still, with a ground surface I couldn't touch. It doesn't pick up blue and its hard to apply an even layer of blue on it. The blue kind of peels off when rolling over it. Maybe a property of my blue?

OK. Then we agree. Just refresh with the roller (without charging the roller). Depends on the surface. For fine work, when I don't get they layer of blue thin enough, I make a few touches that I wipe off of the work until the layer on the granite is thin enough. Happens when starting from fresh.

ACK. Again, depends on the surface and how good it is in keeping blue. Thus the flakes. <G>

If you envision what happens when the reference is sliding over work and what the blue does, you see that pockets / valleys are essential for a clear reading.
Nick
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Mark Rand wrote:

OK, got that working yesterday. Initial charging with blue is more complicated, but then it works. I still prefer pockets, they are easier to handle and I see no drawback (until now).
Nick
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Some do and some don't :-)
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Boo wrote:

Do *you*? Me not. :-)
Nick
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