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 )

Here it is:

But still I think I earned your 5 stars rating at YouTube. :-))

Nick

Reply to
Nick Mueller
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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

Reply to
Mark Rand

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

Reply to
Nick Mueller

Hi Nick, Whilst your English is one hell of a lot better than my Deutsch I must correct you

"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

Reply to
Richard Edwards

OK, to lent / to borrow. There's no difference in German. I try to 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

Reply to
Nick Mueller

Yes, frosting does look lovely, can anyone tell me how =it is done ? Any chance of a frosting video Nick ?

Reply to
Boo

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

Reply to
Dirk PG1D

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

Reply to
Richard Shute

The "real" frosting is achieved by simply scraping to a plate. With enough passes and short strokes (2 .. 3 mm) it is frosted. Decorative frosting is useless. :-) I do have a cast iron plate that I scraped that looks frosted:

For size reference, that a cap of a beer bottle. :-) But I only scraped it to 20 dots per square inches. ;-)

Ha! It floats on the granite plate! Just a slight push and it slides along. Takes a minute or so until it sucks itself to the plate. Took me about 6 hours to scrap (200 * 300 mm).

The other decorative scraping I know of is flowering (we call it "butterflying"). I tried that, but don't have the *slightest* clue how it works. Despite the description in "Machine Tool Reconditioning". One day, I'll find it out too.

Oh, and here's a surface map of that Camel Back:

In fact, it is better, because I didn't subtract the error introduced by my plate (IIRC 4,2 µm). Gonna have to write a program that does better tilting of the plane (another 3 µm) and correct with the known error of the measuring plane. The output is made with gnuplot.

Nick

Reply to
Nick Mueller

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 ) 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

Reply to
Nick Mueller

What a nonsense!

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

Reply to
Nick Mueller

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 ;-)

Reply to
Dirk PG1D

have you seen this guys work

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all the best.markj

Reply to
mark

Yes, I know. What a waste of time. Decorative scraping the Deckel-clone and leaving the ways worn. :-) No, looks impressive, but honestly I think it's only for the show room.

Nick

Reply to
Nick Mueller

Good God that looks just like my shop except for...........

The quality of the machines The complete absence of clutter The lack of swarf on the floor The missing leak in the roof The missing pile of scrap waiting to be turned or milled into "projects".

But I am happy

Richard

Reply to
Richard Edwards

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

Reply to
Mark Rand

Note that what I and Nick referred to as flaking (the half-moons on the work piece) is what Connelly refers to as frosting. and What I referred to as frosting (regular, light scraping patterns like the frost on a window or in a chess-board pattern) is what Connelly refers to as flaking...

After the work is finished, one last pass is made all over the work. A grid is drawn on the work with a pencil 1/4"-1" square as appropriate to the part. Alternate squares are gently scraped over their entire surface in one direction and the other squares are scraped all over at right angles to the first direction. It is entirely a decorative effect, but if done carefully and consistently, it will damage the finish by less than a micron (0.4 tenths of a thou). This is perfectly adequate for the top of a milling machine table:-) No point in doing it on a non-visible sliding surface or a standard, since it'd wear off the sliding surface in a very short time and standards don't need to look pretty.

Using deep half-moon gouging for decoration, as Bridgeport do, just looks like crude butchery to my eyes.

Mark Rand RTFM

Reply to
Mark Rand

Funny confusion. Maybe triggered by me. :-) Or maybe the reason is, that different countries do have different names. I do have my names from the US (and I think I got them right).

Frosting is irregular (90° diagonal) short strokes. Either functional (but with the same appearance) or purely decorative (without flatness) Flaking functional or decorative. flowering, purely decorative (at least never seen on a guide)

I have no word for this. And frost doesn't make a regular square pattern on my car's window (maybe because I don't have a car ). I tried that once -just for curiosity- and you even can keep that pattern without a last "destructive" pass. But it's a bit of a pain. Scrap to flatness and then continue with maybe 3 passes -still touching- but keep the scraping direction within the square boxes. Looks very nice.

OK. But then, there are people that can make shallow half-moons (unlike me) that look nice. The ones I made are quite deep. Didn't measure them, but I estimate them to be almost 0,01 mm. Oil pockets should be 6 .. 8 µm for heavy load, about 4 µm for light load.

Nick

Reply to
Nick Mueller

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

Reply to
Nick Mueller

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

Reply to
Mark Rand

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