Scraping flat?

[GunsOfNavarone]

I bought the stones last night too, thanks @FOMOGO I went at it against n yesterday with more understanding & it went much better. Really rthe biggest error I made the 1st time was expecting more material to be removed with each scrape. I can see how this could be consider ZEN, and if it works out acceptably my 1st time…,I could love this.
It was me, I sort of hi jacked this thread, but no reason to start a new one, this one was asking questions about the process so….
Thanks guys

 

[Optic Eyes]

look at this it might help you, rebuilding is scraping for bearing so machine members can move on high points with a film of oil between the distributed points, one surface can be flat, the other one high points.
Most people rebuilding never scrape a surface flat, one big smear.A Hardinge lathe bed is ground very flat and smooth. the saddle and tail stock are scraped to fit with evenly distributed high points with the interval of low spots holding oil. Hook scraping can produce either type of result depending on the operator, the text and drawings show this.

Daryl and should do a video showing this with carbide blades and high speed blades, it is not hard to do.


High in the middle can be caused by rubbing the part on the master and if it's high in the middle already the print represents the blue spots printing both ways from a high middle to the ends. Beginners fall for this frequently, nobody tells them to use a good ground straight edge and check, it can get so bad you can tap one end then the other and you will hear the thumps, this test should always be applied when spotting to check for warping and false readings, buying a good ground straight edge should always be used every other cycle to detect errors

Hinging is awfully close to the airy points, or so it seems, but to get something real close, 68° overnight on a lab grade plate.

 

[GunsOfNavarone]

So, I might have one of those situations where it appears to be one thing, but it maybe the exact opposite.
This plate I'm making (remember, this is more the journey than the need) will sit on the bed ways of my lathe. When attaching a DTI to the compound and running it across the plate, it hits low where I have blue ink and high where there is none. WTH? This is the exact opposite of what should be true. Is there some kind of anomaly going on above my pay grade? A straight edge laid across it in the X & Z axis (think of it's position on the lathe) agrees with the ink.
I have tried hinging as well, but as this is a perfect square, my skills are not refined enough to pick up a pivot point. MAYBE in one direct, but not in the other. I probably need to not go too much further with this until I receive my stones Tuesday.

 

[Optic Eyes]

Indicators have some problems and the biggest one is determining a datum, as well as even if your surface plate is your datum, are you measuring high and low spots or parallelism. bluing gives a comparison between a tested flat surface and a surface needing testing, Lathe bed ways are notorious for being worn on the flat tops of the prismatic ways.

So I didn't want to start a new thread, so maybe I'll continue here...
I am finding that I am getting scratching more than peeling. Not that the tool I bought is great, but I put a radius on the end and about 5* of relief. It's probably .750" wide and my approach is just enough of an angle so it doesn't skate. Now, being that I can't sharpen HSS tools well enough to use anything but carbide on my lathe probably points to a large part of the problem, I'm really getting a grit off the surface I'm scraping instead of, I don't know, small curls? @Cooter Brown what do you mean by "hinge the part"? Put it down on the ink in a hinged motion over straight down?
How do you use feeler gauge when the space between ink spots (low spots) is so small? I watch plenty of YT videos before jumping in, but I guess I didn't come across any that were for 1st timers.

Scratching is because of improper sharpening of blade, I also teach scraping with a straight blade I. E. , no radius
and no corner gouges, again proper technique is the answer, What king of scraper do U have.
please reply to dennismdanichATgmail.com