Scraping flat?

[vtcnc]

You will not easily get curled chips off cast iron, although I have seen it done by a professional with very heavy pressure, it will be more like dust you will see, if you are getting scratching, grind a small corner break on the corners of the insert, what are you using to sharpen the insert? scratching can be the result of a poor finish on the insert's cutting edges.by hinging, the meaning is that if you lay the scraped surface on the surface plate and push either end and if it "hinges" on the center and the other end moves, you know that it is high in the center and needs material scraped off the center area, not the ends, on the other hand, if it does not hinge in the center, but on wither end, the opposite is true, the part does not have to be inked up to do this.

This may be completely unnecessary to clarify on this forum, but I was once a newb and recall having some difficulty with the phrase “hinging”. It wasn’t until I saw somebody in a video, using the actual word, that I was able to make it click in my brain. For those struggling like I did early on, the hinging can be thought of as “pivoting”.

High spots create pivot (or hinge) points.

Now that I understand and have a fondness of the colloquial language used in earlier machining publications, I like using the word “hinge”.

Edit: I’m still a newb!

Sent from my iPhone using Tapatalk

 

[GunsOfNavarone]

I am trying my shot on this on a piece of steel. I think it 1045? The wheel I bought is for carbide and it’s a carbide tool. I feel it biting and even have a very shiny edge on my blade as I went over it with a diamond sharpening plate. Is there a recommendation on a precision flat stone to clean the burrs of the surface?

 

[FOMOGO]

I picked up a set of these on ebay. They seem to be doing the job quite nicely. Be sure to read the directions before use. Mike

Precision Ground Flat Stones, Diamond Ground Tool Room Stones -Ground on 2 sides | eBay

Two professional quality precision ground flat stones - new aluminum oxide stones, diamond wheel ground on a precision surface grinder. Compare the before and after grinding photos. The sides and ends are left as received.

www.ebay.com

 

[Uglydog]

After a cursory search I couldn't find a free video showing hinging on the internet.
Here is a quick and dirty video with all the pimples and scars of a ground parallel I have.
Note: This is not a good example of how to put something on a plate. But my other hand was on my phone/camera.
Anyway, I think you can get the idea.

I did QA in medicine, but not as a machinist. But in many ways the concepts (not techniques) are similar.
Thereby, please also understand that this is a qualitative vs quantitative assessment.
Each has their place.

Daryl
MN

 

[vtcnc]

Video is relatively good. Go to 13:37 to see and hear the “hinging” discussion.


Sent from my iPhone using Tapatalk

 

[Uglydog]

vtcnc,
Strong find!!
Done well with explanation.

Dudemanrod,
Please know that like much of living in this crazy world, there is a huge learning curve with scraping.


Daryl
MN

 

[vtcnc]

vtcnc,
Strong find!!
Done well with explanation.

Dudemanrod,
Please know that like much of living in this crazy world, there is a huge learning curve with scraping.


Daryl
MN

Your short clip does a good job of seeing the hinge points real time, right over the top of the part. What is interesting about hinging is that it will move and you can definitely see the effects of scraping on hinging.

More so, and this may sound strange, but I feel it necessary to say on this particular narrow thread that we have so kindly hijacked...lol. Scraping is one of those skills that as you do it you can literallly feel your sixth sense kicking in. Man, I felt that hinging when you were turning it! It is a visceral experience, connecting mind and matter. Sorry, don't mean to get mystical here, but I think this is why there is an appeal to scraping and to our hobby; that people who suddenly discover that through the use of manual machines, they are engaging their senses in the natural world to make something meaningful...in this case something flatter and more square than can be easily imagined yet full of little hills and valleys. It's fun, scientific and rewarding all at the same time and taps into parts of you that you didn't know existed.

Ok, all done! Hijack over!

 

[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.

gettin there,
high in the middle

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

 

[Mill Lee farm]

I picked up a set of these on ebay. They seem to be doing the job quite nicely. Be sure to read the directions before use. Mike

Precision Ground Flat Stones, Diamond Ground Tool Room Stones -Ground on 2 sides | eBay

Two professional quality precision ground flat stones - new aluminum oxide stones, diamond wheel ground on a precision surface grinder. Compare the before and after grinding photos. The sides and ends are left as received.

www.ebay.com

I bought a set of 2x6 from this seller and am loving them

 

[Janderso]

If you have a surface grinder you can easily make your own precision flat stones.
They do come in very handy.