Thread: Scraping Projects

Hi Nick

The parallel scraping was just to take the rust off but no material the ripples where already there the radius is i think 90mm

Cheers
Harty

A long vid on youtube on scraping.... Have not watched it all yet... too tired

K & J Scraping Training Video - YouTube

Novel way I discovered of checking a straight edge for things like stiffness as well as flatness..

I surface ground a couple of cheep 1.2.3 blocks as a pair and they came out very identical in dimensions, sat the straight edge on them first at the ends and then at the airy points... And used a 0.0001" indicator to check any deviation...

Found out the straight edge does not seem to sag to any appreciable degree if supported at the ends.... Also hard to determine flatness as the scrape marks are 0.0001-0.0002 deep, but it seems pretty good...

Then put my 36" steel scraped straight edge on it and got the same results..

Also something to do with canode.... Using it as a marking medium to print out a gasket

Interesting so whats not flat your casting or your gasket material.

Buying a gasket set from Malaysia and having one turn up in 6 pieces was the problem..

Originally Posted by pipeclay

Interesting so whats not flat your casting or your gasket material.

The bench.

Novel way I discovered of checking a straight edge for things like stiffness as well as flatness..

Back to Straight edges, so what you are saying is the sag doesn't measurably change as you move the support points... did I get that right?

Regards
Ray

Yes... One discussion I read somewhere was straight edges can sag if supported only from the ends.. This camel back pattern was a light weight one, with less of a pronounced hump then other designs leading to thoughts it would not be rigid.. Turns out that is not the case.... They only move from unequal temperature changes...

Although Ray I think you may be able to measure some sag with some of your equipment

Are you also saying that the bar in the 3rd pic that you are measuring is scraped and not sagging either?

Yes, is it a piece of 75mm X 20mm flat bar scraped flat... It has never moved since I scraped it..

The bar may well be scraped but it will sag,you couldnt really tell with the measuring gear involved.

If it sags less then 0.005mm then I could not care less... Some of us know how much 5 microns is...

It puts the idea of a fabricated camel back in my head. Of course scraping it would be much harder than scraping a cast one, but it would be much cheaper to make. Is there any reason other than ease of production that camel backs are cast iron?

I finally got around to doing some scraping for myself. I managed to pick up this small surface plate from the Restorers Barn in Castlemaine for $20. I am guessing it was a trade school project from back in the day before someone decided we didn't need to know how to do this stuff anymore
The plate measures 6" x 7.5" and was badly domed in the centre. After 2 days of scraping I decided to have it surface ground. Saved a lot of time
Hopefully I will finish it off today

Phil
IMG_3091 - Version 2.jpgIMG_3092 - Version 2.jpgIMG_3093 - Version 2.jpgIMG_3094 - Version 2.jpgIMG_3095 - Version 2.jpgIMG_3096 - Version 2.jpgIMG_3097.jpgIMG_3098 - Version 2.jpgIMG_3099 - Version 2.jpgIMG_3100 - Version 2.jpg

Hi Phil,
Great work(other than whimping out and getting it surface ground )
The only thing I would question is it it looks like you were being far to nice in the first in 4th or 5th picture until the 4th or 5th picture. Though pictures of bluing can look very different to the real thing.

Stuart