Scraping

[Pete RimmerParticipant @peterimmer30576]

Posted by Mark Rand on 26/06/2019 23:14:54:

Connelly Refers to the 'half moon' oil retention process as frosting and the 'blocks of squares' decorative process as flaking.

Personally, I think he's got that bass-ackwards, but he wrote a book and I didn't.

Any company that puts half moon type gouges on the visible (and thereby subject to dust and grit) surfaces of ways should be sued for sabotaging their own products…

I guess that I call flaking an oil retention process because Biax produce a tool for doing it and call it a flaker 😀

[Michael GilliganParticipant @michaelgilligan61133]

Posted by ronan walsh on 27/06/2019 01:28:57:

I think scraping as a process has been put up on a pedestal and is being worshipped as a "long lost black art" by some. I think its like filing or hand fitting or something similar, not a process that is to be feared or to be overawed by. But to be undertaken with patience and common sense.

.

Hence my reference to the Whitworth book, which contains a clear concise description.

MichaelG.

[Iain DownsParticipant @iaindowns78295]

I've done some scraping. Well, I've tried to do some scraping. I've done quite a bit of work on my CMD10/X1 and that may have been one of the things which significantly improved it.

I've also had some success in scraping in the bearings of my steam engine.

However, my attempts at making a straight edge against a surface plate have cost me many hours of effort and resulted in going round in circles trying to get a consistent surface.

I think that there are some techniques which are quite hard to pick up without some kind of personal tuition.

That's what I've found anyway. The basic idea is simple, but getting to a 'professional level' is difficult. I've asked before on this forum if any time-server engineers would provide a course or tuition.

Iain

[George ScopelParticipant @georgescopel96574]

Thank you to all the replies and advise .. I will follow certainly look through the you tube for hints before I start scraping

Regards

George

[Pete RimmerParticipant @peterimmer30576]

Where are you George? I have taught the basics of scraping to several people and they have taken it from there to improve their machines. My time is precious but if you're near North Kent and desperate to learn I could find a few hours spare.

[Kiwi BlokeParticipant @kiwibloke62605]

One often sees deep crescent 'oil pockets' applied to the upper face of horizontal sliding ways. If these surfaces can be exposed in use, the pockets can accumulate fine, abrasive crud, not just oil. My belief is that the pockets should be a feature of the upper surface only, the lower being smooth, so the way wipers can keep the muck out. The problem is that visible crescents = $$$ of added showroom appeal. This isn't to say that the lower surface shouldn't be scraped, just that one should aim for a relatively smooth surface.

[David AndersonParticipant @davidanderson16743]

In general, old files need best be properly old files for re-use as scrapers. These might have names such as Osborne etc' stamped into rather than etched onto them. Newer (old) files tend to be case or surface hardened, out of lower quality steels which don't lend themselves to re-purposing as scrapers. A good quality old file can be first annealed then flared by forge hammering its end, then linished all over, ground down to 2mm and flat at the end then re-hardened and tempered. The finish lapping (manually done) is an art in itself. These type of scraper will hold a micro-burr at the edge, sharp enough and therefore ideal for cutting bronze-based re surfacing materials or the modern plastics which even the keenest carbide scraper will skid over. Excellent also for cutting steels.
I was told that an old steel bearing-race can yield up very good material for making scrapers but never tried it myself.

How to scrape is mostly a series of informed decisions, sound application and suitable tools and equipment. The entire rationale must suit the application and technique etc' must likewise suit. No short-cuts!

D.A.

[Author]

Posts