Hand scraping

[John McNamaraParticipant @johnmcnamara74883]

Hi All

This video is in French and the music is a little French also…

He is using a Swiss type a pull scraper off his shoulder. Another tool I have to make. As the video shows the tool is perpendicular. What I really like is the way you can see the work, unlike the push type that obscures it.

I like his method of working pretty efficient. He could have done another pass or two the get the spotting a little more even,

**LINK**

Regards
John

[Martin DowingParticipant @martindowing58466]

Hi, I am new on this forum.

I am not a professional engineer, just an amateur, I can turn and mill plenty of rather simple items, such as screws, ACME screws and nuts, simple lathe accessories and make working models of certain pressure valves for gases, even from so called difficult materials like Hastelloy. However before I attempt to make working model of ICE (or a Quorn…) a lot need to be learned. I have also much interest in old machine restoration.

Is there any tuition book dealing with subject of flat surfaces and in particular bearing scraping?

I am an owner of ML7, it is serving pretty well until now. I have installed new hardened spindle/phosphorus bronze bearings.

Machine seems to work OK (so there is no spindle play, cuts are paralell and parting off in 95% cases goes well, even with 1.5-2 inch MS bar) but as per rules of art bearings should be scrapped in to improve fit and to extend life of spindle and bearings, perhaps bearings in particular as spindle is hardened.

I would like to learn about, how to approach this subject.

I understand, that scrapping bearings of my machine as the first job of this kind is not rhe best idea so I wish to train on some less critical (and cheaper) surfaces to acquire necessary skill.

How to start? What to read? How to make suitable scrapers or which ones are worth buying?

Thanks for any suggestions

Martin

[Roger HeadParticipant @rogerhead16992]

Hi Martin, welcome. There are many good books, but some of the standard 'classics' are:

'The Whitworth Measuring Machine' by T.M. Goodeve and C. P. B. Shelley

'Foundations of Mechanical Accuracy' by Wayne R. Moore

'Machine Tool Reconditioning and Applications of Hand Scraping' by Edward F. Connelly

Do please exercise your web search skills to find these books yourself – besides the immediate exercise, you will find a lot of other useful literature. However, if you really get stuck, PM me with your email address and I will send you a link.

Good luck,

Roger

[Iain DownsParticipant @iaindowns78295]

I've also bumbled my way through a bit of scraping recently on they ways of my small mill and have become fascinated with scraping – though not skilled!

I'm in the process of attempting to make and scrape a 55 degree wedge out of cast iron so I can get my dovetails straight. Rather challenging to cut / mill a 55 degree angle on a 12 inch bar with a micromill that needs tuning up! We'll see how that goes.

I would welcome an article in MEW on scraping; The various you tube videos all have different views on how things should work, as do the referenced books.

And we do seem to have proper experts in the forum!

Iain

[Martin DowingParticipant @martindowing58466]

Many thanks for your assistance. Have to get mentioned books and of course practice, practice, practice… Seems for me that scraping becomes to be an art which is gradually forgotten, yet very powerful one.

[BrevaParticipant @breva]

This is a very informative discussion indeed!. Thanks to those who shared their knowledge.

A relevant question then. I had reason to straighten a gib strip on the lathe cross slide recently. I stoned it flat and matched it to the opposing face with blue.

Should the face of the gib strip have been scraped with any kind of pattern to hold oil on it's surface or can it be left flat?

John

[Neil LickfoldParticipant @neillickfold44316]

You can make scarping tools from O1 tool steel and double temper at 150C or very light straw colour. This will be about 61 Rc hardeness if it is good O1 steel. Scraping takes time to learn and it's work taking the time to learn it.

Neil

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Breva on 30/09/2016 23:03:15:

A relevant question then. I had reason to straighten a gib strip on the lathe cross slide recently. I stoned it flat and matched it to the opposing face with blue.

Should the face of the gib strip have been scraped with any kind of pattern to hold oil on it's surface or can it be left flat?

.

John,

In my limited experience the [cast iron] dovetails are scraped, but the [steel] gib strips are smooth.

MichaelG.

[mark smith 20Participant @marksmith20]

I have all the gib strips off my mill and they look to have been scraped .but have obviously worn mostly smooth now.

[Author]

Posts