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View Full Version : Machine Jerked with Stick Slip on Way, Now repaired



Richard King
02-06-2018, 05:10 AM
Hello everyone.

I want to share a thread on another forum that can help all of you and readers in the future understand why it is so important to scrape oil pockets in the ways of machines. When we rebuild machines we scrape the worn ways using bearing blue and scrape high spots to make the machine accurate again plus the low spots left over create oil pockets that average about .0004" low. Many times we also 1/2 moon the ways to get extra deep oil pockets plus it looks nice. For an example 1/2 mooning is used on Bridgeports. 1/2 moon low spots are approx. .002" low

In the info below the OP did not need to rebuild his Studer Grinding machine as it ground great, but Jerked or we call that "Stick Slip".

I walked him through the scraping process on how to Square Cut using a hand scraper to make new low spots so oil could adhere to the ways in low spots that average .0004". We never 1/2 moon the exposed ways on machines as we do not want the .002" low spots with grinding grit.

These are the sorts of problem and fixes I want to share with you before I go the the happy scraping land in the sky. I also will be teaching a few more classes with gods help for a few more years or teach you on line like I did the fellow below. Enjoy and please ask me if you need any help too. Rich

http://www.practicalmachinist.com/vb/abrasive-machining/studer-rhu-450-1960s-343863/

dian
02-06-2018, 05:17 AM
i your opinion, does a pull scraped surface need moon flaking? im not sure i ever saw it.

Richard King
02-06-2018, 07:19 AM
It depends on how deep the scrape marks generated average the same depth of a 1/2 moon flake. A 1/2 moon flake by hand averages .001" deep and with a BIAX Power 1/2 moon scraper / flaker averages .002" depth.

The Studer looked like it was pull scraped from the Factory and by a rookie as it had a lot of scratches. Many say the extra scratches are extra deep oil pockets. ha ha. Anyone who scrapes and says he never gets scratches is a liar in my opinion...lol As we wrote about in the thread.

I was never taught to pull scrape, but have studied it and watched it done. From testing the depth of the low spot I have never seen it cut deeper then .0002". I see you have a you tube show pull scraping. How deep are your pull scrape marks?

I have worked with men who were trained in pull scraping in Europe and they had huge biceps as pulling is alot harder the hip or body scraping.

I believe it is more for finishing scraping and not roughing to finish scraping as you can see the Swiss/French drawings below. The illustrator draws both methods. Sip rebuild techs I met in John Deere Tractor Works used biax power scrapers until the last few passes and then pulled scraped so the Sip Jig Bore has the Sip signature look or scrape mark.

I did this post a few years ago. http://www.practicalmachinist.com/vb/machine-reconditioning-scraping-and-inspection/pull-scraping-303305/

10KPete
02-06-2018, 12:38 PM
Now Richard, don't go taking jobs off this earth quite yet! We need you around for a while to keep us straight...

Cheers,
Pete

3 Phase Lightbulb
02-06-2018, 12:50 PM
We need you around for a while to keep us straight...

That's disgusting.