Couple of scraping questions (Part 1 of ???)

[macardoso]

How do you measure the height? From a raw casting to the water top, no thanks. I used to use that method when I was a Boy Scout and was setting up a fire pit grill Water in a fry pan...not to precision. I can call John Saunders (Nyccnc) and see if he would host one again in Zanesville, OH next fall....

Fair enough

Had the pleasure of briefly meeting John once in DC two years ago. Been following his shop/Youtube saga for a long time. I'd definitely be interested.

 

[Hellkell]

Fair enough

Had the pleasure of briefly meeting John once in DC two years ago. Been following his shop/Youtube saga for a long time. I'd definitely be interested.

In one of the other scraping threads i believe it was mentioned that you only scrape the bottom surface of the upper piece. In the machine reconditioning company video above they scraped both upper and lower pieces. Did I misunderstand this concept? or is it you only flake the bottom of the top piece?

 

[Cadillac]

You scrape both surfaces and flake only one.

 

[Richard King 2]

On some machines with hardened and ground ways you DON'T Scrape them and scrape one side. Like a lathe with a hardened bed. Most soft both sides cast iron machines we scrape the longer side first using a master straight edge, or I say the are a portable surface plate that you scraped to a surface plate. In 2% of of machines the longer side is to flimsy that you scrape the shorter solid side first. An example is a Excello Boreomatic or Heald ID Grinder. I teach to 1/2 moon oil flake the unexposed side of the way surfaces. Like the underside of the saddle on that hardened lathe bed. In my opinion Bridgeport 1/2 moons the wrong side. But it sure looks pretty.

 

[macardoso]

Ok have a new question. I’m about halfway through Machine Tool Reconditioning and I am following along in the chapter describing the process to completely scrape a lathe.

Before reading this, I had the preconception that you scrape “bottom-up” , working from the bed to the carriage, then the cross slide, and finally the compound. At each step you can verify overall alignment to the components below and minimize the material needed to be removed.

This book describes scraping the compound first, then the cross slide, then the carriage, and finally the bed. This seems counterintuitive and could potentially require more scraping to correct for alignment that wasn’t done perfectly. All parts are individually scraped true, but the final fit up can’t be done until the bed is scraped.

What gives here? Is this the way it is really done and I am missing something obvious?

 

[macardoso]

Ok have a new question. I’m about halfway through Machine Tool Reconditioning and I am following along in the chapter describing the process to completely scrape a lathe.

Before reading this, I had the preconception that you scrape “bottom-up” , working from the bed to the carriage, then the cross slide, and finally the compound. At each step you can verify overall alignment to the components below and minimize the material needed to be removed.

This book describes scraping the compound first, then the cross slide, then the carriage, and finally the bed. This seems counterintuitive and could potentially require more scraping to correct for alignment that wasn’t done perfectly. All parts are individually scraped true, but the final fit up can’t be done until the bed is scraped.

What gives here? Is this the way it is really done and I am missing something obvious?

I do get the feeling this has to do with using the upper components as patterns to print the lower components, but still seems backwards to me.

 

[Richard King 2]

You can scrape a compound anytime when rebuilding a lathe. My Dad used to have me scrape them when I was an apprentice and heck I tell students to bring them to classes, as they are scraped co-planer to its self and if you scrape every thing co-planer from the bed up or the saddle. You will be fine. There are parts of the Connelly book that can be debated. My Dad would not allow us to read it when I was an Apprentice. I tell people who buy them, to not figure it is 100% right.

The way I teach and do it is. Start at the bottom and work up on most machines. If the main spindle is fixed on a lathe like a Warner and Swasey Turret lathe you start at the spindle and work out. Back when I was scraping for a job and a customer had a lathe that only wanted to re-scrape the cross-slide, we would take the Saddle off and bring it to the shop and scrape it off our surface plate. The surface where the carriage bolts on is original from the factory. So we would set that area on a parallel and jack screw the back side of the saddle or lay it on a ground test bar and set the saddle V on it. After we had the saddle top done we would take it back and fit or match fit and align the saddle to the worn bed.

So there is an exception to every rule.

 

[macardoso]

You can scrape a compound anytime when rebuilding a lathe. My Dad used to have me scrape them when I was an apprentice and heck I tell students to bring them to classes, as they are scraped co-planer to its self and if you scrape every thing co-planer from the bed up or the saddle. You will be fine. There are parts of the Connelly book that can be debated. My Dad would not allow us to read it when I was an Apprentice. I tell people who buy them, to not figure it is 100% right.

The way I teach and do it is. Start at the bottom and work up on most machines. If the main spindle is fixed on a lathe like a Warner and Swasey Turret lathe you start at the spindle and work out. Back when I was scraping for a job and a customer had a lathe that only wanted to re-scrape the cross-slide, we would take the Saddle off and bring it to the shop and scrape it off our surface plate. The surface where the carriage bolts on is original from the factory. So we would set that area on a parallel and jack screw the back side of the saddle or lay it on a ground test bar and set the saddle V on it. After we had the saddle top done we would take it back and fit or match fit and align the saddle to the worn bed.

So there is an exception to every rule.

Thanks for the reply. I sort of figured that there was some leeway in the exact method to be used.

I haven't found a written collection of information on scraping as detailed as the Connelly book, so even if some of it is antiquated or incorrect, I still feel that I'm learning a lot.

 

[macardoso]

OK one more question - not that I have any immediate need for it.

What is a good supplier of Turcite/Rulon 142 and the associated epoxy in single machine quantities and non-criminal prices? I did a quick search but did not find anything obvious (other than McMaster Carr in very limited sizes/thicknesses).

 

[Richard King 2]

https://www.tstar.com/ is who I buy mine from. They only sell 12" or 24" wide by the foot. You cut it to size with a utility knife. . Make sure to leave room for creep. I cut mine 1/2 to 1" longer on each end. If the machine is level when you do it, it doesn't creep much