Ready to glue on the Rulon

[Richard King]

Use the hand scraper ground at 40 r neg 5 with the neg 5, same as for iron. and hold the handle vertically and pull scrape it. The picture is Ted, my assistant teacher at the Taiwanese research center I taught at. The pull scraper we made out of a aluminum shaft and we bolted a Biax blade to the end. Ted was showing off. PPI was 40 PPI. 20 PPI is good enough.

 

[Richard King]

My classroom and students in Taiwan

 

[Gard]

Scraping the rulon was very nice, only a couple of passes got the cross slide into alignment. I think it is good enough now that I can use it in the next step of scraping in the headstock and tailstock, will probably do some touch up after that. I am still looking for a larger precision angle plate, granite triangle or large square.

I will share my first experience scraping Rulon. I started scraping in a conventional orientation with the 20 mm radius. I realized I had no easy way to confirm the depth of the scrape marks on the slopeing V surfaces. My goal being the 0.002" depth recommended by Richard King. I did a simple calculation of the width of the cut vs the depth and determined a 0.12" wide scrape mark will be 0.002" deep with vertical pull scraping and 20 mm radius tool. It seemed to work well to brace one hand on the part and use almost a pivoting movement on these small areas. I also used the 6 mm radius cutter on the end of an old screwdriver with a pushing movement with 0.06" wide mark. This ends up being more like the scraper Richard shows with a blade mounted vertically on the end of an aluminum shaft (an excellent idea I think). I found this easy to control in tight areas. Here is an end-on view of the modified screwdriver scraper.

Following is my calculation of the cutter radius and cut width to get to 0.002 inch depth for vertical pull or push scraping.

I also did the calculation at some more typical scraping angles. For example a 40mm radius tip at 10 degrees to the surface would require a cut about 3/8" wide, almost the entire width of the V surface on this small machine. This confirmed for me at least, the advantage of vertical scraping to get the depth. I have never tried some kind of flaking where the blade is twisted, I am sure that could work also but the math is not as easy as a strait pull.

 

[4GSR]

We sure didn't have all of the fancy charts and tables when I went to school. Of course, we were still using candles and lanterns for lighting!
Do what Richard said to do, go about midways on the front vee and scrape out a section about 4" long by about 2-4 thousandths deep. So that way your saddle does not create a "rocking horse" affect on the ways. Unless your bed ways under the headstock were re-cut, there should be no need to re-scrape the headstock to the bed IMO.

 

[Richard King]

Ken is right about the down pressure in the center caused by tool pressure. Also as the dirt gets into the ends, the middle get high. From the photo, you don't want and blue in the center 40%. Gard your doing a great job, Thanks for the charts. Ken some folks with an analytical mind need charts. Its part of their education. Journeymen who have grown up in the trades saw what was happening as we had a Journeyman teaching them. Some on here (PM) need to share their info with charts. I like this as not all people learn the same way. One great thing about Gard he listens and experiments with advice. He is not like some on here who have a high IQ and automatically questions advice from someone without a higher education degree. I used to belong to the local SME and Machine Tool associations and they asked me to talk to high school kids because I was well know and successful without a college education. We passed out charts showing a machinist could make $80,000.00 + in 2 years compared to a degreed engineer would start out at $40,000.00 plus have to pay for the education student loans. IQ has little to do with how much one makes in my opinion. I know a few of engineers who have problems making ends meet. I know many PHD Engineers who if you didn't know what they did or who they were you could sit down and have a beer with them and never know they had 17 patents and were super rich. They didn't need to put Dr. on their name.

 

[Richard King]

Gard has some great PHOTO's too. If you didn't take the headstock off or grind the bed, then if they made it right from the factory it should be good. One thing one needs to remember when they made the machine most factories scrape the tailstock first and then scrape the headstock. A rebuilder most times has to raise the height of the tailstock, so if Gard doesn't want to shim up or make a new sole or apply a hard wearstrip on the bottom of the tailstock he can scrape the headstock. He see's all this as he is a smart dude. :-)

 

[Richard King]

For those who are one of those DR's who are always questioning my advise. I could have gone to university, but didn't as I was getting my education as a Apprentice. I recall being called into the high school councilors office, wondering why I didn't sign up for college as I passed my SAT tests. I said I could learn a trade from my Dad and start making big bucks right away. A few of you know I had my 21st birthday in Masjid-i-Solemon, Iran when my Dad had a contract setting up machinery for BMY of York PA in 1971. They built Army tanks. I also worked all over the USA getting my education as a Machine Rebuilder. The Taiwanese didn't care if I had a college degree when I worked at The Taiwanese Precision Research Center who advised the machine tool builders in their country. Neither did Timken, 6 divisions of GM, Cummins, etc. etc. My carer has taken me around the world. When I came home from Iran I flew around the world, stopping in India, Pakistan, Singapore, Bangkok, Australia, Hawaii and Alaska when I was 21 years old.

Take a look at the references in my Website. http://handscraping.com/about-us.html

 

[Gard]

This lathe has been an ongoing project for me, I enjoy the challenge of measuring things and then trying to understand and make equations that predict those measurements and using the equations to refine what the next step will be. This is in my mind, the definition of engineering. No question in my mind it is possible for a skilled person to get the same results quicker without doing this. The bed of the lathe has been planned. The headstock is currently out of alignment by about 0.003" at the end of a 12" test bar. I was thinking about glueing on some more rulon on the bottom of it because it is so nice to scrape but will probably scrape the bottom of the head. Perhaps I should check the height of the tailstock, If I remember correctly, the Connelly book says do the tailstock before the headstock.

I have several posts on this forum asking questions and getting advice on earlier parts of this project. I am not sure if this is better than one really long post lasting years for the entire project.

Funny comment about candles and lanterns, it reminded me exploring caves in my youth, we used carbide lights, they were lighter than the battery powered lights of the day, I imagine all the kids these days have newfangled LED lights. This is just a little off topic...

You could probably guess I am a retired mechanical engineer.