Scraping a mini lathe?

addertooth said:
Bummer, I just checked, and some of the issues in the ten part series are no longer available. However, they incorporated the topic of scraping mini-lathes in a separate book for the mini-lathe. The book is about 29 bucks.
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Richard King sells a DVD on how to scrape. It is going on my Christmas list this year.
 
addertooth said:
Bummer, I just checked, and some of the issues in the ten part series are no longer available. However, they incorporated the topic of scraping mini-lathes in a separate book for the mini-lathe. The book is about 29 bucks.
Click to expand...
I wasn't aware of the separate book, good to know!
 
addertooth said:
Bummer, I just checked, and some of the issues in the ten part series are no longer available. However, they incorporated the topic of scraping mini-lathes in a separate book for the mini-lathe. The book is about 29 bucks.
Click to expand...
For the record, I just bought the book minutes ago. It will probably take a couple of weeks to show up.
Here is the link to the book:
The Complete mini-lathe workshop
 
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I'd be interested to know if the scraping section was written by Michael Ward, the author of the 10-part series. It looks like the scraping topic is just 3 or 4 pages long so there can't be a whole lot of in-depth discussion on the subject.
 
I have smaller straight-edges. Before scraping it, you may want to check how bad it is first. Then have it ground or planed and then scrape it for oil pockets. The bed is the hard part. Fitting the other parts are easy scraping. You could bring some of the part to a class where I would teach you to scrape. I have a class in 10 day in Minnesota. If you can't make it, but the Edward Connelly book. Machine Tool Reconditioning. I sell them on ebay and will give you a 10% discount by private messaging me. We had plans on a class in Springfield VT but we had to cancel it because of Covid and some Canadians could make it..
 
I scraped my minilathe when I had it, it was pretty much a must since the uneven thickness caused binding at certain places.
After scraping I could run the gibs tighter and still have a smoother travel.
Start with measuring with a micrometer along the ways to get an idea of how uneven it is.
Another fairly big upgrade is bolting it to a thick and solid plate of steel, it will make the bed a fair amount stiffer.
 
This is one of those things where you have to ask, just because you can does that mean you should? It'll certainly make it better than when you started but the big question is would your time be better spent on another project? Only you can answer that question.

John
 
I'd say go for it.

I have made a little foray into scraping and here's my thoughts:

  1. Financially speaking, it doesn't make sense for the machines we work with. Takes too long and if your time is worth money, you're better off getting it ground at a good shop for a few hundred bucks.
  2. Physically it is quite tiring, especially hand scraping. I'm 27 and my arms/hands would be pretty beat by the end of a session.
  3. The tooling and instruments (scraper, surface plate, indicator, straightedges, etc.) to do the job are expensive and you'll likely need to machine and scrape your straightedges before using them. Estimate $1-2k if you have nothing to start with.
  4. Understanding geometric errors and knowing how to correct them is much harder than scraping a surface flat.
  5. Scraping is a great way to improve what you have, especially if you don't want to spend the money on higher end machines and you have time.
  6. When complete, the results feel worth the effort.
  7. Scraping the top and bottom of my milling vise bed flat and parallel (2 surfaces, approximately 4 x 14") took me 45 hours. They were out quite a bit, but so is most import stuff. This was my first practice/learning project and I likely took the finish further than was necessary. In the end I took the wedge and bow out of the bed (0.0035") and got the surfaces flat and parallel within 0.0002" all over. If I had access to a 6x18 surface grinder, I probably could have completed the job in 2 hours with similar results. Obviously less practical on a full machine.
 
A friend of mine and student who has taken 5 of my classes has a good You tube show on scraping a Myford lathe. It has flat ways. He has several others on rebuilding and scraping. I also sell a DVD and HSB stick on scraping to get you started. I sell it on ebay or direct. Message me.
 
matthewsx said:
This is one of those things where you have to ask, just because you can does that mean you should? It'll certainly make it better than when you started but the big question is would your time be better spent on another project? Only you can answer that question.

John
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I scraped in a mini lathe. It was worth it because learning the skill was fun. What i didn't know before starting was how much of a skill it actually is. I thought the actual act of scraping metal was the hard part. I learned quickly that the physical act of scraping was the easy part. Measuring, and understanding the how and why of measuring took a ton of research and learning. The payoff is that all of that knowledge you learn can then be applied to all other aspects of machining. The scraped in mini lathe is just a side bonus. Connelly's Machine Tool Reconditioning (as Richard often suggests) should be the starting point if you really want to understand the fundamentals of measuring, aligning, and scraping.
 
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