Tadd's Southbend 9" Scraping Project

[turbotadd]

This thread will be a place for me to document my project so that hopefully myself and others can learn more about scraping and machine repair.
Background - I acquired a 9" Southbend Workshop lathe last summer (2011), and it sat practically unused until this summer when I attended a scraping class taught by Richard King (July 2012).
I disassembled most of the lathe and brought it along to class to aid in demonstrations, and to begin work on. At the end of the class, I had only begun scraping the compound rest base.
After the class, I spent my free "me" time making tools for scraping (carbide tipped scraper blades, scraper handles, diamond wheel grinder, power diamond lap). I have pictures of all of these in my photobucket album titled scraping.
I also acquired various measuring tools (indicators, micrometers, surface gauges, and a 36" x 24" granite surface plate with stand). So now I'm finally to the point where I can begin scraping at home!
I scraped one surface of a cast iron angle plate just to see if I could get something to blue up ok on the surface plate to start. Last night was the first time I resumed work on the compound.
I'll post pictures as I make progress, and will definitely have questions for Richard.

Here are a couple scrapers I made


This is a couple of cycles into the angle plate, (there is some weird flaws and pitting in the casting)


A couple nights ago I setup a dial indicator to get a rough estimate of how worn the v-ways on the bed are... By zeroing the indicator on an un-worn surface, I measured about a .0045" drop as I slid the tailstock back. Not good.



First question for Richard: I remember that wear exceeding .005" should typically be machined (milled, ground or planed) before attempting to scrape for alignment, do you think a 9" bed could be tackled on a Bridgeport and if so, how would you determine the tolerance the mill might be capable of attaining? Or if that is just a bad idea all around....
The other option I have is to just scrape the v-ways start to finish.
Also, would it be practical to tackle the v-ways with only my surface plate and say a 12" straight edge? The outermost two surfaces I should be able to spot on the plate, but the inner surfaces I don't think I can get. I have enough material to make a 12" straightedge.

Tadd

 

[Richard King]

Dear Tadd,

It's nice to see one of "My Kids" scraping. To those who don't understand, I had a student bring me to tears once tell me he felt like I was his Father while I was teaching the class. So I now call all my students "My Kids". I get attached to my students in my cram courses and feel they are family.

To be honest I would search the area for someone with a planer and have it machined. You don't say how long the bed is, so I'm guessing at 36"..I don't recall it from the class. You have 2 options. Get it machined / ground or scrape it after buying a straight-edge (SE) longer then the bed. Using a 12" SE to lap scrape the bed would be a real head-ache. Your angle could change on your V's. Scraping double V's is a pain for me to do even after 45 years. The company who bought my planner when I closed shop is in Hammond WI and I'm sure he could do it for you. I think I told you his company name but I'm not sure I should say his name in the post, so PM me if I didn't.

The rule of thumb is you always use a SE longer then your part unless its over 12' long. I am busy now rebuilding machines around town and am using mine now. I have a 48 camel back I could let you use I think...but if I was doing it I would have it machined or ground. Another thing I would separate the tail-stock and mount a mag base and indicator to shorten the distance, your way is OK, but the shorter the distance the better and less chance to introduce errors.

Have fun,
Rich

 

[turbotadd]

Thanks for the info Richard. I just spoke with A&D Machine, and they were thinking $400-$500 to plane all of the surfaces. Would it make sense to just have them plane the outer V-ways if a guy was on a tight budget? After planing, is it just a matter of hitting it with a couple of scraping cycles to get checker-board, then go for points? Would the planing mean subsequent turcite?

 

[corey607]

Thanks for posting the pics of how you measure your ways. I'll have to check mine tonight.

 

[turbotadd]

As Richard mentioned, the pictured setup for measuring the ways is not optimal, better to take the tailstock apart and put the mag base directly on the tailstock base, this would allow measuring further back on the ways too. I believe there is also some error in this setup because the tailstock ways have wear too, so you're not traveling on a flat plane necessarily - BUT usually the tailstock ways aren't worn as bad as those for the carriage.

 

[Richard King]

Be sure to measure the ways now so you will know how much they take off. I think I told you how to drill a 1/4" hole in the center of the V ways on the end of the bed /.\ insert a 1/4" dowel pin and depth mic the distance from the way to the pin on both sides and flat ways so you know how much you will have to mill off the saddle to accommodate the Turcite. Ask Rick to take off the same amount of the V's to keep it uniform. He will know this. I would also make a sketch with all the measurements and give him a copy and ask him to write on it so you can double check.
I bet if you ask him if you pay him in 2 payments he will go for it. OR maybe you can barter with him. Tell him about yur work and you can give a card to your boss, etc. Have fun

 

[HotAire]

Tadd

Tried to find your info on PhotoBucket = Total Waste of Time!
Wanted to know What you used & Where you got the pieces to make your scrapers.

Charlie
Ft. Smith, AR
hotaire@sbcglobal.net

.

 

[Richard King]

I was teaching a class in Peoria and needed a couple of scrapers. I use the German made Biax hand scraper, but the company could not generate a PO fast enough, so I drove over to Home Depot and bought a 3/16" x 1" x 48" piece of flat bar-stock. We cut 2, I think 20" long, a sawed a tang on one end to fit a file handle and drilled 2 - 1/4 20 holes in it to bolt a Biax / Dapra blade to it. It worked good as new. In a class in Dallas the Host student bought some steel a Home depot and silver soldered a piece of 1/16" x 1/4" x 1 1/4" of carbide he bought off MSC. He said he paid 3 pieces for $25.00 I think, the steel cost us about $10.00 I think. The blade I use are from DAPRA.com and are model 25/150 and 20/150 blades. I put a rubber sanding pad on the end so when I'm body scraping. "it spreads out he pressure".

 

[turbotadd]

http://s222.beta.photobucket.com/user/turbotadd/library/Scraping is the link to my photobucket stuff.

Some notes I had sent in e-mails regarding the scrapers:
The carbide I used was 1/16" x 1/4" x 1." I used Mapp gas for brazing and it seemed to work well. The silver solder i got was in strip form with white flux. I layed the strips right at the joint which worked well especially because have a hard time keeping a steady hand. I just made a point to keep the flame off of the strips and constantly moving, seemed to do the trick. The carbide was sourced from KBC tools, and the silver solder from somebody on E-bay.

 

[turbotadd]

Had a little time to play in the garage tonight... I was having difficulty getting the compound base to blue up using sliding piece that had been scraped flat so I set the base up on some parallels and indicated the surfaces I was scraping. There were a couple of spots that were about 5 tenths low, so kept scraping the blue and eventually got it to indicate flat. I still struggled to get it to blue up nice, so I went back to check bottom sliding surfaces of the compound slide that I was applying the blue to. I found there was a "hole" on one of the flats about halfway down the length, and towards the center. I figured this was giving me the trouble bluing up the base. I started to try to correct the "hole" situation, then decided I should probably take some measurements to see if I was deviating from the original plane. Using some parallels and a depth mic I measured the distance between the sliding surface and the flat that was machined during the milling of the dovetail. I measured a range from .417 to .421. Next I am going to try to step-scrape the sliding surfaces parallel to that original milled surface in hopes that the 60deg dove will be in better alignment. Another issue I was having when I started scraping the slide was when I would stone the burrs, it seems like I was wiping out a lot of points, and in some cases taking entire areas out of blue, but I could tell the stone hit there because they would shine as if polished on before spotting. I'm thinking maybe my stone wasn't flat.... Richard, should someone with a history of over-stoning resort to different method of knocking down the burrs? I'm using the two types of stones as we did in class. Also, should I be using a smaller radius blade? Currently I am using a 60R. Is it normal to have the streaking when you spot the fixed part of a slide with the moving part, or do I have other issues too?