# Looking for some scraping tooling tips



## macardoso (Feb 1, 2021)

OK, I've dabbled in scraping a bit and have watched more hours of video on the subject than I care to admit, but the seemingly high barrier to entry (in terms of tooling) has kept me from getting serious about trying to learn. The small amount of scraping I have done has been rather successful in terms of accuracy, but terribly slow. I am currently using a file with the front ground into a scraping blade.

*What I do have:* 

18x24" surface plate, grade B
Dial test indicators, 0.0005" and 0.0001"
Dial indicators (0.0005" and 0.0001"
Dykem Hi Spot Blue
Several files ground for scraping
Crappy bench grinder with coarse wheels
My file scrapers work, but the relatively rough ground edge leaves a scratched cut rather than those shiny crescents you see people doing on YouTube. I also have difficult with removing any substantial quantity of material. I know scraping is slow but I bet I'm working at 1/10 speed with the file. It just doesn't want to bite.

So I started looking at scrapers. I see two options easily accessible to me: Sandvik scrapers through MSC and Anderson tubular scrapers. Both are about $100. OK, a lot of money for a metal stick but it will last a lifetime so I can deal with it. I have heard mixed thoughts about both due to their relative stiffness. I have also seen some shop made scraper plans floating around, although I can't remember where. If it takes me more than a few days to make the scraper myself, I'd rather just buy one. With work and family and other shop projects, I don't have the time I want to spend on it. I've checked eBay, but scrapers there are few and far between with prices almost that of a new one.

Next up, my file scrapers dull fast, and while HSS would be way better, I do see the draw to carbide scraper blades. First off, holy moly, $50 a blade on eBay sure seems like a ripoff, but maybe that's how much they run. Again, if it gets me going, the price is fine. But now you need to be able to sharpen carbide. Don't think a green wheel will cut it so now I have to find or build a slow speed lapping disc. Again not an impossible task but the cost and barrier to entry grows.

Any tips? What is a good scraper to start with. Are the prices I'm seeing just market value? Anyone have a used one they want to part with? Do you need a separate tool for flaking? I would imagine a Biax would be absolutely overkill for a hobby guy unless an eBay steal came my way.

So next to marking compounds. Hi Spot Blue seems to work OK, but it goes on very heavy and within an hour it is dry and barely transferring at all. Great for later stages of scraping but not at the beginning when you actually want to see your blue. What works better?  

What other measuring tooling is needed? I've seen those scraping flats (steel disc that bridges across your high points) but don't know what they are called or where to find them. 

Any tips on learning resources. At this point in time, I have neither the money nor time to attend a scraping class, but I'm all for video instruction. Have no issue biting it off and trying to learn more myself. This is all a hobby, but I do identify it as a useful skill to know.


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## hwelecrepair (Feb 2, 2021)

I have only scraped one machine in, my WB Knight #2, and I absolutely hated it.  I was blessed to have 3 guys who scrape for a living to guide me through the process.  I am not sure I would want to learn it without someone there to explain why I am doing it wrong and what causes it.  

I am sure King will know more of how to do distance learning/teaching.


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## Braeden P (Feb 2, 2021)

i used a wood lathe on slow speed with cheap diamond wheels on a threaded rod worked fine for me i just used a tormek table as a rest but they are easy to make if your birthday is soon ask for a scraper i did for Christmas and i got a Anderson.


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## Liljoebrshooter (Feb 2, 2021)

I bought the Sandvik.   I was going to build one also and changed my mind.    It is nice.   I also bought another carbide insert on e bay.   I  am not sorry for spending the money on it.
Joe


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## benmychree (Feb 2, 2021)

I have both Anderson and Sandvik hand scrapers; I think the Anderson is a POS.  I have had the Sandvik for about 55 years and have used it quite a lot and sharpen it in a diamond wheel on a Baldor  grinder, Glendo gives better finish, but the Baldor does a good enough job.  I started out with a homemade scraper made with a file with the teeth surface ground off on both the faces and sides, then forged the end down to a thin point, ground it smooth and re hardened it, and finished the point with a India stone; it worked well, but needed frequent re sharpening with the stone.
I now mostly use the Biax scrapers, except for small dovetails.


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## Rex Walters (Feb 2, 2021)

I highly recommend the Dapra design for a hand scraper because you can move blades between a Biax power scraper and your handscraper (if you eventually acquire a power scraper): https://www.dapra.com/biax/universal-hand-scraper

The scraper body itself is a simple enough thing to make. There are dimensioned drawings floating around. The carbide blades do get spendy and used ones are getting rare, as you noticed. If you only get one, you want a 20-150 or 25-150 blade. It will definitely last a lifetime.

A green wheel should be able to shape carbide, but if you can find a real Biax blade it should already have a decent curve. It *is* possible to hone by hand if you're patient (but you'll want to build or buy a diamond wheel grinder like a Glendo eventually). You'll need a (cheap for once) diamond stone and a jig to hold the blade at a 5-degree angle to hone it (a beveled hunk of 2x4 would suffice).

They no longer make Glendo Accu-finish grinders any more, sadly. The company is still around, though, and sells stuff for engravers. They still sell the wheels and a similar grinder for engravers without the fence and table fixture (https://grs.com/product-category/products/tool-sharpening/grs-apex-sharpening/). They are *very* expensive, unfortunately (which is why they no longer sell the Accu-finish grinder - no buyers for what they cost). I don't see even any old ones on ebay at any price right now.

I still use hi-spot blue, but the cool kids are using water-based printer's inks these days (Charbonnel is the brand I"ve seen). Dapra also sells water-based spotting ink.

As for what other measuring tools are required: all of them.


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## benmychree (Feb 2, 2021)

The marking mediums that Rich King uses are quite good, and what Rex says above is good advice.  Scraping inserts that are wider than recommended can be bought considerably cheaper than the most desirable and be cut down in width.  For years, I used red lead as a marking medium, it works just fine, but don't lick your fingers.


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## Rex Walters (Feb 2, 2021)

hwelecrepair said:


> I am not sure I would want to learn it without someone there to explain why I am doing it wrong and what causes it.



Yeah, this is *exactly* why Richard King's classes are so valuable if you can attend one. Scraping something flat isn't that hard of a skill to learn (about the same as learning to grind an HSS lathe tool by hand) but it takes a while to figure out how to do it, how to diagnose what's going on, and how to correct problems. The learning curve is dramatically reduced if you can spend time with someone that already has the skill (true of many things).

Learning how to scrape something flat to a high tolerance is easy. Learning how to rebuild and align machine tools is a whole 'nother story. The best book on the subject is Connelly's Machine Tool Reconditioning available from Dapra. It *will* put you to sleep, though, and some of the content is questionable (Rich says nobody really used the water-based leveling techniques that are described, for example). It's still the best overall reference for the principles involved, though.



benmychree said:


> The marking mediums that Rich King uses are quite good



I think Rich still uses Canode water-based spotting medium, but he also likes the Charbonnel stuff. I notice that Dapra no longer calls it Canode, they seem to have their own brand on their water-based inks now. I know the last bottle of Canode I bought from them had bits of grit in it (the last thing you want when marking up!). Rich said it was just a bad manufacturing run and not foreign media, but I've not tried a mortar and pestle or heat to get rid of it.


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## benmychree (Feb 2, 2021)

*The possibility of grit contamination is why we spread it with out with our fingers, we will sense its presence and eliminate it.*


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## Rex Walters (Feb 3, 2021)

benmychree said:


> *The possibility of grit contamination is why we spread it with out with our fingers, we will sense its presence and eliminate it.*



Heh. If it was just a few chunks of dust or swarf I'd agree with you, John, but the batch I got was *mostly* grit. It was like someone had mixed a handful of sand into the ink.

It's not a foreign contaminant, though, it's something in the recipe that either crystallized or clumped up for some reason, or the stuff was never manufactured correctly originally (unsure which). If I take a small amount and mash it up good and keep stirring, it eventually seems to go away (hence the mortar and pestle comment). The individual grains almost look like glass shards (they aren't sharp, though). Never had a problem with hi-spot blue or Charbonnel, though.


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## Larry$ (Feb 3, 2021)

I've watched the videos, got interested enough to see if I could do it. Just a practice piece. Having never seen the tool I just used what I had. A laminate file that I ground a recess in to hold a piece of a broken carbide from a molder head. I silver soldered the carbide in the notch. Thought it might not work since the carbide wasn't the kind intended for brazing. But it stuck w/o cracking. Using a diamond wheel on my tool grinder I shaped the end into a curve and ground the edge square  in the up/down plane. After a couple of  tries ground a tighter curve to reduce the contact area. I had some blue artist oil paint so tried that. It was too thick so added a bit of mineral spirits. I played with angles and the like and found a position that worked OK. My pattern never did look as uniform as the videos but it worked. I ended up getting a decent flat surface. I can sure see why a power scraper was invented. 

So I'd like to know a bit more about the tool and the process. Is the tool flexible? What is the shape of the carbide cutting edge?


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## benmychree (Feb 3, 2021)

Rex Walters said:


> Heh. If it was just a few chunks of dust or swarf I'd agree with you, John, but the batch I got was *mostly* grit. It was like someone had mixed a handful of sand into the ink.
> 
> It's not a foreign contaminant, though, it's something in the recipe that either crystallized or clumped up for some reason, or the stuff was never manufactured correctly originally (unsure which). If I take a small amount and mash it up good and keep stirring, it eventually seems to go away (hence the mortar and pestle comment). The individual grains almost look like glass shards (they aren't sharp, though). Never had a problem with hi-spot blue or Charbonnel, though.


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## benmychree (Feb 3, 2021)

Yes, I have seen some Prussian blue that crystallized as you described, a friend was giving a bunch of tubes of it away, besides being gritty, the consistency of it was thin and did not mark well at all.


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## Rex Walters (Feb 3, 2021)

Larry$ said:


> I've watched the videos, got interested enough to see if I could do it. Just a practice piece. Having never seen the tool I just used what I had. A laminate file that I ground a recess in to hold a piece of a broken carbide from a molder head. I silver soldered the carbide in the notch. Thought it might not work since the carbide wasn't the kind intended for brazing. But it stuck w/o cracking. Using a diamond wheel on my tool grinder I shaped the end into a curve and ground the edge square  in the up/down plane. After a couple of  tries ground a tighter curve to reduce the contact area. I had some blue artist oil paint so tried that. It was too thick so added a bit of mineral spirits. I played with angles and the like and found a position that worked OK. My pattern never did look as uniform as the videos but it worked. I ended up getting a decent flat surface. I can sure see why a power scraper was invented.
> 
> So I'd like to know a bit more about the tool and the process. Is the tool flexible? What is the shape of the carbide cutting edge?



That's great that you were successful with just your own persistence. It may not be the most efficient way to learn, but the lessons sure stick!

I think the main thing with scraping is consistency and learning to read the blue. As long as you can make regular patterns of shallow rounded diviots (0.0002' to 0.0005" typically) and you learn how to read the blue-ups you can get there eventually, no matter what tools you use to do so.

The ideal pattern has equally spaced rows of equally spaced scrapes, where each scrape is roughly the same length. The longer the scrape, the deeper you're scraping and the faster the progress (so you shorten the line lengths as you progress). You want the spaces between the scrapes to be about the same width as the scrape marks themselves. Same thing for the spaces between the rows. It's very important to alternate the direction of the rows between passes: one pass with the rows oriented 45° to the work, the next pass with them oriented at 135°. It's also extremely important to stone off the burrs from scraping before bluing up. Every time!

Basically, after two passes to create a checkerboard pattern, you blue up to see where you are. Then scrape a pass or two to remove the blue. Then stone, blue-up, and repeat until you get the coverage you're after (typically 20 to 40 points per inch).

That's the basics, but there is some physical practice required to get consistent scrapes, and it takes a fair bit of practice to understand how to read the blue-ups.

The process is a *LOT* faster and less irritating with decent tools, though. In particular, a little flex in a scraper blade holder is definitely preferable (you'll want something stiffer for final flaking vs. scraping).

The carbide cutting edge is shaped into a crescent (half-moon) shape on the edge. The edge is beveled at about 5° from each face (for cast iron). The 5° rake and a normal stance while holding the blade creates significant negative rake at the cutting edge. In other words, if you look at the blade flat on the work, you'll see a half-moon shape at the front edge. If you turn the blade 90° and look carefully at the edge, you'll see a little tent shape rather than square corners all along the curved edge.

For scraping steel (to be avoided if you can) or other materials you might want positive rake on the cutting edge. One advantage of negative rake is you can bevel from each face, so you can flip the blade over when it gets dull and double the time between honing sessions.

Good luck!


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## macardoso (Feb 3, 2021)

Rex Walters said:


> That's great that you were successful with just your own persistence. It may not be the most efficient way to learn, but the lessons sure stick!
> 
> I think the main thing with scraping is consistency and learning to read the blue. As long as you can make regular patterns of shallow rounded diviots (0.0002' to 0.0005" typically) and you learn how to read the blue-ups you can get there eventually, no matter what tools you use to do so.
> 
> ...



I know this wasn't directed at me but I appreciate the knowledge. I think I may pick up a 20mm Sandvik scraper from MSC. $85 gets it to my door with a carbide insert included. Even if I don't immediately jump into it or take a course, it will be nice to have on hand. I've watched enough videos and messed with bluing enough that I just barely understand how to read blue and identify the existence of bow and twist. I can get down to a good flat surface with decent bearing, but I don't have a tool that generates the scraping marks I see others doing. I hope the correct tool can change that.

I also think I pretty much understand scraping for parallelism. Where my knowledge ends is understanding how to measure and scrape specific angles into parts, or scrape surfaces where there is a boss or feature that sits above the surface to be scraped (like the bottom of a lathe compound).


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## Liljoebrshooter (Feb 3, 2021)

Buy yourself a 12" camel back straight edge and go to town on it.  Check out Martin Mold and Pattern.  He has a nice selection of straight edges that are quite affordable. 

Joe


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## macardoso (Feb 3, 2021)

Liljoebrshooter said:


> Buy yourself a 12" camel back straight edge and go to town on it.  Check out Martin Mold and Pattern.  He has a nice selection of straight edges that are quite affordable.
> 
> Joe



If I were going to do this, what would be the best method for accurately scraping the 45 degree? I think I could get it flat, but what about the accuracy of the angled surface.

Would a 12" allow for printing of larger dovetails?


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## macardoso (Feb 3, 2021)

One final question - for now. My machinery is a benchtop mill and a 12x36 lathe, hence any scraping I would do would be relatively small. Would you recommend a 20mm or 25mm scraper to start out with?


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## Larry$ (Feb 3, 2021)

Rex Walters said:


> That's great that you were successful with just your own persistence. It may not be the most efficient way to learn, but the lessons sure stick!
> 
> I think the main thing with scraping is consistency and learning to read the blue. As long as you can make regular patterns of shallow rounded diviots (0.0002' to 0.0005" typically) and you learn how to read the blue-ups you can get there eventually, no matter what tools you use to do so.
> 
> ...


Thank you. I was doing the 45/135 passes and stoning. If/when I try this for real I will need to position the work & my body in better relationship. My body was wearing down faster than the iron. (Old, worn out body!)


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## Rex Walters (Feb 3, 2021)

macardoso said:


> If I were going to do this, what would be the best method for accurately scraping the 45 degree? I think I could get it flat, but what about the accuracy of the angled surface.
> 
> Would a 12" allow for printing of larger dovetails?


Please keep in mind that I'm just a hobbyist who barely knows what he's talking about at the best of times. I'm a long way from an expert! Please read all of the following accordingly,

The angle of the bevel on a straightedge isn't important, you just want a narrow enough angle that it clears going into dovetail ways. You only use one side or the other as the flat reference to mark up the ways. You want *both* sides of the angle scraped flat because the bulk of the straightedge will interfere with the work in one orientation or the other, but the actual angle just needs to be smaller than the dovetail angle. You only print and scrape one side of the dovetail at a time.

Even the exact angle between the mating dovetails on the work doesn't really matter. Who cares if it's off a degree or two as long as they are mating perfectly and nothing gets tighter or moves off-axis as the table slides? In practice, you usually scrape the moving part to match the fixed part, first getting the fixed geometry right with a straightedge, then bluing up the fixed part to mark up and scrape the moving part.

Getting the actual geometry right for sliding prismatic or dovetail ways is far too complex to write about in a paragraph or three, refer to the Connelly book mentioned above for a full explanation (or if you just need a nap).

Despite my joke above about needing every measuring tool, the absolute best tool to own (I don't, sadly) is the one Richard King's dad designed, the King-Way alignment tool. It's a clever arrangement of precision levels, sliding joints, indicator mounts, and hemispherical and ball feet to assist in measuring any misalignment of machine tools. It's not a mandatory tool, but you'll be cobbling together custom jigs without one.

The King-way was designed with sound kinematic principles. Not every jig I've made has been!

I think I'm replying to multiple people here, but in my opinion, the only truly mandatory metrology tools are a (hopefully calibrated) surface plate, a decent surface-gauge/indicator-stand, a 0.0005"/graduation dial test indicator, and a precision machinist's level (on the order of 0.0005"/12in per graduation). I'd really want to add a 0.0001"/graduation indicator, too, but it's only useful for the particularly persnickety stuff. Other things like feeler-gauges/shim-stock, parallels, 1-2-3 blocks, and jo-blocks/gauge-pins can also come in *very* handy.

Lastly: either a 20mm or 25mm blade is fine for scraping flat, unobstructed surfaces. In general, the wider the blade the easier it is to handle, but the more likely you'll have trouble fitting into tight spaces. The compound on a small lathe will require a much narrower tool to get into the dovetail than 20mm. I use a 20mm blade for almost everything, but a 10 or 15mm blade when I need to get into tight spaces. A 10mm blade is *much* more difficult to handle well — it's all too easy to tip the blade accidentally and catch a corner. (It's worth rounding the corners of all your blades for exactly this reason.)

The most important tool is your brain and patience. Rich calls it "detective work" for a reason.


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## macardoso (Feb 4, 2021)

Rex Walters said:


> Please keep in mind that I'm just a hobbyist who barely knows what he's talking about at the best of times. I'm a long way from an expert! Please read all of the following accordingly,


Disclaimer noted! If you are a hobbyist, then I have no idea what that makes me   




Rex Walters said:


> The angle of the bevel on a straightedge isn't important, you just want a narrow enough angle that it clears going into dovetail ways. You only use one side or the other as the flat reference to mark up the ways. You want *both* sides of the angle scraped flat because the bulk of the straightedge will interfere with the work in one orientation or the other, but the actual angle just needs to be smaller than the dovetail angle. You only print and scrape one side of the dovetail at a time.
> 
> Even the exact angle between the mating dovetails on the work doesn't really matter. Who cares if it's off a degree or two as long as they are mating perfectly and nothing gets tighter or moves off-axis as the table slides? In practice, you usually scrape the moving part to match the fixed part, first getting the fixed geometry right with a straightedge, then bluing up the fixed part to mark up and scrape the moving part.


Interesting... I'll have to think this through. I assumed your straightedge would be used to print both surfaces at the same time thus defining flatness and angular accuracy. I guess, without knowing better, I thought you would scrape both mating sides of the dovetail and the gib separately and then assembly. Perhaps a bit of light fitting would be needed then, but the flatness and dovetail angle would be set on the bench.

If the exact angle of the dovetail is unimportant, then it would be on the gib to take up for the discrepancy in mating angles. I guess thats OK.

Is there a standard to scrape the male or female dovetail first, or just what is convienent?



Rex Walters said:


> Getting the actual geometry right for sliding prismatic or dovetail ways is far too complex to write about in a paragraph or three, refer to the Connelly book mentioned above for a full explanation (or if you just need a nap).



I have that book in my eBay watch list, but ouch! They are expensive! 



Rex Walters said:


> Despite my joke above about needing every measuring tool, the absolute best tool to own (I don't, sadly) is the one Richard King's dad designed, the King-Way alignment tool. It's a clever arrangement of precision levels, sliding joints, indicator mounts, and hemispherical and ball feet to assist in measuring any misalignment of machine tools. It's not a mandatory tool, but you'll be cobbling together custom jigs without one.
> 
> The King-way was designed with sound kinematic principles. Not every jig I've made has been!



Looked it up. Pretty interesting. I immediately see the use in lathe ways, but don't yet see how it measures dovetails. Need to think more.



Rex Walters said:


> I think I'm replying to multiple people here, but in my opinion, the only truly mandatory metrology tools are a (hopefully calibrated) surface plate, a decent surface-gauge/indicator-stand, a 0.0005"/graduation dial test indicator, and a precision machinist's level (on the order of 0.0005"/12in per graduation). I'd really want to add a 0.0001"/graduation indicator, too, but it's only useful for the particularly persnickety stuff. Other things like feeler-gauges/shim-stock, parallels, 1-2-3 blocks, and jo-blocks/gauge-pins can also come in *very* handy.



Got most of that. Short the gage blocks and pins.



Rex Walters said:


> Lastly: either a 20mm or 25mm blade is fine for scraping flat, unobstructed surfaces. In general, the wider the blade the easier it is to handle, but the more likely you'll have trouble fitting into tight spaces. The compound on a small lathe will require a much narrower tool to get into the dovetail than 20mm. I use a 20mm blade for almost everything, but a 10 or 15mm blade when I need to get into tight spaces. A 10mm blade is *much* more difficult to handle well — it's all too easy to tip the blade accidentally and catch a corner. (It's worth rounding the corners of all your blades for exactly this reason.)



Gotcha. Do you have a source for the smaller tools or is it more of a braze your own kind of deal?


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## Rex Walters (Feb 4, 2021)

macardoso said:


> I assumed your straightedge would be used to print both surfaces at the same time thus defining flatness and angular accuracy



I had the same misconception when I started. The order of operations depends on the specific circumstances of the work, but a straightedge is not intended to be an angular reference, simply a "portable surface plate" you can take to the work when it's not feasible to bring the work to the plate.

Without attempting to write a full-blown "how to scrape machine ways" treatise (Richard King's 5-day class is really the gold standard and best way to get an *introduction* to the topic), here's a mini-overview:

If I were scraping in the cross slide of a lathe. I'd first look for an original, unworn horizontal way surface (the mating cross-slide usually doesn't ride on the full surface, so there's usually some unworn areas). This gives you a clue to the original geometry when the machine was new.

I'd then scrape one of the two horizontal surfaces on the saddle flat and parallel to the original plane (most likely the way on the other side of the saddle since scraping will destroy the original surface). Once you get it flat, you check for parallel with an indicator: reference the base on the scraped surface (parallels and 1-2-3 blocks below the base come in handy here) and place the indicator tip on the original surface. If there is tip in either the X or Y plane you'll need to "step scrape" to correct the error. (Step scraping is too long a topic to cover here, but is doubtless described in at least one YouTube video somewhere.)

Once one horizontal surface is parallel to the original surface, I'd scrape the other horizontal way to be *coplanar* (not just parallell) to the way I just scraped.

Then I'd start in on the dovetail on the saddle. I'd start on the fixed side before dealing with the gib side. Again, I'd look for any unworn surface for clues before diving in, with a goal of *minimal metal removal in the most worn areas*. I'd then use a pair of dowels or gauge pins to mic across the dovetail from front (operator side) to back, writing down readings every inch or two. The gib side should be completely unworn (any wear should be on the gib itself) but it's worth a sanity check with the straightedge to ensure it's also reasonably flat.

Note that my lathe uses flat steel, not tapered cast iron, gibs, so I used the gib-side as a rough reference. With tapered gibs, you'll need to first eliminate any bend in the gib and then scrape the outer surfaces flat (but tapered). You'd then mic across the dovetail with the gib in place, scraping as necessary until both sides are flat and parallel in X (across the bed ways).

The exact angles do *not* matter and they don't even need to be the same, you just want to ensure that there is no pinching when the cross-slide moves fore or aft.

Once I mic the same all the way across the four saddle way surfaces (two horizontal and two dovetail sides) with good PPI and truly flat surfaces, I then apply spotting ink to those surfaces and use the saddle itself as a reference for the cross-slide.

You then scrape in the cross-slide to match the saddle.

First, you'd scrape the two bottom surfaces flat at the same time (without the gib in place, of course, when you mark up). Once both sides are flat, you want to check the geometry to ensure the top surface where the compound rides is parallel. If there is any discrepancy in Z (along the bed ways) or especially in X (across the bed ways) you need to step scrape to correct the error.

Once the bottom surfaces are finished, you start scraping the dovetails on the cross-slide. First the fixed side, then the gib side as before. Since this time you need to mic an interior dimension, I use a stack of fixed and adjustable parallels between the dowels, and mic across them to ensure they are scraped parallel.

Once the saddle, gib, and cross-slide are all fully scraped in, lube, assemble and do some system-level verification/calibration to ensure everything operates as expected. Everything should slide smoothly with no pinching or significant misalignment as you move things from one extreme to the other. Connelly does a very good job of explaining how to do this.

If things aren't exactly aligned as expected, choose the surfaces that will create the least amount of work to make the correction. For example, if the cross-slide wasn't moving exactly perpendicular to the spindle axis, it's smarter to correct the saddle-to-bed-ways surfaces than re-scraping the cross-slide because the contacting surfaces are small and far apart from each other (giving you much finer control and creating less work).



macardoso said:


> I have that book in my eBay watch list, but ouch!



It's about $100 new from Dapra. Textbooks are always expensive, but I consider mine a tool purchase. Whatever you do, don't buy from any of the evil people on Amazon trying to scam people out of several hundred dollars for a copy.



macardoso said:


> Got most of that. Short the gage blocks and pins.



I consider a set of gauge pins up to 0.500" indispensable tools. You'll find them *FAR *less expensive than gauge blocks and they suffice for >99% of any tasks a hobbyist might face. I use them for setups at least as often as I use them to measure bore diameters. I pretty much never need finer than 0.001" granularity for setups or measurements (gauge blocks let you go down to 0.0001"). One surprisingly obvious tip: you can measure a bore up to 0.999" diameter with a set of pins up to 0.500" by inserting *pairs* of pins into the bore. Add two more pins (1.000" and 1.500") and you can measure up to 1.999" in one thou increments.



macardoso said:


> Do you have a source for the smaller tools or is it more of a braze your own kind of deal?


The Biax I bought on Ebay years ago came with a couple usable blades. I also bought a few new ones from Dapra (after searching the couch cushions for a *long* time to find some spare change). It's absolutely possible to braze carbide chips onto pieces of mild steel, shape them on a green wheel, and hone them with a diamond wheel, but I'm fortunate enough to be at a point in my life where I can afford to buy rather than build most of the tooling I need. As you've discovered it's also possible to use HSS scrapers, but you'll spend a lot more time sharpening.


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## Janderso (Feb 4, 2021)

Rex Walters said:


> a *long* time to find some spare change)


Don't let him kid you, Rex is loaded 
He is also a very established machinist and rebuilder. 
I've seen his work. The Logan he scraped in is perfect.


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## Janderso (Feb 4, 2021)

I bought the Sandvik hand scraper for Richard King's class.
Based on my limited experience, the Sandvik in it's original form, enabled me to scrape in the test block Richard gave us to learn on. It only took a few hours.
I may remove some material from the shaft before I scrape my Rucker 9".
Maybe put a channel down the center to allow for a little more flex.
Once Richard let me loose with a Biax, I never went back to that hand scraper. It's too bad they run $3,500 and up!!
I think if I ever got the idea of scraping in a machine I wanted to save, I would invest in a Dapra-Biax.
For small stuff, the hand scraper is adequate IMHO.


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## Rex Walters (Feb 4, 2021)

Janderso said:


> Don't let him kid you, Rex is loaded
> He is also a very established machinist and rebuilder.
> I've seen his work. The Logan he scraped in is perfect.


Hmm...

I can't help but point out how easy it is to mistake impulse-buying for wealth, brash confidence for competence, a single rebuild for experience, and pretty surfaces for perfection.

Jeff's shop is full of several big-boy machines I can only lust after, and he knows how to use them (despite his pretenses)!


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## macardoso (Feb 4, 2021)

Rex Walters said:


> I had the same misconception when I started. The order of operations depends on the specific circumstances of the work, but a straightedge is not intended to be an angular reference, simply a "portable surface plate" you can take to the work when it's not feasible to bring the work to the plate.
> 
> Without attempting to write a full-blown "how to scrape machine ways" treatise (Richard King's 5-day class is really the gold standard and best way to get an *introduction* to the topic), here's a mini-overview:



Huh. That's really interesting. So other than the inaccessibility of rotating the straightedge upside down in some instances, you don't "need" both scraped surfaces on the straight edge?



Rex Walters said:


> I'd then scrape one of the two horizontal surfaces on the saddle flat and parallel to the original plane (most likely the way on the other side of the saddle since scraping will destroy the original surface). Once you get it flat, you check for parallel with an indicator: reference the base on the scraped surface (parallels and 1-2-3 blocks below the base come in handy here) and place the indicator tip on the original surface. If there is tip in either the X or Y plane you'll need to "step scrape" to correct the error. (Step scraping is too long a topic to cover here, but is doubtless described in at least one YouTube video somewhere.)
> 
> Once one horizontal surface is parallel to the original surface, I'd scrape the other horizontal way to be *coplanar* (not just parallell) to the way I just scraped.



Following that so far! Have seen step scraping and understand what it trying to accomplish.



Rex Walters said:


> Note that my lathe uses flat steel, not tapered cast iron, gibs, so I used the gib-side as a rough reference. With tapered gibs, you'll need to first eliminate any bend in the gib and then scrape the outer surfaces flat (but tapered). You'd then mic across the dovetail with the gib in place, scraping as necessary until both sides are flat and parallel in X (across the bed ways).



OK so always working with reference to another surface. In this case, the fixed way which you just scraped flat.



Rex Walters said:


> Once I mic the same all the way across the four saddle way surfaces (two horizontal and two dovetail sides) with good PPI and truly flat surfaces, I then apply spotting ink to those surfaces and use the saddle itself as a reference for the cross-slide.



Interesting! So I figured you would scrape the cross slide against the surface plate too, but now that you've made a master surface on the other side, there is no reason to.

Is there a way with dealing with how much material you are removing? I'm sure eventually you will open it up enough that the original gib does not fit. Just make a new one? Or do Turcite?



Rex Walters said:


> or two. The gib side should be completely unworn (any wear should be on the gib itself) but it's worth a sanity check with the straightedge to ensure it's also reasonably flat.



Gotcha. So again, not really trying to correct the dovetail to a particular angle, but rather develop a planar surface. Probably doesn't matter if the two dovetails are angled the same either then!



Rex Walters said:


> It's about $100 new from Dapra. Textbooks are always expensive, but I consider mine a tool purchase. Whatever you do, don't buy from any of the evil people on Amazon trying to scam people out of several hundred dollars for a copy.



OK for that price, I think I can stomach it. I'm not looking at going full blown scraper here, but it seems like a good skill to pick up. I own import equipment which most people would suggest is not worth bothering to scrape at all, but it also makes me more willing to give it a try. I don't tend to rush projects and can be meticulous, so hopefully I can try a few easy things and maybe make my machines better than factory.



Rex Walters said:


> I consider a set of gauge pins up to 0.500" indispensable tools. You'll find them *FAR *less expensive than gauge blocks and they suffice for >99% of any tasks a hobbyist might face. I use them for setups at least as often as I use them to measure bore diameters. I pretty much never need finer than 0.001" granularity for setups or measurements (gauge blocks let you go down to 0.0001"). One surprisingly obvious tip: you can measure a bore up to 0.999" diameter with a set of pins up to 0.500" by inserting *pairs* of pins into the bore. Add two more pins (1.000" and 1.500") and you can measure up to 1.999" in one thou increments.



I love measuring stuff. My first job was in metrology and I just want it all! Gage blocks and pins are definitely in my "next to be purchased" list.



Rex Walters said:


> The Biax I bought on Ebay years ago came with a couple usable blades. I also bought a few new ones from Dapra (after searching the couch cushions for a *long* time to find some spare change). It's absolutely possible to braze carbide chips onto pieces of mild steel, shape them on a green wheel, and hone them with a diamond wheel, but I'm fortunate enough to be at a point in my life where I can afford to buy rather than build most of the tooling I need. As you've discovered it's also possible to use HSS scrapers, but you'll spend a lot more time sharpening.


 
I do have an eBay search for a biax, but A) I haven't started scraping so I feel like I need to be initiated to hand scraping first, and B) I bet the rest of you guys will snatch them up!


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## macardoso (Feb 4, 2021)

Thanks again for taking the time to write such detailed responses. As of today I am the proud owner of a Sandvik scraper, and after a few more days of hemming and hawing over it, I'll probably end up with Machine Tool Reconditioning too.


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## francist (Feb 4, 2021)

Rex Walters said:


> One surprisingly obvious tip: you can measure a bore up to 0.999" diameter with a set of pins up to 0.500" by inserting *pairs* of pins into the bore.


Brilliant !


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## Rex Walters (Feb 4, 2021)

francist said:


> Brilliant !


Hardly, but I had the same slap-on-the-forehead moment when I first heard of the technique. Now I use it regularly. 

I use gauge pins almost daily in the shop for all sorts of things. Literally today I needed to compare the widths of two trepanned channels to get them to the same width (exactly 3/32"). I often find it useful to place a hole or undercut feature on a part a precise distance above the mill vice jaws — much less fiddly to use a gauge pin from the top of a hole than a depth-mic from the top of a part. Have two features you are turning on the lathe precisely 0.279" apart axially? Find the right pin and insert it between the carriage-stop and the carriage.

I prefer to use 123 blocks, gauge pins, and shim stock for setups or measuring whenever possible. I still screw up measuring with calipers or micrometers or even scales on occasion. The only tricky thing with gauge pins is to ensure you read the label from the correct row (the label below the pin, not above!) — the bigger pins are marked, fortunately.

Less useful (at least I've not had occasion to try it yet) but I read somewhere about inserting two hex keys that are half the size of the one you need if you can't find one large enough.


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## Rex Walters (Feb 4, 2021)

macardoso said:


> So other than the inaccessibility of rotating the straightedge upside down in some instances, you don't "need" both scraped surfaces on the straight edge?



Correct. The bevel is for clearance and access, it's not intended to be a precision angle reference. If the top body of the straightedge didn't get in the way occasionally, you wouldn't need to scrape both planes flat.



macardoso said:


> So I figured you would scrape the cross slide against the surface plate too, but now that you've made a master surface on the other side, there is no reason to.



It's often useful to double-check against a plate occasionally, and I'd probably start with a blue-up on the plate for simplicity, but as long as you are confident that the saddle is truly flat there should be no surprises scraping the cross-slide to match. Note that it *IS* possible to get two curved surfaces to mate perfectly. That's why it's important to get the "secondary reference" (the horizontal saddle ways) truly flat first (and to occasionally double-check against the primary reference, your plate).



macardoso said:


> Is there a way with dealing with how much material you are removing? I'm sure eventually you will open it up enough that the original gib does not fit. Just make a new one? Or do Turcite?



With a steady hand, you should be removing roughly the same amount of material each pass. It's important to *measure* how much you remove each pass on average in order to step scrape. You can measure the depth of an individual scrape with a tenths indicator, but I find it more useful to scrape one full pass over an entire area and determine the average depth you scrape each pass. That is: scrape a test bar completely flat. Then do another pass on just the end few inches of the bar. Next, place an indicator stand on the original surface with the indicator tip resting on a gauge block or parallel that averages out the points on the original surface and zero out the indicator. Finally, move the gauge-block over to the freshly scraped surface and measure how much lower it's gotten. Even better, do the same after five or ten passes and average the result.

Other than that, the only trick is what I think Rich calls "tip scraping." Let's say a blue up shows the two ends of the work are high and it's low in the middle. The obvious thing to do is to scrape off the blue at the ends. Less obvious is that you can leave one end alone and scrape down the other end (and eventually a bit in the middle) until it's flat. Tilting the plane this way when you know you need to remove more "meat" from one end rather than the other is often quite useful.

Re: Turcite: I'm reminded of the old joke. If you cut a rope too short you can always splice some more on, but if you cut it too short there's nothing you can do about it! The best answer is not to scrape too much (or wait until there is too much wear to correct the problem with scraping). When you have no choice but to add material, epoxying something like Turcite is a great solution (it's such a terrific way material that some machines are designed to use it from the start).

I'm with you on metrology. Fascinating topic. One of my favorite engineering expressions is "if you can't measure it, you can't improve it." Sometimes figuring out how to measure things is half the battle.

The thing about a Biax is that once you've used one it's hard to go back. I really want a power flaker myself, but I do have an old blue-bullet scraper. You're right, they've become much more expensive and less common thanks to all the YouTubers making the skill valued again.



macardoso said:


> hopefully I can try a few easy things and maybe make my machines better than factory



Depends on the factory, of course!  But better than current is usually a realistic goal. It does take a lot of patience, cleverness, and meticulous measuring but cast iron is usually pretty forgiving. Rule 1 if you find yourself getting deeper into a hole is to stop digging. Fortunately, the digging goes quite slowly with a scraper!

Practicing is an excellent idea. Once you're confident you can make something flat, practice making the top and bottom of a test piece perfectly parallel in two axes. Once you've got something with top and bottom parallel, make one of the ends perfectly flat *AND *square to those planes.

Once you can do those three things confidently you're ready to start rebuilding, which is mostly an exercise in figuring out what are the reference planes, how to indicate/measure deviations from the ideal, and figuring out an efficient plan of attack. The hardest thing about rebuilding is that everything you change tends to affect everything else, so the order of operations really matters.

Somebody mentioned something to the effect of their offshore machines not being worth scraping in. I couldn't disagree more strongly. If it's made out of cast iron, it can be scraped and it's often the cheaper offshore machines that are most often in need of it. The ways on lathes and mills are the most critical things to machine things accurately. Get those right and the rest of the bells and whistles are far less important.

That said, the quality of the castings on WW-II and earlier machinery is often outstanding. If you've got a LOT of free time, you can sometimes turn a very cheap, clapped out, and rusty heap into a precision machine.


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## Liljoebrshooter (Feb 5, 2021)

Another real cheap project for scraping is a set of 4" or 5" cast iron V blocks or an angle plate.   Get an angle plate without holes.   You can practice making a flat surface and then make the other surface 90 degrees.   You can find these for less than $50.  

Joe


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## Janderso (Feb 5, 2021)

Rex Walters said:


> Hardly, but I had the same slap-on-the-forehead moment when I first heard of the technique. Now I use it regularly.
> 
> I use gauge pins almost daily in the shop for all sorts of things. Literally today I needed to compare the widths of two trepanned channels to get them to the same width (exactly 3/32"). I often find it useful to place a hole or undercut feature on a part a precise distance above the mill vice jaws — much less fiddly to use a gauge pin from the top of a hole than a depth-mic from the top of a part. Have two features you are turning on the lathe precisely 0.279" apart axially? Find the right pin and insert it between the carriage-stop and the carriage.
> 
> ...





Liljoebrshooter said:


> Another real cheap project for scraping is a set of 4" or 5" cast iron V blocks or an angle plate.   Get an angle plate without holes.   You can practice making a flat surface and then make the other surface 90 degrees.   You can find these for less than $50.
> 
> Joe


I'm not sure who said this >>>>>>>""Somebody mentioned something to the effect of their offshore machines not being worth scraping in. I couldn't disagree more strongly. If it's made out of cast iron, it can be scraped<<<<<<<<""

Aren't most Asian lathe bed ways hardened? In fact, most lathes produced since the sixties have induction hardened ways right?
I wasn't aware they could be scraped.


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## Rex Walters (Feb 5, 2021)

Janderso said:


> Aren't most Asian lathe bed ways hardened? In fact, most lathes produced since the sixties have induction hardened ways right?
> I wasn't aware they could be scraped.


I’ve no idea as I’ve not tried scraping an Asian lathe bed.

But the bed isn’t the only thing worth scraping on a lathe, and I’m somewhat skeptical that all are induction hardened. It’s an extra manufacturing process that would add to the cost, no?

I’d WANT a lathe with hardened ways assuming they were ground half decently to begin with. The bed ways are the hardest thing to scrape on a lathe (the biggest job)!

Lastly, there’s hard and there’s HARD. Until I make a test scrape, I’ve no idea if scraping is feasible. I suspect “flame hardened ways” might be marketing speak for a guy passing a propane torch over the oil on the ways for a few seconds. True induction hardening can’t be free.


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## Rex Walters (Feb 5, 2021)

Oh, wait! 

I just realized that to Jeff, this is an offshore Asian lathe: https://us.dmgmori.com/products/machines/turning/universal-turning/ctx/ctx-beta-800

I was thinking more on this end of the spectrum: https://www.harborfreight.com/power...nch-x-10-inch-precision-mini-lathe-93212.html

(My tongue is firmly in my cheek... )


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## macardoso (Feb 5, 2021)

My 94' Enco lathe has induction hardened bedways. They are ground true and have little wear. The cross slide and compound are much more lacking and have looseness in the middle of travel and tightness in the ends, not much, but still could be improved.

My CNC converted G0704 is also an import machine and the total fitup of the ways is garbage. If I were to try to scrape anything, this would be where I would start. Could probably cold chisel it closer than it is right now...


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## macardoso (Feb 9, 2021)

Well, I am now the proud owner of a 20mm Sandvik scraper, Machine Tool Reconditioning, and some new marking fluids from Dapra. I need to pick up a beginner scraping project still. Hoping to maybe start with a small cast iron surface plate, then maybe a dovetail straightedge casting, and eventually work up to touching my mill or lathe. 

The lathe is in good shape except for some light fitting of the cross slide and compound elements. I'd rather not go crazy on her since I am pretty comfortable holding tenths already. If I could even out the snugness in the cross slide, I'd be very happy.

The mill is much more rough. Most of the ways have very poor fit and the rigidity suffers. I'd like to correct for accuracy, then fitup. Perhaps I can add a central oiling system at this point as well. I bet I could really improve my machine without risking really screwing up a priceless machine in the process of learning.

I do still need to figure out how to sharpen this scraper. I'm leaning towards the 1000-3000 grit diamond lapping wheels you see people using on YouTube. I have a cheap bench grinder I can mess with as well as some small motors and VFDs to build a basic lapping table.


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## Braeden P (Feb 9, 2021)

macardoso said:


> Well, I am now the proud owner of a 20mm Sandvik scraper, Machine Tool Reconditioning, and some new marking fluids from Dapra. I need to pick up a beginner scraping project still. Hoping to maybe start with a small cast iron surface plate, then maybe a dovetail straightedge casting, and eventually work up to touching my mill or lathe.
> 
> The lathe is in good shape except for some light fitting of the cross slide and compound elements. I'd rather not go crazy on her since I am pretty comfortable holding tenths already. If I could even out the snugness in the cross slide, I'd be very happy.
> 
> ...


I mounted the diamond wheels on my wood lathe but if you use your lathe cover the ways for sure!


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## macardoso (Feb 9, 2021)

Braeden P said:


> I mounted the diamond wheels on my wood lathe but if you use your lathe cover the ways for sure!


Not a bad idea!

Picked up a 1/2HP VFD and 25W 1600rpm motor from the trash bin at work (they are cool with that). Just need to mount it up and get myself a few lapping discs. Took about 3 minutes to get the VFD running the motor with start, stop, reverse, and speed control from the front panel.


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## macardoso (Feb 11, 2021)

Got it! Probably going to need several passes to read and understand.


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