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



## macardoso (Feb 17, 2021)

A newbie just barely getting his feet wet here...

Picked up a copy of Machine Tool Reconditioning, watched about every scraping video I could find on Youtube, bought some spotting dyes (canode and hi-spot), bought a 20mm Sandvik hand scraper, and I am currently building a slow speed diamond lapper to sharpen the blade.

Couple of random questions that have come up already:

1) My Sandvik scraper has a seemingly wide radius which has been giving me some trouble. My accuracy for where the cutting occurs across the width of the blade is very poor and I seem to shoot left and right of my high points with no discernable roll of the scraper. I read online that the factory provides 150mm radius as the default as they don't know what radius people will want to use. Is my frustration normal? I need to finish building the slow speed grinder and then I should be able to put a new radius on the blade.

2) What blade radius is appropriate for general work on small machines by a beginner? I have read 60 or 75mm, but don't know what is appropriate.

3) I don't yet have a piece of cast iron to work with so I have been practicing on a rusty V block. Pretty sure it is steel but soft enough to get a good bite even with a dull file. When I try to scrape it, I find the blade likes to bite, but not let me scrape forward. It just catches in the material and leaves a little flat line. If I push harder it will scrape, but taking off a wider swath of material than I want. Is this a function of the wide scraper blade, the material, or both? Is there a different grind for scraping steel?

4) I have read about the depth of the zones between high points is important for oil retention and too shallow is undesirable. I feel like the entirety of my scraped surface has very little texture. It is very flat, not necessarily in the sense of the "trueness" of the surface, but rather the scraping texture. I have nothing to compare against, but I feel like I am unable to develop the depth of texture required. Again, is this a function of the overly wide scraper blade?

5) I've used hi-spot blue for quite a while and have a good feel for how to develop a thin film on my surface plate. I can get decent spotting this way. The canode blue seems much tackier and I am having trouble getting anything but the thickest film. Any tips? I ordered a rubber brayer, but it has not yet arrived.

6) Are there good substitutes for red lead as a contrast medium? I don't really like the idea of anything lead in the shop, especially with pets and it being my house. Dapra was sold out of canode yellow when I ordered, but I did get some red. Is there another source for the canode inks besides Dapra?

7) I am having a much harder time seeing my spotting on this steel practice part than I was when I was scraping in some bearing blocks on my steam engine a few weeks ago. Those were cast iron. Something with the extra reflectivity of steel is making it hard to see. Any tips?

8) I might have a source of a 12x18 cast iron surface plate and an 18" cast iron parallel. Would these be good projects to start practicing on?

9) After those, I'd like to do a straightedge. my needs are to do a small mill and a 12" lathe cross slide. A 12" straight edge would be plenty long enough to do everything on both machines except the mill column and table. The column is roughly 18" of dovetails and the table is roughly 24". What would be right size straightedge casting to buy? I'd like to keep it as small as possible, both to help with cost and the difficulty of rough machining it (I only have small machines not capable of roughing the castings, so I'd need to make a friend).

10) Is there any good material on the technique for flaking? I have found nothing more than perhaps a 15 second clip of Abom79 doing a draw stroke with a dead blow mallet at one of Rich's scraping classes, but with zero explanation. I have no immediate need to figure this out, but I am curious.

11) I watched Robin Renzetti's video on Moore pattern scraping. Is there any particular benefit to doing it this way? Should I be developing the muscle memory for that? I'm finding it nearly impossible to form the crescents without digging the corners, but I suspect that is also a function of the overly large radius on the scraper blade.

12) Is there an appropriate corner treatment for the scraper blade? Out of the box, the Sandvik insert is sharp all the way to the corner. Should this be blunted?

13) I do not own precision ground flat stones. I do have a cheap fine india stone that I have sanded flat relative to my surface plate (abuse I know...). Is this acceptable for the time being, or are the PFG's a requirement? They aren't cheap and I feel like scraping has turned into $100 here, $100 there, $100 everywhere.

14) I have not found a source for the little lapped steel scrapers block used to bridge high points during measuring. Anyone know where to find one? I don't have a shop full of nice flat ground stuff, so I'm coming up short with anything to substitute.

That ended up being a few more than a couple questions, but I want to say thinks in advance for any answers.

Mike


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## Janderso (Feb 17, 2021)

You can't do anything without a surface plate.





						Grade A 12" x 18" Black Granite Surface Plate
					

Shars Tool




					www.shars.com


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## macardoso (Feb 17, 2021)

Janderso said:


> You can't do anything without a surface plate.
> https://www.shars.com/gradxe-a-12-x-18-black-granite-surface-plate


Whoops, forgot to mention that. I have an 18x24x3 black granite plate, grade 00 (B) with a cal cert showing max deviation of 2um, low in the middle, high in the corners.

It is an import plate, so I only trust the calibration so much, but it is what I have.

Edit, I'm doing research now. I bought the plate new for $120 advertised as a grade B. The cal cert states Grade 00, which upon further research is metrology lab grade. I'm calling BS on that cal cert and now have no clue how flat my plate is. Ugh.


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## benmychree (Feb 17, 2021)

The Canode inks can be thinned out on the surface plate with a spritz of Windex glass cleaner, yes, the corners of the insert should be rounded to avoid digging in, and the radius should be smaller as you suggest, that can be done on a diamond grinding wheel if it is fine enough; I have scraped for many years without a slow speed lapper.  I have always used a India stone for deburring.  Texture is achieved by using more downward angle with the scraper.


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## Cadillac (Feb 17, 2021)

Use a gauge block to span the points. Can be bought separately through places like McMaster Carr or so. You want to get familiar with your technique so that you can control your depth of stroke. Lots of practice and practice.


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## Cadillac (Feb 19, 2021)

I bought my canode at artco.


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## Richard King 2 (Feb 22, 2021)

Go to You Tube and watch my friend and student Stefan Gottswinter 





Robin R does not show the Moore scraping.  It's his take on it.  If you want to see it done the correct way.  check this out





I have been experimenting with Arcryic paint I found in the arts and crafts dept at Walmart.  It's the tubes hanging on hooks and cost around $2.00 for a 8oz. tube.  Squirt out a quarter size amount and dilute it with 4 or 5 squirt of Windex.  There is Yellow, red, white and blue.  I have also had good luck with Canode for years and if you want to see it better mix some Charbonel water based Prussian blue in it.  Spread it with a soft foam roller first and then a hard rubber brayer.  It needs to be transparent  on the plate.   You should be able to find some scrap cast iron at a scrapyard or surplus steel yard.   Many of my students have you tube shows on there. Just search "Richard King Scraping" .  I'll write more later... its past my bedtime...lol    Pic's showing inks, plates, control gage we use to count points and grind blade radius.  I say 60 mm rad for beginners, home made lappers, yours truely working inside BIAX show booth.  PS:  You know if you come to one of my classes I will teach you how to do it all.   I also sell a DVD and HSB Stick showing you how.  Check out my forum at the top of the forum lists


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## macardoso (Feb 23, 2021)

Richard King 2 said:


> Go to You Tube and watch my friend and student Stefan Gottswinter
> 
> 
> 
> ...



Hi Richard, thanks for the response!

I've been through Stefan's videos and many others. They really make up the limited foundation of my scraping knowledge, supplemented by some books, and information given by others here who have taken your class. 

My very first try working with Canode blue was that it did not mark as vividly as an equivalent film thickness of prussian blue, but the clean up was very easy. I should revisit it and try again. I will probably give your Charbonel blue a try as well. 

Having a buddy 3D print me a control gage. I still need to adjust the factory grind on my Sandvik scraper, and them I'm going to jump into some practice pieces.

BTW, I hit the section in MTR where he describes the water bed leveling method. Just curious why this gets so much flak? It seems impractical to set up, but it does sound like it would provide a good absolute reference surface to level to.


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## Richard King 2 (Feb 23, 2021)

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....


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## Richard King 2 (Feb 23, 2021)




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## macardoso (Feb 23, 2021)

Richard King 2 said:


> 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.


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## Hellkell (Feb 25, 2021)

macardoso said:


> 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?


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## Cadillac (Feb 25, 2021)

You scrape both surfaces and flake only one.


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## Richard King 2 (Feb 25, 2021)

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.


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## macardoso (Mar 2, 2021)

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?


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## macardoso (Mar 3, 2021)

macardoso said:


> 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.
> 
> ...



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.


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## Richard King 2 (Mar 3, 2021)

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.


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## macardoso (Mar 3, 2021)

Richard King 2 said:


> 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.


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## macardoso (Mar 4, 2021)

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).


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## Richard King 2 (Mar 5, 2021)

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


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## macardoso (Mar 31, 2021)

I would love some clarification on the roughing cycle of scraping. The largest thing I've practiced on has been a 4" vise body so I'm sure the roughing of a large worn out machine is on a whole different level from what I am doing.

I find myself essentially high pointing with a heavier cut and avoiding low regions to rough out material. I am starting to get the feeling however, that the goal is not to aim for the blue spots necessarily but rather to only focus on cross hatching an area to bring the surface down. I tried to do this but I wonder how you can keep yourself from scraping down the valleys even lower when doing this? Not sure how exactly to phrase my question, but what is the methodology of roughing in the part. In my latest example, I had to correct about 0.0030" of bow across the face of the vise (import garbage). What would be a ballpark time for someone to hand scrape this? It took me probably 2-3 hours to get it flat and I expect another hour to hit the high points to bring up the points per inch.

What is the criteria for switching from roughing to going after highpoints? 

I see about half of the youtube guys who scrape doing discrete strokes, while others do a push stroke and drag back across the part to start the next stroke, like one would do with a paint scraper. I feel like discrete strokes is the "correct" way, but I also find that I can scrape faster and more accurately when I drag back on the part doing a bunch of strokes in quick succession.

Finally, my scraping is a bit haphazard when roughing in the surface. I follow the 45 degree lines and cross my previous pass in the other direction, but I don't put any effort in spaing out my strokes evenly, keeping them perfectly angled to each other, keeping the stroke length consistent, etc. Should I be? Is this just an aesthetic thing or is there a good reason to try to pay more attention? 

Thanks!

Mike


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## Richard King 2 (Mar 31, 2021)

You need to grid out the area you will scrape.  I am not sure if your hand or Biax Power scraping?   Hand is much slower.  But once you have measured the part you need to know how much each of your cut removes so you can use math to estimate how many passes you need to scrape the high area's to get down to the lowest point.  You have to mark the high area's with a "high lighter" so when you scrape the high area's you know you've scraped there.  Many rookies don't use the highlighter and dig holes.  I used to use red lead and now Canode Yellow ink diluted with glass cleaner.  You also mark the low area's with a magic marker so can avoid the low area's  and only scrape off the high area's. 

There are different ways to scrape.  If you measure your part and it is more then .001" .  Grit your part with  a marker drawing 1" x1"  squares  and only scrape the high squares until your with-in .0002".WhenIrough I use an over lapping technique I call "scraping paint" which is  1/8" wide and no more then 1" long.  and as you get closer you shorten your stroke and technique and once your down to .0002" you start the cross hatch checker board technique  before you blue up the part on a blued surface plate  or using a master scraped straight edge.  The yellowed grid technique is what I call "step scraping"  and "blind scraping" .  The blade tip radius and a sharp blade is also important.  I will look for some photo's as you should, add them here,  so we can look at what we are talking about.  I'll do so soon as I am busy doing quotes now.  Rich


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## macardoso (Mar 31, 2021)

Richard King 2 said:


> You need to grid out the area you will scrape.  I am not sure if your hand or Biax Power scraping?   Hand is much slower.  But once you have measured the part you need to know how much each of your cut removes so you can use math to estimate how many passes you need to scrape the high area's to get down to the lowest point.  You have to mark the high area's with a "high lighter" so when you scrape the high area's you know you've scraped there.  Many rookies don't use the highlighter and dig holes.  I used to use red lead and now Canode Yellow ink diluted with glass cleaner.  You also mark the low area's with a magic marker so can avoid the low area's  and only scrape off the high area's.
> 
> There are different ways to scrape.  If you measure your part and it is more then .001" .  Grit your part with  a marker drawing 1" x1"  squares  and only scrape the high squares until your with-in .0002".WhenIrough I use an over lapping technique I call "scraping paint" which is  1/8" wide and no more then 1" long.  and as you get closer you shorten your stroke and technique and once your down to .0002" you start the cross hatch checker board technique  before you blue up the part on a blued surface plate  or using a master scraped straight edge.  The yellowed grid technique is what I call "step scraping"  and "blind scraping" .  The blade tip radius and a sharp blade is also important.  I will look for some photo's as you should, add them here,  so we can look at what we are talking about.  I'll do so soon as I am busy doing quotes now.  Rich


Rich, I appreciate your time to respond. Very new at this so trying to not develop bad habits right at the start.

Right now I am hand scraping. Sharpening is done by hand, although as time permits I drew up plans to build a carbide grinder for sharpening the blade and indexable inserts. I started working with the Sandvik blade as it comes new knowing the radius is too wide. It is slow going, but I have been incrementally working the blade down to a smaller radius. Don't have a control gage, but by guessing if I started at 150mm, I'm probably down to 100-120mm now. I would like to get it to the 60-75mm range.

I need to measure my scraping depth. Do I do that for a single scrape? Or should I scrape the whole surface and see how it it drops in height?

I think I follow your scraping strategy. Let me see if I can recap. 

1) Surface should be treated with contrast to help avoid digging holes
2) In early stages of roughing, the surface should be subdivided into 1 inch squares. The high squares are treated in their entirety.
3) In early roughing, bluing against a surface plate might not even be necessary if the high regions are located with an indicator.
4) Once the surface is flat within 0.0002" then a more refined cross hatch scraping is used with bluing against the surface plate.

Below are a few pictures of my first scraping practice. I'm sure it is all wrong but I'm trying to apply everything I've read and watched.

Initial blue up with heavy canode on the plate. Concavity of 0.003"



Roughing in the bottom for flatness



Step scraping to remove transverse taper and convexity (found by hinging)



Initial blue of the top surface. Bolt holes are blown out, and the bed itself is concave by 0.003"



Roughing for flatness, did damage by trying out a bench stone to assist in roughing. Won't try that again.



High spots marked with sharpie. No blue, just a rub on a clean plate to burnish the spots. Calling this the end of roughing and moving to high pointing for better contact.


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## Richard King 2 (Mar 31, 2021)

Looks good. A tip, get a sheet thin rubber like a truck inner tube and lay the vise on it.   It won't slide as easy.  Your % is real low 0 in some places and 30 in others, your looking for 40 to 60%. I was thinking mail the insert to me and I'll grind it for you.   How did you measure the the .003"  ?   Is it co-planar now to each other?


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## macardoso (Apr 1, 2021)

Richard King 2 said:


> Looks good. A tip, get a sheet thin rubber like a truck inner tube and lay the vise on it.   It won't slide as easy.  Your % is real low 0 in some places and 30 in others, your looking for 40 to 60%. I was thinking mail the insert to me and I'll grind it for you.   How did you measure the the .003"  ?   Is it co-planar now to each other?



Appreciate the feedback Rich! The rubber is a good idea. I screwed down some 2x4's on my bench to make a cradle and that has been working well. Just had the vise loose on the table before that and I could barely make cuts without it sliding everywhere.

Do you think this was too early to stop roughing and start going after only high points? I've done 4 high pointing cycles since the last picture and have gotten more bearing, but the distribution is not perfectly uniform. Maybe this is OK, but would have like to see it better.

Here is after 3 high pointing cycles.



I appreciate your offer for grinding an insert for me. That would be a great way for me to have a reference as I go forward! If you are willing to PM me your address, I'll get an insert off eBay and send it to you directly. I'd like to hold onto the one I currently have so I can keep practicing.

The 0.003 of concavity was measured by placing the vise in the middle of the surface plate, supporting one end with a shim, and walking around the part with a 0.0001" DTI. 

As far as coplanarity, I believe yes the two top rails are coplanar. The bottom is not yet parallel to the top. I started with the bottom hoping that it would be the only surface I needed to scrape, but the top ended up being such a noodle that I had to scrape it flat first in order to be able to measure the parallelism on the bottom. So once I call the top finished, I'll go back and work on the bottom.

Do you have any tips on making smaller scraping tools for fine detail work or dovetails? I can't imagine the Sandvik scraper would easily fit into the tiny dovetails on my mill.


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## Richard King 2 (Apr 1, 2021)

Buy a Dapra 15 - 150 blade. how about showing us the surface just blued and not the magic marker. For practice you could go further on the vise, how about scraping something useful like a straight-edge.   That vise is 10 time better then new


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## macardoso (Apr 1, 2021)

Richard King 2 said:


> Buy a Dapra 15 - 150 blade. how about showing us the surface just blued and not the magic marker. For practice you could go further on the vise, how about scraping something useful like a straight-edge.   That vise is 10 time better then new



I currently have the Sandvik hand scraper, so I'd need to fab something up to hold the blade. Unless you think it is unusable, I was looking for a Sandvik 620-2525 H10 insert (I have a 620-2025 H10, 20mm width, that came with my scraper but I can't find those on eBay). It's also 1/3 the brice of the Biax.

Here are some blued surfaces. I was posting the sharpie versions because I am having a hard time getting a good shot off the blued surface. 

After Highpoint pass #2 



After Pass #3



After Pass #5



Thanks to it being cloudy today, #5 is not super visible, but I feel like it has 25% better coverage than pass #3.

Think I'm about to call the top good and start on the bottom.

Scraping the vise was out of necessity as I could not get good parts made for my steam engine. A straightedge is my next project. I'm having a hard time stomaching the cost of the castings for an 18" camelback. Do you have any thoughts on working on this kind for something as short as 18"

If I can start getting the hang of this I'd like to scrape my G0704. Seems silly for a cheap import machine, but it is what I have and there is a LOT of room to improve it.






						45° Dovetail Straight Edge – Coreprint Castings
					






					coreprintcastings.com


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## Richard King 2 (Apr 1, 2021)

Take a look at  minute 5-17 on this show and see how we "Bump" scrape to get 40 PPI .    I got a bit silly in the beginning as I never thought it was going on You Tube. lol   Bob Goslin one of the scraping host shop owners took some of those 1 x 1 Sanvik blades to a shop with a water jet machine and had it cut in 1/2.


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## macardoso (Apr 5, 2021)

Richard King 2 said:


> Take a look at  minute 5-17 on this show and see how we "Bump" scrape to get 40 PPI .    I got a bit silly in the beginning as I never thought it was going on You Tube. lol   Bob Goslin one of the scraping host shop owners took some of those 1 x 1 Sanvik blades to a shop with a water jet machine and had it cut in 1/2.



Question for you. Is it only about hitting the correct number of high points per inch, or is there also a requirement for the minimum (or maximum) depth of the low points between high points? I guess The reason I am asking is that the bump scraping seems to leave a much deeper scrape (when I tried it) compared to how I was finishing without any instruction as to the right way to do it. I was holding the scraper near the tip and almost rubbing off the high points, removing nearly zero metal in the process. It was a bit slow going for sure, but did get the number of points I was after. As a consequence of that method, the difference between my high spots and low spots is only about a tenth, very flat - maybe too flat.

I could see on a sliding way, maybe the valleys are too shallow to hold sufficient oil? Maybe this wasn't an issue for the semi-static ways on the vise I was working on. The slides on the moving jaw were left much more coarse. Although I think that is what flaking is about right? Rich, I remember seeing a scan of a worksheet you made some time ago that commented on the pattern and depth of scrape marks, but I can't remember for the life of me what was good or bad. 

As a separate question, I haven't found any good videos about hand flaking (either the tool grind or technique). Do you have any references?


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## Richard King 2 (Apr 5, 2021)

You need to check your depth...average it out over the entire surface.  I usually say check 3 places.   I say people need a minimum of .0002" deep and a maximum of .001"  If your were deeper you are pressing down.  You only need to hold the scraper behind the high spot and when bumping the downward hit it cuts.  This technique is only for scraping 30 to 40 PPI.  With that said your using a a 40 radius blade tip ground to a neg. 5 degree for cast iron.  I'm out of the office for a bit.  I only have photo's of the 1/2 mooning.  This week I will take a video from my phone during during this weeks training class.   One of my students in Norway has several you tube shows one shows hand flaking.  search-  Jan Sverre Haugjord -on YouTube....got to go....Rich


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