# Learning how to scrape :D



## ttrikalin

If this part of the forum is to strictly to _give advice_ (as on first look it seems), take this as advice on how not to do what I'm just now learning how to do.  

So indulge me mklotz and dsquire - if you will; if anything, the replies I hope to receive would contain some tips and tricks. 

The objective is to try my hand at scraping (I'm already proficient at scrapping, thank you - I can scrap work in more ways than one). 

Now, I have read what I could online and I am still waiting for books and a DVD I ordered last week... but I was never good at waiting and decided to give it a shot. I will make a small height transfer scriber such as the one Lautard describes in his second book. 

The base started it's life as a former flywheel blank. 

It'll get scraped flat. 

I will show you what I have till now, and then will post a video with the sharpening of the scraper...

The diameter of the stock was 2.375", and from flat to flat is is 1.875" if I recall. This is after a few roughing cycles -- I hope this is the correct amount of blue??. Note the surface. Each stroke leaves little lines, and this is because the cutting edge is not smooth. Mental note to show the chips, they are nice and "curly"... pretty thin though... 
IMAGE 1:






This is after an other cycle. Again, just a tad of blue on the surface plate, worked around with the brayer. Would this be flat enuf for a non bearing surface? 4-5 points per square inch? 
IMAGE 2:





This is after a couple of more rounds. I was only cutting the areas with the blue...


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## ttrikalin

This is later still... I am using very little blue... Now I'm trying to divide the large areas while scraping (dunno why, seemed like a good idea...).
IMAGE 3:






And this is where I stopped. I may be messing it I think, so better stop now... 
IMAGE 4:





Studying IMAGE 4, I see that the blue parts are almost colorless in the middle. This is probably the very apex of the high spot. I therefore should go on and scrape these apexes down to get a better surface. Whould this density be OK for, e.g., a sliding bearing surface? I count 15-20 apexes (white spots with a blue halo) per square inch on average)... This is a closeup... 
IMAGE 5:


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## ttrikalin

Questions in search for answers... 

1. In all the images you can see the marks left by my scraper... they are not a nice surface -- you can see lines... even after honing with a diamond plate... I take it that I have not honed enough?

2. I see a lot of colored (bearing) points in the periphery of the part (IMAGE 4, IMAGE 5). This should not happen, right? 

3. I did not follow any pattern while scraping, just cut the blue parts from the same angle (45 degrees give or take many)... 

4. I do have difficulties in hitting the apexes in IMAGES 3, 4 and 5... I am using a 1" rigid blade... I think I could make a smaller one, but I am afraid that I would gouge the surface with a smaller one... Are you supposed to change tools as you proceed? 

more to come... 

take care, 
tom in MA


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## ttrikalin

ttrikalin  said:
			
		

> more to come...



questions I meant... 8)


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## ttrikalin

and this video shows how I went about the following tasks:
_________________________________________________
1. grinding the scraper:      00:00:00
_________________________________________________
2. honing the scraper:       00:02:24
_________________________________________________
3. preparing the surface plate:  00:03:22
_________________________________________________
4. touching the part:         00:03:50
_________________________________________________
5. some scraping of the part:   00:04:07

Getting comments on things I do wrong is why I post this thread ;D. 

[ame]http://www.youtube.com/watch?v=kMfYAGiI7Ns[/ame]

take care, 
tom in MA


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## pete

Tom,
I don't have any experience with scrapeing so I sure can't answer any of your questions. However for scrapeing on machine tools I'd have to highly recommend "Machine Tool Reconditioning" if you don't already have it. Yeah it's expensive at almost $100 but it's more than worth it. IMO it would be a requirement. You could scrape things in perfectly flat yet still make the tool far worse for true alignment.

Pete


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## tel

I have only very limited experience with scaping, and that looks to be coming along ok, but this bit concerns me;


> I was only cutting the areas with the blue..



... do you mean deliberately? You have to remember that the blue is a negative image of the job, and the high spots are those where the blue has been removed. Cutting away at the blue areas will only serve to dig holes!


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## Florian

Tel

That would be so if you put the color on the workpiece. 
But if you put some color on the touching plate, you will have to scrap away the blue spots! 

Tom: 

You apply too much pressure when grinding the scraper and aswell when honing it! 
-> is that a HSS or a carbide blade? I Assume its a HSS..? (-> different ways of grinding it!) 

You should try to apply very few pressure then you will find out that the ground surface will have a better finish!
To hone the blade should be done with a silicium-carbide (or similar) hone. Diamond is only good when using a carbide blade!

When honing, only few pressure is required. 
And you should rotate the honing file against the radius and not with it (as if you would like to grind a sphere on the opposite side of the blade -> did you understand what i mean? if not, i will look for a movie or make a drawing...) 


For fine scraping (like you show on the movie) i hold the scraper with my left hand nearest possiple to the blade. 
The other hand is directly behind the left hand. 
With the left hand I apply pressure towards the durface and control the conctact point of the blade to the workpiece. With the right hand i move the blade. 

When rough scrapping, The left hand only applies pressure on the scraper and the right hand either controls the contact point and moves the scraper. 

I'll see if I can make a movie from my scraping work so you can see how I do it...

Cheers Florian


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## steamer

Hi Tom,

The bench grinder is OK for roughing out the blade, but it should be honed after. The proper way to hone it would be to stand the scraper on end on an arkansas stone and draw it toward you across the blade while pivoting it to follow the curve of the blade ( in a direction across the end of the blade) 

7 degrees is a good angle for me...it depends somewhat on what your work piece is.

Then lay the end of the blade flat on the stone and rock the blade back and forth along the flat side of the blade. The goal is to get a polished surface on both edges....it will cut noticably better if you do this.

Your first cuts or roughing out, from what I am seeing looks OK.  It will take many passes. After each pass, cross your cuts.  That means approach the next cut of the surface at an angle to the first cut.  If you do two cuts per pass , cut at 90 angles.  If three cuts, cut at 60 degree angles...approximately. If you don't, you will get chatter, which seems evident in the photo you took.

The gray area in the middle with marking compound surrounding is called a "bullseye" and is exactly what you think it is.


Dave


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## tel

Fair enough! I've only ever done with the blue directly applied.


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## steamer

The first photo looks like the surface has "carried". As I understand it, that means you have spots evenly distributed over the whole surface....no bare areas which would be low in this case.

Notice I said evenly. If you had a very high concentration of spots in the middle of that disk, I would say you have false spotting and the center is high. In that case I would make a couple of passes only on the center and get the part to bear on the periphery.  Otherwise it is just a see saw and will give you false spots when you marking and will never progress to full bearing or be "unstable".

Keep going which what your have and remember to cross your cuts...and hone that blade! ;D

I eagerly await more information from our membership...I hope to learn what I'm doing wrong also!

Dave


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## steamer

the honing stuff is in the book your getting by the way.

Dave


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## rake60

I crashed a big machine at work one time.
We're talking major damage! 

The company decided to have the machine totally refurbished
while the damage I had caused was being repaired.

One of the repair companies technicians did nothing but scrape ways.
He used a a reciprocating pneumatic tool with a replaceable carbide
on it to quickly work over the surfaces of the ways.

I asked him if I could try it and he handed me the scraper.
After just a few seconds he took the scraper away from me and said,
"don't worry I can fix that".

I thought I was doing OK.  :

Rick


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## steamer

That would be a "Biax" power scraper made by the Dapra Corporation.

Great tool if you do this alot.....Rebuilding a big machine would be one of those cases..

Dave


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## steamer

"Dividing up the large area's " is called breaking up the surface....and it is a good idea... ;D

Dave


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## steamer

Florian just sent me this.

Hey Dave

I have just a moment ago discovered a Movie where a guy uses pulling-scrapers...: 

[youtube=425,350][/youtube]http://www.youtube.com/watch?v=TFCVO0fXW1k&feature=player_embedded

Was also very interesting for me! 

Cheers Florian 

Its called "pull scraping...and is just another way to do it.

Apparently very Swiss!

Dave


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## ttrikalin

Florian  said:
			
		

> You apply too much pressure when grinding the scraper and aswell when honing it!
> -> is that a HSS or a carbide blade? I Assume its a HSS..? (-> different ways of grinding it!)
> 
> You should try to apply very few pressure then you will find out that the ground surface will have a better finish!
> To hone the blade should be done with a silicium-carbide (or similar) hone. Diamond is only good when using a carbide blade!
> 
> When honing, only few pressure is required.
> And you should rotate the honing file against the radius and not with it (as if you would like to grind a sphere on the opposite side of the blade -> did you understand what i mean? if not, i will look for a movie or make a drawing...)



Florian, thank you -- such are exactly the pointers I was hoping to get. 

Based what you say and what Dave wrote, I reground the scraper and honed it carefully and softly on a stone (not an arkansas stone, but not a diamond lap  this time). I think I understand how to hold it to hone it, but I'll shoot a video and upload on wednesday or thursday (have a business trip coming...).

And yes, any video instructions welcome... ;D 

Nevertheless, I'll be posting what I do...

So gents and ladies (if any), 
"I'm listening..."

t


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## ttrikalin

ttrikalin  said:
			
		

> "I'm listening..."



Yes, I'm watching Frasier on Netflix... 

take care,
tom in MA


PS. Sounds pretty pathetic my friends say, but I do like Frasier...


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## chuck foster

great..................just great.............thanks tom now another thing i just gotta try and learn........... :big: :bow:

i have been readin and watchin you and dave and it looks very interesting............please keep us posted with what you have learned.

thanks guy's

chuck


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## ttrikalin

tel  said:
			
		

> I have only very limited experience with scaping, and that looks to be coming along ok, but this bit concerns me;
> ... do you mean deliberately? You have to remember that the blue is a negative image of the job, and the high spots are those where the blue has been removed. Cutting away at the blue areas will only serve to dig holes!




Tel, 
what Florian said, I put the blue on the surface plate... 

Pete





			
				pete  said:
			
		

> However for scrapeing on machine tools I'd have to highly recommend "Machine Tool Reconditioning" if you don't already have it.



Yep, I got meself a copy of Conelly's book... Pretty nice read I may say... Dave commented it's a tad thin on instruction, but good on procedure... So I ordered a more instructional book... Will post a review 1 day after I get it (I'll surely read it in one swoop). 

take care, 

tom in MA


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## ttrikalin

chuck foster  said:
			
		

> great..................just great.............thanks tom now another thing i just gotta try and learn...



hahahaha, :big: :big:

My wife is totally baffled with this latest scraping thingy. :big: :big:

Wonder if she'll post anything... ;D

tom


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## steamer

Tom,

Found this over at Practical....cool link 

http://www.scribd.com/doc/15780677/Scraping-03

Dave


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## steamer

"...My wife is totally baffled with this latest scraping thingy.  "





Oh and tell your wife it's a fatal disease and there is no known cure...

 ;D

Dave


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## ttrikalin

Your graces,

I would like to make a straight edge at least 4 feet long... I have no blank castings... And I do not plan to buy any.

A McGyver moment: 
I could make a long straight edge using an aluminium 48" carpenters level. On amazon, three of these are ~$30-35. Yes, aluminium is easy to mar but with careful handling they would hold for the odd spotting job... 

Why 3? You need 3 blanks to "automatically" scrape them as straight edges of master quality... You use one as a temporary reference to spot and scrape the other two; and then you take the next as reference and so on.
Conelly describes the process in his book. Lautard also. 

Thoughts? 

take care, 
tom in MA


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## Florian

Id say its not a very good idea... 

Aluminum is so soft and it will evenutally change shape when it gets warm. (at least more than cast Iron) 


Cheers Florian
ps: I think you can buy unmachined castings for straight edges...


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## AlasdairM

A link to a possibly useful .pdf (with illustrations) in case anyone's not seen it yet - "Scraping - why and how" by Ron Gerlach - http://www.schsm.org/SCRAPING.pdf.

Regards, A


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## purpleknif

Been scraping machine tools for a lot of years. Getting it flat is easy. Getting it square & parallel is the trick. If you're just looking for a straight surface why not just fly cut it? That's usually the first step to scraping anyway.


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## steamer

I'm with Florian here. If your going to
and a reference. I would do it right

Hi purleknife
Agree , flat is the place to start and its more difficult from there
my old mill will only do so much, so as part of a lathe rebuild, I have to do the rest
I believe the point of the thread was to investigate the process. I don't think anyone is going to change their current jobs,but would like to understand and add to the experience base.

Feel free to offer some pointers! 


 ;D

Dave


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## ttrikalin

Florian  said:
			
		

> Id say its not a very good idea...
> Aluminum is so soft and it will evenutally change shape when it gets warm. (at least more than cast Iron)





			
				steamer  said:
			
		

> I'm with Florian here.



I here ya... so I drop this half-a$$3d plan. :big: :big:

take care, 
tom in mA


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## ttrikalin

purpleknif  said:
			
		

> Been scraping machine tools for a lot of years. Getting it flat is easy. Getting it square & parallel is the trick. If you're just looking for a straight surface why not just fly cut it? That's usually the first step to scraping anyway.



I do take your word re: aligning, I do see the difficulties of aligning stuff correctly. Tin Falcon said the same, I believe... And as Dave said, any pointers very very very welcome 

take care, 

tom in MA


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## ttrikalin

AlasdairM  said:
			
		

> A link to a possibly useful .pdf (with illustrations) in case anyone's not seen it yet - "Scraping - why and how" by Ron Gerlach - http://www.schsm.org/SCRAPING.pdf.



Karma to you -- very nice! -- had not seen that before.

tom


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## Maryak

ttrikalin  said:
			
		

> Why 3? You need 3 blanks to "automatically" scrape them as straight edges of master quality... You use one as a temporary reference to spot and scrape the other two; and then you take the next as reference and so on.
> Conelly describes the process in his book. Lautard also.



As others have said Al is too thermally unstable and soft. 3 pieces of cast iron say 4" x 4" x 2." Stable and big enough to be useful, especially if you screw in a couple of handles opposite on the 2" sides. Way back when, we worked in teams of three to make 12" x 12" surface plates from castings. The good bit was when yours was the reference plate. 

Best Regards
Bob


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## ttrikalin

Maryak  said:
			
		

> The good bit was when yours was the reference plate.



Nice.


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## ttrikalin

OK, I received the book and DVD from Michael Moore's machinerepair.com. Well written book, concise and to the point. Good schematics, clear photographs, crisp descriptions. Clarified a lot of things for me. 

That being said, Connely's Machine tool reconditioning is a must read, for me at least. Connely goes into details of how and why much more than Moore does. And Connely really discusses alignment, especially after chapter 22. This is not to pick on Moore, his book is excellent and perfectly fits its description. 

I also saw the instructional videos by Moore, and I liked them a lot. He is a good teacher, and the scripting of the video is very well thought out. (those who have seen the otherwise wonderful videos by Jose on, say, milling, will get what I mean ;D ;D )

Honestly, the Moore DVD and book is a purchase I was very very happy I did.  He does document the scraping process very well.



take care, 
tom in MA


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## steamer

Hi Tom,

I'm glad you like the book. My recommendation for the book was based on the "nuts and bolts" of actually scraping.
For the measurement procedures and logic, Connelly is the way to go.  The two books do really compliment eachother.

Making a bit more progress on the SB Here's a link to my latest scraping effort.

http://www.homemodelenginemachinist.com/index.php?topic=14436.225

Dave


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## purpleknif

steamer  said:
			
		

> I'm with Florian here. If your going to
> and a reference. I would do it right
> 
> Hi purleknife
> Agree , flat is the place to start and its more difficult from there
> my old mill will only do so much, so as part of a lathe rebuild, I have to do the rest
> I believe the point of the thread was to investigate the process. I don't think anyone is going to change their current jobs,but would like to understand and add to the experience base.
> 
> Feel free to offer some pointers!
> 
> 
> ;D
> 
> Dave



 Well, as far as pointers go, you got the book so that's a good start. I learned on the job from an old Russian guy who didn't speak a whole lot of English. Maybe by choice for all I know.

 As far as scraping aluminum, that's tough. Its too soft to get much "feel". I would suggest a piece if cast iron to start on. BTW 16 contact pts per sq. in. is considered flat.

 Feel free to ask questions and I'll try to answer them.


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## steamer

Thanks Purpleknife!

Dave


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## TroyO

I'd like to try my hand at this scraping thing. (I am also plenty profficient at srapping... I do THAT all the time, LOL)

I have a couple of questions and am hoping it's OK if I "hijack" this thread since it's pretty much the same topic.

I did a little of this with some ground out files and the crudest possible methods in order to salvage the table on my Mini-Mill, but I would like to take a slightly more official approach this go-round. (Hey, it did work but using granite countertop, magic marker and a hacked up file is not really the right way, LOL.)

Top questions... I would like to make a reference of a good size to use on small benchtop type machines, and with a dovetail angle to match. Can I make it from steel or must it be cast iron? I'm thinking 1.5"x3"x8" as a roundabout figure and I have steel on hand... I would have to order a cast blank and it would be ~$60. Shape wise I am envisioning something like the attached pic, found on Ebay.

Next, does anyone have supplier reccomendations? Searching for scrapers at my usual places doesn't seem to look like the kind of scraper I want to get. And I using the wrong terms? I have been searching for "Hand scrapers" and "Machine scrapers" and I get everything from tools for scraping out caulk to gasket scrapers.

Thanks!
Troy


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## ttrikalin

well, you most definitely are not hijacking the thread ;D

I think that steel would work -- just more difficult to scrape compared to cast iron. I read cast iron is stable, but heck, dunno how bad steel would be, especially when one cheks it all the time on the surface plate, one would catch any warping... 

Florian and dave and other knowledgeable peolpe, please chime in.

tom in MA


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## TroyO

I plan to expirement with it unless an experienced voice shows up and says "it just plain won't work because _____________".

I was also toying with the idea of using one of those vibrating multi-master type tools with a brazed on HSS or carbide scraper tip on a blade.... I bet it would scrape and its a little more approachable than a Biax.

http://www.harborfreight.com/variable-speed-multifunction-power-tool-67537.html


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## purpleknif

TroyO  said:
			
		

> I plan to expirement with it unless an experienced voice shows up and says "it just plain won't work because _____________".
> 
> I was also toying with the idea of using one of those vibrating multi-master type tools with a brazed on HSS or carbide scraper tip on a blade.... I bet it would scrape and its a little more approachable than a Biax.
> 
> http://www.harborfreight.com/variable-speed-multifunction-power-tool-67537.html


I think you'd be wasting your money as far as using it for scraping goes. Awfully fast and a really short stroke. Just my .02. Yes, bi-ax scrapers are nice ( especially the flaker) but unless you're doing a machine Bridgeport size or larger I'd say spend the money on something like tooling or a couple cases of beer.


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## steamer

Im with Purpleknife...I think that will just turn into something that isn't very controlable.

JMHO

Dave


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## Florian

Hi Troy

If you want to use an available tool, you may use a tiger saw. I have seen a conversion with a tiger saw some time ago but i cant remeber where it was. 
Fact is it seemd to work pretty well. And if I remember right, that guy modified the drive gear so the stroke was reduced to something around 5mm. 

But it still will have some disadvantages compared to a biax which has adjustable cutting stroke, adjustable speed (though some tigersaws will have this feature as well) and finally its the shape of the machine which is best suitable for scraping. (unlike the one of a tigersaw) 

I don't know where you have been looking for scrapers but you may search for "Hand scraper". 
I found this: 
www.dapra.com/
http://www.machinerepair.com/
http://www.machinerepair.com/size.html (good to know when starting) 


Oh and by the Way:
You can make your reference from steel but it will be horrible to scrap because the blade will kind of stick to the material. If I remember correctly it is better to use HSS for scraping steel and carbide when scraping cast iron. 
Also the angle of the blade has a great influence on how well you can scrap the workpiece. 
I have just looked up in a document from a BIAX, and they say for steel scraping you need 32° scraping angle. 
This means if you have a blade with a front face which is rectangular to the top and bottom face, the front face will have to be tilted for 32°. And if the Angle is positive, you have to use the side of the blade with the smaller "wedge angle" (when comparing with lathe tools). 
If the Angle is negative (and that is usual when scraping cast iron, mostly somehting around 3 to 7° though you start with 3° negative and for finishing you increase the angle) you will have to use the edge with the greater "wedge angle". 


Cheers Florian


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## vedoula

Florian  said:
			
		

> If you want to use an available tool, you may use a tiger saw.



do you mean a reciprocating saw?


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## Florian

Yes, ecactly 
I only know it as a "Tiger Saw" 8)

Cheers Florian


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## steamer

I have a variable speed "Tiger Saw" which IIRC is a Porter Cable product.

Though I've used it to rip through all kinds of things with a wrecking blade, but IMHO, it is far too unwieldly to be used for scraping....at least finish scraping.

 I suppose If I had to take off .020" by hand...well I might give it a look though.  Then again a disk sander may work even better in that application....or just machine it.

Dave


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## Florian

Well, I found a movie about it: 

[ame]http://www.youtube.com/watch?v=bJPS9SWn6Ys[/ame]

(Tiger saw with shortened stroke) 

And also a conversion Thread: http://www.machinistweb.com/forum/showthread.php?t=501

Cheers Florian


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## steamer

Well, can't argue with that. :bow:  If your shorten the stroke, it does seem controllable.....but it's a heavy saw.

Dave


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## ttrikalin

i have a horrible fright "tiger saw" that broke the second day I used it... Never returned it though... So this may be a good salvage use for it. 

take care, 
tom in MA


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## lee9966

I can't picture holding my big powerful tiger saw that steady, are there different sizes of the saw?

Lee


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## steamer

My reservation is based on the fact that my 120V, 15 amp saw would have no problem cutting my pickup truck In half with a rescue blade. Its not exactly subtle.....even with the stroke shortened its got to be the better part of 20 pounds

Dave


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## vedoula

steamer  said:
			
		

> My reservation is based on the fact that my 120V, 15 amp saw would have no problem cutting my pickup truck In half with a rescue blade. Its not exactly subtle.....even with the stroke shortened its got to be the better part of 20 pounds
> 
> Dave



probably not an HF unit then... Makita?

[tom from anastasia'a account]


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## TroyO

Santa didn't leave me enough for a set of the long handle scrapers AND a chunk of cast, so I am comprimising somewhat.

Current plan.... make my own long scrapers and buy a set of the cheap scrapers with short handles.

(These guys .. http://www.grizzly.com/products/3-Pc-Machinist-s-Scraper-Set/T10086 )

I've got some 1/2x1/2x3/16 carbide blanks and misc HSS to play with, I think I can knock up some effective scrapers with what I have on hand.

So, the extra can go towards getting a decent chunk of cast to work with(1.5x3.25x12")


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## steamer

Hi Tom,

My saw is a Porter Cable "Tiger Saw".

Dave


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## Florian

TroyO  said:
			
		

> ... buy a set of the cheap scrapers with short handles.



These short scrapers are not good for scraping, it is very tiring to work with such small scrapers. 
Well, the three corner and curved scraper can be used for some work like deburring holes and scraping in bearings (bronze-bearings) but the flat scraper is only suitable for removing color (and other dirt) from straight surfaces...

So you better get yourself a diamond grinding wheel to sharpen your scraper properly. 
(-> RDG Tools has cheap ones...) 

Cheers Florian


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## TroyO

I've got one of these to grind with...
http://www.harborfreight.com/1-2-half-hp-6-inch-tool-grinder-46727.html

I like it so far but have been grinding HSS on white wheels. I'll have to put the green ones back on and final lap on diamond hones by hand. I'm going to try with what I have and see how it goes. A diamond cup to fit the grinder probably wouldn't be a bad idea anyway, but money is short at the moment.

I was thinking of the short scrapers more as "Nook and cranny" tools and the long ones as the grunt work/heavy guns.

I dunno... worst case I waste some material that I already had and learn something or best case I end up with a good tool and learn something.

I'll post up pics of what I end up with... for better or worse. ;-)


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## steamer

steamer  said:
			
		

> Hi Tom,
> 
> My saw is a Porter Cable "Tiger Saw".
> 
> Dave




OK went out and inspected my saw. Its a Porter Cable model 737. It draws 10A....not 15...

Its more like 10 pounds....and I still think it'll rip your arm off if given half a chance..... :

Dave


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## Florian

TroyO  said:
			
		

> I'll have to put the green ones back on and final lap on diamond hones by hand. I'm going to try with what I have and see how it goes. A diamond cup to fit the grinder probably wouldn't be a bad idea anyway, but money is short at the moment.



Hi Troy

Well, the green wheels are ok for bringing the blade into shape but not for sharpening. I had to find this out aswell when I started with scraping. 

The Wheels provided by RDG are very cheap but really worth their money! I have the small 50mm one and it did only cost me around 20$! 

The greatest discs cost about 25 to 30 $ and so are still very cheap and though they are cheap, they last quite long (I cant see any loss of diamond on my disc actually tough I am using it alot!)

Cheers Florian


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## TroyO

Ohh, I'm not saying I won't try and get a diamond wheel soon (ish). Right now, no money... maybe next month LOL.

But, I may be out of the woods on that one... I read about someone using a lapping plate with a diamond buffing compound on it to put the final sharpen on carbide bits. The idea that the wheel made of something softer than diamond (easy, LOL) and carbide (Still easy) gets the diamond particles embedded in it.

In his case he was using a wheel made of iron, but aluminium is supposed to work just as well. Dope it up with diamond compound and you can get a razor sharp edge. (In theory).

I happen to have diamond compound already from my knife making days.. old but hopefully still good.

Maybe this weekend I can get started on some of this.

I did realize that I *may* have a source for some cast iron hunks... old window sash weights. 

I may try to salvage some of it... if only for practice surfaces as I realize it's pretty much the crudest cast iron you can get.


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## TroyO

I have seen a few examples of folks using squashed conduit and shoving a carbide insert into it and silver soldering it in place as scrapers. After sharpening it seems like it would work just fine.

I plan to do similar, brazing on to 1/8" flat stock instead because it's what I have on hand.

It just occured to me that I have MILES of material for practice scraping.... there's the drill press table, the back stop part on my jointer, the small drill press that wants to become a tapping stand's table, the jointer bed, heck my table saw top for that matter, etc etc. All kinds of of "Sure you want it kinda flat" cast iron that I can turn in to precision scraped practice pieces while being fairly confident that I'm not going to make it any worse, anyway.

So, yet again the window sash weights I was SURE I would use for something will lie there slowly turning back in to dust... LOL

(Almost forgot to add.... great scraping vid on Youtube... NOT MINE) 
[ame]http://www.youtube.com/watch?v=D1eOQa1gYiU[/ame]


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## purpleknif

Even the Bi-ax scrapes are pretty heavy.


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## TroyO

Some info that may be of use...

SmartFlix has the Hand Scraping DVD as a rental for $10. (You will note, I rented mine before announcing this just in case there is only one copy, LOL. ;-)

www.smartflix.com


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## TroyO

OK, I have the scraping vid on the way and I just looked in my back issues of "The Home Shop Machinist". Sure enough, as I "kinda rememebered" there is a 3 part article starting with the May/June issue about scraping. Unfortunatley I have May/June and Sept/Oct but not the one in between. So, I ordered it from Village press... a whopping $6.

By the way, so far:
May/June:
Basic scraping proceedure and getting stuff flat.

July/Aug:
???????? I *think* this will be about referencing surfaces to each other and scraping to refine alignment?

Sept/Oct:
All about making home made scrapers.

A very good read so far and great pics.... kudo's to Michael Ward, the author!

In further news, I made my first crack at some carbide tipped scrapers with what was on hand... the wide one is about an inch, the smaller one about .7" The carbide on the small one was .5x.5x.187 turned on it's diamond angle to get a little more width.

The wide one was a carbide paint scraper blade refill from Home Depot for like $5

(PS.. no laughing at my crap brazing, LOL... my MAPP/Oxy torch just barellllly melts it, LOL!)

(Not sure why, it keeps saying I already posted this message but it doesn't show up. So, appologies if I actually do end up double posting, but I think it never took the first one but now thinks it's a dupe anyway)


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## steamer

Michael Ward has published another article on scraping in HSM.  I've read through it , It is very informative, and he takes you through the basics of some projects.

I wish he spent a bit of time on step scraping..  I think the person starting out would need to understand that technique.
But all in all a very informative article. Well worth the read and the cover price.

Dave


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## TroyO

So far, there has been a fair amount of information... and some portion of it is actually about scraping but quite a bit centers on making the scrapers. (And on making the tools to make the scrapers.)

I wish (And maybe the 6th and later articles will get there) that more of it was about things like how to make sure one surface is paralell or square or at the appropriate angle to another etc, and how to change from just scraping to "flat" to change that relation between two faces and so on.

For my part... made up some scrapers, made a "Lap" using an old step pulley attached to a spare motor and filed to run true then doped with some diamond compound. So, I'm good on basic tooling. 

I have my large blank faced on one side and will start scraping it in but still have some other pressing stuff ahead of that project.

I will get the latest edition, just need to find who in my area still sells it, I still read... well, anything I can find. 

It will get there... someday, LOL.


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## steamer

Hi TroyO

Yeah this one has a bit more "meat" to it.

Dave


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## zeeprogrammer

Thanks for starting this thread Tom.
I always appreciate seeing videos of basics in prepping tools...not just using them.
I have that same grinder and just seeing how you dressed it was useful.
And thanks to everyone who contributed to this.

I've known about scraping machine beds by hand when you can't use a large power tool. But a couple of questions...

Someone mentioned flycutting as a preliminary step in scraping a small part.
Why isn't that sufficient? I suspect that polishing afterwards leaves dips?

After scraping that base is there additional finishing work?


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## Florian

After scraping, you're done! (except if you want to make some lubrication grooves; Its far easier to first scrape and afterwards make grooves than the other way round!) 

If you had a High precision machine which can mill large surfaces within 0.005 mm, then you may be happy with fly cut guide-ways. 
But if your axis is slightly concave, the guide will stick on the ends while in the middle there may be too much play. 

When scraping, you can easily remove all the high spots and then you get an almost perfect surface. 
But a scraped surface isnt totally plain, instead it is very little dimpeled. And that is even better than a perfect surface because it reduces slip-stick and also keeps the oil better than a perfectly even surface. 

Cheers Florian


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## zeeprogrammer

Thanks! And thanks for the point about oil and slip-stick.


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## purpleknif

After scraping and getting everything right comes "flaking". This is to provide space for the oil and to prevent "wringing". There is a Bi-ax scraper made for this op too. Takes quite a bit of practice to do this by hand.


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## steamer

Another way is to bump scrape.  No quite as technical but still tricky to do consistently.

Dave


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