Learning how to scrape :D
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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
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
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...
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...
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
Regards, A
purpleknif
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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'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
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
purpleknif said:
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
Maryak
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ttrikalin said:
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
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
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
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
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
purpleknif
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steamer said:
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.
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
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
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
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
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 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
