Ulma Doctor

Infinitely Curious
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Feb 2, 2013
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Hello again,
i started another project that will enable me to do more projects, scraping in a precision straight edge. it's dimensions are 2 9/16" wide x 15" long x 3/4" thick!
the straight edge has a 60* dovetail on one side, for use as a reference when scraping dovetails.

A member, John York, graciously offered me a great deal on a cast iron straight edge blank!!!!
i took him up on it- it really was an excellent deal!!!
i took Richard King's class in oakland in 2013, John was in the class but had been scraping long before i met him.
He's a great guy and has a mind strong as a steel trap !
he really knows his craft and he's a really good man.:)

i did an initial scrape and stoning of the straight edge before putting it on my surface plate to get the initial blue up.

Hand%2BScraping%2Ba%2BSrtaightedge%2B1.jpg

about 10 cycles in...
Hand%2BScraping%2Ba%2BSrtaightedge%2B2.jpg

20 cycles in...
Hand%2BScraping%2Ba%2BSrtaightedge%2B3.jpg
 
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Ulmadoc,
That's great!
I took Kings class Fall 2014.
I picked up a closeout Busch 48inch camelback cheap.
And am looking for a 12-18inch casting that I want to afford.

Is it clear to your readers how you are holding the casting on the bench?
Then sharpening the hand scraper and then how to hold and bump it?

Daryl
MN
 
Looking good! Need to do some more heavy scraping in the middle to get the ends to start showing blue. Then work on getting your point per inch!!!
Not trying to butt in, just trying to help!
 
Hi Daryl,
thanks for reading, always good to hear from you!
Scraping has become more than activity, it has become a passion for me!
I'm still searching for a reasonably priced camelback blank to scrape in.

For this scraping operation, i'm using a giant pair of parallel woodworkers clamps that i purchased at HF with a 20% off super coupon!
thanks Inside Track Club!!!
The parallel clamp is secured to the bench with a large pair of Vise Grip 11R locking clamps,
then the work is secured in the parallel clamp by twisting the adjusting handles.

For sharpening my scrapers, i just recently installed a 6" 100 Grit Green Grinding Wheel on my pedestal grinder (link below):
http://www.hobby-machinist.com/threads/delrin-grinding-wheel-arbor-spacer.34482/

The angle chosen for the grinding of the carbide was 3*- which coincidentally changes when scraping different materials.
i'll mostly scrape cast iron- so the 3* was settled on.

to sharpen the scraper, i'll hold my left index finger on the grinders' tool rest and plop the scraper blade on my finger.
then using a arcing motion on the handle with my right hand, i hinge the blade on my finger. it allows 2 things- control of the force of the blade into the wheel and to make pivoting the blade very precise as well. i'll then hone the blade on a diamond stone to finish.

i hold the hand scraper at about a 30* angle in reference to the work, and the work placed at a 45* angle to me.
during roughing operations the strokes are heavy and long- i put a lot of force to the scraper and cast iron dust flies!
the strokes become shorter and less pressure is applied to the scraper as the work starts flattening out.
when you get to near finishing, the strokes are very minute, a simple bump on the end of the positioned scraper will take a very small fine cut for maximizing points per inch. Arguably, 40 points per inch is excellent scraping- most hand scraping is 20-35 points per inch dependent on purpose and skill of the scraper.

The best analogy i could come up with is that you are basically creating a million small mountains, and knocking their peaks off as to have 20 to 40 mountain tops per inch in the same plane of height.
 
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Looking good! Need to do some more heavy scraping in the middle to get the ends to start showing blue. Then work on getting your point per inch!!!
Not trying to butt in, just trying to help!

Thanks for reading 4gsr, I'm obsessed with scraping now!!!!
the scrapes you see outside the blue was the initial reference scrape, i have been concentrating on the center of the blank.
as you can see the contact is broadening every cycle!!!
thanks for the pointers!
I appreciate the help!:tranquility:
 
Thanks, I don't claim to be an expert as Richard is, but been doing it off and on for many years now. I haven't quite caught on to the "technique" that Richard uses, but I don't do it for a living either! In fact I've gotten spoiled to using the Biax to scrape with that I only hand scrape for areas that the power scraper can't get into and for some heavy scraping. I'm planning on meeting Richard when he comes down to Steve's scraping class near Houston next month for a day or two. My health won't allow me to stand for 8 hours at a time much less three days of it! Main thing is , i like to meet him let us put a name to a face since that is the only contact I've had with him is by email. I have a 3 foot straight edge I've been working on for over a year now. Had rough scraped it in and found out that edges and sides were not parallel to one another. I also stress relieved it with a rubber hammer. So it's back at the shop that did the original machining on it for me. With special instructions on getting it parallel for me. Then I'll go in and finish scrape it. I also have a smaller one I made similar to the one you are making. It's also at the same shop getting some alterations made to it too. When done i'll post some pictures of it.

DSCN2072.JPG DSCN2074.JPG
 
Hi 4gsr,
i love to biax scrape !!!
i have an old one that works great, and another one that needs some motor brushes.
they are great to use and make short work of things, no doubt!
the reason i'm hand scraping this project is to graduate to the next step of hand scraping,
namely performing dovetail scraping operations.
i have an Antique Flather Lathe
( http://www.hobby-machinist.com/threads/antique-flather-lathe-16x36-s-n-270.33911/ )
that is going to be scraped back in, in stages, by hand.
I'm doing it as a tribute to Joeseph Flather and his gifts to modern machining practices and to lathes especially.
seems the least i could do.
 
Yes, scraping dovetails is my weakness, too!

And they are very hard to power scrape. I have some carbide blades ground for my hand scrapers just for doing dovetails with.
 
I admire you guys for the patience, ability and passion (as Ulma Doctor expressed it) required to produce those precision surfaces. I also like the fact that you are all "students" of Richard King, who is one of my heroes. He's a remarkably helpful guy with decades of expertise that he willingly shares ! :)
 
Thank you Randy,
a lot of patience is necessary, it forces one to go at a slower pace since we are literally removing a thousandth or less in a scrape.
there is no way to effectively speed the process, less the introduction of power equipment.
Even then there is a lot of bluing up, measuring, stoning and scraping before the next cycle even begins, so one step only sets up for the next stage.
you can touch and handle a piece you are scraping a thousand times or better to get it to precision level.
i tried to keep track but became easily confused because it was another step i failed to train myself to add to the repartois .
but i assure you that you'll become very intimate with anything you scrape.

i find that knowledge is a thing that is best shared whenever there is an ear to hear it, or eye to read.
 
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