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View Full Version : Square corners/Scraping.



Black_Moons
03-11-2010, 09:24 PM
Hmm, todays intresting learning lesson.. Tryed to make some square inside corners along a long peice of steel, thought my endmill did'nt have a corner radius.. but of course it does after inspecting the cut it made. Looked at my files.. Kinda square but not 100% square... still a little radius.
then I saw a blank HSS bit... Hmm, thats square! now.. how to use it? Hmmm Well, the quill shaper method might work but I don't really like abusing my mill like that.

So I just started pushing it by hand into the work.. and suprise suprise, it actualy cut. Supriseingly well, I think I might even make some kinda handle to hold a bit securely for this in the future. Sorta a single tooth file.
with little rake it just made nice little shavings.. Did kinda have a tendency to 'dig' in sometimes but with a little more skill/pratice, or a better grind or something... Took wayy less effort then I thought it would, and that was without even sharpening the HSS blank!

On a somewhat related note, I also tryed using a HSS blank by hand to radius some corners on my lathe in plastic, it also worked supriseingly well as long as I kept a neutral or negative rake. I should really read about wood lathe work before I do something stupid....

Must make a blank holding handle...

vpt
03-11-2010, 09:28 PM
Sounds like an idea!

allthumbs9
03-11-2010, 10:14 PM
Black Moons,

It sounds to me that you have stumbled on to the basis for 'gravers'. Bill Smith, the clock maker has a video on making and using gravers on the lathe. Without going into detail, it is a hss lathe tool mounted in a handle, and used much like a woodturner would do. He grinds them, but just for fun i tried using one blank, and it worked. Man, I love this stuff!

I like the idea of using it away from the lathe, as a bench hand tool. I hadn't thought of that angle.

allthumbs9

darryl
03-11-2010, 11:24 PM
I've often though of making a tool of some sort to 'work' the corners where a true full corner is needed. I usually use a scraper which I've made from some heavy duty bandsaw blade material, with the end ground to less than 90 degrees. I'll have to look into gravers- probably some good ideas there.

Mcgyver
03-12-2010, 12:26 AM
Connelly recommends, and I've used, square end scrapers for getting into corners such as box ways. In my case it was a vise. In general though, a sharp interior corner is not desired from a strength standpoint....the sharper it is the more a stress raiser it is. Better to have a rounded corner and bevel the mating piece

Rich Carlstedt
03-12-2010, 12:27 AM
Yes, square HSS blanks make wonderful gravers or flat scrapers, file handles work well, and so does a pair of Vice-grips when holding a special angle.

Here are two tools I made for square corners.
Photo number 1
A broken tap as a square corner broach , and a HSS tool bit mounted in a flycutter but used as a offset square corner shaping tool.
Both are use in the Bridgeport (no power !)
Photo number 2
The broach is squaring up the bearing cap mount.
note that the semi round milled pocket is being squared , leaving two vertical keys for a bearing cap to drop in.
The part is upside down during this work
Photo number 3
Here the offset tool is vertically digging into the to make the box square
Photo number 4
The very center of this photo shows the finished box with square internal corners. This is a one piece frame, and the only way to get inside the boxed area is with offset broaching
I roughed the area with a woodruff key cutter first. ( see radius corners in # 3)
Rich

http://i273.photobucket.com/albums/jj220/StationarySteam/Shop%20Tools/BroachingTools.jpg
http://i273.photobucket.com/albums/jj220/StationarySteam/Shop%20Tools/MiddleBearingShaping2.jpg
http://i273.photobucket.com/albums/jj220/StationarySteam/Shop%20Tools/OffsetBroachingMonitor-1.jpg
http://i273.photobucket.com/albums/jj220/StationarySteam/monitor1203.jpg

Black_Moons
03-12-2010, 01:17 AM
Rich Carlstedt: Awsome pictures and setups. thanks.

Reading about gravers was quite intresting thanks for the tip. Seems they are mainly used on wood but no reason they can't be used on a mill (as a shaper setup) or even by hand, or on the lathe.. the diffrent profiles are quite intresting.

http://www.ganoksin.com/borisat/nenam/engraving-10-4.htm

Page with some common graver shapes.. mmm.