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Carbide Scraper-Deburr Tool

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These are directions for how to build a simple Carbide Deburring Knife...
 I did this build at The TechShop in San Jose California...
http://techshop.ws/
 Gabriel Aceves
 
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Step 1: Materials...

Picture of Materials...
Ok we are going to need, 6inch length of 1/4 alluminum rod,
 1/8 inch carbide shank ( I used a
 broken .125 endmill), .120 inch drill, .124 inch reamer,
Grinder capable of grinding carbide

Step 2: Step One.. Facing front edge...

Picture of Step One.. Facing front edge...
Ok, Now we are going to face the ends  of our piece so that it is
square and flat...   Chuck up on your part and face of the front using a
 metal lathe....

Step 3: Step Two.. Spotting hole location...

Picture of Step Two..  Spotting hole location...
Now we are going to spot our hole that we are going to put in the end of our part...
 Using a center drill spot the hole so that the chamfer is slightly larger then
 the size of the shaft of the carbide rod...

Step 4: Step Three... Drilling pilot hole..

Picture of Step Three...  Drilling pilot hole..
So now we are going to Drill the pilot hole for our
 reamer to follow with a .120 size drill....  It is very important that your
 hole diameter is no larger then .125...  Otherwise your carbide
 rod will slide and fall out instead of pressing in...  So you are going to want to
drill your hole about 1/2 of an inch deep...

Step 5: Step Five... Reaming your hole...

Picture of Step Five...  Reaming your hole...
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Now you are going to ream your hole out using a .1245 reamer...
 Use care that you get a good hole that is not to large so your rod
 does not fall out...   If your hole is slightly to large you can
 compress the side of your peice to make yor hole slightly
 oblong and your rod may then press in...  but this is less then
 ideal and may lead to failure later...
ironsmiter2 years ago
Since you have the vice already... use it to PRESS in the press fit carbide piece.

provided it can open up far enough


Or, even better, since you used the lathe...
put the carbide in the drill chuck of the tail stock, the handle in the headstock chuck. and use the tailstock advance wheel to press the piece in.

One advantage is, you don't actually need to remove the handle after it's drilling operation. Once drilling is done, you can either ream in place, or, if your drill happens to be sharpened a little off, it probably drilled a bit over sized.
As long as you are close to .0005 under sized, you should be able to make the press fit without trouble.
Even if you end up drilling .001 or .002 under size, there is a trick that doesn't require a reamer.
Heat the snot out of the aluminum handle with a propane torch. You can actually do this right in the 3-jaw chuck. If you're careful, and don't have oil all over the work/chuck/lathe.
The expansion from the heat will open that hole right up a couple ten thousandths. As long as you're quick with removing the heat, and pressing the carbide. I suggest a second set of hands, and a "Three. Two. One. GO!"

For the math fanatics... Aluminum is right near 13 microinch/(in*degreeF).
That makes close to .0005 extra clearance with a "safe" 350F temperature change. You could push as high as 1000F(1.5 thou expansion). but that'd be getting pretty near melting temperature.You'd be just as likely to before your handle, as get a good press fit.

And here come the shocker of all that mumbo jumbo.

Given how soft aluminum is, and a good rigid lathe like you have(no desktop models for THIS job)... you should be able to do the press without even reaming.
I've done .125 steel dowels into .120 holes quite a few times in brass, aluminum, and even silver. A good straight lineup, and a chamfered edge on the piece being pressed in is essential. Other than that, it's just a little muscle. And best to press it all the way in one turn of the wheel.

Sure, .005 is a LOT tighter than .0005, but you're not going to be taking this apart anytime soon, right? :-)
oops. forgot to say how I did it...

Drill press, and a clamped vise.
Once the hole is drilled and cleaned, I put a TINY chamfer(.005? just "a kiss") on it using a center-drill.
then switch the drill out for the thing to be pressed.
Crank down on the handle, and press fit in no-time flat.
Bongmaster2 years ago
neat :)

tho its 'until' not intell ;)
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