Carbide Scraper-Deburr Tool

by gaceves009

5.7K113

Intro: Carbide Scraper-Deburr Tool

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

STEP 1: 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...

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...

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..

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...

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...

STEP 6: Step Six... Pressing Your Carbide Rod Into Place...

So now you are going to press your carbide rod into
the aluminum rod... Clamp the aluminum into a vise
using something to protect the side if you do not want your aluminum
to get marred by the vise... Now hold the carbide in posisition and gently tap
using wood or some other soft material... Be careful because carbide is
brittle and may shatter if hit with steel or just hit to hard... Gently tap intell
the carbide rod is well seated in the hole to the full depth..

STEP 7: Step Seven... Grinding...

This part is the part that requires to most skill
and i find the most difficult.. Using a grinder that is capable of grinding carbide
grind the carbide intell it is shaped like a knife... This will take some practice
and patience... DO NOT QUENCH IN WATER OR OIL TO COOL DOWN>>>
Carbide will shatter if cooled to quickly.... Sorry about the
photos... i could not get my camera to focus...
Ok that is it I hope this was helpfull... I did this project
at the TechShop in San Jose California, Gabriel Aceves...

3 Comments

ironsmiter 12 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? :-)