square to the surface holes?

[SVanderkolff]

I think that the holes that I am drilling in the blades of the folders are not exactly square to the surface of the blade. I have checked the drill press itself and it is out of true by 2/1000 " 3" from the center of the spindle which I would think would be close enough yet when I construct the knives I sometimes end up with the blade not ying square to the rest of the folder. Is there a tool out there that will measure whether or not a hole is square to the surface extremely accurately?
Thanks
Steve

 

[richard j]

you can drill a hole in a flat piece of steel and find a pin that is straight and put it in the hole. get a good square and check the pin for square. hold it up to a light and see if there is any light making it through from the top or bottom. do you have a dial indicator?

 

[SVanderkolff]

I do have a dial indicator. With a 1/8" hole would this test tell you if you were dead square? I would think the introduction of the pin would add another variable. If the pin is not perfectly straight or is bendable it would throw out your testing. Wouldn't it.
Steve

 

[John L]

Steve: There are literally a thousand things that can put your blade off center. I know!! Don't know if you are making slipjoints or liner locks but if slipjoints...put everything together and before peining clamp together with a long nose vicegrip or some other clamp. See if it is then centered. If centered try to leave clamp on and pein. Once peined check for center. If offcenter you may clamp diagonally and move the whole works a bit to true up. At times I close the knife with a wedge between liner and blade....wedged toward the way I want the blade to move....careful here as you can also crack scale material. With the wedge in between... pein just a bit more. This oftern works. Also..try peining in different sequence...knife to your right, for example and pein. At times you are hitting everything offcenter and it pushed everything off. You just have to screw with it until you figure out why it is doing what it is doing!! And also...sometimes it is just screwed up and no fix other than to drill pin out. If using 3/32" pin, drill 1/16hole and push pin out with puch. The pin will collapse on the drilled out center.
If you are making linerlocks try clmping diagonally until blade moves.

 

[richard j]

if you use a piece of reamer blank which is ground on a centerless grinder it would be true. you can also roll a piece to see if it is out of round. i could give you a call which might be quicker and save some typing. pm me your number.

 

[Frank Niro]

Steve. Is the blade square to the hole after heat treat and final finishing including asny hand finishing? Place the blade between two pieces known to be flat and see it the tip is centered. Damascus can have a tendency to bend . Frank

 

[Rusty McDonald]

Use shorter jobber legnth bits they are more rigid and wont flex or wobbel as much. And get the table as square as possible.

 

[Nathan the Machinist]

You can learn a lot about a hole with a good tenths indicator. If you leave your work clamped in place after making your hole you can measure:

positional deviation relative to spindle axis
roundness
bell mouth or taper
angle (if the center of the hole is not the same at the top as it is in center and bottom.

After measuring a drilled hole like this, you'll see why most machinist only use drills for unimportant clearance holes and roughing out holes. An important hole like a pivot hole should probably be drilled undersized and followed with a reamer to get it round, with a good finish and accurately sized. A really important hole is roughed undersized, bored, then reamed. Boring before reaming gets it in position and square to the work piece better than anything.

Drill bits don't drill particularly round straight square holes. And they walk.

You can sweep your table from your spindle with an indicator to check if your table is square to your spindle. You may also be able to position your indicator in a way that you can measure deflection of your spindle and table while drilling. It is always a lot more than people realize...