A.K. Boomer

10-13-2008, 02:24 PM

The recent drill bit discussion and all the doubting tomasses made me conduct my own test this morning as I had theorized in the other thread that a drill bit is like a piece of swarf, if you hold one end and turn the other opposing the direction of the wind the swarf will not only get larger in diameter, it will get longer also,

Welp, the proof is in the pudding

I chucked up a piece of scrap aluminum and took a .312" endmill and went down .250" and then walloed out .1" in each direction with an added .010" off to the sides, I then went down the center of the oval with a .312" drill to give the larger 1/2" test drill a nice place to bottom out and rest;

http://i146.photobucket.com/albums/r249/AK_Boomer/DSC00434.jpg

Next up was bottoming out the half inch Jobber into the aluminum and "feeling" the elasticity of the bit while turning the drawbar with a Dork wrench, I got comfortable with how far I wanted to push the bit and then looked at the dork wrench reading - it said 20 ft. lbs -- so i then pushed it to 25, the bit held, and also self wedged all the way to the bottom of the aluminum.

I immediately knew Paul was way off in his prediction of a drill only getting 1/10 of a thou longer due to the fact that I could see my quill lever raise back up every time I applied torque to the bit.

I then took a static no load measurement of the drill bits diameter - it was .4988" and because the quill was being held down now I took a measurement of what judges the static state of the length of the bit -- its not of the bit itself, its just a number to show change if any, its just a measurement between the free floating quill and the quill adjuster nut at the bottom (because I only have 2 axis dro) That measurement was 2.444"

http://i146.photobucket.com/albums/r249/AK_Boomer/DSC00436.jpg

Next up was holding the dork wrench hands free, an adjustable shower curtainpole was the proper tool of choice,

I proceeded to crank the R/T handle in the direction of what the drill operates in when being properly used (uhhh -ummm)

I cranked the R/T handle till the dork wrench read 25 ft. lbs

http://i146.photobucket.com/albums/r249/AK_Boomer/DSC00435.jpg

Now I went back and checked both measurements --- The drills flutes were now .4992" and the quill measurement was now 2.452"

The bit grew .008" in length and about a half thou in diameter.

Last but not least --- I then applied the mills hand brake very firmly --- this removed all elasticity from the dork wrench --------- I held it and relieved the rotary table from its tension It went from 335 degree's to 347...

The torsional deviance was 12 degree's there was approx. 3 full spirals in the length of this jobber ---- Conclusion; the bit got both larger and longer because these spirals got straightened out some -- kinda like a piece of swarf does when you apply the same kinda loads to it:D

Welp, the proof is in the pudding

I chucked up a piece of scrap aluminum and took a .312" endmill and went down .250" and then walloed out .1" in each direction with an added .010" off to the sides, I then went down the center of the oval with a .312" drill to give the larger 1/2" test drill a nice place to bottom out and rest;

http://i146.photobucket.com/albums/r249/AK_Boomer/DSC00434.jpg

Next up was bottoming out the half inch Jobber into the aluminum and "feeling" the elasticity of the bit while turning the drawbar with a Dork wrench, I got comfortable with how far I wanted to push the bit and then looked at the dork wrench reading - it said 20 ft. lbs -- so i then pushed it to 25, the bit held, and also self wedged all the way to the bottom of the aluminum.

I immediately knew Paul was way off in his prediction of a drill only getting 1/10 of a thou longer due to the fact that I could see my quill lever raise back up every time I applied torque to the bit.

I then took a static no load measurement of the drill bits diameter - it was .4988" and because the quill was being held down now I took a measurement of what judges the static state of the length of the bit -- its not of the bit itself, its just a number to show change if any, its just a measurement between the free floating quill and the quill adjuster nut at the bottom (because I only have 2 axis dro) That measurement was 2.444"

http://i146.photobucket.com/albums/r249/AK_Boomer/DSC00436.jpg

Next up was holding the dork wrench hands free, an adjustable shower curtainpole was the proper tool of choice,

I proceeded to crank the R/T handle in the direction of what the drill operates in when being properly used (uhhh -ummm)

I cranked the R/T handle till the dork wrench read 25 ft. lbs

http://i146.photobucket.com/albums/r249/AK_Boomer/DSC00435.jpg

Now I went back and checked both measurements --- The drills flutes were now .4992" and the quill measurement was now 2.452"

The bit grew .008" in length and about a half thou in diameter.

Last but not least --- I then applied the mills hand brake very firmly --- this removed all elasticity from the dork wrench --------- I held it and relieved the rotary table from its tension It went from 335 degree's to 347...

The torsional deviance was 12 degree's there was approx. 3 full spirals in the length of this jobber ---- Conclusion; the bit got both larger and longer because these spirals got straightened out some -- kinda like a piece of swarf does when you apply the same kinda loads to it:D