Thrust load in hand held drills

[kmurthy]

I am designing a new hand held drill and trying to estimate thrust loads during drilling. Can anyone please help me
Thanks

 

[Haf]

I suspect you mean torque loads, not thrust loads. Either way, you have posted a very open-ended question that leans towards the genre of "please do my work for me." I suggest posting a more specific question after doing some at least some background research and work of your own.

Also, if you are really a computer engineer or scientist, as you have indicated, I suggest you consult with a mechanical engineer.

 

[Timelord]

kmurthy

If you really mean thrust load, simply push your hand drill into a bathroom scale as hard as you can and read the result. The thrust load in a hand drill is simply the max load a user can exert.

Timelord

 

[Iskit4iam]

Timelord is mostly right. If you're 6'4" and 300 lbs us his method; Or decide how strong the user might be. I had to redesign the bearings on a hand grinder because the original design assumed the operator could only apply 75 lbf. Unfortunatly the application was for the railroad industry and those guys managed a lot more than that.

 

[funnelguy]

I know I have balanced all of my 240 pounds on a drill on several occasions. I have seen people 2 people use a lever/fulcrum arrangement on a drill. One person guides/operates the drill while the other applies LOTS of thrust by applying a 2 x 6 for leverage. They were drilling concrete. Good luck...

 

[EnglishMuffin]

I think some of the other posters are being a little unkind to you, especially since you did not specifically ask for the maximum possible load and are presumably not a mechanical engineer by training. You can find tables showing thrust required for drilling steel and other metals as a function of feedrate in Machinery's Handbook, among other places. According to one of these tables, funnelguy might be able to manage about a 1/2" diameter drill in mild steel at .004"/rev, assuming he was doing it vertically. I weigh about 190 lbs and can verify that it's tough going. Books on "human factors" will give you some idea of how much average people of both sexes can exert horizontally.

 

[funnelguy]

I certainly did not intend to be unkind in any way. My post was only meant to illustrate that tools are abused.

The type of abuse I described would probably be limited to heavier duty drills such as a 1/2". Twist drills would not, IMO, be a tool that would abuse a drill's thrust bearing as much as, say, a larger dull masonry bit. There is almost no limit to the thrust that could be misapplied using such a bit.

I have no idea how to quantify "how much is enough" in this case. I'd probably take the coward's route and analyze a competitor's unit. Of course you'd want your marketing department to pick a unit with a good reputation...

 

[Iskit4iam]

I was trying to be funny and helpful at the same time, but certainly not unkind. The engineer that picked the bearings I had to replace thought he had anticipated the operating conditions but he hadn't.

My first thought was to use the drill force charts but because feed per revolution is always going to be unknown I discarded the idea. Then I remembered my grinder experience and thought it would help.

 

[Timelord]

I did not intend my answer to be unkind in any way. I was trying to give him a straight answer by telling him how I would estimate the actual thrust load in a hand drill. Sometimes we forget simple "seat of the pants" ways to come up with some pretty accurate estimates. I figured he would know to insert a safety factor for abuse.

Timelord

 

[EnglishMuffin]

My opening sentence was little more than a harmless rhetorical device, but inadvertently I must have touched a few nerves, since everyone seems to think that I meant them !

 

[funnelguy]

I'm a sensitive kind of guy