How To Counterbore?

RVJimD

RVJimD

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Guys,

two questions (sorry about all my typos...)

1 how do you put a counterbore on a hole? Drill the hole, then use a counterbore cutter that has a pilot? Can this be done accurately without a pilot cutter? I have drills and end mills.

2 is there a list of this sort of stuff for me to find answers to a simple question like this without bothering everyone? I put "counterbore" into the search box, but didn't find it on the first page so here I am...


thanks

jim
 
RVJimD said:
Guys,

two questions (sorry about all my typos...)

1 how do you put a counterbore on a hole? Drill the hole, then use a counterbore cutter that has a pilot? Can this be done accurately without a pilot cutter? I have drills and end mills.

2 is there a list of this sort of stuff for me to find answers to a simple question like this without bothering everyone? I put "counterbore" into the search box, but didn't find it on the first page so here I am...


thanks

jim
Click to expand...


Normally you would drill the hole then use an endmill or a counterbore with a pilot. The end mill is stiff enough to do the job without a pilot, the normal long shank counterbore generally is not. There are also drill/counterbore combos that allow you to do the operation in one pass.

The search feature doesn't always work as expected. As far as I know there is no list.
 
I find endmills to work very well for this. I just make sure I don't alter the setup so the counterbore stays true to the drilled hole.
 
RVJimD, I, for one, thank you for asking the "simple questions". I wish more members would do so without feeling intimidated. Certainly the "pro" members on here have gone out of there way to assure beginners, like us, not to feel embarrassed, and I thank them for that. Good luck with your counterboring, JR49
 
RVJimD said:
Guys,

two questions (sorry about all my typos...)

1 how do you put a counterbore on a hole? Drill the hole, then use a counterbore cutter that has a pilot? Can this be done accurately without a pilot cutter? I have drills and end mills.

jim
Click to expand...

If you are making a counterbore for a socket head cap screw an endmill is more then accurate enough. The counterbore has zero effect on the fastened joint, it is simply clearence for the head. SHCS's are cold headed, the concentricity between the threaded portion and the headed portion is not terribly close so a good deal of clearence is recommended. The reason that counterbores with pilots exist if for production work. You're not doing 2000 per day are you (-:
 
RVJimD said:
Guys,

two questions (sorry about all my typos...)

1 how do you put a counterbore on a hole? Drill the hole, then use a counterbore cutter that has a pilot? Can this be done accurately without a pilot cutter? I have drills and end mills.

2 is there a list of this sort of stuff for me to find answers to a simple question like this without bothering everyone? I put "counterbore" into the search box, but didn't find it on the first page so here I am...


thanks

jim
Click to expand...

In a modern shop the company would furnish a counter-bore.

You would drill a clearance hole then the counter-bore would have pilot that guides it as the counter-bore cuts the larger hole. I usually drill it a little deeper then the length of the bolt head. But it you can spot counter-bore as well if the surface is rough or rounded. If you are cutting one size socket head cap screw then buy one size tool. They do come in sets as well.
 
Wreck,

i hadn't thought about it like that. Makes it seem pretty simple since the concentricity is not a big concern.

thanks for the help everyone!

Jim
 
Robert, thanks! It took me a long time to build, but it was worth it...
 
Not a lot of experience myself, but why couldn't you use an end mill and cut the counter bore first an then drill your thru-hole. Wouldn't that make sure you were centered as long you didn't move the work piece. I'm sure there's something I'm missing, but that's how we learn. Thanks, Mike
 
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