Spotting drill- angle tolerance question.
Spotting drill- angle tolerance question.
(OP)
What should I expect it to be?
My customer print called for an 82 degree spot face, plus/minus 1 degree. We needed a special diameter and requested our supplier grind down an off-the-shelf carbide spotter. Supplier decided to make our spotters from scratch, using plus/minus 3 degrees!!! I said no way. He claimed that's standard. I still say no way!
Internally we have some people that would accept plus/minus .5 degree and others saying plus/minus .1 degree based on the 10 to 1 inspection rule.
What about the angle of a step drill used to eliminate the spotting drill? I think it would be the same, no?
Thanks to any help.
My customer print called for an 82 degree spot face, plus/minus 1 degree. We needed a special diameter and requested our supplier grind down an off-the-shelf carbide spotter. Supplier decided to make our spotters from scratch, using plus/minus 3 degrees!!! I said no way. He claimed that's standard. I still say no way!
Internally we have some people that would accept plus/minus .5 degree and others saying plus/minus .1 degree based on the 10 to 1 inspection rule.
What about the angle of a step drill used to eliminate the spotting drill? I think it would be the same, no?
Thanks to any help.





RE: Spotting drill- angle tolerance question.
BUT... if you bought a total custom part, it would have been better to make a drawing, with tolerances, so there would be no argument about what's "standard".
Mike Halloran
Pembroke Pines, FL, USA
RE: Spotting drill- angle tolerance question.
Spot faces are usually perpendicular to a hole to provide a flat surface for a washer, nut or bolt head to set flat on.
What is a 82 degree spot face?
"Wildfires are dangerous, hard to control, and economically catastrophic."
Ben Loosli
Sr IS Technologist
L-3 Communications
RE: Spotting drill- angle tolerance question.
The tool wasn't considered to be a total custom piece, I just wanted a stock spotter turned down about .050" for clearance issues.
I wonder about standard because tighter than standard generally costs more and our next tool will be a custom made step drill.
Thanks again.
RE: Spotting drill- angle tolerance question.
Other angles are possible, of course, they're just not common. If you actually have 82 degree spot drills, please call them that, not countersinks and not 'spotters'.
Mike Halloran
Pembroke Pines, FL, USA
RE: Spotting drill- angle tolerance question.
My first post used the terms "spotter" and "spotting drill" both refering to the same tool. to-ma-to/to-mah-to
My second post used the term countersink to correct my mis-use of the term spot face, both of which were refering to the feature not the tool. to-ma-to/po-ta-to
Regardless of the terminology used, I believe it's fairly easy to see that the question boils down to:
What is the standard tolerance that should be expected on the angle of one of these tools?
Thanks
RE: Spotting drill- angle tolerance question.
Here is one. http://www.guden.com/countersink.htm
RE: Spotting drill- angle tolerance question.
First, recognize that because the lip may not be exactly radial, the angle measured on the tool may differ from the angle it produces on the workpiece.
But that's not your biggest problem.
Since you didn't specify otherwise, the standard tolerance is whatever your supplier says it is.
The "10 to 1 inspection rule" deals with the necessary resolution of inspection tools, >>>_relative to the specified part tolerance_<<<. Since you didn't specify a tolerance, again, the tolerance is whatever your supplier says it is.
Plus/minus 0.5 degrees is a standard default tolerance in the title block of many companies' drawing sheets. Since you didn't fax a sketch of what you wanted on a sheet with such a title block, and since you didn't fax a sketch at all, the tolerance is whatever your supplier says it is.
If your supplier publishes a catalog, that may define his standard, which he may be mis-quoting. If not ...
... pay the supplier's bill and learn a lesson.
I suggest that it should be SOP to follow up a phone order with a sketch or drawing, specifically carrying:
- an image, however crude, and
- dimensions to show what you want, and
- tolerances to specify what you will not accept.
In the case of something like a cutting tool, it's probably better to just define the important interfaces, i.e. the cut in the workpiece, the shank of the tool, and any clearances that need to be maintained, rather than telling a supplier how to design a tool. You still need the tolerances on the interfaces.
Mike Halloran
Pembroke Pines, FL, USA
RE: Spotting drill- angle tolerance question.
And, for what it's worth, around here a "spotface" refers to a flat region around a hole for a screw head or washer to seat on, like you would machine on a casting. The stubby, combination drill and countersink tool that Mike refers to, we call a "center drill", as it is often used in the tailstock of a lathe to start a pilot without walking and to make a center hole to couple with a live center.
Don
Kansas City
RE: Spotting drill- angle tolerance question.
Mike Halloran
Pembroke Pines, FL, USA
RE: Spotting drill- angle tolerance question.
Don
Kansas City
RE: Spotting drill- angle tolerance question.
htt
Reamer bits
http://www
Countersinks of varying degree.
ht