9 Replies Latest reply on Aug 2, 2018 4:25 PM by Matthew Lorono

    Proper callout for spotfacing a countersunk hole

    David Panak

      should this be something like:

       

      f0.150 THRU ALL

      SF V f0.31 x 82.0 degrees

       

      or call out the spotface separately, then the countersink with the same diameter

       

      f0.150 THRU ALL

      SF f0.31

      V f0.31 x 82.0 degrees

       

      or something else?

      thanks

      David

        • Re: Proper callout for spotfacing a countersunk hole
          Kevin Chandler

          Hello,

           

          There's no depth specified, so on this arched surface, where does the CSINK stop?

           

          An aside, "THRU ALL" implies multiple walls. I'll suggest "THRU" instead for this context.

          THRU ALL is usually generated by a through all end condition in the model. THRU comes from up to next or up to surface.

          I try to avoid through all as it can inadvertently extend through model additions added within its perpetual cylinder.

           

          Cheers,

           

          Kevin

           

          EDIT: Having checked my standard, the spot is called separately with its own height/depth dimension, although I don't really consider this a spot.

          Also, drawings aren't supposed to dictate process, so the order on the drawing technically isn't relevant.

          With the sloped surface, most likely a center cutting end mill will be plunged to establish a flat for other tools to have a proper deck to eliminate side loading.

           

          Aside II:

          Since your CSINK is captured, this may be custom/special tooling.

          The angle matches flat head and most CSINK cutters have ODs greater than what's shown here.

            • Re: Proper callout for spotfacing a countersunk hole
              David Panak

              Thanks Kevin very much for the reply - I really appreciate the help.

               

              My intent with the SF countersink is that the depth would be set when the countersink reaches full diameter (which I think is how SF is defined) so that the tolerance stack for the sloped surface doesn't result in an incomplete countersink.

               

              Agreed on the 'thru' vs 'thru all'. I've had trouble with SW balking on patterned holes using the 'up to surface' and 'up to next' end condition when the stop surface is not contiguous (e.g. surface broken by another feature). I've taken to always specifying 'through all' for the end condition to alleviate this, then editing to 'thru', or 'thru one wall' even - if I remember to make the edit on the drawing, that is.

               

              Understood that the machinist would likely start with an end milled flat, which may be a smaller diameter from the countersink, so the countersink wouldn't walk off center. Without dictating the process, suppose I could specify a SF Counterbore, then follow with the same diameter Countersink, but I think QC may have trouble then with verifying the counterbore. What I would like is a "SF Countersink" similar to the <HOLE-SPOTSF> symbol. I think the intent would be clear, but is it legitimate to make up a new symbol (a "V" cradling a "SF", for example)?

                • Re: Proper callout for spotfacing a countersunk hole
                  Kevin Chandler

                  David Panak wrote:

                   

                  Thanks Kevin very much for the reply - I really appreciate the help.

                   

                  My intent with the SF countersink is that the depth would be set when the countersink reaches full diameter (which I think is how SF is defined) so that the tolerance stack for the sloped surface doesn't result in an incomplete countersink.

                   

                  Agreed on the 'thru' vs 'thru all'. I've had trouble with SW balking on patterned holes using the 'up to surface' and 'up to next' end condition when the stop surface is not contiguous (e.g. surface broken by another feature). I've taken to always specifying 'through all' for the end condition to alleviate this, then editing to 'thru', or 'thru one wall' even - if I remember to make the edit on the drawing, that is.

                   

                  Understood that the machinist would likely start with an end milled flat, which may be a smaller diameter from the countersink, so the countersink wouldn't walk off center. Without dictating the process, suppose I could specify a SF Counterbore, then follow with the same diameter Countersink, but I think QC may have trouble then with verifying the counterbore. What I would like is a "SF Countersink" similar to the <HOLE-SPOTSF> symbol. I think the intent would be clear, but is it legitimate to make up a new symbol (a "V" cradling a "SF", for example)?

                  Hello,

                   

                  This only applies to planar surfaces as the csink tool is larger than the specified csink OD.

                  For your situation, your csink is at the bottom of a hole (partial it may be), so the csink tool's OD must match the bore's diameter (slightly under actually too avoid rubbing and deflection).

                   

                  As I and others have stated, this isn't a "regular" csink operation. And unless you add a true spot, one large enough to provide ample clearance for the csink tool OD, then this is special tooling, essentially a 5/16" drill bit with an 82° nose.

                   

                  Cheers,

                   

                  Kevin

              • Re: Proper callout for spotfacing a countersunk hole
                Newell Voss

                similar to what Kevin mentioned, that doesn't look like a true spot face but rather a counter bore.

                (btw theres a specific symbol for both, not just the letters SF..):

                2018-08-02_7-43-52.png

                I would suggest identifying it as such. You still are left with the problem that most Csinks are larger than the nominal of your bore so you would be circle milling that feature or using a smaller one that wouldn't come up to the outer wall. Would a drill feature work instead? that way you specify two hole sizes/depths and the Csink is added by the default angle on the tip.

                  • Re: Proper callout for spotfacing a countersunk hole
                    David Panak

                    Thanks Newell very much for the comments - I've been using the <HOLE-SPOTSF> symbol for spot faced counterbores, but like I mentioned above, is it legitimate to call out a spot faced countersink; like <HOLE-SINKSF> if such a symbol could be made?

                     

                    I'm not sure a drill feature would work - not wanting to drive process, but I don't want to risk having an off-center hole if the machinist didn't put down a flat first with an end mill.

                  • Re: Proper callout for spotfacing a countersunk hole
                    Frederick Law

                    It is more a CB + CS.

                    I'll mark CB and CS separate and indicate CB first then CS.  For sure you don't want machinist to use CS tool to bore that deep.

                    You do need to locate bottom of the CB for the CS.

                    Check diameter of CS tool and make CB bigger to fit the tool.

                      • Re: Proper callout for spotfacing a countersunk hole
                        David Panak

                        Frederick - thank for the reply,

                         

                        That sounds good. I see what you mean about the CS tool - they are typically larger in diameter, with the diameter of the resulting CS set by the plunge depth of the tool. I may be looking at special tooling like Kevin said since I could run into a wall thickness problem with too large of a counterbore. In that regard with specifying a CB slightly larger than the CS, there would be a residual flat that QC could verify the CB. I think I would need the CB to be spot faced to control the depth.

                         

                        So

                        f0.150 THRU

                        SF CB f0.4

                        V f0.31 x 82.0 degrees

                         

                        is the consensus?

                         

                        Edit:

                        - doesn't look like SW has that option for a single hole - the "Added C'Bore" feature for a countersunk hole has height but not diameter.

                      • Re: Proper callout for spotfacing a countersunk hole
                        David Panak

                        Thanks Kevin,

                         

                        That will work. I'm curious now about SW design intent with the "Added C'Bore" option for a countersunk hole. The callout for such a hole, even on a planar surface, includes both a Countersink and a Counterbore (to a specified depth), but with the same diameter and no option to modify the diameter of the CB

                        • Re: Proper callout for spotfacing a countersunk hole
                          Matthew Lorono

                          For anyone that runs across this thread looking for SW spotface symbol, we've had one for quite some time.  It was actually improved a few releases back too.  <HOLE-SPOTSF>

                           

                          If you use the Library interface, it's in Hole Symbols.