Screw sizes for Side Profile: 2.9 or 3.0mm?
The Enclosure Assembly Manual indicates that the Side Profile 1 and 2 are attached with 2.9mm self-tapping screws. The manual also lists 2.9mm x 9.5mm screws for sale, with a flush countersunk screw conforming to DIN 7982.
It seems likely (but is not entirely clear) that the holes for these should correspond in the Front Panel Designer program to the "For countersunk tapping screws (DIN 74C)" option in size 2.9mm (selected from the pull-down list). This has an 80 degree included angle for the head countersink, a 3.10mm hole diameter, a countersink depth of 1.67mm and a sink depth of zero.
However: The example enclosure design file for Side Profile 1 (and the similar template for Side Profile 2) appears to show the use of the DIN 74C style countersink with a size of 3mm (hole diameter 3.20mm) which uses a countersink depth of 1.74mm and zero sink depth.
I appreciate that there is only a small dimensional difference between the sizes associated with the 2.9mm and 3.0mm screw sizes. However, this apparent inconsistency raises some questions for me. I would appreciate your responses to them.
1) I am planning to use the Side Profile 1 style together with countersunk screws. Which size specification is correct for the 2.9mm x 9.5mm screws in the DIN 7982 style: M2.9 selected from the pull down list or 3mm, entered manually?
2) I notice that the DIN 74A hole parameters (for normal machine screws) specify a non-zero sink depth, while DIN 74C for self-tapping screws specifies a zero sink depth. I am considering having a flat-backed fitting partially overlap the countersunk screw after assembly and therefor require that the assembled screw head is flush with the panel surface. Does the standard zero sink depth for self-tapping screws per DIN 74C allow for this? I prefer not to add any additional sink depth or expose the raw machined surface if there is no need to add additional sink depth. The answer to this question might be related to the answer of the first question.
3) When using countersunk 3mm machine screws (to DIN 965) in 3mm DIN 74A countersunk holes for housing brackets, does the standard 0.25mm sink depth similarly allow for the screw head to be flush with the panel surface?
4) I notice that the housing profile styles specify the use of 5mm machine screws for assembly. Is it possibly to use 3mm machine screws with the side profile parts instead of using self-tapping screws? I appreciate that a somewhat longer screw (e.g. 12 or 16mm) may be needed. Are there other limitations or reasons that would make this inappropriate?
Posted By: Andrew West on Sep 12, 2011 10:42AM Category: Production
Thank you for contacting us regarding your inquiry.
You are correct, the correct countersink for the Side Profile self tapping screws is DIN74C at 2.9mm. This selection from the drop down menu is correctly specified for our hardware.
You are also correct about the M3 machine screws. The head shape is a bit different between the DIN74A and DIN74C, and these differences are accounted for in the drop down menu selections.
In order to use M3 machine screws to attach the Side Profile extrusions, you would need to have us tap the extrusions for you. We can do this by request, but without the threads, the M3 machine screw will not work properly.
If you have any additional questions, please do not hesitate to let us know.
Customer Service Manager
Posted By: Paul Birkeland on Sep 12, 2011 05:31PMReply
Thank you. That seems clear: The Side Profile is best used with the M2.9 self-tapping screws and the drill hole tool for the panel should use the DIN 74C style (for countersunk screws) with the standard M2.9 size.
On the other questions: Can you confirm that the flat-headed countersink screws sit flush with the panel surface (within normal tolerances) if the holes are drilled using the standard DIN 74C (for self-tapping DIN 7982) or DIN 74A (for machine screw DIN 965) parameters?
Posted By: Andrew West on Sep 13, 2011 01:46AMReply