What Fred

[Erfolg]

I have purchased a BL2217/6, which came with mounting kit and screws. The problem is that the mounting kit screws are M3. The holes however are not.

The dia of the thread appeared to be M3.5. However the only M3.5 I have are for mounting light switches to wall boxes and they do not fit. The thread pitch appears to be coarser, not a clue about the form.. 

I then tried some BA screws, These did not correspond to the dia, being to small or to big.

Has any body got an idea what the thread is, perhaps a USA standard?

Also suppliers of small quantities would be helpful.

Erfolg

[Brian Parker]

Probably a No. 6 either an ANC 32tpi or ANF 40tpi.

Or a No. 6 UNC 32tpi  (all 60degrees & 0.138inch OD)

[Erfolg]

I have tried to find some information on ANC and ANF screws, with difficulty. Are they not a common screw type, even in the USA? 

Erfolg

[Lee Burke]

You could give these people a call Model Fixings

[Erfolg]

Lee

You are pobably correct. I had a look at the link. It surprised me that UNF is still used, apparently mostly in Canada.

Is this where the motors were originally made for?

None the less it appears that getting 4 No.6 UNF screws could be next to impossible in the UK. This leaves with a dilemma. it appears that:

• M3.5, dia 3.5mm, pitch 0.5mm, root dia 2.9mm
• 4BA, dia 3.6mm, pitch 0.66mmm, root dia 3.0mm
• No.6 dia 3.502, pitch 0.635, root dia 3.0mm

I have 4BA taps, so it seems that is a practical possibility. Yet the tap does not seem to want to cut, as if the drilled hole is to small. Tet all my M3 screws drop into the tapped hole. Or would I be better buying some M3,5 taps (have M2.5,M3 and M4 but not......). 

I am finding this a real dilemma, as tapping the holes will not be without risk due to the windings being so close.

Thanks for the help

Erfolg