MrShorty I modified it to
Private Sub CMB_Generate1_Click()
'**code to get information from user
loopstep = (WDend - WDstart) / (WDsteps - 1)
'**code to resolve any problems with wdend, wdstart, loopinterval
For i = WDstart To WDend Step loopstep
ActiveSheet.Cells(11, 3).Value = i
'** code to build filename and write text file
DoTheExport
Next i
   DoTheExport
   
   Unload Me

End Sub
And it works perfect!
When i try for example startdepth 12, enddepth 60, steps 6 he creates files 12,24,36,48,60 as it should be.

Edit:/about your main question..
Can we extend the code with a ''rule'' that decimals are not allowed?

so if i fill in startdept 10 enddepth 3 with 3 intervals he will create:
3
6.5
10

Round up is fine by me or do you like a msgbox with ''please adjust intervals'' more?

Regards