
Enrique asked me if he could use a No.4 oscillator on his SP15. The answer is yes. The tubes are the same diameter (3¾”) and the worm gear is the same part (DR-338), but the shaft and tube length of the SP15 is longer (13″) than the No. 4 (12½”). While the No. 4 shaft will fit on the SP15 it can laterally shift in the bracket. I suspect this might stress the form rollers. The SP15 oscillator does not fit in the No. 4 frame.

Beautiful. Thank you for posting this.
Now, I will see if someone can make me the oscillator for the SP-15. It’d be super helpful to have the sides of the oscillator come off, but as you already said they are welded, depending on the price, I might make two instead of one, because the No. 4’s oscillator I have is very scratched, Maybe it could be rectified without affecting the whole system. But well, I’ll update everyone soon with more information on the course of this quest.
Thank you very much Paul!