My Precision Mathews PM935TV Arrival/Setup

excerpt from page 6 of PM manual talks about this if that's what you mean.

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Almost all Bridgeport style mills run in the opposite direction (i.e. Rev. is now For.) when in back gear because of the gear arrangement. On some Bridgeport mills I recall they had a separate switch which you needed to flip to reverse the motor leads. The switch arrangement would vary based on single phase vs. 3 phase and if you are running a VFD. With a VFD, you can use a small micro switch that is engaged by the back gear lever and reverse the VFD run commands. This also varies depending on 2 wire or 3 wire control. On my mill I use a proximity sensor which then triggers a relay which reverses the VFD inputs when in back gear.

My mill came with a digital head (factory VFD), so it has both a mechanical switch which sets the tachometer range (Hi/Low) and a proximity sensor which can be seen as activated below with the mill in back gear.
Back Gear Sensor.jpg
 
My spring return is sticky also but I don't think that is unusual. I've felt that in a few other mills.
 
My spring return is sticky also but I don't think that is unusual. I've felt that in a few other mills.
One of the reasons I dislike the J-head style - positively 19th century design. My Rong Fu 45 had a much better designed head. Sill looking for that Deckel FP2. :)
 
I also feel a certain 'non-linearity' to my 935 quill spring pressure down around 70% of travel. Its not a problem, but also not the silky smooth feel like when I first traversed the 935 table & said mmm... me-like-a. The down force tension feels about right, maybe a bit on the resistance side for small drills. But I figure if I reduce spring tension it will retract even more sluggish than it does now. OTOH I also don't have much run time yet so maybe things loosen up a bit over time? I'm strongly biased to only one machine, my ex RF-45. It was smooth & linear tension going down the whole travel & self retracted quite quickly. Not unlike my drill press I guess.
 
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