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PM-935 Z axis power feed

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petertha

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#1
I know this one of those personal preference hard questions to answer. But is a vertical axis knee PF option on this particular mill a 'nice to have' or one of those 'why did I skimp out, my arms hate me' post-regret type things I seem to have a knack for? I read the post below, the mod looks straightforward, but another chunk of moola because its a larger torque model. My only reference is my RF-45 which lifts the gear head on the dovetail. Its not what I would call demanding, more of an awkward position of the crank handle.
https://www.hobby-machinist.com/threads/pm935-z-axis-power-feed-photos.65011/
http://www.precisionmatthews.com/shop/pm-935ts-tv/

Is it something you can assess hand-crank inconvenience/effort & retrofit at a later point? Looks like there are some specific model/sizing considerations but everything comes in the PF kit? Are the PF clones behaving OK after a few years or is Align 'the' model to get?
http://www.precisionmatthews.com/shop/pf-z-al510sz/
 

mksj

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#2
On both the knee and larger bench top mills, hand cranking the Z axis can be a real PTA, and the crank handle hits you when standing in front of a knee mill. I have a full size knee and have an X and Z axis feed, well worth it in the long run if you use your mill on a regular bases. All the axis are pretty close in pricing, but there are configuration difference for each axis. Mine came installed, but most kits should have the essentials to install it yourself. The Align drives tend to be a bit better made and have better low speed control then some of the knockoffs. More important on the X axis, for the Z axis it is more just up down. I built my drives on my previous bench top mill, was well worth it.

https://www.hobby-machinist.com/threads/how-to-equip-a-pm-935.66495/#post-558922
 

wrmiller

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#3
Plus one for what Mark said.

I have a 935 and when I have to move the knee up or down a significant amount (like most of the time) I am really glad I put a PF on the Z-axis. I also have one on the X-axis as well.

I bought mine from PM after having the mill for a while. Not too difficult to install. I have no complaints about either of mine. YMMV. :)
 

Duker

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#4
I will second and third Mark and Bill’s comments. I don’t use my mill probably as often as they do but when I do I seem to be constantly raising and lowering the table for whatever I am making. I would highly recommend the addition to your mill.


Sent from my iPad using Tapatalk Pro
 

davidpbest

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#5
I'll chime in here too since I just upgraded from an RF45 (hated having to crank that head up/down) to a PM935. The knee movement on the PM935 is a much finer adjustment than the head movement on the RF45. The head on the RF45's moves about 5 times the distance with one crank of the handle compared to one crank of the handle on the PM935 knee. So while the crank handle is better placed than on the RF45, you gotta turn way more revolutions for the same distance. Get a power feeder for the Z axis, or you'll be cranking a lot more than you're used to. :)
 
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