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[4]

RF-45 mill power feed mount improvement

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petertha

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#1
I've been using this Chinese (Align knockoff) X-axis power feed on my RF-45 mill for a couple years now. Mostly it worked OK but I perpetually had to fiddle with the alignment (shall I say misalignment) of the motor gear & lead screw gear. Once set up it runs OK. But a few hours of traversing & its starts teeth growling .

The culprit is the mounting plate assembly. Its intended to be a bolt-on affair. An adapter casting is fixed to the table by 2 bolts that 'set screw' into the pocket. Trouble is, my table pocket has substantial draught taper & its a rough casting, so the bolts have nothing substantial to bite onto. They eventually slip & loosen on the casting & the motor assembly slides out of gear alignment. After a few to many re-adjustments the (cast aluminum) bracket finally cracked. I found out Shars sells the plate combo for 50$U but I wanted something better.
 

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petertha

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#2
So I had this idea to replace my lead screw casting with a plate that served double duty for the power feed mount. I also wanted to incorporate a proper bronze bushing for the lead screw to run in. My stock end casting is the classic shaft running in a cast iron hole. It does have an oiler. (btw once this style of PF assembly is mounted, the oiler nipple becomes essentially inaccessible so you have to disassemble & give it a squirt.) I think a bushing was a good idea because I could see some wear on the CI hole, I suspect self-inflicted adjusting the gears closer on the shaft & putting some down pressure on it?

Here is my wood mock-up which saved me a lot of wasted metal trying to guess dimensions of the mill & power unit. The mill is 95% metric but the bolts are 5/16-18 ( go figure, yup even says so in the manual). After many trial & error measurements, I determined the bolt/shaft spacing is definitely nominal millimeters. Or maybe odd-ball inch, just not drilled & tapped accurately LOL? Oh well, eventually I had a layout I thought would work.
 

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petertha

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#3
And here is the end result. I was going to notch out the bottom of the plate a/p the wood template but after mulling it over, a simpler 45-deg corner lop-off worked fine & preserves more meat in the plate. The plan was to permanent Loctite the bushing in the plate but I'm sourcing ball oiler nipples. I want the ball oiler to face horizontal so I can get at it. If I make the bushing permanent now it will be a difficult to drill & install. Its a tight press fit now so I'll just leave that way until oiler shows up. Well, so far so good. The table traverses quieter than it ever did manual mode or power feed because I can establish the right gear mesh & it stays put. I think that bronze bushing really helped too by removing the lead screw free play that was developing.
 

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tweinke

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#4
That looks like a much more solid mount then the previous mounting. That is what has stopped me from purchasing a similar power feed for my mill. :encourage:
 
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