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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:
 

pontiac428

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#5
Great work! I like this so much better than the supplied mount. Mine ain't broke, but this looks like a fix that should be applied either way.
 

ronboult

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#6
Thanks for the post petertha.
Have just ordered the same power drive for my Sieg SX4 mill and your mounting method should adapt to my mill. Did you have to adjust the height of the mounting screws to get correct engagement of the gears? or is there some adjustment built in to the mount. I suspect that the lead screw distance from the top of the mill table on the SX4 might be quite different to your mill
Thanks Ron
 

petertha

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#7
Hi Ron. There is still adjustability to tune gear mesh via the slot in the mounting bracket (red arrow). Once set it does not seem to drift. Its the other useless pocket clamp part we are tossing. Attaching my mockup drawing if its helpful. I made my tester out of 1/2" MDF wood just to verify everything before committing to aluminum. Assuming you get the same gear kit, the layout/distances between the PF bolts (upper holes) & lead screw center should be the same. But yes, if your stock shaft end casting has different bolt pattern (lower holes) that would have to be matched accordingly.
 

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pontiac428

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#8
Cheers for the pdf drawing!

(from mobile)
 

ronboult

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#9
Hi petertha
Thanks for the response
I can now go and measure my mill to see the differences.
I have already realised that I will have to make an extension for my lead screw as my mill does not have a hand wheel on the LHE and the lead screw barely extends past the end of the table.

One further Q if I may. In pictures 13 & 14 above there appears to be a Cast Au Adapter mounted on your lead screw that links to the new large drive cog. ( three segment drive) Was this part of your original hand wheel on the RF45? If so I will have to try and buy a spare part or more likely mill it as part of my lead screw extn.

Unfortunately my Power Feed is on a slow boat from China and won't be here for quite a while so I can't really start making the adapters until it arrives.
Cheers
Ron
 

petertha

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#10
If you mean this part, it's part of my stock assembly. It attaches to the lead screw. The spline/fingers engage the back of the hand wheel. It is retained on the lead screw with a roll pin through the shaft. The gear I believe has a set screw just to retain in position.
 

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ronboult

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#12
Thanks petertha. Your pictures help a lot.
I don't have a part #24 so will have to fabricate something as part of my Lead Screw extension. My lead screw is much too short and will require an significant extension that can be supported by the bearing in the adapter plate.

I have measured the distance from the top of my table to the centre of my lead screw and it is 2.375 " which is only a small difference to the 2.328 on your RF45. But then I remembered that your adapter plate seems to protrude above the top of your table. Can you please advise on the size of this protrusion.

Still trying to get my brain around what this means but I think that if I make my adapter plate level with the top of my table the gearing will still almost exactly line up with my lead screw.
Cheers
Ron
 

petertha

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#13
I'll measure it for you. Its been a while since I looked at these drawings but do recall the extruded motor bolt bracket edge ends up above the table top just based on how the gear diameters line up & how the pocket clamp casting was intended to work. So I made my plate also extend above the table this same amount +/- minor gear adjustment. I figured this would look & function better than having the plate flush with table & bracket sticking above that. Looking at my working sketch this amount was 0.329". The PF drive & mill is a Frankenhybrid if inch & metric so dimensions are funny.

Here is the PDF drawing of actual part. I just realized I included an earlier drawing in earlier post, sorry. I believe the bolt pattern is same, just opted for a simpler, meatier rectangle with lopped off corners underneath.
 

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