# New X axis power feed for my Ferro milling machine



## John Conroy (Nov 8, 2017)

I was talking to Matt at Precision Matthews a few weeks back asking some questions about a power feed for the knee on my mill. I have a bum shoulder and cranking the knee up and down by hand is a pain, literally. He told me there are 2 different models, one for machines with 3/4" by 16 TPI SAE thread on the knee lead screw and the others have a 19 mm X 1.5 mm metric thread. I checked mine carefully with thread pitch gauges and found it to be the SAE thread. He offered me a great deal and I ordered one as an early Christmas gift to myself.

It arrived a few days later and I got to work installing it on the weekend. It comes with an extension shaft for the lead screw to add the extra length need for the drive unit plus all the other hardware required. The instructions are the usual chinglish so I did some research online before starting. This unit is made in Taiwan by the same company that made the Align brand power feed that's on the X axis of my mill. That one has been trouble free and all the hardware looks to be top quality so I'm confident this thing will last.





I started by removing the original drive clutch, it is keyed to the shaft and just slides off.





Then the micrometer dial and it's lock nut.









The hub that the dial rides on is threaded onto the 3/4" X 16 TPI threads on the shaft. It is these threads that determine which model to order and where the extension shaft in the kit will thread onto.





Then the bearing retaining plate. As you can see, on my mill it is held on by 3 hex head bolts. There would normally be recessed socket head cap screws here but the plate was damaged when I got the machine so I used the hex heads instead. The good news it the kit comes with a new plate.









At this point the lead shaft can just be pulled straight out with the 2 bearings still attached.









The new extension shaft will now be what holds the outer bearing into it's support so it must be threaded completely on until it sits against the inner race of the bearing, then pinned in place so it doesn't simply back off when turning the shaft counter clockwise.









I put the whole shaft in the vise and used a wrench to tighten the extension shaft firmly against the bearing. Then I levelled the flats and drilled a 3/16" hole for a roll pin.

















Of course I had to make sure the table was at the correct height for drilling before I removed the shaft. It was sheer luck that it was at the correct height.

Then I reinstalled the shaft with the new bearing retaining plate which has the 2 mounting holes for the drive unit. You can orient the unit in 3 different positions but I wanted it to be vertical.





When it was mounted like this I had a small amount of interference between the drive unit body and the knee. I removed a little material from the knee with an angle grinder to provide a little clearance.

















John


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## John Conroy (Nov 8, 2017)

The most challenging part is determining the size of shim to use to provide the correct backlash between the pinion gear you can see in the drive unit and the bronze bevel gear that goes against it. I got so engrossed in this process that I forgot to take a picture of the bronze gear. It slides onto the extension shaft against the pinion and the kit comes with a large selection of shims to provide space between the 2 gears. Too little clearance and the gears will be preloaded together and bind. Too much and they will not have sufficient engagement and will slip/fail quickly. It was pretty easy actually. The bronze gear is keyed to the shaft but to determine the correct shim you leave out the key. The new "clutch" is threaded onto the shaft and pushed the bronze gear into engagement with the pinion. I started out with two .020" shims and as soon as I threaded the clutch on by hand against the gear I could feel the shaft bind and there was no backlash. I just kept adding shims until I could feel a little backlash when turning the shaft back and forth. There are some .005" shims for getting this backlash to the smallest amount possible with no binding. My total shim pack thickness ended up at .105".





Once the correct shim size had been determined I installed the key, a short spacer and threaded on the clutch. The clutch must now be pinned to the shaft so it doesn't just thread off when turning the shaft counter clockwise. I mounted the clutch in the vise and drilled through one side of it, then reinstalled it onto the shaft and drilled through the shaft and the opposite side of the gear by hand. With the hole started straight in the mill I managed to keep it straight the rest of the way by hand and I installed another 3/16" roll pin. The new clutch is recessed for a spring in the kit to keep the manual crank handle disengaged unless you push the handle inward. Obviously you don't want the handle flailing around when the power feed is engaged. I had to machine the recess deeper in my home made drive adaptor to provide enough room for the spring. Then I made a square washer to fit inside the 1/2" square drive in my adaptor and with a screw it keeps the adaptor from falling off.

































Next will come installing the travel limit switch and hardware.

John


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## John Conroy (Nov 8, 2017)

The bracket that holds the upper and lower travel stops is an aluminium I beam and pretty flimsy. I made some spacers to fit inside it so it didn't collapse when the mounting screws were tightened. I made a couple more spaces so it could be mounted perpendicular to the knee travel on the tapered mill body. Then I made a right angle bracket to mount the actual switch to the knee and position it out of the way of the knee lock handles. Drilled and tapped a bunch of M6 holes in the mill for all the hardware and routed the cables out of the way. This thing is awesome! I only wish I'd done it sooner to save some wear and tear on my shoulder.













I really do need to replace that bitch fixed oil line one of these days!

John


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