Hi All,

I have a Centec 3B mill from the late 60’s. Most of the mill is in relatively good condition. I have made a new heavy duty table on casters that has levelling plates in the casters that screw down to level up. Eight drawers on heavy duty bearing slides are built into table hold all the tooling etc.

The mill now has 1.1kw 3-phase motor powered by a VFD with fascia mounted power and control switches etc. The Centec was offered in 2 maximum speed variants of either 1400 or 2800 RPM. From what I could workout the real difference between the variants was whether a 2 pole or 4 pole motor was supplied (or that’s my assumption for the difference because all i could see change was the electric motor was 2800RPM) as the gearbox and bearings was unchanged. On that basis my my 1400 RPM 4 pole motor can be spun to 2800 RPM with the VFD (100Hz) and the bearings in the motors are the same for both 2 and 4 pole motors. If I am wrong please let me know as I am expecting to be able to hit 2800 RPM and make maybe 3000 RPM on the vertical head (not production pushed but just occasional).

I am about to disassemble the machine into the paintable components and will cleanup, smooth and prime all castings and then paint with 2 pack epoxy (folding open front spray booth is now finished and operational). Maybe I will replace the bearings but will check to see the state once its striped down. On reassembling I will be paying attention to mating surfaces on both the column ways for the knee and the table ways. I have not done scraping before but I have watched plenty of videos about the process. I  have the surface table and tools so I am hoping to scrape them back to near new working (don’t laugh too loud as I might hear you from here). I said I would try.

One of my goals is to improve the finish quality from tools like a fly cutter on aluminium surfaces so a power feed would do that. A couple of things I am considering.

1. Cast and remake the lead slide nut in bronze (perhaps make it backlash adjustable as well) and do away with the disengaging mechanism thus not having fast-speed movement of the table and then remove the fast movement capstan. Any thoughts? If anybody has already done this and or sells the blanks (so I dont have to cast) please let me know (casting is new to me).

2. There are many cheap Chinese Bridgeport mill table power feeds available. I was thinking of adapting one of these to power feed the Centec table. I dont like my chances of getting a genuine Centec power feed even though that may be better. The import offers the high speed burst to move the table fast without the fast capstan whereas the original probably expects fast table movement to be done by disengaging the half nut and use the capstan and rack.

Thanks in advance and I look forward to your replies.

Graham