What's new
What's new

Suggestions for a good BP Z-axis drive?

borne2fly

Hot Rolled
Joined
Feb 7, 2008
Location
California
I have a 1984 step-head with drive on the x-axis only. I don't mind cranking the y-axis but I'm getting really tired of cranking the z-axis. Are there any good z-axis drives out there that won't break the bank, and (hopefully) bolt right up?
 
I have a 1984 step-head with drive on the x-axis only. I don't mind cranking the y-axis but I'm getting really tired of cranking the z-axis. Are there any good z-axis drives out there that won't break the bank, and (hopefully) bolt right up?

Servo makes a drive for the knee. It is just like the X and Y axis drives, though somewhat beefier.

You can also buy an Asian clone of the Servo brand. It is about 60% of the price and will last about 75% as long. If this is a hobby machine you will never wear it out.

Before we got our VMC's all our mill work was done on knee mills. The Z axis drive is incredibly useful, particularly if you have a DRO scale for the knee.

The last few Servos I worked on were also Asian, so don't let the American name influence your sentiment for American workers.

Servo claims their model 200 knee drive is "made" in the US. I think "assembled" is the correct term.
 
I bought mine from here
150 Lbs Power Table Feed Bridgeport Milling Machine Z - eBay Workholding, Metalworking Tooling, Manufacturing Metalworking, Business Industrial. (end time 30-Mar-10 09:34:34 AEDST)

My knee power feed is under a lot of strain but still works fine. One turn of the handle of mine raises the table 0.250 were as the Bridgeport's raise the table 0.100 per turn. I have read of blokes breaking 1/2 inch end mills with these type of power feeds.
I think the servos would be good for industrial use, taking big cuts and being used by everybody.
These cheaper ones come with the full fitting kit, just like the servo brand does.
Davo
 
Thanks for the input, guys. I think I'll go for it, and maybe even get the y-axis drive too.

Davo, did that thing bolt right up or were there some modifications required?
 
I bought both the Y and the Z from them as well. As you can see from the link, my mill is different to yours so I couldn't use the supplied Y or Z axis extensions because of the tread size, but you will be fine being a Bridgeport clone. I chose to make my own spacers to bolt the power feeds onto the machine, as the holes didn't quite work out, and mine being a different machine and mounts, but could have used them if I really needed to.
Mine have been on for about 3 years with no problems.
I had something fall between the knee and the saddle that I didn't see one time, and the power feed stalled, and then wouldn't work. After scratching my head and thinking I'd blown it up, it only needed the reset button pushed, so there pretty robust.
You will get everything you need for the axis you buy in the kit, with a few extra bits and screws as well. You will get all the shims, keys, track for the limit switch, etc.
The price for these power feeds over here are $750 eachAU. I bought the Y and Z from over their for $630AU shipped, and that was when our dollar was low.
This is the mill I fitted them to.
https://www.machineryhouse.com.au/Products?stockCode=M161D
Davo
 
I adapted my Z from a cheapo HF X. Other modifications were to drill & tap the handle to point back so it dosen't get caught or bumped, also reversed the field windings.
 
I bought one of those gizmos that goes in a 1/2 inch drill motor about 8 years ago and love it. I can still easily put the crank back on for fine adjustment of the knee. If I have more than a couple of hundred thousandths to go I slap the DeWalt 18 volt drill on it and let it rip. I also made an adapter that goes in a 1/2 inch drill motor with a 3/4 inch socket on it. I use it on the vised and Y axis nut. I have two old DeWalt 18 volt drill motors with the adapters in them sitting right next to my Bridgeport. Sometimes simple is the best. Also in the 8 years that I have been using it I have yet to burn out a drill motor. I think JRIowa has a point about the knee on your mill having too much resistance.
 








 
Back
Top