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legendboy
12-07-2011, 11:51 AM
I am wondering if a 135"lb servo power feed has enough torque to be used on a Series 1 bridgeport knee?

lakeside53
12-07-2011, 01:06 PM
Servo recommends that you do not... and use a 150 or 200... My 140 really "notices" my knee... and that's with just a vice on it. Load it up and it groans.

Their site still lists the 140 as "ok" for the standard BP - not for series 2 or clones with heavy knees.

RWO
12-07-2011, 01:16 PM
You could check the torque with a simple fish scale and a wrench or the original handle. My BP takes about 8ft-# to budge the knee upwards. Triple that for running at speed ( WAG). I'd say it would work.

RWO

legendboy
12-07-2011, 01:23 PM
You could check the torque with a simple fish scale and a wrench or the original handle. My BP takes about 8ft-# to budge the knee upwards. Triple that for running at speed ( WAG). I'd say it would work.

RWO

good idea, will try

macona
12-07-2011, 01:43 PM
Plus the mounting kit is totally different than the horizontal axis kits.

legendboy
12-07-2011, 02:56 PM
^ true

I have had this thing kicking around for years brand new in the box, figured i might be able to adapt to my new mills knee

lakeside53
12-07-2011, 03:16 PM
You could check the torque with a simple fish scale and a wrench or the original handle. My BP takes about 8ft-# to budge the knee upwards. Triple that for running at speed ( WAG). I'd say it would work.

RWO

if your wag is correct... triple 8ft lb is nearly 300 inch lb.

My 140 (inch lb) is sluggish at best which isn't good for it.

Sparky_NY
12-07-2011, 03:32 PM
I have the knee on my series one set up with a servo. I used a allen bradley PM DC motor that I got on fleabay new for $125. I am driving the original shaft where the crank used to be with a 2:1 belt driveand the original screw/gears. The motor is 40 lb-in stall torque rated nema 42 nearly identical to the factory bridgeport servos on the other axis. Originally, I designed for 100 in/min max feedrate but screwed up because the motor rpm I later found out was its unloaded speed, loaded speed is more like 80% of that. At any rate, it will run at 80ipm reliably but I set it at 70ipm which it has run at for over a year now. I used no gas springs or counterweights at all. With a change in the belt drive ratio it may be capable of more but 70ipm is scary fast for that amount of iron to be moving.

I am very pleased with the performance. My quill is servo driven also and used for cutting moves. I use the knee to send tool length offsets to only, not for cutting moves.

Davo J
12-07-2011, 03:35 PM
My mill came with a X power feed and I fitted a Y and Z axis power feed. For the Z they give you and extension shaft to go over the original shaft, but if you put some thought into you will be able to adapt it no problems.

When I fitted it to my HM52 which is the Grizzly 3617 over their I just made up a new knee elevation shaft so I could keep the original one if I ever needed it latter on when I sell it. I then fitted the extension to this, but you could just machine it to suit the power feed needle roller bearing.
Here is a link to mine
http://www.woodworkforums.com/f65/installing-knee-power-feed-hm50-52-grizzly-3616-17-a-116608/

As for if it will have enough power, Bridgeport mills lift the knee .100 per turn, where mine lifts the table .250 per turn. I can hear the 150 load up a bit, but it does the job fine and has been in use for around 4 years now, so a 130 on your should do the job.

I have a picture on my computer somewhere where one guy used a chain and sprockets on a power feed to gear it down, and it was a compact set up.
Just found the link
http://www.chaski.org/homemachinist/viewtopic.php?f=24&t=83981&hilit=knee+power+feed

Dave

legendboy
12-07-2011, 05:58 PM
^ i might rig something like that up, maybe make a cover for the chain and sprockets.

I don't really care if it is slowish, as long as i don't have to hand crank it. series 1 cnc knee is pretty heavy


I have the knee on my series one set up with a servo. I used a allen bradley PM DC motor that I got on fleabay new for $125. I am driving the original shaft where the crank used to be with a 2:1 belt driveand the original screw/gears. The motor is 40 lb-in stall torque rated nema 42 nearly identical to the factory bridgeport servos on the other axis. Originally, I designed for 100 in/min max feedrate but screwed up because the motor rpm I later found out was its unloaded speed, loaded speed is more like 80% of that. At any rate, it will run at 80ipm reliably but I set it at 70ipm which it has run at for over a year now. I used no gas springs or counterweights at all. With a change in the belt drive ratio it may be capable of more but 70ipm is scary fast for that amount of iron to be moving.

I am very pleased with the performance. My quill is servo driven also and used for cutting moves. I use the knee to send tool length offsets to only, not for cutting moves.

I read about that in one of your threads somewhere, I already have this power feed, don't really want to spend any more money at this point

quasi
12-08-2011, 01:15 AM
legend boy , I have 135's on my x and y feeds, a 150 on the knee feed, it handles the knee pretty well. This is on my Bridgeport.

If buying power feeds one axis at a time, I would go X axis, then Knee feed , then y feed.

Buy your feeds in the U.S., KBC Canada's and Travers prices are nuts.

legendboy
12-08-2011, 03:56 PM
legend boy , I have 135's on my x and y feeds, a 150 on the knee feed, it handles the knee pretty well. This is on my Bridgeport.

If buying power feeds one axis at a time, I would go X axis, then Knee feed , then y feed.

Buy your feeds in the U.S., KBC Canada's and Travers prices are nuts.

My mill is a series 1 cnc bridgeport, so I only need a feed on the knee.

i think the series 1 cnc knee is way larger and heavier then the standard bridgeport

RWO
12-08-2011, 05:50 PM
According to this: http://servoproductsco.com/html/type_140_power_feed.html

a 140 will do the knee on a BP series 1.

RWO