Bridgeport quill ball screw conversion

This will be a complete conversation using hiwin ground ball screws, dc servos, Machdrives BRA dual encoder servo drive along with Sino glass scales for the second encoder with mach3 or 4

I know everyone has seen a lot of BP conversions so I’ll focus on the quill drive setup much like the Keith Elrod kit.

I just got the ball screw since everything will be reverse engineered from the ball screw attached to the quill, it will have a removable link so the quill can still be used manually.

Stay tuned

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Just got the new ball screws today

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I originally made a yoke with a pinch bolt that allowed me to release the quill for manual operation. However, once the CNC system is up and running, I find there's no need for manual operation anyway. The DRO display is the best way to position the tool and the manual MPG pendant gives you that manual operation anyway. It's easy enough to move the work using the MPG in the same way as you'd use the handwheels or feed lever - that includes both milling and drilling. That's just my experience.

I also looked at the approach taken by Elrod, Southwestern Industries etc and didn't like the large overhang of the ballscrew from the quill (to clear the features on the head) or the truly massive castings they used to house the ballscrew and belt drive. Instead, I fitted a 16mm ballscrew where the feed trip screw usually lives (it fits in there without any modification required to the machine). This makes the job of mounting the servo motor a lot simpler and minimises the overhang. It sounds as if you've already coughed up for the ballscrew but it might be worth a thought.

Do you have some pictures of the setup? I have my attachment done for the screw to the quill once in place I can start on the mounting points. I need access to the nuts so the head can still be swiveled.

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Here's a quick vid. You can see the concept at least. With a 4mm pitch ballscrew and 1.8:1 reduction, a 2Nm closed loop stepper can manage a pretty decent downforce and a reasonable rapid.

The strap across the front of the yoke is simply a target for the proximity switches. I need to make something more final but I got a bit impatient to see it working so that can wait until later.

https://www.youtube.com/watch?v=B1qaZ0Sz-ww

Quote:

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Originally Posted by Muzzer

I originally made a yoke with a pinch bolt that allowed me to release the quill for manual operation. However, once the CNC system is up and running, I find there's no need for manual operation anyway. The DRO display is the best way to position the tool and the manual MPG pendant gives you that manual operation anyway. It's easy enough to move the work using the MPG in the same way as you'd use the handwheels or feed lever - that includes both milling and drilling. That's just my experience.

I also looked at the approach taken by Elrod, Southwestern Industries etc and didn't like the large overhang of the ballscrew from the quill (to clear the features on the head) or the truly massive castings they used to house the ballscrew and belt drive. Instead, I fitted a 16mm ballscrew where the feed trip screw usually lives (it fits in there without any modification required to the machine). This makes the job of mounting the servo motor a lot simpler and minimises the overhang. It sounds as if you've already coughed up for the ballscrew but it might be worth a thought.

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Muzzer, I have to disagree with your views on the manual quill. I find that mine is very useful, but I did design a system that allows nearly instant switchover between manual and CNC. A lever flip and a mouse click is all it takes to change over. Even with the quill in manual I still have the DRO readout for the quill.

I did look at Elrod's system, but like you, I didn't like the big casting on the front of the head.

EDIT, that is a nice clean installation. I like it!

Yes, mine still has a 3 axis DRO from before the conversion, too. The Z axis one fits in front of this assembly but I need to get the limit and home switches etc set up before I put that back on and restrict access. The X and Y are still in play, which is useful for telling me if my feed calculations are correct. And how much backlash I have......

My other machine is a Shizuoka that can't be operated manually and I was surprised how much I use it in manual mode eg for squaring something up or drilling holes etc.

I spent a while thinking about how to make the installation functional but simple to make and install, with minimal impact on the machine. There are also not too many parts to make. It only requires two M6 / 0.25" tapped holes to hold it to the machine. Many of these installations are way over the top when you look at the forces at play. Elrod comes to mind again. The Shizuoka is very robust but even so it's not overdesigned.

EDIT - here's a closer look at the installation. Forgive the idiosyncratic content - it's as much for my own records as anything. Besides, I obviously don't get out enough.
https://mightyshiz.blogspot.com/2020...assembled.html

That is an awesome and clean quill setup, that gave me a couple ideas. I’m going to go with lighter weight plate mounts, I was going to use 1/2” steel, I’m cutting that in half.


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I have the ball screw attachment made so the quill can be released and used manually. Now I can work on the frame to hold the thrust bearings etc.

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Getting the xy ball screws installed.

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Just picked up an Anilam quill kit at a local auction for $5 I’ll see how it mounts, maybe I can use that instead of building one.

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This is going to work awesome, the heavy mounting fixture bolts to the mill stand offs and fits perfectly just drill and top 4 holes.

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Slowly getting there have one dc servo setup with the 2.5k encoder

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I want to see what you come up with I’d love to be able to run the quill manually


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