[How-To] Mounting a Z axis DRO on a Bridgeport (Clone) Quill

Eddyde

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Hi All,

A few years back I completed the DRO installation on my mill by adding the Z Axis to the head, that is my mill is a bed style where the head raises and lowers not the knee or table. However, I found it not be as useful or at least user friendly as I thought, mainly due to the fine adjustment hand wheel being mounted high on the column, towards the back of the machine. And while the head height is also motorized, it moves too fast for precision adjustment. The solution was to mount a scale on the quill and use that for the Z Axis read instead of the head height. Ultimately, a 4 axis DRO that would combine the two Z axises together would be the way to go but for now, I'll just swap out whichever one I need for the height range required. Though the quill Z will probably suffice for at least 95% of my work.

So I ordered a 150mm scale off AliExpress and got to work. Making a bracket mounted to the bottom of the quill and having the scale off to the side was my first thought, as I wanted to leave easy access to the depth-stop. However, that approach was fought with too many issues, mainly where and how to attach the scale to the head. So I decided to mount the scale using the mounting bosses already on the head, presumably for that purpose. The read head would be mounted to the depth-stop itself. I started by making two blocks to attach to the mounting bosses out of some mystery-alloy steel I had on hand. I mounted them to the bosses by drilling and tapping one #10-32 hole in each boss, then screwing them in place, I also drilled and tapped the blocks for #6-32 set screws that would impinge on the side of the bosses, to ensure tight alignment. I then made a plate out of Aluminum that screwed to the blocks. I now had a solid platform for mounting the scale. Also, the blocks held the scale far enough away from the mill head to allow, albeit somewhat impeded, use of the depth stop.

MC TS - 1 (1).jpeg
MC TS - 2.jpeg
MC TS - 3.jpeg

Next was mounting the read-head to the ring shaped, depth stop boss that is mounted to the quill. I first figured on making a bracket with a radius matching the stop and fastening it with screws. but that seemed like too much of a headache and it wouldn't give me any meaningful opportunities for adjustment. I decided to mill a slot on the side of the stop, that would also allow for the bracket to be adjusted forward-backward and thus eliminate the need for any intermediate brackets, etc. Milling the flat went easily, I was able to register it position in the vice by sliding a .625" bar through the hole and setting the ends on two V blocks bottom of the neck of the stop that attaches to the quill was registered against the fixed jaw. This gave fairly accurate alignment square to the quill and the bosses.

MC TS - 1.jpeg

MC TS - 4.jpeg

I made the bracket that attaches the read head mounting base to the stop from a piece of ¼ thick, structural steel, angle iron. I milled slots for the screws and shoulders to fit into the slot on the stop that would allow for adjustment without it rocking up or down (it is a very tight fit). I also milled slots to allow adjustment of the read head mounting base right or left. Even though this setup didn't allow for every possible adjustment, I figured having referenced off the known, true surfaces of the machine, when making/altering the parts, would get me close enough in those dimensions. Indeed that was the case.

MC TS - 1 (2).jpeg

The read head mounting base was also made from Aluminum, I milled a slot on the back to receive the angle bracket, again so not to allowing for any twisting, only side to side movement. All looked good and I attached the scale and head to the mounts, the DRO was now reading the Quill movement. However I discovered a problem. The quill was free to rotate slightly causing the read head to pull away from the scale body by an unacceptable amount.

MC TS - 6.jpeg

My first thought was to make a piece attached to the stop/read-head that would hook around to the opposite side of the scale mount and ride along its left edge. But that was kind of wonky and would have further impeded access to the depth stop. I also thought I could use the neck of the depth stop by making a new one altogether that would better fit the slot in the mills head it rides in. But that would have meant eventually wear and tear on this parts and there isn't much room to add guide strips, etc. So I figured I would make a additional "track" guide just to the right of the read head.



I made the guide and its mounts from Aluminum and made guides for the redhead mount out of Delrin. On the inner face riding on the scale mount, I bored two .200" holes about .300" deep and through drilled and tapped for a 6-32 setscrew in the bottom. I then mede the Delrin guide "plugs" which proved to be a bit of a challenge as I only had .25" sheet material I attempted to cut a .25" square bar a couple of inches long and turn it in the lathe, it sort of worked but even the short length and having it supported by a center in the tailstock there was still too much deflection. I wound up having to only have .5" protruding from the chuck and turning it with a very sharp HSS tool. Thus the Delrin plugs were adjustable.

MC TS - 12 (1).jpeg
MC TS - 15 (1).jpeg

I also made Delrin shoes to ride on the new track, I mounted these in slots cut in the back of the of the read-head mount. They stick out the right side, they have slots in them and are fastened with screws. I couldn't do the hole & plug method on that side as there would be no way to get at the adjustment screws. I assembled the whole thing and it worked perfectly. The quill could no longer rotate and the read head stayed right at its specified distance from the scale body, throughout is entire travel.

MC TS - 8.jpeg

Then my thoughts turned to the cover and I realized Duh, I should have simply made the cover part of the track, I surmised a piece of .25 X 3" wide X1.5" deep aluminum C channel would be perfect, McMaster got it to me the next day. I drilled and tapped the screws for it in the side of the scale mount, though while doing so I accidentally reversed the order, and had to do them, twice.

After the cover was on and I was satisfied everything was operating well I decided to dress up the aluminum channel with a "Jeweled" (AKA Engine turning) finish. I had screwed around with this in the past but never when I had a DRO to make it easy. For the "spinner" I use a 1" diameter "Scotchbrite" abrasive drum and some 400# Clover compound. The results weren't perfect but good enough for my needs.

IMG_4239.jpeg
IMG_4241.jpeg
MC TS - 2 (1).jpeg
MC TS - 4 (1).jpeg
Thanks for looking.

PS In my musing on if I should upgrade my DRO to a 4 channel that could combine the two Z axises, I came across a dongle that does the combination and used the existing DRO, for only $60. I ordered it however its back ordered, Ill update when it arrives.

Oh, here's a random picture of the Dogs!

IMG_4244.jpeg
 
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The engine turning looks so awesome....just got done mounting mine, not gonna lie I kind of cheated since I scored a fagor 3axis kit cheap and it came with the mounts but this has got me a bit jealous. Really nice work
 
The engine turning looks so awesome....just got done mounting mine, not gonna lie I kind of cheated since I scored a fagor 3axis kit cheap and it came with the mounts but this has got me a bit jealous. Really nice work
Thanks!
Hey I would have probably taken the easy way out if it was readily available. Though, I did see a DRO mounting kit for the Bridgeport quill, made by Acu-Rite. But it is for their DRO's and I would have had to modify it, it wasn't exactly cheap either, so...
 
I think I have the same mill - Mine was repainted grey but is an RB1 and I recognize the castings and layout. Color was the same as yours at some point.

I would have missed the slight rotation in the quill if you hadn't mentioned it and that will save me considerable grief knowing to expect it.
I am opting to use a magnetic scale on the quill while all the rest of the scales will be linear glass scales.

You mentioned the inconvenient location of the manual wheel for the column height - there was an option (mine had it) with a second, gear and shaft driven lower handle that mirrored the upper wheel - but while easier to reach, it was so far around the side of the machine that I removed the extension and lower hand wheel.

I "converted" my 3 phase machine by using two VFD's - spindle and column - I still use the variable belt drive for controlling the spindle but control the column motor speed from the control panel - allowing me to creep along or speed off to the top or bottom - it actually made the column a useful axis which will now have a scale (soon) and be included in the DRO.

Thanks for the heads up and detailed look at what you did.
 
I think I have the same mill - Mine was repainted grey but is an RB1 and I recognize the castings and layout. Color was the same as yours at some point.

I would have missed the slight rotation in the quill if you hadn't mentioned it and that will save me considerable grief knowing to expect it.
I am opting to use a magnetic scale on the quill while all the rest of the scales will be linear glass scales.

You mentioned the inconvenient location of the manual wheel for the column height - there was an option (mine had it) with a second, gear and shaft driven lower handle that mirrored the upper wheel - but while easier to reach, it was so far around the side of the machine that I removed the extension and lower hand wheel.

I "converted" my 3 phase machine by using two VFD's - spindle and column - I still use the variable belt drive for controlling the spindle but control the column motor speed from the control panel - allowing me to creep along or speed off to the top or bottom - it actually made the column a useful axis which will now have a scale (soon) and be included in the DRO.

Thanks for the heads up and detailed look at what you did.
Welcome to HM!

And hello fellow RB-1 owner, IMHO it is a great mill, more rigid than a traditional Bridgeport style knee mill, albeit slightly less versatile. They were still made up until just a few years ago under the parent company, Long Chang Machinery's, brand "First" model LC-50. Some of the older First machines are grey. There are also CNC versions of the mill.
I have the same dual VFD setup you mention and use the variable drive on the head, rarely the VFD for spindle speed. I installed a 5 position momentary switch to control the head Z axis, giving 2 travel speeds. I also have that lower Z hand wheel, but never mounted it. I have a copy of the manual if you need?

Here are some links to my journey with this mill:





I would like to hear more about your mill, maybe some pictures please!
 
I apparently have to post several times before I can include pictures...

I did get my new DRO mounted up on the RB1 and am quite pleased - its a five axis with a rotary I will fit to one of my rotary tables and I opted for a magnetic scale just for the quill. It also supports a touch probe, which has somewhat limited functionality but measures well and will be a "Poor Man's" CMM for me

I will post pictures when I'm able - My column DRO has a pot on the control panel to vary the speed of the column and two buttons for up or down. The spindle has a three position momentary "return to center" switch to engage forward or reverse for the spindle with a dedicated stop button just below that.

My RB1 was water damaged when I bought it (knowing it had been rained on and water evident in the head) and I stripped the head and several other parts to bare metal before rebuilding it. Got to know the insides quite well. Very happy with it and being short, at least some of the time, I can reach the draw rod without a step stool - can never reach it on a Bridgeport. Definitely meets my needs.

My other frequently used machine is a 1922'ish South Bend 9" Jr that I received as a pile of parts - mostly disassembled - but stripped everything to bare castings and rebuilt. The 9" Jr has a wider bed (from the heavy 10 machines) and split bronze headstock bushings that with a little tuning have a runout of less than 0.00005" - making it a useful machine - "Steam Punked" the Lathe - two 3p motors - direct flatboat to the spindle with full speed control and a little tiny 1/8 HP 3p with a link belt to the lead screw when not turning threads - disengage gears and have continuously variable feed like the big boys,

I also determined that its is far wiser to decide to upgrade your DRO while the old one is still working (and can be used for making the new brackets) I felt a bit like I was back in High School shop class without a DRO - Dykem blue and scribe lines again...

I also see that you managed to get several pieces of machinery into a basement - I grew up outside Chicago and basements were it for shop space - Dad's shop had a small Clausing mill and a really old Putnum 16x60 flat belt driven lathe - bed was slid in through one of the small slit like windows - "gravity fed" so to speak and I doubt it could be taken back out...
 
I apparently have to post several times before I can include pictures...

I did get my new DRO mounted up on the RB1 and am quite pleased - its a five axis with a rotary I will fit to one of my rotary tables and I opted for a magnetic scale just for the quill. It also supports a touch probe, which has somewhat limited functionality but measures well and will be a "Poor Man's" CMM for me

I will post pictures when I'm able - My column DRO has a pot on the control panel to vary the speed of the column and two buttons for up or down. The spindle has a three position momentary "return to center" switch to engage forward or reverse for the spindle with a dedicated stop button just below that.

My RB1 was water damaged when I bought it (knowing it had been rained on and water evident in the head) and I stripped the head and several other parts to bare metal before rebuilding it. Got to know the insides quite well. Very happy with it and being short, at least some of the time, I can reach the draw rod without a step stool - can never reach it on a Bridgeport. Definitely meets my needs.

My other frequently used machine is a 1922'ish South Bend 9" Jr that I received as a pile of parts - mostly disassembled - but stripped everything to bare castings and rebuilt. The 9" Jr has a wider bed (from the heavy 10 machines) and split bronze headstock bushings that with a little tuning have a runout of less than 0.00005" - making it a useful machine - "Steam Punked" the Lathe - two 3p motors - direct flatboat to the spindle with full speed control and a little tiny 1/8 HP 3p with a link belt to the lead screw when not turning threads - disengage gears and have continuously variable feed like the big boys,

I also determined that its is far wiser to decide to upgrade your DRO while the old one is still working (and can be used for making the new brackets) I felt a bit like I was back in High School shop class without a DRO - Dykem blue and scribe lines again...

I also see that you managed to get several pieces of machinery into a basement - I grew up outside Chicago and basements were it for shop space - Dad's shop had a small Clausing mill and a really old Putnum 16x60 flat belt driven lathe - bed was slid in through one of the small slit like windows - "gravity fed" so to speak and I doubt it could be taken back out...
Yeah, I think it's 3 posts before you can post a picture, we do this in an attempt to reduce spam.

It sounds like you have great setup on your mill. I like the variable speed up down, I might want to add that feature to my machine.

I soon might have some questions for you on rebuilding my mill's head, it intermittently makes a hellacious sound usually when run fast but goes away after a minute or so. I haven't felt it an urgent problem but I know I shouldn't ignore it for too long either. Time to do it has been my biggest issue in getting to it.
Awesome setup on the South Bend, Please post some pictures of it too, when you can.

I have 3 Southies, 2 nine inchers and a heavy 10 (but only 2 are currently commissioned) I also have a 13X40 Clausing Colchester lathe, a 6x12 surface grinder, the mill, 4 drill presses and a lot of other stuff in the basement, it is getting too crowded, I need to lighten the load, LOL...
 
Sadly, I didn't take any photos as I rebuilt the head but I have been astounded at how hard and ineffective grease can become over time - there were parts that I believe were intended to be oiled but had been greased at some point - the quill feed was a mess.

Noting was particularly challenging to pull apart or put together and even the "notorious finicky" parts of the quill feed and stops wasn't a problem - I've taken apart seemingly simpler things that were a much bigger challenge to reassemble.

Research also showed that the spindle bearings are often replaced with sealed bearings (greased) and the design originally called for open bearings and a "total loss" type lubrication with oil (mine still had open bearings when disassembled)- I went the open route and had to buy bearings with shields and grease and remove both before installing - open bearings and feeding spindle oil through the spindle bearings is a little messy but works very well if using higher spindle speeds - nothing heats up like with greased bearings and seals. In theory, it provides slightly less shock protection to the bearings when using a big multi-insert shell mill or face mill but I'm usually working with smaller tooling and in aluminum. Bearings actually designed for spindle oil would have had tighter tolerances and a closer fit than greased bearings but it seems to be a minor compromise as my spindle run out won't move the needle on a 0.0001" indicator when turning by hand and has a really minimal offset when pushed to one side with some force.

There are several oil cups on the head and each feeds a different area but I've seen machines where some had grease fittings in their place - the inside of the head does not seem conducive to being greased from those locations - just my opinion - but there are at least two different oils necessary and little information on which cups are for where - There's also an instructions saying to oil the spline shaft from the top - which seems necessary to keep the quill retracting smoothly.

I would be curious to see what the manual you have has to say as I have never seen a complete manual - only comments and generic information from "Bridgeport type heads" which is a fairly wide range of heads...

If the manual can be emailed, that would be great- mark.d.volle @Gmail .com (spaced out lest the filters not like an email address)

The horrible sound on startup - especially at fast speeds could be nearly anything -

I also keep the quill feed "off" unless actively using it - this disengages a whole chain of gears inside that could be grumpy at high speeds and are only rated for use below certain spindle speeds (I forget the limit) If keeping the quill feed gearing "off" eliminates the noise - that would significantly narrow the search. My head made alarming noises when I tried it before the rebuild and the feed gearing was quite noisy (very quiet now with everything cleaned and running oil)

Its also typical of a greased bearing that's drying out or a bearing with either or both contact surfaces slightly loose - bearing spinning on the shaft or in the housing - it goes away quickly because the bearing heats up - either grabbing the lose surface or melting a little grease and it running into the working area of the bearings - LocTite makes a bearing retaining product I used when putting the spindle back together jut for safety sake.

Grease can be an odd thing as it can age and harden used or not - I've built several things using bearings that were "new old stock" or "spares" that were never put in service - some from very high end semiconductor machines that had very high end lubricants and were sealed in "clean room ready" packaging but wouldn't even turn when opened - flushed and relubricated, the've been fine and getting a new $1,800 bearing for $40 surplus is more my design budget.

If it only happens at high speeds - not every cold start - its likely not the motor bearings although my motor bearings were "quite sad" and got replaced as well as the spindle bearings.
 
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