[mactec54]

Just a short post this morning.

Description of photos are:

1) Before disassembling the machine, the drive assembly sounded overall quiet and generally smooth. The bearings were a little rough and the belts had taken shape as all belts do in time without running. Overall, it was something to work with. As I tore the machine apart I found the spline drive shafts worn, as shown in the photos. The top shaft, attached to the belt hub shows slight wear with rounding on the edges. The bottom driven shaft shows more wear, with much more rounding on the edges. I reassembled the head anyway, knowing the head would come back apart soon with a redesign on the horizon.

2) A blank piece of 6061 was thrown into the vice for a 'First Cut' test of the machine with varying result. I used a feed and speed calculator to determine the initial cut. Unfortunately, the SFM numbers vary quite a lot for 6061, so for a first test of the machine, this material is probably not the best. Regardless, the overall surface finish needs improvement.

3) New spline drive shafts. Notice the sharper corners of the teeth. Sit firmly in the chair as you price these parts out!

4) This is a handy book to have if you plan to disassemble the machine. There are detailed disassembly and reassembly procedures here with great photographs. My copy has an H&W sticker on the front. I'm not hawking their products, but their pricing is competitive and they ship quickly.

That is good to show others that they may have the same worn/damaged parts, and by replacing them you ended with a better cut result, these parts were damaged by bad gear changing, when they changed from high to low speed, you have to feel them as you engage them, by moving the spindle back and forward by hand, and it will drop into place, a lot of new user's would just move the lever, and press the start button, well they make a very loud grinding noise when that happens

[WilliamT4450]

I got around to replacing the Driven Spline Shaft on the machine yesterday. I became so tired of hearing the old shaft rattle and feeling the vibration coming through the head. See the photos at post #18 with photo #2 being the old shaft, and photo #4 showing the new shafts. The machine sounds so much better now, whereby, I can now hear the frequency noise of the drive motor over the other noises within the machine while running.

[WilliamT4450]

Stuff That Gets Broken

Going through the old Bridgeport is interesting. My 1965, Series 1 had problems when I bought it. Today, I'd like to discuss four of the problems I found with the machine and how I addressed them.

1) Spindle Pulley Bearing Sleeve ($138) Cam Ring Pin ($8) Socket Set Screws ($1) photo 1
When I disassembled the top of the machine I found one of the Cam Ring Pins loose and just spinning freely in the socket. I realized it was stripped, and indeed found the Socket Set Screw still in place. I used a Dremel and Fiber Disk to saw through the stripped Cam Ring Pin. It was an ugly, costly mess; about $160 for the new parts and saw disc, a couple of hours to cut the Cam Ring and to clean the saw dust, and of course a couple of days to order in the new parts.

It is easy to damage the Bearing Sleeve during disassembly. For those that don't know, the Bearing Sleeve is held in place by two Cam Ring Pins, 180 degrees apart. The Cam Ring Pins are held in place by two Socket Set Screws. These Set Screws must be removed first, before loosening the Cam Ring Pins, otherwise, the threads of the Bearing Sleeve will be damaged. Do yourself a favor, follow the disassembly procedures.

2) Cam Ring ($120) and the Spindle Clutch Lever ($21) photos 2 and 3
The Cam Ring is used to engage and disengage the upper Spindle Pulley Hub shaft from the lower Splined Gear Hub while using the back gear set. As shown by the photo, the Cam Ring was whacked many, many time over its service life. The threads of the handle and ring were stripped, and the handle was flopping around.

Replacing the Cam Ring and the Spindle Clutch Lever, given my non-existent use of them, for the moment is a low priority. I had them tig welded together instead of shelling out another 150 bucks. Yes, for you pixel peepers there is a surface crack in the weld. Be careful with your Cam Ring. It is cast iron, not machined steel.

3) Bearing Retaining Ring ($14) photo 4
The Bearing Retaining Ring is used three places on the machine. As the name implies, it is a bearing retainer and is used to hold the screw shaft bearings; the X axis (one side only), the Y axis, and the Knee Drive Shaft. There is not much to say about this failed part, except, the retainer is made of aluminum, looks like 6061. Just take care not to over torque the cap screws that hold it in place.

4) T-Bolt Assembly ($21) Lower Clamping Bolt Spacer ($19) photo 4
The old Bridgeport has seven T-Bolts; three attach the gear Housing to the Quill Housing, and four attach the Quill Housing to the Ram Adapter. The ones shown in the photo are the Quill Housing T-Bolts. I've read a number of discussions regarding these bolts and it appears they break quite often.

When I bought the machine, one of the T-Bolts was missing on the Quill Housing. After removing the Quill Housing I found the head of a broken T-Bolt laying in the T-Slot of the Ram adapter, meaning, the bolt had previously been broken off. No problem, since I ordered a replacement for it and another to have as spare.

Upon reassembly and while applying torque to the bolts, one of them snapped off at 40 ft/lbs. So, I had to remove the Quill Housing again to replace, yet another broken T-bolt. Lucky for me, having the spare T-Bolt on hand allowed me to finish the assembly. So be careful with them. Keep one or two spare bolts and nuts on hand. Apply good assembly methods, cross torque smoothly and evenly. And do not exceed the recommended torque value of 45 ft/lbs.

[kenztasos]

X and Y axis photos attached

all three handles remain

Please William do you have the design plans from y axis bracket assembly..
Thank you in advance

[WilliamT4450]

kenztasos, I'm unsure what you're asking. Are you seeking drawings, equipment specifications?

[kenztasos]

Hi William.
If my measurements is correct .... all I need is this dimension from y-axis bearing assembly bracket...attached picture with "???????"



thanks for reply

[WilliamT4450]

You've got the same numbers I came up with.

I chose the midpoint, both horizontal and vertical. With the hand crank on I drove the ball screw clockwise/counterclockwise a number of times to let it settle in before applying the final torque to the bolts.

[kenztasos]

Midpoint both ??? In vertical position is eccentric..
with your installation I think is wrong because ball screw and YOKE is not centering ....
thanks anyway..

[WilliamT4450]

I checked the drawing again and you are correct. The center is above the midpoint, at least 0.135"
But, the only way to know for sure is to take the bearing holder off, trace it onto paper, scan it, import the scan to AutoCad, check the scale, and then measure the center of the bearing against the bolt pattern. I did not do that because the bearing offset was not important to me.

[kenztasos]

I checked the drawing again and you are correct. The center is above the midpoint, at least 0.135"
But, the only way to know for sure is to take the bearing holder off, trace it onto paper, scan it, import the scan to AutoCad, check the scale, and then measure the center of the bearing against the bolt pattern. I did not do that because the bearing offset was not important to me.

I know that is the best , but I don’t want to take off the bearing because I need my BP to built the brackets manually .... :/ I do this method with the pdf file from BP cross slide power feed , the only data I found in web but the results is about 0,866” above the center ??? And I need to confirm before I start to built the bracket. ...
The bearing offset in not important fot me too... the only important thing for me is the bearing center!!!

[WilliamT4450]

Ok, there is a little maintenance for me to do on the y-axis anyway.

So, I'll pull it apart, make an impression of the bearing block and develop a CAD drawing. I can't do it today, however. My day today is already full. This will have to wait till tomorrow.

[kenztasos]

OK I would appreciate if you do that..
Thank you in advance anyway..

[WilliamT4450]

The bearing block is not flat on the backside. So it is impossible to make an impression of the bearing faces, and therefore make good measurements.

So the best to be done is to make hand measurements with a digital caliper. While this is not the best method, it will be close (kind of).

In looking at the bearing block, it is a piece of cast iron, machined where applicable, and left natural but somewhat cleaned where dimensional tolerance is not necessary. The cast iron block also has a slight draft from the backside facing forward. Finally, the perimeter of the bearing block is not machined, and therefore, is not a perfect surface to measure from.

For example: The top of the bearing block is generally flat across the middle for about three inches, then the surface angles down slightly until the edge fillet. This is common to all four corners. All this means is, considering the face drafts and imperfect edges, precise measurements cannot be produced.

But we get close. To get the measurements I simply measured from the top of the bearing block to the top of the cavity. Then I measured from the bottom of the bearing block to the bottom of the bearing cavity. Then I measured the OD of the bearing. The dimensions are, TOP 0.935, BOTTOM 1.195, BEARING 1.845. When they are totaled together the dimension measurement is 3.975. When the part is measured from top to bottom, the measurement is 3.985. So there is about 0.010 difference. So we're ten thousands off, using incorrect tools and methods.

I said yesterday that the center is at least 0.135 up from the midpoint. With the recent measurements today, it appears to be closer to 0.130.

[mongoose]

I take no notice of how people respond to my posts, I used to fire back, but that solves nothing, I don't think there was any controversy, I just made a statement, that other should look at all options before buying

Until you posted the Photos of your Build most, can't relate to what you were Posting, so Photos are good, if you want reply's, You will always have lots of lookers, I used to rebuild build Bridgeport machines, by the dozen, and CNC retro fit them, I only have one now that I just experiment with, like trying different servo Drives Motors Breakout Boards and different controls, here is a photo of the one I have left, this has may modifications, 6,000 RPM Spindle with Rigid Tapping, this mill now is getting a full Z axes with linear Rails, so will have a Head like a Machining Center has, this is just a spare time project

Mactec, that is a beautiful machine, do you have a build thread on it ? Im starting the journey on building my own and would love to know what steppers / servos / power supplies / drivers you used

Joe

[Johns tool room]

The motor is a 3 hp 3 ph Bridgeport motor 3450 RPM some had these motors as standard, it is driven by a Yaskawa VFD Drive at 120 Hz giving it double the rated RPM, the spindle has a Erickson 30 Taper, which was also a standard on some machines, this spindle can run to 12,000 RPM as I have modified most of it, nothing in the Head is standard Bridgeport, the Head in the photo, is 5" shorter than the standard Head

A Servo can work quite well for a spindle drive, and you have the benefit of being able to set it up just like an axes and have very tight positioning control, you would need different type of pulleys if you want accurate positioning of the spindle, servo motor size also would want to be no less than 1.5Kw if you were just replacing the 1Hp you have, the problem is as the servo motors get higher Hp the RPM also drop

so basically if I want those high end RPM on MY V2XT I need to get rid of that pesky back gear drive system. Wouldn't mind having greater than 3 Kw servo motor on that thing, but you thinking a dedicated inverter motor is the best option, one hat has an encoder on there? What does getting rid of that back gear entail? I know not too long from now will be getting rid of the vari drive parts, so just add the back gear to that equation.

[mactec54]

so basically if I want those high end RPM on MY V2XT I need to get rid of that pesky back gear drive system. Wouldn't mind having greater than 3 Kw servo motor on that thing, but you thinking a dedicated inverter motor is the best option, one hat has an encoder on there? What does getting rid of that back gear entail? I know not too long from now will be getting rid of the vari drive parts, so just add the back gear to that equation.

Today a 3Kw or 3.5Kw Ac Servo motor / Drive would be a better choice than the original Ac motor, which was only 3Hp, there are some other choices, there are some Chinese Spindle motors that will run to 8000 RPM 4 pole which are good also for machines like yours here is a link to these Spindle Motors

https://www.alibaba.com/product-deta...10503134JWlTL3

https://szghauto.en.made-in-china.co...Motor-Kit.html

[Johns tool room]

Since you got me convinced hook line and sinker. Was thinking. I Have a brake resistor for my VFD about 2 days away from arriving and if it is only a temp part of the cabinet. Have any idea how to temporarily mount it on? Use two magnets that are threaded? Something else?

[mactec54]

Since you got me convinced hook line and sinker. Was thinking. I Have a brake resistor for my VFD about 2 days away from arriving and if it is only a temp part of the cabinet. Have any idea how to temporarily mount it on? Use two magnets that are threaded? Something else?

Just clamp it on the side some where you don't want the Braking resistor to fall off and short out as that would fry the VFD Drive, does your VFD Drive have the Braking resistor in the specs for the drive, not all come with the needed electronics installed