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Related Manuals for Bridgeport J-Head Series
Summary of Contents for Bridgeport J-Head Series
- Page 1 Bridgeport J-Head Series I Mill Rebuild Document Number: BPJ1RBLD_002 Document Version: 2.0.01 Document Version Date: January 31, 2011 Hoffman Mechatronics Prepared By: 496 Albrough Blvd. Colonial Beach, Va 22443 mike_hoffman@verizon.net...
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Page 2: Table Of Contents
Hoffman Mechatronics Bridgeport Mill J1 Rebuild Table of Contents Document Information ..................... 6 1.1 Disclaimer ............................6 1.2 Notes from the Author........................6 1.3 Copyright............................6 1.4 Document Organization ........................7 1.5 Change History ..........................7 1.6 Dedications and Acknowledgements....................7 Mill Overview........................ - Page 3 8.1 Knee Section Removal ........................48 8.2 Knee Section Inspection ........................50 8.3 Knee Section Reassembly....................... 51 Tramming the Mill ......................52 9.1 Bridgeport Method ........................... 52 9.2 Bearing Race Method ........................53 9.3 Tramming to the Vice........................53 10.0 Maintenance & Lubricants ..................... 54 10.1 Backlash Adjustment ........................
- Page 4 Hoffman Mechatronics Bridgeport Mill J1 Rebuild 12.6 Phase 4 – The Z Axis ........................63 12.7 Phase 5 – The Planetary Gearhead for Z Axis................64 12.8 Software packages .......................... 65 12.9 The Moral of the Story ........................65 13.0 Reference Documents and Websites................67 13.1 Documents............................
- Page 5 Hoffman Mechatronics Bridgeport Mill J1 Rebuild Table of Figures Figure 1 - Mill ID Plate ..........................8 Figure 2 - J Head Figure 3 - Table and Knee ..................9 Figure 4 - Grub Screws, note the hollow locking screw................11 Figure 5 - Motor Nuts..........................
- Page 6 Hoffman Mechatronics Bridgeport Mill J1 Rebuild Figure 57 - Knee Lube Fittings ......................... 56 Figure 58 – CNC Electronics ........................60 Figure 59 – X Axis Drive Tube ......................... 62 Figure 60 – Y Axis Drive Tube ......................... 62 Figure 62 – Z Axis Installation ........................64 Figure 63 –...
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Page 7: Document Information
1.2 Notes from the Author This document was created during the rebuild of my personal 1963 Bridgeport Series I J-Head, Stepped Pulley Mill. Much of the information presented in this document is from my own personal experiences, and all of the images that are located throughout the document were taken by me using a Nikon Coolpix 4300 and a Nikon D70s. -
Page 8: Document Organization
You will quickly note that I have tried to organize this document to the corresponding parts of the Bridgeport Mill. I believe it will make this document easier to follow should someone be trying to solve a specific problem. It also tends to follow the order of disassembly if someone is starting to completely disassemble their mill for the first time. -
Page 9: Mill Overview
2.1 Mill Description The mill that I am rebuilding throughout this document is a 1963 Bridgeport Series I J-Head Mill. The mill was identified by a brass plate in Figure 1 below that was installed by the US Navy. -
Page 10: Why Would I Do This
I needed a mill, and why should I buy a mill that is advertised as a Bridgeport Clone, when I could have a Bridgeport? My decision to rebuild this mill was quickly justified after a 5pm telephone call one evening from a technician at Hardinge Tools. -
Page 11: Disassembly/Reassembly Suggestions
I also tend to make notes and draw pictures of things that I find “very interesting”. With regards to the Bridgeport, one of the items that I marked as “very interesting” was the type of grub screws they used for securing parts, then securing the grubs. I had never quite seen an arrangement like this, so I noted it with pictures and notes. -
Page 12: Figure 4 - Grub Screws, Note The Hollow Locking Screw
This list of parts helped me tremendously, because during the teardown I began to see Bridgeport parts that I needed on the online auctions. I would venture to say that I have saved about $200 on the rebuild of this machine by finding items online for much less than the replacement costs. -
Page 13: Motor And Drive Section
3.1.1 Motor Removal The motor on a Bridgeport mill is fairly easy to remove. You need to release the nuts that secure it to the drive housing portion of the mill as shown in Figure 5 below, remove the belt, disconnect any power cables, and lift the motor off the unit. -
Page 14: Motor Reassembly
Hoffman Mechatronics Bridgeport Mill J1 Rebuild inspection on the motor is the motor bearings. Once the motor has been removed from the mill, you should be able to easily turn the motor shaft with your hand. The operation should be smooth and uniform. -
Page 15: Drive Housing Section
Hoffman Mechatronics Bridgeport Mill J1 Rebuild Modulation (PWM) to the motor to maintain the selected RPMs even under load. I have done this before in my line of work at 12 and 24VDC. I am just hoping that I don’t kill myself with the 90-110VDC that this motor requires. -
Page 16: Figure 7 - Power Head Mounting
Hoffman Mechatronics Bridgeport Mill J1 Rebuild Power Head Power Head Mounting Nut Mounting Nut Power Head Mounting Nut Figure 7 - Power Head Mounting I found it easier to separate the drive housing cases by removing the timing belt from the larger timing belt pulley first. -
Page 17: Drive Housing Inspection
Hoffman Mechatronics Bridgeport Mill J1 Rebuild Drive Housing Bolts Alignment Pin Alignment Pin Back Gear Shifter Figure 9 - Bolts Fastening Drive Housing Together 3.3.2 Drive Housing Inspection There are several sets of bearings in the drive housing that should be inspected prior to placing the drive housing back in service. -
Page 18: Drive Housing Reassembly
Hoffman Mechatronics Bridgeport Mill J1 Rebuild 3.3.3 Drive Housing Reassembly As you can see from Figure 10 above, you will want to grease all of the bearings very well during reassembly. Ensure that you grease the shift linkage as well. Check all items for freedom of movement and then reassemble the gear housing cover as shown in the Figure 11 below. -
Page 19: J-Head Section
Hoffman Mechatronics Bridgeport Mill J1 Rebuild 4.0 J-Head Section This by far is the most important and most complex portion of the mill. The J-Head houses the Quill and Spindle which are the main moving parts responsible for the milling operations. The spindle holds the bits that you will use in your milling operations, and the quill provides for the vertical movement, and bearing surfaces for the spindle. -
Page 20: J-Head R & R
Hoffman Mechatronics Bridgeport Mill J1 Rebuild In this section of the document I will attempt to clarify the disassembly and reassembly of the various subassemblies that make up the J-Head. The order of disassembly allows someone to fully disassemble and categorize their parts on a subassembly basis. -
Page 21: J-Head Reassembly
I have not included any procedures for adjusting the overload clutch simply because unless something is broken in your clutch assembly, it rarely needs adjusting and the Bridgeport manual states that it should be done by an authorized Bridgeport Repair Facility. -
Page 22: Quill Pinion Shaft Inspection
Hoffman Mechatronics Bridgeport Mill J1 Rebuild Note: Be careful when removing the clutch cover not to lose the overload clutch lever spring or plunger as illustrated in Figure 14 below. Overload Clutch Lever Spring & Plunger Figure 14 - Overload Lever Plunger and Spring The next part that needs to be removed is the worm gear assembly which contains the overload clutch ring and the worm gear. -
Page 23: Quill Pinion Shaft Reassembly
Based on Figure 16 below, you will note that there are a few pieces that have to be removed before the micrometer screw can be removed. The Bridgeport Owners Manual covers the removal of the Micrometer Screw very well. There is a small screw pin that holds the trip lever in place. -
Page 24: Quill Stop Inspection
Hoffman Mechatronics Bridgeport Mill J1 Rebuild With these parts removed, you should be able to remove the micrometer screw by pulling down as you screw the micrometer dial and locknut towards the top. Once the screw has been removed, you can remove the quill stop by removing the 3/8” cap screw. -
Page 25: Quill And Spindle Inspection
Hoffman Mechatronics Bridgeport Mill J1 Rebuild Figure 17 - Homemade Spanner Nut Wrench Once you have the removed the motor and drive sections from the mill then follow the steps for removing the Quill Pinion Shaft and the Quill Stop. Once these parts are removed, lift the quill skirt out of the upper part of the J-Head, and the quill and spindle assembly should be able to be pushed down and out of the J-Head. -
Page 26: Spindle Bearing Reassembly/Replacement
If you examine the race carefully you will note that there is a thick side and a thin side to the faces. In the Bridgeport mill, the orientation is that the thick sides face each other, see figure 18 above. -
Page 27: Figure 19 - Note The Alignment Marks On Outer Races Preparing For Next Step
Hoffman Mechatronics Bridgeport Mill J1 Rebuild asterisk (*) on the inner race of the first bearing with this mark on the spindle. I then pressed the first bearing down into place. After having checked to ensure that the bearing did not erase my mark, I slipped both the inner and outer bearing spacers onto the spindle, and taped the outer spacer to the outer race on the lower bearing just to keep it in place for the next pressing operation. -
Page 28: Figure 20 - Aligning With Nosepiece Screw Hole
Hoffman Mechatronics Bridgeport Mill J1 Rebuild Figure 20 - Aligning with Nosepiece Screw Hole 4.4.2.3 Pressing the Upper Spindle Bearing into the Quill The upper spindle bearing is much simpler in both makeup and installation. Prior to installing the upper spindle bearing, you should install the upper spindle bearing spacer. You can now insert the bearing and press it into place. -
Page 29: On Machine Spindle Extraction
Hoffman Mechatronics Bridgeport Mill J1 Rebuild to form the quill skirt around the quill, and then slide it into place and secure it with one of the screws. NOTE: On my mill, the quill skirt faced down with the tabs at the top, and the opening was towards the pinion gear for the quill. -
Page 30: Feed Driving Gear Assembly Removal
Hoffman Mechatronics Bridgeport Mill J1 Rebuild 4.6.1 Feed Driving Gear Assembly Removal To disassemble this unit, you will need to first remove the Cluster Gear Shift Fork Cover and the Feed Engagement Cover. You can then remove the Worm Gear Cradle Assembly. The Worm Gear Cradle Assembly is held in place by the Worm Gear Cradle Grub Screws as shown in Figure 23, and the nut on the top of the Input Shaft. -
Page 31: Feed Driving Gear Assembly Inspection
Hoffman Mechatronics Bridgeport Mill J1 Rebuild 4.6.2 Feed Driving Gear Assembly Inspection Inspect all of the gear teeth to ensure that they are not worn, and that there are no teeth missing. If you find excessive wear, or absent teeth, replace the offending part. You will want to inspect the roller bearing at the end of the Cluster Gear Input Shaft for dirt, rust, or jerky movement. -
Page 32: Turret Section
I don’t think I can emphasize enough that the Bridgeport is a heavy machine, and some of these components are just dangerous to move. The turret assembly is one of the heaviest and most awkward components. -
Page 33: Ram Adapter Rir
Hoffman Mechatronics Bridgeport Mill J1 Rebuild 5.1 Ram Adapter RIR The Ram Adapter allows you to tilt the J-Head forward and back through an arc of 90 degrees, 45 degrees up and 45 degrees down. It also provides you with the ability to rotate the J-Head along the Z axis through an arc of 360 degrees. -
Page 34: Ram Rir
Hoffman Mechatronics Bridgeport Mill J1 Rebuild 5.2 Ram RIR The Ram allows you to move the J-Head in and out utilizing a Locking Rack and Pinion arrangement. Figure 27 - Ram Assembly 5.2.1 Ram Removal Figure 28 below shows the clamps that are used to lock the Ram to prevent movement. Loosen these clamps prior to attempting removal of the Ram. -
Page 35: Ram Reassembly
Hoffman Mechatronics Bridgeport Mill J1 Rebuild oil. It creates a nice flat surface without removing too much material, and if kept lubricated, leaves a nicely polished surface that will slide easily. The stones are also relatively cheap. Please keep in mind that this procedure is for cleaning an already trued surface. If your surface is not flat to start with, you may be required to scrape it true first. -
Page 36: Turret Rir
Hoffman Mechatronics Bridgeport Mill J1 Rebuild Figure 30 - Ram Sliding Fixture You can then reinstall the pinion gear for the Ram. You may have to jiggle the ram back and forth to engage the teeth of the ram pinion. Once it has been inserted, you can insert the ram pinion retaining bolt which completes the Ram Reassembly. -
Page 37: Turret Inspection
Hoffman Mechatronics Bridgeport Mill J1 Rebuild Turret Retainer Bolts Turret Cross Member Figure 31 - Turret Bolts and Cross Member 5.3.2 Turret Inspection The sliding surfaces on the turret for the Ram Assembly should be cleaned and lubricated to ensure smooth movement of the Ram Assembly. You should also examine the Ram Pinion Gear and the Ram to ensure that none of the teeth are broken or chipped. -
Page 38: Figure 33 - Turret Cross Member
Hoffman Mechatronics Bridgeport Mill J1 Rebuild Once the turret is in place on the base pedestal, you can reach through the pedestal door with one arm to hold the cross brace while inserting the bolts through the turret. Figure 33 below shows a view of the cross member that most people don’t generally see. -
Page 39: Lead Screw Bearings & Brackets Rir
Bridgeport Mill J1 Rebuild 6.0 Table Section The Bridgeport Table was designed for a very specific set of purposes. It was designed to hold the work piece, and to provide a precision flat surface. To accomplish these tasks, the table has been designed with T-Slots to assist with the holding of work pieces, and milled and scraped to a precision flatness to increase the accuracy of milling operations. -
Page 40: Lead Screw Bearings & Brackets Inspection
I was fortunate enough to find a bracket from a gentleman who had performed a CNC Conversion on his Bridgeport and made up new brackets. Figure 35 below illustrates the broken bracket, and the replacement bracket is illustrated in Figure 36. -
Page 41: Figure 36 - Bearing Bracket With Bearings Installed
Hoffman Mechatronics Bridgeport Mill J1 Rebuild Figure 36 - Bearing Bracket with Bearings Installed 6.2 Table X&Y-Axis Gib RIR The X-Axis Gib slides in from the left front portion of the Saddle. It is adjusted with the Gib Adjusting Screw as seen in Figure 37 below. -
Page 42: Figure 39 - Y-Axis Chip Wiper Cover
Hoffman Mechatronics Bridgeport Mill J1 Rebuild 6.2.1 Table X&Y-Axis Gib Removal Removal of the Gib starts with the removal of the chip wiper covers and felt chip wipers. The chip wiper covers are secured to the Saddle with small Flat Head Screws as shown in Figure 39. - Page 43 6.3 Table RIR The table on the Bridgeport Mill comes in various sizes. My table is 36” x 9”, and I have seen the following table sizes as well: 32” x 9”, 42” x 9”. Most of the tables on the Mills are interchangeable as long as you are willing to change the X-Axis Lead Screw, and scrape the ways to match the table to the Saddle.
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Page 44: Figure 41 - Table Nearly Ready For Removal
Hoffman Mechatronics Bridgeport Mill J1 Rebuild Figure 41 - Table Nearly Ready for Removal With all of these components removed, the table should be free to slide off of the mill. The only exceptions could be any way oiling, or flood fluid return plumbing that may be connected. Please ensure that all peripherals are removed prior to sliding the table off. - Page 45 Hoffman Mechatronics Bridgeport Mill J1 Rebuild made to fit the way surfaces and milled the surface to remove most of the defects. I still have some small drill marks, but these do not adversely affect the accuracy of the surface.
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Page 46: Saddle Section
Hoffman Mechatronics Bridgeport Mill J1 Rebuild 7.0 Saddle Section The saddle is used to support the table and to house the acme lead screws which are used to control the X and Y axes for the table. There are several lubricant fittings on the saddle. It should be noted that these are not grease fittings. -
Page 47: Saddle Section Inspection
Hoffman Mechatronics Bridgeport Mill J1 Rebuild NOTE: If your machine utilizes ball screws instead of lead screws be sure to secure the ball screw nut so that the ball screw cannot be removed from the ball screw nut. In the case of ball screws there are generally bolts that secure the ball screw nut to the ball screw nut bracket. -
Page 48: Saddle Section Reassembly
Hoffman Mechatronics Bridgeport Mill J1 Rebuild cleaners through these passages to ensure that they are unobstructed. I used a combination of cleaning brushes designed to clean oil ports in automotive engines, and pipe cleaners. You will also want to check all the way surfaces to ensure that they are clean and free from rust, and debris. -
Page 49: Knee Section
Hoffman Mechatronics Bridgeport Mill J1 Rebuild 8.0 Knee Section The knee provides the gross vertical movement for the table. In most cases you will perform your gross vertical movements with the knee crank, and then use the quill micro feed for any fine adjustments. -
Page 50: Figure 47- Removing/Reinstalling The Knee
Hoffman Mechatronics Bridgeport Mill J1 Rebuild Figure 47– Removing/Reinstalling the Knee Once you have removed the knee from the mill base, you can start to disassemble the knee by removing the crank assembly. Start by removing the crank and dial assembly as shown in Figure 48 below to expose the Bearing Plate Bolts. -
Page 51: Knee Section Inspection
Hoffman Mechatronics Bridgeport Mill J1 Rebuild Elevating Screw Nut Figure 49 - Knee Elevating Bevel Gears Once you have removed the nut, the bevel gear can be slid off the elevating screw. You should then remove the bevel gear key from the elevating screw. The elevating screw can then be pushed through the bearings and out of the knee. -
Page 52: Knee Section Reassembly
Hoffman Mechatronics Bridgeport Mill J1 Rebuild All of the bearings are easy to change, and thanks to the knee lock and removable elevating screw housing, even the elevating screw bearings can be removed with or without disassembling the entire knee and table assembly. If you intend to attempt this, you will need to raise the knee as high as it will go with the elevating screw, attach a lift to the table, and then raise it another inch and lock the knee in place using the knee lock. -
Page 53: Tramming The Mill
Basically, tramming is the act of aligning the mill with respect to all of its axes. Since there are several ways to do this, I have broken this section up to illustrate the Bridgeport method, and the bearing race method. As people provide me with additional methods, or improvements on these methods, I will include those as well. -
Page 54: Bearing Race Method
Hoffman Mechatronics Bridgeport Mill J1 Rebuild 9.2 Bearing Race Method You will note that in the above procedures you have to be very careful with the dial indicator while tramming the mill. The interference caused by the T-slots can be annoying, induce inaccuracies, and be downright dangerous to your precious dial indicator. -
Page 55: Maintenance & Lubricants
To adjust the X-Axis feed nut backlash, you should first move the table all the way to the left. Reset the Bridgeport dial to 0. While watching the dial on the X-Axis handle, start to turn the handle to move the table back towards the right and observe how many tick marks pass before the table starts to move. -
Page 56: Feed Trip Adjustment
Bridgeport Mill J1 Rebuild 10.2 Feed Trip Adjustment The Bridgeport Quill Feed is a very useful feature of the Bridgeport Mill, but it must be adjusted properly to prevent damage to the feed mechanism within the mill. Figure 54 below illustrates the components used during the feed trip adjustment. -
Page 57: Way Lubricant
Hoffman Mechatronics Bridgeport Mill J1 Rebuild 10.4 Way Lubricant Way lubricant is used to provide the sliding surface protection and lubrication for the way surfaces. Because the way oil must remain on vertical surfaces it is designed to grip and stay on all surfaces. -
Page 58: Troubleshooting
Hoffman Mechatronics Bridgeport Mill J1 Rebuild 11.0 Troubleshooting 11.1 Quill does not go more than 3-4 inches down. Generally this is an indication that the quill skirt has either been placed in the machine upside down, or has been reversed front to back. -
Page 59: Where Do You Start
CNC mill that has a bad controller. There are people in the CAMS group that have taken older Bridgeport CNC machines and converted them to use the Gecko drives and Mach3 software with the existing stepper motors. There are others that have had to replace the existing drive systems completely. -
Page 60: Phase 2 - The Electronics
12.4.1 Open Loop System For my Bridgeport Mill, I was fortunate enough to have an old HP eVectra computer. It is a small frame computer with a 1Ghz processor, 1gb of memory, and a 40gb hard drive. While this system cost me nothing, you can figure on spending about $200-400 for a decent computer capable of running a CNC mill. -
Page 61: Figure 58 - Cnc Electronics
Hoffman Mechatronics Bridgeport Mill J1 Rebuild Design, during a meeting of the Chesapeake Area Metalworking Society and have always found him to be more than helpful. His products are well thought out and the interfaces are painless. As motor drives, I used the Gecko Drive products from https://www.geckodrive.com... -
Page 62: Closed Loop System
Bridgeport Mill J1 Rebuild 12.4.2 Closed Loop System For my Bridgeport Mill, I could like to complete the mill as a closed loop system. To date I have looked at two options; the GRex-G100, and a full fledged PCI Stepper controller. -
Page 63: Figure 59 - X Axis Drive Tube
Hoffman Mechatronics Bridgeport Mill J1 Rebuild drawing issues. You will also see that in the drive tube pictures, the hole for the Y axis handle is significantly different from the hole for the X axis handle. This is because the X axis bearing cap could easily be assembled with the drive tube and then installed on the mill, but the Y axis could not. -
Page 64: Phase 4 - The Z Axis
12.6 Phase 4 – The Z Axis I have looked at a lot of commercial CNC mills based on the Bridgeport design and I have been less than thrilled with their implementations of the Z Axis. Mine is not the most accurate, but does preserve the original machine without destruction. -
Page 65: Phase 5 - The Planetary Gearhead For Z Axis
Hoffman Mechatronics Bridgeport Mill J1 Rebuild to drive the Z from the rack and pinion of the hand crank. I did not want to lose the ability to pivot the head on the mill, so I centered the drive system at the pivot shaft. While a 3:1 reduction was not ideal for this installation, it did suffice until I was able to find a planetary gearhead for this axis. -
Page 66: Software Packages
Hoffman Mechatronics Bridgeport Mill J1 Rebuild Figure 63 – Z Axis Planetary Gearbox Installation 12.8 Software packages I am not going into a great deal of detail here because too many other people have already done this and I would only be plagiarizing their work. Suffice it to say that I currently run MACH3 software on my mill from http://www.artofcnc.ca... - Page 67 Hoffman Mechatronics Bridgeport Mill J1 Rebuild about the capabilities of my machine as I moved forward. There was even a great satisfaction in using the machine to build its own parts. As for all the parts, I have drawings for all of them. Some need some tweaking, others are just fine the way they are.
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Page 68: Reference Documents And Websites
Hoffman Mechatronics Bridgeport Mill J1 Rebuild 13.0 Reference Documents and Websites 13.1 Documents Bridgeport Series I Vertical Milling Machine Operation and Maintenance Manual, Part # 1800234. Bridgeport Machines Inc, Operators Manual, 1966. 13.2 Websites Chesapeake Area Metalworking Society http://www.cams-club.org/ CNC Zone http://www.cnczone.com/... - Page 69 The following image depicts the drawing I used to develop the spanner wrench that could be used to adjust the clockwork spring on my Bridgeport Mill. If you need specifics on this wrench, please let me know. I actually even have the TurboCAD and CNC g-code to generate this handy little tool.
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