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Hoffman Mechatronics 

Bridgeport Mill J1 Rebuild 

BPJ1RBLD_002  

 

January 31, 201111 

1.4  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. One of the last sections of the 
document deals with troubleshooting. Although this portion is rather small now, I am hoping that 
I can add to this as more and more people provide questions, and solutions to common and not so 
common problems. 

NOTES:

 are included in the document where I think something bears bringing attention to. 

CAUTIONS:

 are highlighted where someone may be injured if proper safety precautions are not 

taken. 

1.5  Change History 

Revision   Date 

Changed By 

Change Description 

Draft 

8/29/2005 

M. Hoffman 

Initial draft 

Draft 0.01 

10/15/2005 

M. Hoffman 

More images, callouts, and tense corrections. 

1.0.00 

8/22/2006 

M. Hoffman 

More images, more text, and review of all figures 

 

 

 

 

1.6  Dedications and Acknowledgements 

First and foremost I want to dedicate this manual to my wife who has put up with my insane 
hobbies and business ideas for some 21 years. She is the one who carries me to the hospital when 
I do stupid things, and then cares for me at home until I am once again able to do more stupid 
things. 

Secondly I want to thank my brother for showing me this amazing machine, and putting the idea 
in my head that I could rebuild it and make it new again. 

I also wanted to send out a special thanks to the Chesapeake Area Metalworking Society 
(CAMS). From the very beginning they have supported my efforts and offered to help with 
everything. Sorry guys, I won’t be bringing the finished mill in for “Show n Tell”, but I will 
bring pictures! 

The following people have helped me considerably along the way, and this document would be 
so much less without their inspiration and guidance. 

Kirk Burns & Machinist Preston 

(Burns Machine Shop, King George, Va) 

Gary 

Gelts 

 

   (Hardinge/Bridgeport) 

Jonathan 

Gavel   (CAMS) 

Eric 

Hoffmeyer   (CAMS) 

Leigh 

Basset 

   (CAMS) 

 
 

Содержание J-Head Series

Страница 1: ...ad Series I Mill Rebuild Document Number BPJ1RBLD_002 Document Version 2 0 01 Document Version Date January 31 2011 Prepared By Hoffman Mechatronics 496 Albrough Blvd Colonial Beach Va 22443 mike_hoff...

Страница 2: ...n 18 4 1 J Head R R 19 4 1 1 J Head Removal 19 4 1 2 J Head Reassembly 20 4 2 Quill Pinion Shaft RIR 20 4 2 1 Quill Pinion Shaft Removal 20 4 2 2 Quill Pinion Shaft Inspection 21 4 2 3 Quill Pinion Sh...

Страница 3: ...on 46 7 3 Saddle Section Reassembly 47 8 0 Knee Section 48 8 1 Knee Section Removal 48 8 2 Knee Section Inspection 50 8 3 Knee Section Reassembly 51 9 0 Tramming the Mill 52 9 1 Bridgeport Method 52 9...

Страница 4: ...ld 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 67 13 2...

Страница 5: ...9 Figure 23 Feed Driving Gear Assembly 29 Figure 24 Reverse Feed Gear Assembly 30 Figure 25 Reverse Feed Gear Removal 31 Figure 26 Ram Adapter 32 Figure 27 Ram Assembly 33 Figure 28 Turret Base and Ra...

Страница 6: ...ild 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 Z Axis Planetary Gearbox Insta...

Страница 7: ...I thought that others may want some of the same information Secondly I wanted to give something back to the home machining community that has provided so much useful information to me Where possible I...

Страница 8: ...0 01 10 15 2005 M Hoffman More images callouts and tense corrections 1 0 00 8 22 2006 M Hoffman More images more text and review of all figures 1 6 Dedications and Acknowledgements First and foremost...

Страница 9: ...2 2 Repair Estimates After my initial look at the mill I estimated that it would cost about 1000 to get the mill operational again and based on the articles I have read in the forums I estimated that...

Страница 10: ...expecting them to brush me off because I am a home user with a 42 year old machine I left a voicemail message and went about trying to find the information I needed elsewhere Imagine my surprise when...

Страница 11: ...se a lot of the cheap zipper sandwich bags and boxes from the local super market I find that I can throw a note or drawing inside the bag with the parts and it will keep things together until I am rea...

Страница 12: ...egan 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 repla...

Страница 13: ...rsepower motor was considered a powerful motor and many of the larger surfacing bits were not being used I would recommend that you attempt to work with the motor that you have before considering a re...

Страница 14: ...the motors differ slightly among the models you should do what works best for your motor Once the bearings have been installed and the motor has been reassembled you can loosely install the step pulle...

Страница 15: ...igure 6 below houses the stepped pulley assembly spindle brake assembly and all of the spindle drive components for the mill including the back gear Within this assembly the power from the motor is tr...

Страница 16: ...and over the top of the pulley You will not be able to remove the belt at this time but at least it will be out of the way These screws secure the top portion of the pulley Removing them makes timing...

Страница 17: ...Spindle Bull Gear Bearings are located beneath the Spindle Bull Gear Assembly To remove the Bull Gear Bearings you will have to remove the Bull Gear Assembly by removing the spanner nut located on th...

Страница 18: ...round the pulley using a cable tie You can then slide the timing belt over the spindle drive timing pulley You are now ready to start assembling the drive housing As you move the two housings together...

Страница 19: ...vement and bearing surfaces for the spindle The J Head mill has a wide variety of options and functions that may be controlled such as quill feed speeds quill feed directions quill feed engagement and...

Страница 20: ...removed the motor and drive assembly before attempting to remove the J Head This makes the unit more manageable and much lighter J Head Mounting Bolts J Head Mounting Bolts J Head Mounting Bolts J Hea...

Страница 21: ...d tighten them up 4 2 Quill Pinion Shaft RIR The Quill Pinion Shaft provides the drive mechanism for raising and lowering the Quill both from gross manual movement which uses the Quill Feed Handle to...

Страница 22: ...ft has been pushed through Note that there is a spacer behind the worm gear assembly Cir clip that holds the worm gear in place Figure 15 Overload Clutch Ring and Circlip 4 2 2 Quill Pinion Shaft Insp...

Страница 23: ...It also provides you with a means to turn off or trip the quill feed at a specified depth 4 3 1 Quill Stop and Quill Indicator Removal To remove the quill indicator scale there are two small 6 32 rou...

Страница 24: ...removing the quill and spindle as an assembly and then disassembling on the bench If you however just need to change spindle bearings there is an On Machine Spindle Extraction procedure listed in sect...

Страница 25: ...above concerning the removal of the spanner nut then your task ahead is really very simple You will need to remove the nose piece from the quill This nosepiece is secured by a small grub screw Once th...

Страница 26: ...t for my unit they came in a single box packaged together and had a small set of instructions that detailed their installation guidelines One of the items you must pay close attention to is the axial...

Страница 27: ...igure 19 illustrates the spindle assembly ready to go into the quill You will note that I used masking tape to hold the marks in alignment The tape is removed as the parts are all pressed into the qui...

Страница 28: ...Supporting only the quill will result it you pressing the spindle back out of the quill again Once you have pressed the upper spindle bearing in install the lock washer and the spanner nut Tighten th...

Страница 29: ...thing is attached to it but leave the spanner nut tight as you will be pushing out the whole spindle assembly with bearings installed Place a board or something on the table to protect the table in th...

Страница 30: ...ar Cradle Assembly Once you have removed the Worm Gear Cradle Assembly you can remove the rest of the Feed Driving Gear Assembly Start by removing the grub screws that secure the Cluster Gear Shaft as...

Страница 31: ...o not so loose that the teeth chatter excessively Experiment with tapping this shaft downwards until the gears no longer move smoothly and then backing the shaft up until the gears once again move smo...

Страница 32: ...set of maintenance 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 mo...

Страница 33: ...vent and wiggling back and forth before it would come off the ram Once it was off I could see that the internal cavities of the Ram Adapter had acquired some rust and hardening of grease Cleaning the...

Страница 34: ...ly heavy and cannot be managed alone When I slid this unit off of my mill it was supported with an engine lift and the sliding was performed using a hydraulic ram remember my ram was stuck to the turr...

Страница 35: ...the turret base and center them in the base so that the Ram will not hit them when slid back on Lubricate the slides liberally with a high quality lubricant and slide the ram back onto the turret base...

Страница 36: ...5 3 1 Turret Removal You should first follow all of the procedures for removing the Power Head J Head and Ram from the Turret Once you have completed these there are 4 bolts that secure the Turret to...

Страница 37: ...n Gear and the Ram to ensure that none of the teeth are broken or chipped My unit was rusted quite a bit and I was also required to clean the dial indicator portion of the turret 5 3 3 Turret Reassemb...

Страница 38: ...ow shows a view of the cross member that most people don t generally see I took this picture from inside of the base pedestal looking up to illustrate the boss extrusions that the cross member will re...

Страница 39: ...years of use and abuse and sometimes need to be resurfaced to restore the original flatness of the heads Machine tables are very much the same They can be machined ground and scraped just as with aut...

Страница 40: ...acket 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...

Страница 41: ...Figure 38 below the Gib and the Saddle form a parallel with matching angles By sliding the Gib in you effectively increase the thickness of the saddle wall which squeezes in on the table I would norm...

Страница 42: ...Gib Adjusting Screws Chip Wiper Retaining Screws Figure 39 Y Axis Chip Wiper Cover The Gib Adjusting Screw for the X Axis is located in the forward left portion of the Saddle The Gib Adjusting Screw f...

Страница 43: ...hine wears the centers of the ways will wear first Your first indication of this might be binding on the ends of travel if you happen to adjust the Gib while the axis is in the center of its field of...

Страница 44: ...rebuilding facilities this is done with the use of specially built granite or cast standards These standards are manufactured to the correct angle and dimension of the ways and used with surface plat...

Страница 45: ...sliding it onto the saddle You should install the gib next and loosely secure it before you remove you lifting device from the table If your ways are extremely well done it is possible for this table...

Страница 46: ...an automatic or manual pump lubricant system to the mill you will most likely replace these fittings with tubing and fittings to supply the lubricant The Saddle is shown in Figure 43 below Figure 43...

Страница 47: ...ilizes ball screws you want to do everything you can to make sure the ball screw nut does not come off the ball screw Once the lead screws or ball screws have been removed you can remove the lead scre...

Страница 48: ...ll screws 7 3 Saddle Section Reassembly Saddle reassembly follows the reverse order of disassembly Be sure to lubricate all way surfaces and the lead screws There are a couple of key items to remember...

Страница 49: ...ng bolt while slowly moving the knee downwards This puts less pressure on the section of the Gib that the Gib adjusting bolt presses against I have heard numerous reports of people breaking off the to...

Страница 50: ...n in Figure 48 below to expose the Bearing Plate Bolts With the Dial removed you can remove the bearing plate bolts and pull the elevating shaft from the knee Bearing Plate Bolts Figure 48 After the C...

Страница 51: ...over and remove the bearing retainer ring as shown in Figure 50 below The bearings can then be pressed out through the bottom of the knee Figure 50 Elevating Screw Bearing Retainer Ring 8 2 Knee Secti...

Страница 52: ...ing it down over the dovetail joint I accomplished this using a chain hoist to lift the knee into the air aligned the dovetail and slowly lowered knee until the knee lead screw started to make contact...

Страница 53: ...a dial indicator with a 4 arm in the spindle for a 9 table 3 Rotate the Spindle so that the dial indicator provides a reading for the outer edge of the table 4 Rotate the Spindle so that the dial ind...

Страница 54: ...ts in an older table I tend to make sure that I tram my mill utilizing the area of the table where I will be working If you are very industrious and looking for the ultimate in precision you could acq...

Страница 55: ...l 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...

Страница 56: ...justment screw about 4 5 turns Engage the quill feed lever and slowly turn the trip lever adjustment screw upwards until the quill feed lever trips and tighten an additional turn Re tighten the locknu...

Страница 57: ...tay on all surfaces This makes it a wonderful lubricant for surfaces but it has a tendency to clog pores or lubrication holes so it should not be used as a spindle lubricant or any other lubricant tha...

Страница 58: ...ring mechanism is working and adjusted properly Please review the clock spring section in section 4 12 0CNC Conversion 12 1 Why would you convert to CNC I really think after having run my mill as a CN...

Страница 59: ...ot be shy about grabbing an older 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 Mac...

Страница 60: ...ields a motor that can be moved 200 individual steps per revolution A servo motor is very similar to most of the motors that we use on a daily basis They can be either DC or AC powered and generally h...

Страница 61: ...c Vendor Qty Price Units G201 DC Stepper Driver www Geckodrive com 3 114 00 Each PMDX 131 4 Axis Breakout Motherboard http www pmdx com 1 189 00 Each PMDX 135 Power Prep Module http www pmdx com 1 119...

Страница 62: ...had to What good is a conversion if it destroys the machine in the process To this end my drive tubes connect to the mill via the bolts that hold the bearing retainers for the ball screws My drive co...

Страница 63: ...e Y axis could not This necessitated cutting a much larger hole in the drive tube large enough to feed the 30 tooth gear through Figure 59 X Axis Drive Tube Figure 60 Y Axis Drive Tube Figure 61 below...

Страница 64: ...50ipm during rapid moves 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 A...

Страница 65: ...ead arrived was to turn the input shaft I felt some resistance and figured I would disassemble the gearhead Planetary gearheads are not very complicated and after about 15 minutes I had this unit comp...

Страница 66: ...ne for machining It provides better configuration management and keeps the mill uncluttered with design files I have also considered the EMC software package as a means to be able to close the loop of...

Страница 67: ...n 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 I will be more than happy to email them...

Страница 68: ...tes Chesapeake Area Metalworking Society http www cams club org CNC Zone http www cnczone com Flint Machine Tools http www flintmachine com High Quality Tools http www hqtinc com H W Machine Repair ht...

Страница 69: ...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 Tu...

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