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    Default Bridgeport power feed repair help

    When we moved the knee mill (2J head) in to our lab the fuse case for the X-axis feed was busted. We replaced that, threw in a fuse, and it worked for a while. The handle did need to move slightly over center to stop the motor.

    The other day the fuse popped, although not the one in the feed case. There is a box with a large transformer on the back of the column, it has a small fuse on the transformer that powers this drive and the DRO. Replaced the fuse, blew again. Moved the table a bit, changed the speed, replaced the fuse, blew again. Ok, seems I need to take it apart.

    I don't know if this is a 6F or 8F, and (it wasn't me) a lot of the unit has been painted over. Reading other threads on here it sound like the common failure points are oil in the motor and oil in the electronics. We have plenty of electronics cleaner and denatured alcohol.

    1) Are there any places I shouldn't open because oil will come pouring out if I do?
    2) Are there any particularly good places to start?
    3) If I do drain the oil out, what is the appropriate oil to replace it with? Is this something I should go ahead and do anyways?

    I don't mind digging in and seeing what I find, but I'm wary opening something that's supposed to be full of oil without asking questions first. Pictures attached.

    p1160035-copy.jpgp1160036.jpgp1160037.jpgp1160038.jpgp1160040.jpg

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    That's an 8F. There is a drain for the oil on the left side of the case; I'd drain it before taking the motor off, but you can remove the electronics without taking the motor off. Unfortunately, more than that I don't know how to help your specific issue - but John from H&W frequents this forum, and he is an expert on all of the BP electronics.

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    More information:
    The motor brush on one side didn't want to come out, but wasn't oily. The brush on the other came out, was at least a half inch long, and looked just fine. No sign of oil inside.

    If we the drive on while already commanded to drive to either end it does not blow the fuse, but it is stuck in rapid traverse. The rapid traverse switch reads 1.2 MΩ normally, then changes to 0.1 Ω when depressed. I did not try disconnecting it.

    If we turn it on in the neutral position (center) it will blow the fuse. To make sure it was not mechanical binding I turned the drive on with the switch in neutral with the motor removed from the drive. The motor seeks back and forth both directions for a second or so before the fuse blows. The motor also spins freely by hand.

    I did notice that when the lever was in the right position both microswitches inside read 587 Ω across NO to NC. We disconnected all wires and tried this on a bench where those positions read as open circuits, so it is something else in the system causing that. A full list of resistances across the switches is attached as a chart. Disconnected they read the expected 0.1 Ω in closed positions and >10 MΩ in open positions. Wiggling wires didn't change anything. A drop or two of oil at most in the board area, although I rinsed everything down with electronics cleaner just in case. No obvious failures on the board.

    bridgeport-switches.png

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    You may need a new circuit board. H&W carries them, and I think also some other suppliers. But before you replace anything, I would talk with John at H&W - give them a call; they are incredibly helpful.

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    Quote Originally Posted by awake View Post
    You may need a new circuit board. H&W carries them, and I think also some other suppliers. But before you replace anything, I would talk with John at H&W - give them a call; they are incredibly helpful.
    Just to be a stickler, @Awake is close, but wrong. Its a 6F power feed. With the cover with the oil sight on it being flat and saying "Bridgeport" on it, that designates a 6F feed. The 8F doesn't say Bridgeport on it and has a bump near the top.

    So ya, couple things to look at. Make sure your microswitches (that control left and right directions) are not simultaneously closed. You can fry stuff if both of the switches are on at the same time. It is common for oil to seep down onto them and short one from time to time. Ok so now that I re-read the thread, I see you have already checked the switches. Interesting that you are getting measured ohms across some of the points. That is... well I like the word interesting so we will go with that.

    Next thing I would look at is the motor. Take it apart (two long screws hold the motor together). With one of the brushes being kinda stuck, that could indicate that oil has gotten into your motor and has mixed with the carbon dust from the brushes and gunked everything up. Super simple cleaning job (I use scotch brite on the armature, rinse the bottom and brush holders with some alcohol and then dry clean. I use q tips to clean the brush holders. Not that its the right way or wrong way, but its my way) can get you going a long way. Also inspect the armature for obvious damage and bigger gaps between the teeth. That can cause you issues and be a sign that someone ran the brushes down to the spring and they arc to the armature.

    While you are inside of the motor, check the wires going to the field. These normally can be super brittle and even have exposed wires. If you can do any repairs to that, go ahead and go for it.

    New brushes have about 1/2 of carbon and about a 1 inch long spring. There are times when I am repairing a 6F/8F where the springs on the brushes are super short and condensed and they dont make good contact.

    At this point... if your switches are good and if your motor is clean and doesnt have any visible damage... wait, does your motor have 4 or 5 wires coming off of it? If it has 4 wires, ensure that green is NOT going to ground. White and green wires go to your switches. Ok, so if you have those things all verified as good or replaced or seem to be in good working order, then I would go with the circuit board being an issue.

    If any of this doesnt make sense, you can msg me on here or call the shop. I wont be in today or tomorrow though, I will be installing a MillPWR G2 system. But if you leave a msg with the girls I will call you back when I get a second.

    @Awake, thanks for the plug. Hope you didnt mind me busting your balls a little bit. :P

    Jon
    H&W Machine Repair

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    Not at all - this was a classic example of a little knowledge being a dangerous thing. Having worked on my 8F (with your extensive help), I thought I could tell the difference! Ah, well - this is why I encouraged the OP to get in touch with you.

    On edit: John, in the manual that I have, the 6F looks like it has fewer controls on it than this one. Is there more than version of the 6F, some with fewer controls?

    As I have thought about the symptoms that the OP described, I can see why you focused on the microswitches - the motor "seeking back and forth" makes it sound like it is getting commanded to go both directions at once!

    On the circuit board - is this basically just a PWM DC drive, or is there something more involved? I'm wondering how hard it would be to repair a circuit board - not that I need to (knock on wood), but if the occasion should arise down the road ...
    Last edited by awake; 09-20-2017 at 01:40 PM.

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    There were (at least) 3 types of 6F models... the A, B, and C. If you look at the parts breakdown, the A looks different then the B and C. The A model had the circuit board mounted in a casting that typically was attached to the base of the mill. The less amount of controls you are talking about would be just the rapid button and the speed pot. The on/off switch, fuse, and light were on the casting that the circuit board were in. The B&C models had the same angled casting that the 8F used, but used different microswitches, different "cam assembly" (for lack of a better term), and circuit board.

    The circuit board (to my knowledge) is is uni-directional board, which simply uses whichever switch is actuated to apply power to the motor. As far as the repairing side of it, I have at least 6 different versions of the circuit board here. While I have found replacement parts for some of the components, I have no access to schematics or parts breakdown for the circuit board. And unfortunately for me, I just dont have the time to sit down and figure it out. If I did, I would be able to fix the 100+ 6F circuit boards I have here.

    As far as your microswitches comment, I brought those up for a different reason and I should have clarified. If you have both switch closed/actuated/whatever term you want to say for the control thinking that both switches are on, then you are sending power to everywhere at once and the motor cant turn properly. Typically when this happens, the circuit board will fry and if its done long enough, the motor. Its just a guess, but I would assume that there will be physical damage to the armature and maybe one of the brushes was at the spot where there was damage... but thats purely a guess.

    I am attaching a picture of my "show" Bridgeport power feeds. I have them setup like this so that if someone else at the shop is trying to ascertain what feed someone has, they can come look at my setup and be able to figure it out.20170921_072109.jpg

    From left to right is the old gear driven feed, 6F-A, 6F (whether its a B or C doesnt really matter), and an 8F.

    Jon
    H&W Machine Repair

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    I had no idea there were 6F models that looked so similar to the 8F - now I'm going to have to go back and look at mine again to see if it is really an 8F, or one of the B/C 6F models!

    Out of curiosity, what was the major functional difference between the later 6F models and the 8F? You mentioned different microswitches, cam assembly, circuit board - but what did those differences amount to in terms of function, reliability, power, or whatever?

    On edit: Okay, mine is definitely an 8F - not only does it have the "hump," but it says 8F right on the label.

    Question: what is the purpose of the bolt that protrudes to the right of the neutral position - on the front case, near the top of the upper case?
    Attached Thumbnails Attached Thumbnails 20170427_135959.jpg   20170427_140012.jpg  
    Last edited by awake; 09-21-2017 at 10:58 AM. Reason: Added pictures and a question

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    Jon,
    That picture of all three next to each other is very helpful (as for that matter are all of your forum posts, and every phone call I've ever placed to your shop. You guys are a great thing for us Bridgeport folks, thank you). I went looking for a 6F vs. 8F picture on Google and didn't come up with anything. Now that I see those I think most of the ones labeled as an 8F were in fact a 6F as well.

    We got the motor pulled apart yesterday. The inside was clean and dry, but there was a lot of carbon/gunk on the commutator. Unfortunately we don't have a before picture, but do have an in progress picture I'll upload later. Bearings are still smooth, with some grease coming out of them. We have a lot of IPA, and along with a plastic brush the commutator is cleaning up nicely. It does not feel ridged.

    Someone has been in there before as one of the connections was re-crimped. All commutator contacts are 0.2 Ω between adjacent contact bars. Windings are:
    Brown to yellow 1: 292.2 Ω
    Brown to yellow 2: 292.0 Ω
    Yellow 1 to yellow 2: 584.4 Ω

    The other brush did come out, the rubber seal on the cap had come loose and was stuck in place. Both brushes look good (picture also pending).

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    Here are the motor pictures promised earlier. We put everything back together and still have the same symptoms. Rather, it is still stuck in rapid traverse mode in both directions. I haven't put it to center/neutral yet as the fuse that will blow also powers the DRO, and we're temporarily out of spare fuses. Two of our techs are quite proud of their electronics repair skills and seldom get to use them, so I'll probably give them a crack at the board before just replacing it, despite the fact that just replacing it will likely be cheaper. Is there anything else I should check?

    img_5457.jpg
    img_5458.jpg

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    For future reference to people who may read this thread, the overall system and board schematics are on pages 5-10 and 5-11 of the manual.

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    When you are that far in I'd automatically change out the microswitches for new, good quality ones. Not silly expensive and that way you know you are good for the next couple of decades.

    The little springs that give the nice snap action to the control lever are probably tired too. Another auto replace in my book albeit of the don't do as I do do as I say variety, my new ones have been waiting nearly a decade for me to get round to fitting them.

    I'd do the speed control pot too. The ones on UK built Bridgeports are OK but not super wonderful, I imagine US built ones are of similar quality. Mine now sports a top line military spec hybrid wire-wound / cermet one which I just happened to have about the place.

    Clive

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    Quote Originally Posted by awake View Post
    I had no idea there were 6F models that looked so similar to the 8F - now I'm going to have to go back and look at mine again to see if it is really an 8F, or one of the B/C 6F models!

    Out of curiosity, what was the major functional difference between the later 6F models and the 8F? You mentioned different microswitches, cam assembly, circuit board - but what did those differences amount to in terms of function, reliability, power, or whatever?

    On edit: Okay, mine is definitely an 8F - not only does it have the "hump," but it says 8F right on the label.

    Question: what is the purpose of the bolt that protrudes to the right of the neutral position - on the front case, near the top of the upper case?
    @Awake I think the biggest difference in the two (aside from the circuit board) is simply the microswitches. The ones on the 6F can be a pain to get in the proper position so that they both turn on/off when their are in gear/out of gear. I am not sure what all difference it makes in power or function, but to me its the reliability factor and those switches are much better protected than the 6F switches.
    But that is just a personal opinion.

    The bolt on the right of neutral where the hump is, that bolt hold in the "arm" or lever that holds the feed in gear/neutral.

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    Quote Originally Posted by jccaclimber View Post
    Jon,
    That picture of all three next to each other is very helpful (as for that matter are all of your forum posts, and every phone call I've ever placed to your shop. You guys are a great thing for us Bridgeport folks, thank you). I went looking for a 6F vs. 8F picture on Google and didn't come up with anything. Now that I see those I think most of the ones labeled as an 8F were in fact a 6F as well.

    We got the motor pulled apart yesterday. The inside was clean and dry, but there was a lot of carbon/gunk on the commutator. Unfortunately we don't have a before picture, but do have an in progress picture I'll upload later. Bearings are still smooth, with some grease coming out of them. We have a lot of IPA, and along with a plastic brush the commutator is cleaning up nicely. It does not feel ridged.

    Someone has been in there before as one of the connections was re-crimped. All commutator contacts are 0.2 Ω between adjacent contact bars. Windings are:
    Brown to yellow 1: 292.2 Ω
    Brown to yellow 2: 292.0 Ω
    Yellow 1 to yellow 2: 584.4 Ω

    The other brush did come out, the rubber seal on the cap had come loose and was stuck in place. Both brushes look good (picture also pending).
    I am a little confused on the Brown to yellow 1 and brown to yellow 2... If you looked at the wiring in the casting, can you relate those colors to the colors of the wires they go to? They should go to a white, green, red, and black...

    Personally (and when I say personally, I do believe its an opinion... like 1911 vs glock. One is for men, and the other is a glock :P ), I dont like those brushes or those little seals. I dump the seals whenever I take them out. Those springs on the brushes are much shorter and can cause issues when the carbon gets shorter. Here is a link showing the ones we put in...

    38-281 - Motor Brush

    Again, that is just a personal opinion.

    @Clive I can definitely agree with the switches. With how much oil always gets in the casting, it is a nice easy way to get rid of that possible issue.

    Another possible part to check out/change is the seal in the main gear housing. If it hasnt been changed, the seal is probably about 1/2 inch tall and seals about as well as a .22LR can punch through SAPI plates. If you look at the link below, this is the new seal and fully covers the brass bushing and seals nice and tight against the cam shaft.

    38-161 - Shaft Seal

    Jon
    H&W Machine Repair

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    Default Bridgeport mill axis feed non functional continued.

    Quote Originally Posted by HWElecRepair View Post
    Just to be a stickler, @Awake is close, but wrong. Its a 6F power feed. With the cover with the oil sight on it being flat and saying "Bridgeport" on it, that designates a 6F feed. The 8F doesn't say Bridgeport on it and has a bump near the top.

    So ya, couple things to look at. Make sure your microswitches (that control left and right directions) are not simultaneously closed. You can fry stuff if both of the switches are on at the same time. It is common for oil to seep down onto them and short one from time to time. Ok so now that I re-read the thread, I see you have already checked the switches. Interesting that you are getting measured ohms across some of the points. That is... well I like the word interesting so we will go with that.

    Next thing I would look at is the motor. Take it apart (two long screws hold the motor together). With one of the brushes being kinda stuck, that could indicate that oil has gotten into your motor and has mixed with the carbon dust from the brushes and gunked everything up. Super simple cleaning job (I use scotch brite on the armature, rinse the bottom and brush holders with some alcohol and then dry clean. I use q tips to clean the brush holders. Not that its the right way or wrong way, but its my way) can get you going a long way. Also inspect the armature for obvious damage and bigger gaps between the teeth. That can cause you issues and be a sign that someone ran the brushes down to the spring and they arc to the armature.

    While you are inside of the motor, check the wires going to the field. These normally can be super brittle and even have exposed wires. If you can do any repairs to that, go ahead and go for it.

    New brushes have about 1/2 of carbon and about a 1 inch long spring. There are times when I am repairing a 6F/8F where the springs on the brushes are super short and condensed and they dont make good contact.

    At this point... if your switches are good and if your motor is clean and doesnt have any visible damage... wait, does your motor have 4 or 5 wires coming off of it? If it has 4 wires, ensure that green is NOT going to ground. White and green wires go to your switches. Ok, so if you have those things all verified as good or replaced or seem to be in good working order, then I would go with the circuit board being an issue.

    If any of this doesnt make sense, you can msg me on here or call the shop. I wont be in today or tomorrow though, I will be installing a MillPWR G2 system. But if you leave a msg with the girls I will call you back when I get a second.

    @Awake, thanks for the plug. Hope you didnt mind me busting your balls a little bit. :P

    Jon
    H&W Machine Repair

    Hi Jon,
    That was a great explanation and one I am going to put to use tomorrow. I have the same problem with my mill. No function at all to the axis drives. I will do exactly as you describe and see what happens. When one is serviced as you describe will it work if the y-axis drive has the same problem ie, is the wiring connected?

    Also another very strange issue I have is s follows:

    I am using a rotary converter to power my mill. I only wired it in today, the mill starts fine seems to run smoothly but only goes for around 2 minutes before stopping?
    Any ideas here? I am baffled?
    Best regards,
    David.

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    Dear Sirs,

    I have today finally wired up my Bridgeport and got the engine running properly. Yesterday I ralised I haev the negatine incorrectly. Now the speeds and working fine as are the reverse etc. So all good.

    But no power feed? I followed your thread and opened up the motor. The brushes although slightly moist with oil were not clogged nor was the inside of the motor soaked. In fact it looked very free of oil?

    When I turn on the power feed switch I hear the realays click over but no activity to the motors? Both X and Y are non-functional?

    Any advise here will be much appreciated.
    Cheers,
    Dave.

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    Ok, is the first part about the "engine" running about the spindle?

    I am assuming you have a good fuse, good 120VAC power...

    Does the circuit board have any visible damage or blown circuits?

    Jon
    H&W Machine Repair

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    Quote Originally Posted by Abmeboy View Post
    I have today finally wired up my Bridgeport and got the engine running properly.
    Damn, a gas powered BP, what's the world coming to.

    There is a lot of missing information here. It sounds like you have a mill with an electrical enclosure on the back or side of the base. If that is so, you need to post a picture of the inside of the mill.

    Also, which type of power feed to you have, If you don't know, post a picture.

    What power are you running the machine from? Single phase thru convertor? What does the plate on the enclosure give for requirements. Again, a pictue would help.
    JR
    BTW, it's always better to post a new thread than to open and hijack an old one.

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    Hi Jon,
    Thankyou for your reply. I apologise for not using the correct terminology. I am a beginner to engineering but a seasoned live steam loco hobbiest.
    So details are as follows:

    1. I am running the mill on a rotary converter. This initially was wired incorrectly but once I corrected the wiring everyting is working well. The spindle works perfectly, my lathe also and the bandsaw is working well. So I guess I got the electronic part OK?

    2. So, the mill cuts great and has amazing power I was using it today and all good.

    3. The power feed is non-responsive. When I flick the switch on the front of the mill to activate the power-feed I can hear relays switch on the control board.

    4. The coolant also does not pump, could this be related to the power feed?

    I am attaching pics that may aid in this diagnosis?

    Thankyou again for your feedback, it is really helpful to me to have some experts comment on this as I don't know where to start.

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    Default Images of my Bridgeport Mill

    [/ATTACH]20180122_183927.jpg20180122_183914.jpg20180122_183910.jpg20180122_183744.jpg20180122_183726.jpg

    I have dismantled the motor on the X axis and could not see any amount of oil in it? The brushes were slightly oily but the inner of the motor showed no signs of oil leaking in?
    I did not carry out any electrical checks with resistance or voltage measurements?

    Both X and Y axis are non functional as is the coolant pump?

    Also there does not seem any evidence of damage to the control board?


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