Bridgeport Help

jorsborn · Jan 25, 2015

I recently bought a Bridgeport mill and am having a few issues. As you'll discern, I don't know what I am doing. I am not a machinist. I just (now) own a machine

. So, here it goes:

1) I can't tram the head because it appears that the worm may be broken where that adjustment is made. Looking at an exploded parts diagram it appears to be a rather simple replacement if it weren't for the weight of the head. I was thinking of a way I could pull it off to investigate. I started welding up a fixture which I could secure to the table and insert into the quill using a collet. I am thinking that alone would probably stress the bearings too much so I was also thinking I could I could take the load off by using a few straps and my forklift.

2) Most important is all the slop I see in my table. When the table is all the way to one end or the other I don't see the slop. However, when the table is in the middle and I move it in your out (Y axis) the whole table cocks and based on what I measure, moves about .010 in the X direction when it does. This is really concerning because I fear that this might be an expensive fix. I also note that the table is very difficult to move around (X and Y). My point of reference is another friends Bridgeport which takes very little effort to move the table around.

Any thoughts on either issue? Any help is appreciated.

swatkins · Jan 25, 2015

Exploded parts diagram for the base... Along with prices for parts...

To remove the head it is easiest with a fixture that bolts to the table... Chuck the head into the fixture and use the table to move it down and away,, Looking for that fixture for you now

swatkins · Jan 25, 2015

Post for removing the head.. Item #10 in the bottom of the page.. Pretty simple to fab your own if you have the time and scrap laying around...

Richard King · Jan 25, 2015

This guy has the same issue...https://www.youtube.com/watch?v=HFE_nXQCH6E

The other problem is simple. The other users used it a lot in the middle and wore X screw out in the middle. You need to order a new screw and nut. If the Y is loose like that then order a new screw / nut for it too. I buy my parts from High Quality Parts. To remove the screws you will need to pull the table. May as well pull the saddle too and clean and lube it up. I suspect if the screws are worn out the ways are bad too. How about yu take it apart and take some photo's and show us. Then we can advise you further.

Probably dirty and needs the lube system cleaned and repaired too. Rich

jorsborn · Jan 25, 2015

Thanks! Seems logical. I am noticing that if I grab the table from either end and push/pull the table will cock back and forth. I'll figure out how to take this thing apart and get some pictures.

jhruska · Jan 25, 2015

I have my own views on removing the head but..............

Lets go back to "the worm may be broken" and take care of that.
A few things can go wrong here and it is likely the fault of a previous operator, Bridgeport, or both.

Bridgeport shares the blame here for being lazy. It is likely that the worm shaft is only supported on the right side of the head. Bridgeport may not have poked a blind hole in the far side so the worm shaft is only supported at the hex nut side. With support at only one side and the head bolts tight the shaft either bends or snaps. My fix was a guide sleeve for drilling and reaming the far hole. When a new shaft is purchased the length is correct only if the blind hole is there.

The key for the worm has sheared. Goes back to the head bolts are too tight. A good heavy soft face dead blow is the friend here to tap the final thousandth rather than torquing on the worm.

The worm gear wheel is stripped, the socket head caps screws are sheared or loose. If the gear is stripped, rotate it and bolt it back in. I had to relocate some worm wheels and added dowel pins so the cap-screws can take a load off.

John

jorsborn · Jan 31, 2015

It would appear that the shaft is the piece I need. Now I need to figure out the best way to remove the worm.

jhruska · Jan 31, 2015

This can be easy or not. For me it's drill and tap, 1/4-20 will do, right in the center of the old shaft. Bring out the slide hammer and insert an extra long set screw in one end of the long rod that the slide weight moves on and the other in the tapped hole.
For you it depends on what kind of stuff is laying around that can be put to use. If you have a lathe make a guide bushing for the drill tap. Even a piece of dowel rod will work, single use only and likely better than trying to eyeball the center of the shaft.
John

jorsborn · Jan 31, 2015

I have a lathe and some brass stock laying around. I don't think my tap is long enough however.

Seems like if I just used a 3/8" drill with the bushing and took that approximately 1/2" deep could probably rotate the worm out? I'd rather not damage the worm though. I think I need to pull the head all the way off so I can get a better view... make a better decision.

jhruska · Jan 31, 2015

I have tap handles and some with extended length.
Without those I would consider a piece of stock of usable length and of a width or cross section to tap two small holes directly opposed. Drill a hole at one end so the square end of the tap can be inserted and the body of the tap will slide in for a close but not tight fit. Drill and tap for two opposed set screws that will engage the flats of the tap. This will be a home-made extension. Make it fancy or not.

jorsborn · Feb 1, 2015

I've got a bushing made up and I have also fabricated a tap extenstion. I would have thought the toughest part was behind me but I can't drill into the remainder of that shaft. My bit seems plenty sharp but I am just rubbing.

Richard King · Feb 1, 2015

Take a file and file the end where the broken worm and stud broke, it maybe hardened and your drill bit is to soft to drill into it or the worm stud is turning. Many times you have a hardware store drill bit made for wood or soft material. If the bit is soft, order an American made drill from a local or mail order industrial supply. Move the head out and over and look inside the hole as the worm will be visible then use a 3/8" straight punch ( a 1/4" punch will probably bend) and see if you can tap it out (hit it) or a screw driver to pry it out. Rich

jhruska · Feb 1, 2015

Bet the worm is turning like Richard said. A small C-Clamp on the OD should stop it with out hurting it.

Richard King · Feb 4, 2015

What did you ever figure out????

jorsborn · Feb 7, 2015

Richard King said:
What did you ever figure out????

I *JUST* managed to get the shaft out. It was not easy by any means but it is done. Thank you!

The job is not complete though as the new shaft is longer and so I need to drill out the opposite side roughly 1/2". I'd love to get this done tonight... but unfortunately I have no bit which will reach that distance.

jorsborn · Feb 7, 2015

Neighbor had a drill bit long enough to get in there. I got the shaft installed and everything put back together. I just noticed I left out the set screw which retains the shaft. The shaft isn't going anywhere right now so I am not too anxious to pull the head off anytime soon... though I should probably do it while I have everything out.

I am going to start looking at how to pull the table off to get some pictures.

jorsborn · Feb 12, 2015

I haven't had time to research how to remove the table by myself but I wanted to try to tighten up the gib to see if that would help in the meantime. I removed the cover and tightened the gib as much as I could. I did this with the table in the sloppiest location... the middle of the X travel. I placed a dial indicator on the side of the table with the mag base on the casting. Pushing and pulling on one end of the table I get 0.020" of movement. Basic setup is shown in the attachment. Obviously 0.020" really makes this mill unusable. Am I missing something on the adjustment? Seems like it just couldn't possibly be this bad.

kevink · Feb 12, 2015

jorsborn said:
I haven't had time to research how to remove the table by myself but I wanted to try to tighten up the gib to see if that would help in the meantime. I removed the cover and tightened the gib as much as I could. I did this with the table in the sloppiest location... the middle of the X travel. I placed a dial indicator on the side of the table with the mag base on the casting. Pushing and pulling on one end of the table I get 0.020" of movement. Basic setup is shown in the attachment. Obviously 0.020" really makes this mill unusable. Am I missing something on the adjustment? Seems like it just couldn't possibly be this bad.

View attachment 130434

You are measuring movement of the table and saddle since your mag base is on the knee. Plus, the plate that the mag is on moves in the knee, so you have all kinds of slop going on. Put the mag base on the saddle, which is the part that the table slides on.

Richard King · Feb 12, 2015

put the mag on the saddle (the part just below the table) out to the farthest you can go and then put the indicator just above the right end of saddle on the table and push and pull the table. Write down how much you get, Then move the mag base to the left end of the saddle and do the same thing. I would adjust the gib so you get .001 to.002" on a worn table and bent machine. The do the same on the top of knee to saddle front and back, have to remove the wiper cover then adjust the same way. Be sure the locks are loose. Rich

jhruska · Feb 13, 2015

If the gib was loose to the table..........the crud that is on the ways of the table/saddle will be trapped when the gib is adjusted. Pull the gib and clean it. Clean the dovetails table and saddle, both sides.
John

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