[Malzra]

Hello does anyone know how to tighten up the backlash on a Bridgeport Series II Interact?

The big problem is on the X axis the Y axis I think is still ok.


Thanks in advance

[gus]

Its a ballscrew, you do not adjust it

it is more likely the[end support] bearings. if the screw has backlash you send it out to be reloaded

[Malzra]

I was reading this nice walkthrough somone had made at

http://www.metalworking.com/Dropbox/...&-backlash.pdf

and was really more curious if anyone had ever done tightened up the blacklash on a interact model.


I was wondering if there was any real differances I need to be aware of before I go tearing the bed apart.

[Malzra]

Another day I figure out I need to spend more money and time to play.

Turns out my "Thrust Bearings" on ither end of my saddle are just fine, So only two options left.

Ither my "Ball Nut" in the center under the bed is trashed (Of which I think it is) or my "Ball Screw" is just that bad out and needs refurbishing. Anyways here's the pics thus far on my teardown of the bed.

Oh and by the in case anyone is wondering the bearing replacements for the FAFNIR Ultra Precision bearings that comes with this machine cost $501.80 PER SET!!!!!!!

Oh and another thankyou very much to BP for makeing me have to build a custom "Spanner SOCKET" to take the spanner nuts off:tired:

[polaraligned]

I have a BOSS 6 that pretty much looks the same. I had the ballscrews re-balled and I still have .002" backlash. Bearings are also new. I need to dig further to see what is going on.
Let me know what you find.

[Malzra]

Update:

Well I lifted the bed today and it was quite a easy process when you have all the right tools.

I have access to the entire Ball Screw and Ball Nut now and I'm trying to get the Ball Nut off the Screw and there are some black bearings on ither end of the Screw that is preventing me from removeing it. I can't find anything about them from of the manual so anyone have any ideas before I go hacking at it?

Pictures as always

[dreammstr6]

most of the time if you remove the ballnut from the ballscrew it not pretty and is costly. but yours may be different i would ask someone who knew before i risked it.

[Malzra]

I've heard the same from a few people, Saying when you pull them out the ballbearings fall out and makes a huge mess.

So my thoughts are If I remove the ballscrew with the ballnut attached and send it out to winter engineering and see what can be done with it

I've heard good things and good prices out of thier shop.

Next up! Saddle removal to get to the Y axis to see why the hell is it "Sticking"

[dreammstr6]

that sounds like a good plan. when i took my ez-trak's apart to move them in i did the same. took the screws off complete with nuts installed. y axis you have to be really careful with on a ez-trak. nothing stops you from screwing the ballnut off the back side of the screw which is a major no no. maybe you will get your mill straightened out for a reasonable price.

[polaraligned]

If you remove the ballnut, you will be sorry.
Just send the assembly out to be re-balled. Hopefully it is not too late. You probably want to replace the angular contact ballscrew bearings. Not cheap.
I had mine re-balled and replaced the bearings and have zero backlash now

[Malzra]

Fair enough if you just had yours redone where did you sent it and about how much was it if you don't mind me asking?

Edit: when you say angular contact ballscrew bearings? you mean the ballnut itself that the bed attaches to or the bearing on ither end of the table?

[ichudov]

I have a question, how exactly do you guys know that you have backlash?

How do you establish that, as a fact?

i

[Malzra]

When I can turn the shaft back and forth and it takes more than a sixteenth of inch before it engauges I don't need to break out the calipers to know somthing is terribly wrong. My Y axis engauges just fine but it "Sticks" in certain places of which I am worried about it.

So I'm going to tear the bed assembly down tomarrow and ship both X,Y out to get Reballed.

This machine made somone lots of money because it was heavily used in fact it seems to me that it was refurbished at one point. So this is it's third life at least.


Once again at the end of all this I'll know stuff about this machine I never wanted to know but it'll be a good machine for years to come (I hope) Maybe even get it working great and try to sell it and get a VMC! (haha)

[Malzra]

Also if anyone has any better idea on how you remove the Right Hand bearing from the saddle I'm all ears. I was thinking a brass bar and lightly tapping on the shaft it to remove it but I'm not so sure it's a good idea.

I can't get any bearing pullies on it or would it be a better idea to get a socket and push the Whole bearing out with the shaft then reseat the bearing later


I'm unsure at the moment the manual doesn't quite cover this


Also I do have the nut off I had to build a custom Spanner Socket to do it but it works great just wondering about the bearing

[polaraligned]

Fair enough if you just had yours redone where did you sent it and about how much was it if you don't mind me asking?

Edit: when you say angular contact ballscrew bearings? you mean the ballnut itself that the bed attaches to or the bearing on ither end of the table?

The bearings set on the left side is what controls backlash. The bearings on either extreme end of the ballscrew is just for support. I was having a little backlash problem because I did not tighten the bearing locknut enough. Once I did that a few days ago, the ballscrew is smooth and has near zero backlash. These bearings wear and need replacement also.

I use RP Machine in Orwell, Ohio 440-813-0920 to re-ball the screws. I think it was about $150 each axis. He did the screws 2 years ago and I only now got the machine finished assembled. I was very happy with his service and the results that I see now. If you send the ballscrews to anyone, pack super well. I suggest making a small plywood crate. These things ARE NOT REPLACEABLE.

I used another guy who advertises on the internet (big company, Esco I think) to rebuild my series 1 ballscrews, and he ruined them. The jackass polished the bearing journals. He charged me $1500. I got screwed.

[polaraligned]

I have a question, how exactly do you guys know that you have backlash?

How do you establish that, as a fact?

i

Put a dial test indicator on the table and single step your controller in say .001" increments. With my series 2 I was able to just turn the drive pulley and feel the "dead zone".
On a smaller series 1, you can use a dial indicator on the table and just push the table back and forth and see the movement on the dial indicator.

[polaraligned]

When I can turn the shaft back and forth and it takes more than a sixteenth of inch before it engauges I don't need to break out the calipers to know somthing is terribly wrong. My Y axis engauges just fine but it "Sticks" in certain places of which I am worried about it.

So I'm going to tear the bed assembly down tomarrow and ship both X,Y out to get Reballed.

Once again at the end of all this I'll know stuff about this machine I never wanted to know but it'll be a good machine for years to come (I hope) Maybe even get it working great and try to sell it and get a VMC! (haha)

Good idea to get them reballed. I did my Z axis also. Actually, I completely rebuilt my machine. I would never get my money out of this machine if I had to sell it. But, for hobby stuff there is no reason to have a VMC. This Series 2 knee iron is the beat BP ever made. Huge box ways just like VMC's. The only thing you are missing is speed (spindle), the enclosure, Z travel and a tool changer. All things that a hobbiest or even small shop can live without.
The guy who did my re-balling said that I got them re-balled just in time. I guess there is a point when re-balling is not possible to produce zero backlash and you need to regrind them.

On edit: Who the heck is that on your avatar? Doesn't look like he does any machining.

[Malzra]

Well I'm off to do battle this morning wish me luck I'll post some pics later today

Also my avatar is me in the pentagon behind the offical podium

[polaraligned]

No Update?
You were providing inspiration to get my butt out of the chair and work on my Series 2!

[Malzra]

Sorry! I was waiting for my ballscrew to come back in before I posted again but I'm expecting it back next monday then I get the honor of trying to get it back in place. BTW just for future ref when somone 8 years from now looks at this thread.

Before I start GUS you are correct just to give credit where it is due.

Series One BPs have a adjustment for backlash

Series Two BPs DO NOT

It's a clear cut case of if you have backlash you remove the offending axis ballscrew. Then send it to somone

I used winters engineering he said it was a very worn ballscrew and would take 400$ to fix.

If I can get off from work early today I'll go take some new pics and post