Boss 3 Tramming Issue

[austin.mn]

I have had this Bridgeport Boss machine for a few years now and have had constant issues keeping the head trammed. It seems to nod quite easily. I have never tried to tighten the three bolts that hold that position extremely tight as I was always told they just need to be tight, not so much that you need a breaker bar to get them loose.

I have been thinking of adding a strut from the rear of the ram to the top of the head to try and alleviate the problem, unless others out there have any suggestions.

I don't use the machine for any heavy cutting, most of the bits that I have are actually quite small, even my fly cutter only takes a 3" swing. I don't believe that I have ever really pushed the machine very hard, but would really like to figure out a way to keep it from falling out of tram during regular use.

When it does go out of tram, it isn't like it moves so much that you can see it or anything. but it is quite evident when I go to clean up a larger part than my fly cutter can cut in one pass. you can definitely feel a ridge between passes. Then when I check the tram it is usually out by .020" over a 12" swing.

How tight should the bolts be torqued to? Is there anyone else that has had this same issue and fixed it easily?

[hitachibos]

check the knee not the head. tram it with the knee up high then lower it as much as the quill will allow and check tram again. check it both with knee clamp tight and loose.
then put an extended bar in spindle and check tram again as low as you can.


i do not think the head is moving as much as you think.

[mactec54]

austin.mn

This has always been a problem with the Boss machines that have the knuckle head, the extra weight of the head is some of the problem, I took 5" out of the head of my machine builds which helped, the next thing I did,was to make a new Knuckle Pin it looks like a clevis pin when machined, with a head on one side, a large machined washer for the other side, & a .500x20 Grade 8 bolt that has a hardened washer, You can then torque that up to 100 foot pounds the other 3 bolts need to be at least 60 foot pounds


hitachibos
If you move the Knee to check the tram & it is out by a large amount, you need to rebuild the machine as it is worn out

[austin.mn]

Hitachibos,

I had already thought of that, however, I didn't detect any issues there. I had thought for sure that there would have been at least a slight change when tightening and loosening the knee locks but I didn't even see a .0005 change over 12" when I did that.

Mactec54,

Wow, what a beautiful machine.... mine needs a paint job at a minimum. Do you have any more info on your machine, like a build thread or website?

I had also worked at a tool grinder repair place for a while, lots of hand scraping. I do recall that we had an issue with one of the tool grinder heads. It turned out that the two faces that clamped the head to keep it from rotating were not parallel. So when it was clamped really hard, you could still give it a light tap with a dead blow and get it to swivel quite a bit. The fix for it was to scrape all the faces to be sure that there was good surface to surface contact.

I have been considering pulling the head off the machine and bluing everything to check that out.... but was hoping to avoid that until I move into the new shop in the future. Your solution looks like it may be a bit less time consuming than all the scraping. So I will try that first.

Thank you for the help.

Austin.mn