Millport Bridgeport

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Can anybody here tell me if the slack can be adjusted out of a Millport or Bridgeport  milling machine table or not. The thing has about 3/8s in. slack in the table. Really rough when trying to cut a keyway.
Reply:Hello Welderskelter, if you are talking the table, there are gibbs that can be adjusted to take out play. If you are talking the screw, you will likely need a new nut, screw or both. That's the quick and dirty answer. Good luck and best regards, Allanaevald
Reply:Yes, I am talking about the table as you are standing in front of it using an end mill bit to cut a keyway in a shaft , it will sometimes take to big of bite and jump from left to right, it is hard on the bit.
Reply:That sounds like a screw issue. You may need to take a look at the screw/nut combo to see if there is a lot of play in it. Some of those machines had an adjustable nut/half-nut combo. Take a look to see. Best regards, Allanaevald
Reply:Originally Posted by aevaldThat sounds like a screw issue. You may need to take a look at the screw/nut combo to see if there is a lot of play in it. Some of those machines had an adjustable nut/half-nut combo. Take a look to see. Best regards, Allan
Reply:I just looked it up on bing. Under Bridgeport mill table diaghram. Just take it apart and cut the nut into put back with a space in between and adjust out the play. I will have to find out Wednesday. Thanks guys.
Reply:Play in the ways will cause slop and the gibbs need adjustment. Play in your lead screws can be compensated for by changing how you dial in your adjustments. So you'll dialing out the slack. Plus using the locks and you won't have a jump at all.
Reply:Furthermore....Bridgeports and their clones don't like to climb mill.  Thats a trait of the machine design.Always advance the work INTO the cutter, not the cutter into the work.  Climb milling on a vertical mill only works on very light cuts where the teeth on the cutter can't advance the table (overcome the slideway resistance).I believe you are attempting to climb mill and it won't work.  I do it all the time but there are special considerations involved.  It's not something you can just do.Far as the lead screws, there are 2 types, split and ball, depending on machine age.  Ball screws aren't adjustable, split is.The biggest enemy of any machine tool, especially a vertical mill is lack of lubrication to the slideways and lack of proper lubricant in the spindle.I lube my slidways via the one shot lubricator every morning on all my mills and the spindles get their oil cups filled 2 times a week, every week.  I use a mix of spindle oil (Shell Donax or Tellus) and light machine oil in a 50-50 mix and Shell Heavy way oil medium in the one shot.  Oil is cheap, accuracy isn't.My spindles all run Class 5 Fafinr bearings.
Reply:^ What that guys said about climb milling. Climb milling really should only be done on machines with ball screws.From what I remember reading BP's have split nuts that can be adjusted to take the slop out of the screw but only in that certain spot if the screw is worn. Out at the ends it will tighten up probably to the point that you can't turn the screw.Also a FYI McMaster sells acme screw of all sizes and L/R hand thread. I made up a bunch of new screws for all my machines in my shop.Even made up new nuts.
Reply:.........^ What that guys said about climb milling. Climb milling really should only be done on machines with ball screws"..........Actually, you really shouldn't attempet it whether you have ball or split because the machine itself lacks the rigidity in the base/knee/ram assembly to overcome the tendency to move that slight amount as the cutter tooth engages the material in climb milling.I won't say it can't be done because I do it but not on pocket cuts and not in high strength materials with less than perfect cutters (with adequate relief angles).  Ball or screw, it really matters little because climb milling aggrivates the freeplay in the table and all machines have freeplay, even new, unused ones.  Thats a condition that arises from the mating of mechanical assemblies that intermesh with easch other.Climb milling is easily accomplished on an overarm horizontal milling machine because it's much more rigid and less adaptable to various scenario's as well, the main reason they have disappeared from shops everywhere.Keeping in mind that a Bridgeport on clone is really nothing more than a fancy drill press with power down feed and a spindle that can absorb radial loads without self destructing and has a table capable of accurate positioning of the workpiece within 0.001 or better is how one should virw it, not as a hogging machine or a rigid, accurate machine, because they aren't.When you build a multi use machine like a vertical mill, it becomes a tradeoff.  always.
Reply:Heh heh, climb milling........some people only know enough to switch the machine on......all of our production horizontal mills climb milled, and that was using side and face cutters too.......but they were also equipped with air over hydraulic buffers for the feed......without the hydraulic cylinder holding the table back against the air feed cylinder they'd go into orbit.Ian.
Reply:Originally Posted by WelderskelterI just looked it up on bing. Under Bridgeport mill table diaghram. Just take it apart and cut the nut into put back with a space in between and adjust out the play. I will have to find out Wednesday. Thanks guys.
Reply:Originally Posted by puddytatHeh heh, climb milling........some people only know enough to switch the machine on......all of our production horizontal mills climb milled, and that was using side and face cutters too.......but they were also equipped with air over hydraulic buffers for the feed......without the hydraulic cylinder holding the table back against the air feed cylinder they'd go into orbit.Ian.
Reply:To give you an idea of tooling costs, I run a semi production job in 3 series stainless where I form mill a slot with a specific radius trough, 4 times deeper than the diameter of the cutter.  I have the cutters (M42 Cobalt, chip flow finish, Cat 40 through coolant) custom ground by Weldon at a cost of $125.00 per cutter so long as I buy 10 at a time..  I get maybe 50 parts from each. running Trim SC Synthetic EP flood coolant...... and it takes about 3 months to get them.The cutters have to be custom ground because the radius slot is metric and the dimension isn't a stock item in cutterland.  It sucks but the customer provides the print.  I make it to print.Run 'em just a little to far and not watch the surface finish (for chip welding and galling) and wham, the cutter breaks and scraps the part and this slot is the last of a series of operations (and expense).You Tube is full of video's where cutters break and work is scrapped..  Most are because the cutter is past it's useful life so it goes down the toilet...real quick.While not germane to the discussion, it's advisable for anyone with a home shop to understand the basic dynamics of how a cutter works and when it's dull and what to look for.  Cutters can tell you when it's time to replace them just by looking at the cutting edge.