How should I level my Bridgeport mill?
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  1. #1
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    Default How should I level my Bridgeport mill?

    Hello all, Today I was finally able to get my mill up and running after installing a VFD. The brand is Eaton by-the-way....works perfectly so far. When the mill was moved into my shop, my helper and I rolled it in on round bar stock. We pushed it into the corner of my shop and planned on leveling it later. So I am a bit nervous about how to lift it high enough to put bar stock or levelers underneath it. I had one old-timer tell me to jack it up, put a piece of 1/8" steel plate on the bottom of the mill, then spray, spray-foam on the floor, letting it set-up a bit, then lower the machine/plate. This was to somehow reduce vibration and "fix it" in place.... I raised my eyebrows after he left and came back to just using rubber leveler's. I have also seen others use 1/4" wall square tubing to make a "H" frame with levelers on the ends as feet, then bolting it to the mill....seems like it may be a bit of overkill....How can I lift it high enough with only a pry bar and stock? ANY and all suggestions and previous experience is very appreciated... Thank You!

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    Hi Jimmy , You can lift small machines like a bridgeport with a pry bar ( crow bar in England ) quite easily. Bar one corner up , insert a packing (3/8" max ), lower back down. move on to the next corner, insert your packing. So on and so forth until your machine is level. I've also used very fine taper steel wedges to raise machines.
    I don't like admitting this but on one occasion, when I was desparate ( the machine had been backed right into a corner of the building and there was no room to use a bar or anything else).I cut a piece of 3"x2" timber to the right length, cut a vee in the top, placed it under the cross axis index collar and wound the knee down. This raised the front of the machine high enough for me to slip a length of 1/2" round bar in underneath the machine. When I got the bar past the centre of gravity I raised the knee , lowered the front and the back came up. I put my packings in the back, raised the front and levelled the machine that way. I'm not sure I'd try this method with anything heavier than a Bridgeport though.
    Another thing, I'm a bit old fashioned so everything I install gets firmly bolted to the floor, that way they stay level a bit longer and there's no chance the machine will tip over ( I have seen a milling machine go over and it made quite a mess) . Regards and best wishes Tyrone.

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    When it comes to levelling crow-bar up and try some packing works but gets old fairly quickly, especially if you are working on your own. A Bridgeport can be lifted from the four holding down bolt holes by inserting expansion studs, generically known as Rawlbolts in the UK and used for holding things down onto concrete bases, into these holes so that suitable brackets can be fixed onto the machine. Four screw jacks will enable the machine to be lifted and adjusted until level so the right thickness of packing can be put in place and the machine dropped back down. Undoing the expander bolts will allow them to be removed from the top, with a bit of wriggling and verbal encouragement if my case was typical.

    Obviously the brackets need to be sufficiently stout so as not to bend and the expansion fixing needs to be long enough so that the expander bit is below the casting for a positive hold. Those things can generate pretty large side forces and I'd not want to rely on expanding them into the casting due to the risk of breaking. Bolt the brackets to the jacks fro stability. I used 4 brackets and 4 lightly modified SAAB 900 / 9000 scissors jacks to lift my Bridgeport off the heavy duty castor trolly used to move it in. I set it level during the dropping process. Worked fine but, in retrospect, it might have been better to use two longer brackets spanning either side to side or front to back hole pairs. There was a bit more tumble-home on the jacks than I really cared for during the process and it was quite clear that trying to do the job without bolting the brackets to the jacks would have been very chancy.

    A selection of expander bolts come in real handy as a get out of jail resource for all sorts of things. My most common use is as improvised bearing pullers. Tip if you've not got one big enough just make an alloy sleeve and slit it like a collet. Similarly the scissors jacks. Lift a ton (ish) and at £ 1 each from Mr Scrappy a disposable item so no worries if I need to weld a bracket on. Just don't forget that side to side stability isn't wonderful when re-purposing any car type jack.

    Clive

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    I don't think anything mentioned so far is going to work well with regards to lifting the BPT off the ground. To drill and tap the base holes for leveling screws is also something that I chose not to do when I set up my machine.
    What does work well is to raise the mill off the ground, and keep it there. You may have to use the pry bar method, but you must be extremely careful! The mill weighs 2100 lbs + and is very top heavy.
    If it starts to tip over, just run for your life. A better method is to use a lift to pick it up from the top.
    Once there, you can do what I did to provide the level screws. But, to tell you the truth........ in my opinion if your mill sits on a nice level patch of concrete floor there is little need to level the machine. It is not like a lathe which does need to be leveled to eliminate the bed twist. If your mill does not rock where it sits, then I would just leave it as is. A Bridgeport, while it is a lightweight mill in some opinions, is still quite a chunk of iron sitting there and is unlikely to need leveling if sitting on a flat surface.
    My mill sits on an uneven concrete floor. The floor goes up as it gets close to the wall, so leveling it was a must do for me.





    The two 3x4x3/8 inch wall tubing pieces are bolted to the mill base (front and back) with 5/8x6 long inch bolts. The level bolts are 1/2-13 bolts with a 2 inch square plate under each to keep the floor from being ground up.

    I made my set up only because I have to move the mill from time to time using a pallet jack. Since I also needed floor space to store the jack, I found I can just leave it parked under the mill.
    A couple of pumps on the jack handle, unplug the mill from the wall and just roll it away. This works for me and maybe it will give you some ideas..........pg

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    Sorry you saw fit to rubbish my comments Pinion gear, looks like I've spent the last 45 years in the wrong job. I'm just glad none of my employers realised I was talking nonsense. Regards Tyrone.

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    Put the mill up on sturdy wheeled casters, and just roll it to a spot on the floor where your coffee mug won't fall off the table.

    ;-0

    CalG

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    Quote Originally Posted by Tyrone Shoelaces View Post
    Sorry you saw fit to rubbish my comments Pinion gear, looks like I've spent the last 45 years in the wrong job. I'm just glad none of my employers realised I was talking nonsense. Regards Tyrone.
    Tyrone........
    I did not 'rubbish' your comments in any manner. In fact, I said that lifting it with a pry bar may have to be done and that care must be taken. This is not as easy a job as it sounds however, and you well know that.
    So, if I offended you I apologize because that was certainly not my intent. The same goes to all of the others who have posted comments here on the subject.
    Lifting a Bridgeport is a chore and if it sits on level concrete there is really nothing to gain by trying to level it IMHO........pg

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    I agree lifting a Bridgeport is a chore and that by the very nature of things they are somewhat less than stable however given that the lift needed to level is rather less than an inch, if its more levelling is the least of your worries, it won't have enough tilt to become unstable. Going from the bottom is far less than ideal but Tyrones crow bar and my modified jack method both work well enough although the crow bar method is, ideally, a three person job one to lift, one to slip the packing in and one to watch the level so the lifter pulls it up by as close to correct as can be managed. The crow bar method can be done with two although peering at the level may not be easy. Theoretically it can be done alone but I'd hate to do it, did a lathe that way solo. Not fun quite apart from the dangers of working with heavy stuff on your own. All too easy to have a rush of blood and do something really stupid / risky without thinking things through. Bin there, dunnit, got the tee shirt and, by the grace of god, no wounds. The usual in the corner small shop positioning of a Bridgeport is a bit cramped for crow barring too.

    The main advantage of having a Bridgeport or any other mill set with the table level is that you can use your machinist level or a clinometer to help set-up work. Much quicker than tramming or probing with an indicator. Sometimes good enough to work with, other times just a quick way of getting nearly there for final set up. When you have to clamp down, pack-up and jack a knobbly base so you can work on the front at the right angle anything that speeds the job is a godsend. If you have to do the sequential unclamp business to get at different parts a sensitive level can be great for verifying that nothing is moving.

    Clive

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    Well stated Clive!...........pg

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    Thanks for the info everyone... I have a specific question for piniongear, did you use specific grade bolts for your set-up? I have the same situation as you do, in that the concrete floor comes up in the coner of the shop. I should have spoken better in my question.... I am not so concerned about leveling the machine as I am in coming up with a remedy for the "rocking" motion caused by the unlevel floor. So I could use a portion of piniongear's method buy only using the 6" bolts and nuts, running them through the machines' base holes, onto the floor. These could be installed once the machine is up on blocks, then simply lower it down on the bolts/nuts combo and stop the rocking... sound good?

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    I had to level a different type of milling machine and the method that was recommended by that manufacturer was to make a cut on a block and use that freshly cut surface to level from. I guess this was incase the table was not inline with the head. That way the top of the work would always be level after machining.

    I used a similar approach to the pics above that used the square tubing and bolts for levelers except I used 1/2"X4" plate. I had some 5/8" grade 5 bolts left over from a job so I used them, dont notice any vibration. I use a pallet jack also mentioned and get under the machine from the rear or front. I find it easier to balance the machine by moving the table side to side when moving. There are all kind of ways to skin a cat...

    wm

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    Quote Originally Posted by jimmysgarage View Post
    Thanks for the info everyone... I have a specific question for piniongear, did you use specific grade bolts for your set-up? I have the same situation as you do, in that the concrete floor comes up in the coner of the shop. I should have spoken better in my question.... I am not so concerned about leveling the machine as I am in coming up with a remedy for the "rocking" motion caused by the unlevel floor. So I could use a portion of piniongear's method buy only using the 6" bolts and nuts, running them through the machines' base holes, onto the floor. These could be installed once the machine is up on blocks, then simply lower it down on the bolts/nuts combo and stop the rocking... sound good?
    I used grade 8 bolts, but only because I had them on hand. You can see my 1/2 inch leveling bolts use a nut welded onto the tubing and then use a lock nut as well.
    The problem with using a 5/8 inch bolt through the base as a leveling bolt is that the base would have to be tapped for this to work. And then I cannot guarantee that the base would be strong enough around the tapped hole. Also to turn such a bolt and lift the equivalent of 500 to 600 lbs (2200 divided by 4 bolts) is questionable to me.
    I have seen Bridgeports that have leveling bolts on the base but these were special Bridgeport items with sleeves that fit through the untapped holes. The details of these sleeved bolts I do not know.
    So, for me, using the mechanical tubing was the easiest thing for me to do. My mill rocked back and forth too because the concrete floor goes up sharply when getting close to the wall. Now it is rock steady...........pg

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    If you only want to stop it rocking there is no need to go sophisticated. Three corners on the floor is stable so just decide which of the front corners is the low one, crow bar it up until it stops rocking i.e. you feel the full weight on the bar and shove metal scraps under the corner until you can't rock it with the bar. 4 to 6 inch squares should do it. Now that you can do on your own.

    I know a guy who did the one corner lift bit by winding the table full out on the Y axis slipping a hefty lumber frame under the table close in to the base and winding down the knee to jack the low corner. Not as cruel as it sounds because, unless you have oodles of tilt, its pretty close to balance anyway. However he isn't allowed within 6 ft of my machines!

    Clive

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    Shimming a machine works and doesn't cost anything. Or another option is a leveling system. When I bought my mill new I had these put on. It might be over kill, but the mill is rock solid. I forget the price.

    Tom
    Attached Thumbnails Attached Thumbnails 100_0736-copy.jpg   100_0737-copy.jpg  

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    Just my $.02 worth: I have used a couple of different methods of lifting and moving the mill, based on how much room and "stuff" was at hand in my shop. Moving on rod/tube stock rollers, then jacking up and down with crowbar and spacer blocks is a time-honored millwright tradition, and works well, even if you are doing it solo. I have also used the standard "cherry picker" engine hoist (the special Harbor Freight 2-ton version with high-tensile orange paint) to lift the mill and work all 4 corners at once, as well as (very carefully) using the hoist to move the mill from one spot to another. As far as final leveling after placement, shimming works very well, just to make sure the machine doesn't rock in use. I actually have mine set up on 2x4 (Douglas fir) blocks about 6-8" long at 45 degrees under each corner, with some metal shim plates on top of a couple of the blocks. I like to think that the wood helps to damp some of the vibration....
    I like the pallet jack approach as well; that looks like a nice way to deal with more frequent moves if required.

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    Lots of opinions here,here is another one. Saw some wedges out of some scrap and drive them under the corners that are off the floor. As has already been stated the reason for leveling a machine is to eliminate twist,important with a lathe. Anyone that tells you need to level your mill or your lathe would have a tough time aboard ship.

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    I bought some self leveling rubber feet from McMaster, 63965K63, they are about 14 each. Then I got some 7" 1/2x13 bolts and some hard washers and thin stop nuts. Works like a champ and a lot less than dedicated machine mounts.

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    Alsternatively:-
    1. Paint the concrete floor where the mill is going to go with whatever gloss paint you have to hand, this acts as a release agent if you later want to move the mill.
    2. Move the mill into position on rollers.
    3. Jack the mill further up in 1/2" stages using a crowbar, shims, 2x4s etc. until you can get your hand comfortably under the base. It's only a ton, not very difficult.
    4. Fit some jacking bolts through the hold-down bolt holes with nuts under the base. Screw the bolts down far enough that the nuts will be held against the base when you lower the mill.
    5. Build a frame around the base with 1x1" or 2x4" as available and appropriate.
    6. Fill the frame with non-expanding grout.
    7. Lower the mill onto the lake of grout to the point that the grout overflows the frame. Level table with machinist's level as part of the operation.
    8. Trowel the grout around the frame flat and let it set.
    9. Remove the frame.
    10. Use mill.
    Works for half million £ machining centres, will work for a simple Bridgeport or surface grinder. Will be used for my Beaver VBRP 48"x10" mill after I've rebuilt it.

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    Quote Originally Posted by jkilroy View Post
    I bought some self leveling rubber feet from McMaster, 63965K63, they are about 14 each. Then I got some 7" 1/2x13 bolts and some hard washers and thin stop nuts. Works like a champ and a lot less than dedicated machine mounts.
    Can you please clarify the bolt issues... I mean the hike is 5/8" and you used 1/2" bolts and washer so I am thinking you tensioned the McMaster level pads flush to the bottom of the mill? Kinda confused because these pads have "wobble" to self adjust and makithe flush defeated this feature. I'd like to make hight adjustments (to level) so I'm thinking some sort of (base bottom) threaded sleeve?

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    Seems like a controversial subject here; One member said you could mount a Bridgeport on a wall and it wouldn't make any difference? I tend to lean the other way and want to have my machines level as the manufacturer suggests.
    The only way I level a machine is shim it under the corners; floors aren't flat enough IMO to lay something down the size of the base without it rocking. The pry bar and some shim stock will get the job done. For shim stock I've used steel, brass, pieces of vinyl siding and 4"X4" pieces of ply wood for a corner that needed a lot of material.
    I use the pry bar to inch it up enough to get the shim under it and check for level each time until I get it. I like to leave it in that position and check it again after a couple or days or so use and re do if necessary.
    Dan


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