Mill repair.

Hello all,

Last week I decided to check my mill colum for accuracy and when moving the head up the colum it is within 0.02mm over 225mm in both the x and y great me thinks,but then decided to try the quill and it's well off 0.17mm over 75mm!!!! Its not a thing that I have ever checked before and it's not affected any holes that I have bored [although there have never been any very deep ones] so would it be best to leave it as it is ? or I can take the whole head to the brothers employers and have the quill housing rebored true on a Deckel Maho but then I would need to sleeve the resulting enlarged bore for the quill ,any thoughts? The mill is a Chester LUX.

Regards,

Raymond.

Apart from the comment you get what you pay for. How old is the mill and have you contacted Chester?

Got same problem on mine and noticed a few weeks back quill movement. No apparent wear on quill or bore in the head, still got the honing marks!

Got to the point within a week every job i picked up, near on scrapped 0.8mm out. Now you cant put metal on! The quill or housing will be oval, exagerated. All chinese mills are like this or will be. Ideally needs a hone before it gets out of hand and chrome or electro plating with the quill.

Also if quill is moved down the head, rack and pinion in quill itself has less contact area than fully up. Easier way to explain is say 3" diameter round with a 1/4" flat machined away at rear, any play will be amplified 3 or more times. Theres also a cutout in back of the casting amplifying this, again like all other chinese mills.

If theres no quill movement with the lock off, unlikely you can alter the head by shimming or just tighten up the gib strip more, it all has that effect, really crap design like many others. That head really weighs and not enough grab on the dovetail. ie tighten top lock the head will tilt rearwards and pull to the right, nip bottom up, the heads already tilting downwards and will just pull in to the right.

Kwil, the mill is about 7 years old now so no use contacting Chester. It was only recently when reading about people having to shim the colums that I decided to do the checks.

Jon, The colum is fine within 0.02 over approx 225mm it's only the quill downfeed that is off .I can't go shimming because that will throw the tram off and it's trammed to less than 0.02mm through a circle of about 200/225mm . but now that I am aware of the error it will probably "bug" me till I resolve it [or convince myself to leave it]. I have been thinking of getting a cnc mill and keeping the Lux so I may well leave it as it is.

Raymond.

Ps, there is no noticable play in the quill, it is just that the housing has not been bored true.

Hi Raymond .

I own a similar machine to the lux (dovetail column i hope ?) and also had some issues but had a play around and found that the column had gunk under it and was not truely at 90 deg to the table .

Now you say that it trams within a thou @ 225mm circumfrence and about the same if you wind the head up the column - what are you using to test against ? an angle block ? Make sure it is 100% parrallel to the axis you are using as a datum .

When you raise and lower the head the locks must be loosened so the HEAD would follow the inside of the dovetail and not the flat base it is meant to bear against when locked - could be mis -leading .

So try clamping the locks at each end of the travel so the head is bearing against the flat parts of the column and confirm the readings .

Have you tried to tram the quill with the locks on the column dove tail as loose as when you checked the vertical movement of the head for trueness ?

You could try to tram the quill to column and see if they are parrallel but this is a mission and would need some tools made . also the spindle needs to be locked so it cannot rotate but can move freely up and down .

I'm sure they use a taper gibb set up on the column and , maybe there is an issue there ?

Have you tried placing a block of wood under the quill then using the downfeed apply a small amount of pressure before locking the column locks ? - see if there is any change .

I would also ensure my table locks are tight before doing any vertical measurement - just to be sure - after all that what you are ultimately using as a datum .

IAN

Raymond, if you have been using the mill for 7 years and its newly discovered error has not been a problem before then I recommend that you do not take any drastic action like re-boring the quill housing. Learn to live with the error and make allowances for it when necessary. All budget machines are likely to have some inevitable errors and short comings if you want a "tool room" quality machine you will have to pay a small fortune for it.

Ian, Eric,

I have decided to live with it,as it has never been a problem when I did'nt know about it.

The LUX is a nice machine it does all I ask from it and is nice and rigid and [quill problem aside] is still very accurate. the error has not affected anything before so I won't get the quill rebored as it is a fairly involved process [ take it to bits, drain the gear box new sleeve for the quill and it's no lightweight.] it's just not worth the hassle.

Ps, If ever I decide to get another mill [ Manual] I would have no hesetation in getting another Lux

But it would be stipulated that the quill must be at least equal to the colum accuracy or better, and I would want a test chart to prove it. and not a chinese one either , but one from the sellers or forget it. Regards,

Raymond.

Ray theres three nuts to swivel the head, you could drop a packer in there but wouldnt recommend.

They are a good mill had mine labelled Zay ZX7045 powered head model 8 years used daily. Parts are dear mill cost £930 on one of their June sell offs was £1500, transfer box for powered head motor £244.

Good advice from Ian, as said before the head is heavy and hanging off too small a footprint. Seen the new Grizzly ones with hollow rear upright casting the electrics fit into.

Seen a few converted to cnc and have to wonder if any good as the gib strips are left loose. Yes there is a gib strip on upright column to head.

Just keep an eye on the quill play, lead screws can be replaced with cheaper better ball screws when the need arises.

Hi Jon,

What a CLOWN I have been , During testing ,when checking the quill I put the mill in lowest gear and took out the slight gear backlash but did'nt lock the spindle, when I told one of the millers at the brothers work he took over a granite square [they use it for checking the Dekel Maho's and Mori Seiki's] It is extremely expensive and very very accurate. And when I told the miller how I was performing the test he instantly new what was happening .The shaft was rotating as I fed the quill, the external splines on the shaft were touching the fixed internal ones and as a result the spindle was rotating hence a reading of over 1mm at full depth but now it is set up at only 0.03 over the 125mm or so, and, due to the granite square the column is now at l 0.02 over 350mm I made such a stupid basic error. With the results I have now I am very happy.

Regards,

Raymond.

I have an old Alpine mill which I bought second-hand. The previous owner had done a very good modification to the main head casting, in that he split the casting through the centre line of the quill, put three large socket capscrews through to pull the bore in, but had put in two pushing screws between the pinch screws. This gives me the ability to micto adjust the fit of the quill and , although only adjusted a couple of times in the last ten years, it has remained a useful tool. The only drawback is the need for a pal with a bigish mill to slit the casting.

Regards,

Alan.

Ray,

That's twenty "hail curly's" and no beer for a month as penance

Neil