How to Face, the end of square bar in mill

I have difficulty, no failure, in attempting to square off the end of say a 100mm x 20mm x 20mm in the precision vice in my Arc Euro trade Super X3 mill, I mount the bar horizontaly in the vice and then using the side of an endmill and the Y feed make many passes but the cut is never vertical, I had the sames trouble with my previous mill a Warco GH universal, I do not like using the Four Jaw in the Lathe due to the intermittant cutting forces.

Any Ideas anyone

Paul

Sounds like the head is not trammed vertical or you are using a too long / too slender tool and it's deflecting.

[Edit] Just re-read your post and you are feeding in Y which means the head, if out cannot be trammed on that model. Try spinning your work 90 degrees and using X feed to face off and see if that improves it.

Edited By John Stevenson on 20/10/2014 10:03:38

Are you making fine passes across the whole 20mm depth or one deeper cut and lowering teh cutter in stages?

There is a tendancy for a blunt cutter to deflect sideways, same if there is play in the spindle bearings so make sure anything that can be tightend is tight and you are using a sharp cutter of the largest dia you can hold.

I have no problem doing the same sort of thing on my x3 but 20mm in one pass even if not removing much metal is not the best way

J

EDIT, just saw JS's edit you can tram these mills by shimming under the column.

Edited By JasonB on 20/10/2014 10:13:43

As John says, sounds like something is out - tramming the Mill would be a start. But before you embark on that could you give us a bit more info please. First off, what is this bar made from? Steel, Aluminium?

Next, what sort of cutter are you using? Diameter, length, number of flutes? How are you holding the cutter?

graham.

Is the work lifting when you tighten the vice?

Martin.

Ditto all of the above... I would double check the tramming first... is your vice base flat & jaws vertical to your quill... ?run a DTI down the edge of your vice jaws to give you any indication of vertical run out... if so you may need to skim the base/ slides of your vice true to the quill / table.

George

My understanding of this is that you are moving the head down in small increments Paul.

I don't have an X3 but do own two 'knee' mills. So if we assume that your mill's head is moving down in a truly vertical plane to the table (and you might want to check it) then another possibility is that the 'tilt' of the head is not set exactly at 90 degrees. Depending which way it's tilted, you will not cut at a true right angle and as you may not have side clearance (if it's tilted the other way you would be cutting a series of ridges) you may also start to deflect an extended cutter no matter how sharp it starts off.

So I'd check both the vertical movement of the head and that the tilt is set correctly as a start.

Another thought - and this is just a personal thing. I don't have the ability to sharpen my end mills at the moment, so I tend to save them for when I really don't have other choices (e.g. narrow slotting). For this kind of job (which I can do easily in a shaper by the way) if I was 'down' cutting on my smaller mill - as there is lots of room on the outside of the work, I'd probably use a 'side' version of a small fly-cutter. Just bar stock with a cutter held at 90 degrees by a grub screw. Very easy to make. Then I get the advantage of an easily sharpened single point tool, no clearance problems and a far less flexible tool holder.

Also, I don't know what kind of lathe you have but with a large enough chuck, a sharp tool and very gentle cuts I think you could face off this bar in your lathe. The cut will be interrupted on the corners but will be fine once into the centre. You will probably be able to see the cut 'transition' but it should still be flat (given that "flat" is a relative term!).

Anyway - hope this gives you some other things to think about.

Regards,

IanT

Edited By IanT on 20/10/2014 10:45:49

Paul, like the others have said tram your head first. Then face machine using the X axis so the the relationship between the table ant the cutter centre line remains constant whilst machining.

Then if you can do away with the end mill. Use either a fly cutter or if you have one, or can afford opne, use a face cutter using replacement carbide tips. our friends at ArcEuro do a great one for not too many English Beer Vouchers..

I have a Super X3 from ArcEuro and it does the sort of work you are talking about with no problems. If you are near Leicestershire then you are welcome tp pop in and try the tipped cutter.

P.S. We don't charge for the mugs of tea either.

Paul look at the test cuts I did in this thread, similar to what you are trying to do, came out square.

We are assuming the cut is out of square vertically, if its out front to back then you need to clock the vice fixed jaw in with a DTI.

Dear all that replied to my plea for help, many thanks and you have given me things to check out, I have trammed the vice and mill in X and Y directions and no errors found, I was /am using a RC32 Collet chuck with a 4 flute 12mm endmill, I will first turn the vice 90 dgrees and try in the X direction, I do have a face cutter with carbide tips that might cut on the side, but I have never thought of using it in that way, I could stick with the four jaw in the lathe but measuring the stock whilst in situe I find difficult, OOps another problem!

Many thanks again

Paul.

If you have a face cutter, use it as a face cutter, rather than trying to dress the side of the block.  Last time I had to do a similar sized bit, I clamped it to a pair of V blocks, and stood it on end, and clamped it to the table, but normally I would use the four jaw in the lathe.  You could of course put it in the four jaw chuck and clamp that on the mill.

Ian S C

Edited By Ian S C on 21/10/2014 11:04:33

When I needed to face the end of a piece of 42mm square aluminium for my toolpost-mounted spindle, I simply stood it on end and clamped it to an angle plate, vertically restrained with a cylindrical square. Then I used a 12mm end mill to face the end, ensuring that the Z axis was securely locked. Tramming obviously needs to be spot-on - but you say you've checked this and it's OK.

John

Co-incidentally I've just faced off a couple of 140 mm lengths of 20 mm square to length in the lathe - no problems, five minute job. It would have taken much longer to set up in the mill.

Russell.

I suppose a lot depends on the size of Paul's lathe spindle and bore of the chuck, could end up with the work sticking out a long way

I also misread the original message. Must go back to Specsavers.

If you merely want to face off the 25mm square end the frankly a 4 jaw chuck in your late will do it very well and very quickly. The bar is only 28.28mm across the diagonals and so if it will go into the spindle then this really is the solution. The intermittent cutting at the corners will not affect the facing, and you can always adjust the speed and feed rate to suit. I often face mild steel, of various types but never good old EN1A leaded, aluminium and stainless in my 4 jaw chuck with no detrimaental effect on the finish. HTH and sorry for the confusion earlier.

Paul mentioned that this happened on his other milling m/c as well and the tramming setup is ok. With my limited experience I also wondered if it could be the vice as suggested by Bogstd2, or the cutting and checking procedure.

Paul,

- Did you resolve the issue on the other mill, if so, how?
- How much of the work piece is sticking out of the vice?
- Does the vice have any burrs or embedded debris in the base surface?
- How deep a cut are you taking on each pass and do you take a finishing pass?
- Is the collet fully in place (as mentioned Jason.B) in the linked thread?
- Is your device to check it's square really square itself? (sorry if that's sounds a bit forward or rude, it's not meant to).
- When the work piece is in the vice and it's been cut does it have a longer end at the bottom? suggesting deflection.
- Or, after a cut is the front or back face longer? suggesting the vice is not square to the axi's.

Cheers,
Ed.

There are lots of tasks where using the side of an endmill to machine a vertical face has to be done, and as the machine is all-square and this isn't working we should look for a why. An X3 should be plenty stiff enough. Is there a problem with the slides not being sufficiently tight, or is there insufficient preload on the spindle? Or it could be technique.

I would approach any task like this by machining down the height in steps of, say, 5mm, leaving the part overlength by about 0.2mm, then taking one or two shallow finishing cuts across the whole face to take it to depth. I'd probably take 2 or 3 cuts at the final setting if there was any chance of spring in the tool.

Many thanks for your further feedback, It will probably be a few days before I will be able to exhaust all your suggestions and reply as to my results.

Further history: When I had the problem with the Warco, I did not find a reason and was never happy with the results, so I continued to use the lathe, but when I changed to the X3 I thought I would try again but with no improvement, I used the same procedure suggested by Neil, I am not sure what the PRE-LOAD is that Neil mentioned.

I suppose I am lazy and find that protecting the job from jaw marks and then trying to measure the job in situe I am never confident of the resultant measurement My Chuck and spindle would have no problem accomodating said job.

My Vice is the largest of the Arc Euro precision type and is new and unmarked.

Thanks again,

Paul

I've just squared both ends of 1.1/4" square bms using 4"vertex vice squared to column with the ends of material sticking out of jaws. I used a 7/8 end mill set full depth of material & a couple of 10 thou passes job done, I didn't take my machine apart when I bought it as some people seem to do to check it over I relied on the tolerance certificate and in 18 months I've had it the factory settings were spot on, I do spend try to spend time setting up work/vice etc,if there is a problem with a machine's factory settings it will soon manifest itself and adjustments can be made,

Mick H

Preload is put on (or off) by the adjustable screwed rings at the top of the spindle. it is used to remove any 'slop' in the bearings which may manifest itself as poor finish, chatter and inaccurate cuts.

Neil