Datum point problem

OK I have now moved on to my second project although the first isn't quite finished. Its Harolds grinding rest. Now I have a number of pieces of 50mm square bar cut for me by the supplier to a couple of mm over size. I need to mill the two sawn sides.

Heres the question. How do I mount the chunks so that I can mill the first side and have it at right angles etc to the other sides. I don't own and currently can't afford a proper milling vice although I do have a drilling vice (of dubious quality).

Hi Wolfie .

You don't need a vice mostly but they can be convent.

For square bar i use an angle plate with a piece of flat bar set up as a fence fitted to the angle plate ( and 90 degrees to the mill table or the face of the angle plate that will contact the mill table ) then mount the angle plate on the mill table so its face( the same one that the fence is bolted to ) is 90 degrees to the X axis , pack up the part i want to machine so its top surface clears the top of the angle plate with sufficient clearance for the needed removal of metal  then clamp it to the angle plate ensuring that is also set hard against the fence that is bolted to the angle plate .

Check out Harolds book ( Milling a complete course ) It is worth every penny and you will keep going back to it for reference many times !

If you dont have an angle plate it can be set up using a fence on the mill table itself but this requires a lot of care as you can mache into the table if not carefull !

Once again the book will reveal all !

Ian

Edited By ian bertenshaw on 13/03/2012 02:33:17

Face them off in 4-jaw, or clamp 4-jaw to table as a vice (very useful).

Good tip! I'm suprised I haven't heard it before.

I agree, using the four jaw is a possibility. I think though Wolfie's pieces may be quite long so do not rely on the jaws pulling it adequately into line. In this case, check with a square off the chuck's face.

The angle plate will though be the best approach once one gets beyond a certain length say three times the chucks jaw length, certainly no more than four times. Don't forget, being square the machining will start off intermittent.

Harold

Hi
If you have a lathe similar to the ml 7 s 7 clamp it down square on x slide Less tool post of course and mill it to size with a cutter or small flycuter .If not got with the angle plate idea clamped with toolmakers clamps Not G clamps
Nobby

Hi Wolfie.

Harolds posting jogged my memory and i remembered a little trick that one should always do when squaring up material on a Mill and that is to run an engineers square over the whole piece to ensure that the four sides are square to each other then do the same for the ends to find the highest point on the end and mark with a texta or some machinist blue etc .

This will allow you to set your first cut so it is removing material from the high point and the cutting forces will lessen as it traverses towards the lower portions , if you start at the low point and start cutting the cutter will have to remove more metal as it traverses the along and the cut will deepen .

If the ends are out of square more than say 2mm i would clean up first with a bastard file or small angle grinder .

Another source of info is some of the DVD productions available through Little Machine shop as these are set up on the X2 Mill and i found them quite well made and informative (they may be available through a retailer in the UK but i'm not sure as i'm in Australia and just about anything usefull has to come from overseas and that's where i bought mine.

IAN

When you put it in the 4 jaw, get it near as possible to an average if its not square, and face it off, that will be the face you work from to square the rest of it. Ian S C

Aha cheers all some good tips there as usual.

I went back and had another look at the book and this time spotted the angle plate hiding behind the set up in the picture.