Milling – Longitudinal Traverse

This topic has 7 replies, 6 voices, and was last updated 21 January 2013 at 17:31 by Tony Pratt 1.

Viewing 8 posts - 1 through 8 (of 8 total)

Author

Posts
20 January 2013 at 07:25 #109330
Ian Robinson 4
Participant
@ianrobinson4
I am wanting to buy a milling machine and I'm looking at the Warco VMC Turret Mill. Whilst most of what I want to do will be within its longitudinal/cross traverse capabilities (370mm x 152mm) some will not be. How practical is it to stop & move the position of a piece during milling to allow a longer piece to be worked and can an acceptable finish & accuracy be achieved doing this?

Ian R
Advert

20 January 2013 at 07:25 #6532
Ian Robinson 4
Participant
@ianrobinson4
20 January 2013 at 23:03 #109453
Michael Gilligan
Participant
@michaelgilligan61133
Ian,

"Possible, but very tricky" would be my opinion.

Just how tricky will depend upon
1. The acceptable accuracy
2. The shape of the workpiece
3. How it is clamped
4. The meauring equipment that you use
If [for example] you are milling a flat edge, and a 0.1mm step would be acceptable; then it's relatively easy. But if you need 0.01mm; then you will soon be wishing for the long table !!

Could you please let us have some indication of what the oversize workpieces might be. … Then I'm sure you will get plenty of good advice.

MichaelG.

P.S. Welcome aboard!
21 January 2013 at 11:33 #109497
Anonymous
Ian,

Perfectly possible; here's a picture of the rear wheel rims for my traction engines being machined to width in stages:

The rims are a bit over 6 feet in length, while the milling machine table is 4 foot, with 790mm of travel. I also machined a V-groove down the middle of each rim using the same clamp and shift routine.

I have machined parts on my CNC mill that exceed the table travels. With careful jig design, tool setting and attention to cleanliness, ie, no trapped swarf, it was possible to achieve sizes appropriate to the accuracy of my machine, about ±0.03mm.

Of course, as we all know, bigger is better, but that will depend upon budget and space.

Regards,

Andrew
21 January 2013 at 13:30 #109517
mick
Participant
@mick65121
Tap tennon blocks into the Tee nut slots and simply advance the work piece along the table, ensuring that the job is tight against the tennons when re-clamping
21 January 2013 at 15:15 #109530
Ian Robinson 4
Participant
@ianrobinson4
Firstly, thank you for the replies to date – much appreciated.

Milling flat edges and longitudinal slots [round and square] on [say] 1200mm lengths of Mild Steel/Stainless Steel/Aluminium flat. Milling a 1200mm long rack. Being flat, the pieces should be easy to clamp and advance against guides but will simply stopping and starting show in a milled face? A good visual finish will be needed for many pieces – which includes aluminium parts that are to be anodised.

Ian
21 January 2013 at 15:24 #109531
David Littlewood
Participant
@davidlittlewood51847
I'm not sure a milled finish will ever be the best for anodising; it therefore could be worth taping a large sheet of very fine silicon carbide paper to the bench and cleaning up the surface on that. This should remove any very minor discontinuity mark on the finish. Won't remove a palpable step, but with care you shouldn't get that.

David
21 January 2013 at 17:31 #109540
Tony Pratt 1
Participant
@tonypratt1
Ian, all what you want to do is possible with care! I found It is best if you can do a portion of the workpiece and then swivel the turret so you can machine another portion etc, but of course sliding the workpiece will work also. If you want a machine that has 1200mm of X travel you are looking at a serious piece of kit.

Tony
Author

Posts