Advice for Myford Mill

Hi,

Having enjoyed using my Myford Mill for a few light jobs I recently tried taking a slightly deeper cut than I normally would. I will point out that I tend to mill only aluminium and this was the case recently.

Spindle speed was 380rpm and tool was a two flute, half inch diameter end mill, intended depth of cut was 1.5mm at 5mm wide, hand fed.

I noticed a little vibration and quickly reduced the DOC. However I am left thinking that I should service the table and try to reduce the backlash in both the x and y axis.

Does anybody have any experience of doing this with this particular machine? If so can you offer any ideas or advice please?

PS, I also think my cutter speed should have been higher ?

Thanks,

Ian

Not got a myford mill (unless myford claimed that the last of the Raglans were myford!)

Surface cutting speed is far too low. Were you climb milling? Too heavy hand-fed? Cutter damaged/blunt? Any lubricant/cooling?

I'd agree that the cutter speed is a bit low. Chatter is most often associated with too slow a feedrate; try winding the handle faster. Assuming you weren't climb milling the backlash isn't important, and the axis not feeding should be locked anyway.

Andrew

Hi NDIY and Andrew,

Yes I was climb milling, feed rate was a bit slow as I tend to wind in a bit on the slow side, no coolant or cutting fluid in use. The tool seems to have good clean cutting edges laterally but maybe the edge on one of the ends is a little dull.

I was traversing the x axis and both y and z were locked. The vibration deffinitely seemed to be coming from play in the tables x axis. I know from hand feeding (taking out backlash as I go) that there is room for improvement but not sure on the best way to achieve this.

Thanks again for your input gents, I value your views.

Ian

Right, don’t climb mill, increase speed by about four times and feed quickly with WD40 as lube. I don’t climb mill ever, unless in error, and my power feed is always flat out with aluminium.

An interesting topic for me. I have been using an old Kondia mill, that has ball screws for the X and Y. Just a wonderful old machine. The best part is the zero backlash, and the ability to climb mill. So my next upgrade to my ZX45 mill will be to get or find a set of ball screws for it. Then I can also climb mill etc. Later down the track if I decide on power feed etc can fit some stepper motors for that as well. Although it does have the bolt up nut to reduce the backlash in the threads, I'm not convinced it will be any good really, compared to the zero backlash ball screws.

If you are going to do any rebuild, I would recommend trying to find a set of ball screws to give the anti backlash. They are a little bit of work to fit at times as well.

Neil

Oh dear, I climb mill on a regular basis on my vertical mill. If the WOC is shallow, say less than 20 thou, then it doesn't seem to grab. With larger WOC it can grab, my mill has about 15 thou backlash on X. Although it grunts a bit I haven't broken a cutter yet. Either I've been lucky or it just shows that people are far to cautious on chip loads. Has anyone actually broken a cutter when climb milling, or is it another model engineering myth? Lightly clamping the X-axis lock still allows the power feed to work, but adds just enough drag to prevent the snatching.

Of course that's the trouble with forums, you end up with contradictory advice and opinions.

Andrew

Spindle speed is way too low for cutting aluminium. Paraffin is a good lubricant for cutting light alloys and a lot cheaper than WD40.

Agreed Neil, I would love to have ball screws on my VMC and I have seen it done but it’s too much work for me.

As a £2 19s 3d a week apprentice toolmaker first time climb milling was accompanied by "Doownt do that lad,thall hurt thisen" Second tome was a crack at the back of the head, no one chanced a third time. Only allowed(?) on the heaviest machines, surface finish was obtained by surface grinding after machining. Ball screws have changed ability to get away with that on industrial manufacturing but most of our toy lathes and millers will jump about when trying it and cutters DO last longer when cutting from thin end.

Ever tried cutting a stake starting at the pointed end rather than paring it?

Another don't, DON'T fit a milling cutter in a drill chuck.

Regards Ian.

I often fit a milling cutter in a drill chuck. Drills or enlarges holes much more accurately than a twist drill.

There is usually an exception to most rules.

I’ve broken cutters in more ways than one. One of them was climb milling.

With an end mill in a drill chuck, just don't go side ways.

Ian S C

I will have to look at fitting a new lead screw with Ball Screws, although not expensive it might be very time consuming. Funny but I did think the cutter speed should have been higher, not sure where I got the lower figure from. I do sometimes use WD40 as coolant/lubricant but haven't tried parrafin, will give that a go as well, Oh and no more climb milling, although I have always got away with it until now.

Thanks everyone,

Ian

General note. A lot of the larger old mills have an adjustable nut so it might just be worth checking to see if yours has. If it doesn't perhaps you can design and make one. Could be easier and less expensive than a full ball set-up.

Thanks for the idea Bazyle, I will check it out, although I don't think Myford did any adjustment on the nuts it will be pretty easy to check.