Milling lesson



Faaaaarrrrkkk! - Gunner, you still have the capacity to blow me away sometimes - thank you - a lot of what I have learnt is from this group, even the political Neanderthals....... Andrew VK3BFA.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Andrew VK3BFA wrote:

I think I pretty much demonstrated that. I was surprised that the effect is apparent in slots as short as 0.050".
Speed? - almost

I tried that, but for some reason the mounting holes on the top part of the viseare just enough off so the vise cannot be mounted parallel.

E-type collet.
Have you set up the mill properly (or at

Yes.
The belt drive conversion helps

So far no evidence of that. Belt conversion is the next thing if there is any doubt about the state of the gears.

Or I can take up knitting...
--
Michael Koblic
Campbell River, BC
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Yes, you could take up knitting - no doubt there are knitting groups you could argue with too. You have been given good advice, try some of it out. You have an X2, and a lot of really good work is done on them by people who work within the limitations of the machine. For what your doing, it would be quicker and easier (for you) if you drilled it out as much as possible and then used a file - a technique used before milling machines were invented. If you can, enroll in a trade course - that way, you will have enough knowledge to know if its your own limitations or the machines.....
Andrew VK3BFA.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
It would seem to me that if the cutting path errors aren't caused by unintended table movement, then the wandering path is likely to be caused by flexing of the endmill.
It's not easy to see the length of the endmill, or just the cutting section of it, from the photo.
Another significant problem that happens when a small endmill is used to cut the full width of a slot, is chip evacuation, or lack of it.
With cut chips present in the cutting area, the endmill is frequently jamming as it's rotating, causing the endmill to try to cut fresh material, plus the thickness of the chip(s) passing by the flute on the opposite side of the endmill. Chip interference can be heard as clicking or crunching sounds as the endmill is cutting. Some erratic table movement can probably be detected by placing a finger at the point where the table dovetails meet.
The two conditions will lead to a wandering cutting path. The limited rigidity of the minimill may also be a contributing factor.
Using a cutting tool lubricant in a squirt bottle, to constantly flush the chips out of the cut should improve the results, but the sides of the slot probably still won't be perfectly straight. The spiral of the flutes will help carry chips away, but only to a limited degree (less at lower RPMs). Using a medium viscosity cutting lubricant will help the chips flow outward from the cut.
The other recommendation of drilling the ends of the slot location with a rigid drill, followed by material removal with a smaller diameter endmill would likely be the best procedure, especially with a light duty machine.
Flooding a cutting tool lubricant to flush chips away can obviously be fairly messy, so coming up with a method to recover and contain the lube might be worthwhile. A small endmill isn't going to be slinging much lube, but the flooding action should be constrained to the table area.
It might be possible to retrofit a gutter system around the edge of the table, or the workpiece clamping methods might need to be reconsidered, to allow the small parts to be cut with them sitting in a shallow pan on the table.
The type of dispenser bottle I prefer for cutting lube is the wash bottle with 90 degree spout shown near the bottom of this page (but in a 6oz version)
http://www.zeph.com/dispensing-bottles-squeeze-flux-dispenser.htm
or
http://www.2spi.com/catalog/plasticware/plast4.shtml
These types of squeeze bottles doesn't need to be inverted, and the tip allows very good visibility of the work area.
--
WB
.........
metalworking projects
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
<snip>

If you can get away without coolant, you can keep the chips out of the slot with a vacuum cleaner. I had to mill some ~ 5/8" diameter holes in some aluminum extrusions, where the hole intersected several cutouts. I had a good stiff end mill, but a not absolutely rigid Clausing 8520 mill. Chips would constantly get caught between the end mill flutes and the interrupted cuts, and cause momentary jams & lots of vibration. You could hear & feel the machine jumping around. I set up my shop vac with a nozzle to keep the chips clear, and it worked MUCH better.
Doug White
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I found that coolant/lubricant and ease of chip removal are mutually exclusive. I find it hard to get the chips out with a shopvac *after* I finshed milling. The best I find is what someone else suggested and that is blasting the chips out by compressed air. They of course end up in other undesirable places.
Having said that I find it difficult to believe that chip removal is the *main* cause of the phenomenon described in a 0.050" slot.
--
Michael Koblic
Campbell River, BC
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

......................
1) You cannot legislate the poor into prosperity by legislating the wealthy out of prosperity.
2) What one person receives without working for, another person must work for, without receiving.
3) The government cannot give to anybody anything that the govern- ment does not first take from somebody else.
4) When half of the people get the idea that they do not have to work because the other half is going to take care of them, and when the other half gets the idea that it does no good to work because somebody else is going to get what they work for, that my dear friend, is the beginning of the end of any nation.
5) You cannot multiply wealth by dividing it.
- Adrian Rogers, 1931
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Jim Wilkins wrote:

That would be a 'DE9' cutout, even though a lot of people use the wrong name. The second letter is the shell size.
--
The movie 'Deliverance' isn't a documentary!

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
<snip>

Right. Forgot you can lock X *and* Y this way. Maybe I won't even have to use the fine feed this way.
<snip>

Got it! The centre line is the reference. Makes sense.
<snip>.

I try to use dial indicators whenever possible. I guess backlash comes into it even on the near side, depending where one left the wheel to start with.

Now I understand it. Thanks.

Yes. I might even discover what these quills and tables going up and down are all about....:-)
--
Michael Koblic
Campbell River, BC
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

You have a Sieg X2, right?
The quill feed makes a mill handier as a drill press but on an old worn machine like mine it's an extra wear surface contributing to inaccuracy. In geometric terms your single dovetailed Z axis should be more precise and rigid. I suspect that with heavy production use it might wear faster than a quill plus a knee supported at its center of gravity. Unless you need to duplicate complicated broken machine parts you may have a better hobby mill.
The Clausing has too many adjustment joints to be solid enough for heavy cuts. You can see them in use here, http://www.lathes.co.uk/clausing%20vertical/ Like a Shopsmith or my Toolmaker surface grinder, each additional degree of freedom that increases versatility also decreases stiffness.
jsw
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Not if they are tightened before starting a cut.
Btw..I have an 8540 horizontal Clausing mill for sale..in decent shape if anyone is interested. Ill even toss in some tooling, arbors etc etc.
Gunner
"Lenin called them "useful idiots," those people living in liberal democracies who by giving moral and material support to a totalitarian ideology in effect were braiding the rope that would hang them. Why people who enjoyed freedom and prosperity worked passionately to destroy both is a fascinating question, one still with us today. Now the useful idiots can be found in the chorus of appeasement, reflexive anti-Americanism, and sentimental idealism trying to inhibit the necessary responses to another freedom-hating ideology, radical Islam"
Bruce C. Thornton, a professor of Classics at American University of Cal State Fresno
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Jim Wilkins wrote:

The X2 is what it is. Looking in Grizzly catalog the shipping weight is 149 lbs. The next one up (X3??) is 418 lb. Putting an indicator on a mag base on the table with the point against the column (not the spindle or head, just the column) about 2/3 up I can make it flex 0.020" in both directions.
I do not know how it compares with anything else (which, in a sense, is why I started this thread in the first place) but I suspect that the difference will be significant even against the X3.
I know that people pour concrete into their column and devised all kinds of brackets to strengthen it - I am not sure if that amounts to flogging a dead horse.
At this point it does not matter too much as few thou either way are not kill me. If it ever becomes an issue one will probably consider an upgrade.
--
Michael Koblic
Campbell River, BC
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I really only have chatter problems with deep cuts with 2-flute end mills or large drill bits cutting pipe, with the knee all the way down for clearance. Then the dumbbell-shaped head and motor assembly twists back and forth. When tightening everything and reducing the feed don't help I drop to the lowest speed, which usually kills the resonance.
The head rotates 0.001" / 60 Lbs relative to the lowered and clamped table.
jsw
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Filling the column with concrete will increase the weight and reduce chatter. If I were going to fill the column with concrete, I would include as much rebar as I could. Especially trying to have the rebar next to the wall of the column. That might increase the stiffness a noticeable amount.
Dan
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Jim Wilkins wrote:

Quill? Raise the table? What are these wondrous things you speak of...:-)

Do you do this with 2-flutes or 4-flutes?
I now have 3 different ways to do the same job. It will be interesting one day to do another comparison run. I shall try to design it so the measurements are more meaningful.
Thanks.
--
Michael Koblic
Campbell River, BC
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Here is some basic reading on the subject: http://www.finelinehair.com/home/end_mill_nomenclature.pdf
However for your machine, technique is usually going to be the biggest factor in the selection of the number of flutes, so I would keep it kind of simple. Select a two flute if you need it to cut in the center, other wise a 4 flute should work just fine.
The number of flutes and teh geometry of the flutes gets really critical when you are talking high speed production runs and the like but it is not going to be much of an issue for you.
One important factor is going to be the length so use the shortest length you can for greater rigidity.
--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

At work, whatever is still sharp. I'm an electronic tech and don't usually get the big jobs so what milling I do there is more like light hobby work. At that level feed and depth of cut have more effect than the number of flutes. I speed up the crank until the tool or machine starts to complain, then back off. On that lot of plastic boxes for in- house test use the slots were only for clearance so I pushed the cut to see what would happen.
I think the idea is to make each cutting edge take a healthy bite because edges wear more from distance travelled than thickness removed, then have enough flute spacing for the chip produced. In practice there isn't that much difference between 2 and 4 or the 8 flutes on my shell mill, they all work well with the right feed, speed and depth of cut.
jsw
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.