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Climb Milling any implications

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Chris TickTock24/09/2020 12:15:15
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.

Just consider your own sketch, and what would happen if you decide to widen that slot by shifting left or right on the X axis.

Good point Michael. My sketch wrongly has cutter force represented as a single force. In the sketch as is opposing forces cancel out trouble. However it is an interesting point if I went to widen the slot. I could cheat and just take light cuts of course which is probably all that is needed. If a larger increase is called for then if I was to use the same cutter, each side would need to be positioned accordingly.

Chris

Emgee24/09/2020 12:20:13
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Posted by JasonB on 24/09/2020 11:30:14:

Chris, the first hit on dave's web search gives a good image of cutter in relation to each sid eof work for external cutting.

These are the drawings I commented on in my post, I believe they are giving the wrong information, Standard direction gives Climb milling if the view is from above.

Emgee

JasonB24/09/2020 12:25:21
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Emgee the straight arrows are the direction of the work, compare my video on previous page with what's shown in the drawings and it's conventional. See the text that goes with it

Edited By JasonB on 24/09/2020 12:28:39

Chris TickTock24/09/2020 12:25:48
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Posted by JasonB on 24/09/2020 11:30:14:

Chris, the first hit on dave's web search gives a good image of cutter in relation to each sid eof work for external cutting.

Thanks Jason, when struggling to first get this understood the arrows can be confusing. Here they show cutter movement which translates to stock feed with cutter still. It is easier to understand with arrows denoting the stock feed direction. Not a problem now i get it (hopefully).

So a quick summary, please put me right if I go wrong:

1. Lead screw mills should use conventional milling as table forced with each flute against back lash)

2. if only light cuts are to be made you could mill in either direction

3. No baring on plunge cuts (hole making and slots)

4. If heavy cuts are taken opposing forces cancel each other out. (why on earth would you take such a big cut, not on my Sherline I think/)

Chris

JasonB24/09/2020 12:30:05
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Posted by Chris TickTock on 24/09/2020 12:25:48:

4. If heavy cuts are taken opposing forces cancel each other out. (why on earth would you take such a big cut, not on my Sherline I think/)

Chris

Forces only cancel out if as shown in your sketch the whole width of the cutter is being used, needed when cutting a slot

John Haine24/09/2020 12:31:44
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As to where to start, often it depends on where the chips will go! I prefer to mill in a direction where they fly off to the left/back rather than all over me!

Dave Halford24/09/2020 12:33:25
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Climb milling tends to drag the work in, in other words it can self feed. Standard starts with a slight rub and opposes the feed.

 

Edited By Dave Halford on 24/09/2020 12:35:53

Emgee24/09/2020 12:54:56
1695 forum posts
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Posted by JasonB on 24/09/2020 12:25:21:

Emgee the straight arrows are the direction of the work, compare my video on previous page with what's shown in the drawings and it's conventional. See the text that goes with it

Edited By JasonB on 24/09/2020 12:28:39

Reading the text below the picture is clearly something I didn't do, unfortunately the text is not visible in the search page shot.
Clearly changing from tool movement to work movement turns it around.

Emgee

Emgee24/09/2020 12:56:49
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Posted by John Haine on 24/09/2020 12:31:44:

As to where to start, often it depends on where the chips will go! I prefer to mill in a direction where they fly off to the left/back rather than all over me!

John

Surprised you don't have chip guards fitted, they do save a lot of floor sweeping.

Emgee

John Haine24/09/2020 13:27:15
3320 forum posts
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Emgee, so am I!

Chris TickTock24/09/2020 13:47:28
576 forum posts
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Clearly changing from tool movement to work movement turns it around.

Emgee

Would do if they were correct for cutter movement but I don't think they all are...correct me if i am wrong?

If the text that we cannot see states X axis is for cutter movement and the Y axis for work feed then fine, otherwise in error.

Chris

Edited By Chris TickTock on 24/09/2020 13:48:23

Edited By Chris TickTock on 24/09/2020 14:15:14

Emgee24/09/2020 15:05:10
1695 forum posts
225 photos

Chris

My original comment was that they were both wrong because of the direction of cutter and relationship with the arrows that I mistakenly took as cutter movement, not workpiece movement.

The video link I uploaded starts with climb milling and then moves to back of the work to conventional milling.

Emgee

Edited By Emgee on 24/09/2020 15:09:05

Chris TickTock24/09/2020 15:20:05
576 forum posts
41 photos
Posted by Emgee on 24/09/2020 15:05:10:

Chris

My original comment was that they were both wrong because of the direction of cutter and relationship with the arrows that I mistakenly took as cutter movement, not workpiece movement.

The video link I uploaded starts with climb milling and then moves to back of the work to conventional milling.

Emgee

Edited By Emgee on 24/09/2020 15:09:05

Yes having a second look they are both right for work movement

Chris

Mike Poole25/09/2020 12:03:10
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The sketch showing cutting a slot in a block is a situation where a slot drill cutter is best employed, it is difficult to cut an accurate slot width with a normal end mill in one pass but a slot drill can do this quite well, a slot drill can also plunge as they are ground so they have a centre cutting edge, it used to be that simple but some cutters also have a centre cutting edge with three or more flutes. However more than two flutes will tend to cut oversize. If a very accurate slot width is required it is best to take a finishing cut to open out a smaller slot.

Mike

Chris TickTock25/09/2020 12:10:19
576 forum posts
41 photos

My Contribution after taking on board all posts and further research. (Any comments welcome)

Climb Milling:

Downward force is exerted on work so can pull out an end mill out. Backlash is potentially added to depth of cut. This is especially important in lighter machines and those without back lash elimination. In more robust / rigid machines with heavy iron tables and tight gibs may not be an issue.

In lighter machines though the back lash if poor can be dangerous e.g. if milling at an intended .005 inch and the machine is poor with .020 backlash then you may get 0.025 cut which could break the machine. So depth of cut plus back lash is key.

Finally climb milling is reputed to give a better surface finish. However there are opposing arguments as always one being that tool deflection can introduce some surface imperfection.

Final advice from my findings is at least be aware of the dangers of climb milling, something I was totally ignorant of before asking on this forum.

Chris

Emgee25/09/2020 12:47:07
1695 forum posts
225 photos

Chris

As you state always be aware of the dangers if and when climb milling, if using the side of the cutter for a light finishing pass it is not so much the depth of cut that causes the problems but the amount of backlash that can be taken if the cutter grabs the work, taking very light cuts with all unused axis locks on and some drag applied to the moving axis you should be able to climb mill without problems, try on some scrap so you are familiar with the operation.

Emgee

Chris TickTock25/09/2020 12:51:15
576 forum posts
41 photos
Posted by Emgee on 25/09/2020 12:47:07:

Chris

As you state always be aware of the dangers if and when climb milling, if using the side of the cutter for a light finishing pass it is not so much the depth of cut that causes the problems but the amount of backlash that can be taken if the cutter grabs the work, taking very light cuts with all unused axis locks on and some drag applied to the moving axis you should be able to climb mill without problems, try on some scrap so you are familiar with the operation.

Emgee

I note additional point about using unused axis locks

Chris

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