correct way to feed when milling

[Ian L2Participant @ianl2]

Hi I have done some milling about 2 days 40 years ago. and I cannot remeber which way I'm supposed to feed the mill is rotating clock wise looking at motor end should I bring table towards me or away from me on the cut in photo.

Edited By Ian L2 on 29/02/2016 19:42:45

Edited By Ian L2 on 29/02/2016 19:46:03

[Ian L2Participant @ianl2]

[pgk pgkParticipant @pgkpgk17461]

[Roger WoollettParticipant @rogerwoollett53105]

The way I think of it is that the teeth on the cutter and the workpiece should be travelling in opposite directions. If they are in the same direction you are climb milling.

[Ian L2Participant @ianl2]

Ok is it me or is his cutter moving while workpiece remains still?

[JasonBModerator @jasonb]

Posted by Ian L2 on 29/02/2016 20:09:51:

Ok is it me or is his cutter moving while workpiece remains still?

As the question was which way to move the table I think its you

Looks like the full width of the cutter is being used so direction is not critical, it's only when using te side of teh cutter that you need to watch teh direction.

[Ian L2Participant @ianl2]

Posted by JasonB on 29/02/2016 20:12:46:

Posted by Ian L2 on 29/02/2016 20:09:51:

Ok is it me or is his cutter moving while workpiece remains still?

As the question was which way to move the table I think its you

Looks like the full width of the cutter is being used so direction is not critical, it's only when using te side of teh cutter that you need to watch teh direction.

Ok just watched video again and I can see if I don't look at cutter but focus on background yes its the table moving but he is showing cutting in both so still unsure but based on him saying light machines (which mine is) am i correct in thinking I should start with table close to me and wind away as I cut?

[JasonBModerator @jasonb]

Can't quite see from your photo but are you using the full width of the cutter? if so will the square in the middle be waste once its all cut out?

Edited By JasonB on 29/02/2016 20:37:35

[Ian L2Participant @ianl2]

Posted by JasonB on 29/02/2016 20:37:06:

Can't quite see from your photo but are you using the full width of the cutter? if so will the square in the middle be waste once its all cut out?

Edited By JasonB on 29/02/2016 20:37:35

the cutter starts on first pass just to edge then little deeper on second and third and is just about full width on last

No the square is not waste, Think about internal house doors.

[SpurryParticipant @spurry]

Imagine: If you tried to mill an unfastened piece of material, which way would the material fly? If it would fly away from the cutter… then that is usually called normal milling. However if the cutter pulls the material towards itself then that is climb milling.

You should be able to picture the above without actually attempting to mill loose items. Just try it with a vertical rotating pencil on the edge of a piece of paper….Much Safer.

[Ian L2Participant @ianl2]

Posted by Spurry on 29/02/2016 20:48:46:

You should be able to picture the above without actually attempting to mill loose items. Just try it with a vertical rotating pencil on the edge of a piece of paper….Much Safer.

Having little problem understanding but I'm a sparky by trade please excuse

[Steven VineParticipant @stevenvine79904]

Loads of pictures here

**LINK**

[Ian L2Participant @ianl2]

Ok hope this shows what I'm doing is it correct or incorrect?

http://s1118.photobucket.com/user/irlunn/media/milling/correct%20or%20incorrect.mp4.html

 

Edited By JasonB on 01/03/2016 07:54:11

[SpurryParticipant @spurry]

Quite what you have there I'm not sure. If I am correct it looks like you are machining a piece of material on it's right hand side with another similar piece also present. You are moving the table away from you.

If you released that cross-piece holding the piece being machined, which way would your piece go? Answer should be – it will fly out the back, therefore you are climb milling.

There is no problem in not understanding…it's the explainer's fault.

[JasonBModerator @jasonb]

OK Looks like you are trying to make a miniture raised and fielded panel door and have the head tilted to do the raising cut. Sheet of metal held with a single clamping bar across the middle

You are feeding in the correct direction for conventional milling I would add something to hold down th eend of teh plate as well

[John FieldingParticipant @johnfielding34086]

Conventional milling techniques have changed over the last twenty years. Today climb milling is the preferred method, but there are some items that need to be addressed before you use it.

Somta Tools has this to say about conventional and climb milling.

In conventional milling the end mill engages the work piece at the bottom of the cut. The end mill teeth slide along until sufficient pressure builds up to break through the surface of the work. This sliding action under pressure tends to abrade the the periphery of the end mill with resulting dulling. Also in conventional horizontal milling the cutting action has a tendency to lift the work piece, fixture and table from their bearings.

In recent years, milling machines have been greatly improved through eliminating backlash and stiffer and better tables and bearing surfaces. To such an extent that climb milling is now possible. Climb milling improves surface finish and increases tool life. Climb milling will often provide better product finish, permit greater feed per tooth and prolong cutter life before sharpening is required. It is particularly desirable to climb mill such material as heat treated alloy steels and non-free machining grades of stainless steels for better tool life and to reduce work hardening. It is not recommended on materials having a hard scale, such as cast or scaly forged surfaces.

Climb milling is not applicable to all milling operations, but where it can be utilised it is a better method.

However, for the home workshop users with small and often less than ideal milling machines, which often have a lack of rigidity and ample power to drive a cutter at the required depth of cut and feed rate, it is better to stick to conventional milling techniques. In any case the milling machine will protest and cause chatter if too high a depth of cut or rate of feed is attempted. Not to mention breakage of cutters if the cutter is not stiff enough to resist flexing or bending. Back lash in lead screws and slides is a common problem with the less expensive machines and the user often needs to resort to locking any unused slide to prevent the cutter trying to pull the work into the cutter – the so-called "climbing action". Tightening of the gib screws to make the slide stiffer to move can also eliminate the sudden taking up of any back lash in the lead screw nut.

A good full flow cutting lubricant feed system does more to reduce chatter, heat removal and promote longer tool life than anything else. The chips that get sheared off the work if they are not removed from the cutter will clog and jam the cutter and spoil the surface finish and cause localised heating of the tool and the work. For those who do not have a full flow coolant system, you don't know what you are missing!

And whilst on the subject of cutting oils, they are designed to be mixed with water, not paraffin or other oils. The water does the cooling, the oil does the lubrication and prevents rusting on the work and machine. Normally a mix of 1 part cutting oil to 20 parts of water is a good starting point. Some oils today work best with a 50:1 mix ratio.

The cutting tool and machine manufacturers are largely driven by the production environment where rate of metal removal is paramount to maximise profit. The amateur machinist does not have this requirement!

[John ReeseParticipant @johnreese12848]

If your machine is tight ( no backlash or very little) and your machine is rigid climb milling is generally preferred. If there is backlash in the lead screws or the machine lacks rigidity you are forced to use conventional milling.

[Ian S CParticipant @iansc]

Climb milling is ok on an industrial machine, but with a light duty machine, stick to conventional milling for all except very fine finishing cuts if need be.

Ian S C

[AjohnwParticipant @ajohnw51620]

Climb milling gets good press for 2 reasons. Sweeps the swarf away from the cut and less power needed for the same cut.

It applies when the side of a cutter is being used – most/all of the time on a horizontal machine. The cutter is rotating and when fed in one direction the cutting forces don't tend to pull the work into the cut. Fed in the other direction they do – that's climb milling.

Being able to climb mill relates to how well some one knows there machine really. It can give a crap finish on some machines and even that will depend on how the slides are set up. There is always the chance that the table will jump just as the cut is started and then be ok as the jump has removed the back play in the lead screw. So in essence that will depend on the size of the cut in relation to the machine table weight etc and lead screw back play. This might suggest that people should set the slides really loose. I don't think that would be a good idea at all. It can work out on some machines if the slides are set a little stiff and some thought given to the feed rate and cut depth.

John

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[Ian L2Participant @ianl2]

Thanks guys after sleeping on it and with clear head this morning think I've got it think what in getting confused with is thinking I'm doing cut with side of cutter when really I,m using end of cutter to do the work. As for the pieces of wood there just holding the work piece in place as I have no proper clamps (now ordered) along with rotary table.

Jason yes you are correct it is a door the wood under it is fastened with 4 x 8mm screws to bed and the strip across top holds the aluminium in the wood as it has routed out section just enough to make door tight fit in it.

One might ask why I'm making aluminium door! simple "I have no piece of wood around" and I don't want big sheet form Wicks at there prices so the plan is to get some at weekend without paying over the odds and use what I've learnt to make another.

Its for a refurbish on very old Dolls house I'm doing for granddaughter.

Thanks again.

[Martin ConnellyParticipant @martinconnelly55370]

I was milling some copper sheet this weekend. I was using the side of a Ø16mm 4 flute milling cutter to square up 1 edge about 100mm long so had the sheet held flat in the vice. I found that using climb milling the finish looked like it had been cut with a saw going hell for leather, not pretty at all. Went back over the edge with a small depth of cut and conventional milling and got a fine smooth finish. When set up to cut out a section to leave a U shape with the part clamped at all 4 corners with a Ø10mm mill conventional milling gave a rough cut and going back to climb milling gave a smooth finish. The point of this is that sometimes climb milling is best and sometimes conventional is best, it is all dependent on a lot of factors.

I think this item on the CNC Cookbook web site explaining climb versus conventional is worth a read.

**LINK**

Martin

[Howard LewisParticipant @howardlewis46836]

As already said, climb milling is for rigid machines with no backlash, or backlash prevention.

The risk is that the cutter will grab the work and pull the two together, risking a broken cutter and scrap work piece.

For our Model Engineering world, it is not a good option. The workpiece should always travel towards the cutter teeth, so that the relative speed is increased, (climb milling gives decreased relative speed, because both are travelling in the same direction.)

Howard

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