Milling edge of Material

Hi All,

I am hoping someone can point me in the right direction. When using a slot drill or end mill in the mill, it is my understanding that you can use the side flutes of the cutter to clean up the edge of a piece of material when held in the vice - for example cleaning up the sawn edge of a flat bar. However, whenever I have tried, the finish is about as good as the edge of a housebrick - to the point I avoid this operation. I have the same problem when using different materials.

I have checked all ususal suspects - speeds, feeds, made sure the work is rigidly held, no overhang, etc. My machine is a bridgeport. I don't have any problem with other techniques - just this one.

Clearly I am doing something wrong - can someone offer any advice?

Thanks,

James

Edited By James Burden on 13/08/2012 09:56:28

Edited By James Burden on 13/08/2012 09:57:06

I use slot drills / end mills for cleaning up sawn material on my not very rigid Chester Cobra mill . This works OK but to get a reasonable finish I need to feed uphill , downhill produces a much poorer finish.

Have you tried feeding in both directions ?

Hi There

Are you taking off too much material?

On a Bridgeport you should be able to clean up fine.

Is the cutter blunt?

regards David

Bridgeport is more than an adequate machine for this type of work, you can get a mirror finish. Is your Quill lock engaged, do you clamp the non moving axis table lock during this work?

All of the above plus, is the slide that isn't being used securely locked,, are you using coolant or cutting oil and are you climb milling

Hi,

Thanks for the replys.

Climb Milling i usually try to avoid, but would be worth a try.

Have tried various depth of cuts, down to a couple of thou - the same result. Have also tried different cutters, but could try a brand new one I have to make sure.

Regarding locking the travel / quill - might have been one of the problems - will check and retry with locked travels and a new cutter.

Should I need to work down the material in steps (in the Z axis, like milling a slot) or should I set the cutter at a height to cut on the full material width in one pass?

Thanks,

James

Also, coolant doesn't seem to make a difference to the finish - I think it may be not locking the slide that is the culprit...

Thanks,

James

Have you tried putting a dial guage on the side of the quill and checking the sidewards play?

Russell.

Hi,

I have not long finished rebuilding the machine - slides have been reground, all correctly adjusted, and no play in the quill. I am thinking this must be related to speeds / feeds, possible sharpness of cutter, and maybe locking the appropriate slide / quill during the operation. I will have another go tonight and see where I get to.

John - could I ask roughly what speed (RPM) would you expect to run a 1/2 cutter at to mill the edge of say a 1/2" thick piece of Ally?

Thanks,

James

Up to 2000 RPM with a new cutter, if you must, a drop of paraffin as a lubricant.

James, I don't know what sort of mill you have, but on my old Dore Westbury the motor was vibrating noticeably, causing the spindle head on the top of the (not very rigid) round column to nod slightly, producing a corrogated effect in the sort of milling you describe (and horrible gouges when flycutting a surface).

Just a thought.

Andy

It would help if we knew what material you're cutting. Is it all materials you get a poor finish on or just one particular one?

Have you checked the mounting hardware for the cutter ?

Maybe something is not seating properly in the spindle or collet ?

Maybe if you could post a photo of a piece showing the rough cut it may jog someones memory .

IAN

Hi All,

Thanks for taking time to reply with your suggestions.

Cutter Speed I would normally go for 1500 - 1800 for that application, so about right looking at your notes above. Hadn't used any lubricant, but will try some paraffin or WD40.

My mill is a bridgeport, holding the cutter directly in a R8 collet to avoid any additional factors. As above, I don't have any problems with other operations - just whenever I try this I hend up with a bad finish - certainly nothing like Johns photos above. Material either steel or ally.

Wasn't allowed out to play last night, so didn't get a chance to test, the above, but quietly confident that clamping the static slides up, and with a new cutter, I should get some better results. I was wondering if I was approaching the operation incorrectly, but you have reassured me - must be down to the above, plus feed rate maybe.

I will let you know how I get on.

Thanks.

James

Hi James

A couple of things to try.

Check the key is intact inside the spindle?

Sometimes they break off and leave a lump so the collet runs out.

Put a cutter, preferably a new flute, in the machine and use a test indicator to check all four flutes are running true.

regards David