Milling – What am I doing wrong

[Anonymous]

Posted by Bazyle on 04/03/2017 11:25:44:

A word of caution. When you move down to a 3mm cutter don't go hell for leather late on Saturday if you haven't got a few spares already in stock

Too true!

The rule of thumb is that if you have a spare cutter you won't break the first one. If you don't you will. The smaller the cutter the firmer the rule.

I've recently made some bevel gears using a 1mm ballnose cutter. In all 20 hours of machining with the same cutter; but of course I had a spare.

Andrew

[Nick_GParticipant @nick_g]

Posted by Bazyle on 04/03/2017 11:25:44:

A word of caution. When you move down to a 3mm cutter don't go hell for leather

.

Been there, done that. …………………

Nick

[Neil WyattModerator @neilwyatt]

Posted by petro1head on 04/03/2017 09:46:11:

I removed the tool and took a couple of photos. oh dear its fooooked

See above, use my tip about grinding the corners to 45 degrees then relieving them.

Feeding a cutter too slow or taking too shallow a cut can rapidly blunt them as they end up rubbing not cutting and the tips do all the work.

If you don't want to feed at manic speeds, slow the rpm.

Neil

[JasonBModerator @jasonb]

I'd get another HSS ARC one probably 12mm, one thing I do find with the ARC ones is that the shanks are a fraction smaller than other brands and they are loose in an untightened collet so you have to make sure they don't drop out and hit the table when fitting as this will chip the corners off.

Either go 7mm wide and say 2mm deep or as Andrew says full depth and come in 1 – 1.5mm.

[Neil WyattModerator @neilwyatt]

The advantage with full depth and shallow cuts is that you spread the wear over a lot more flute.

The advantage with shallow depth and wide cuts is that all the wear is on the end so easier to resharpen the cutter.

Neil

[petro1headParticipant @petro1head]

Posted by JasonB on 04/03/2017 13:24:09:

I'd get another HSS ARC one probably 12mm, one thing I do find with the ARC ones is that the shanks are a fraction smaller than other brands and they are loose in an untightened collet so you have to make sure they don't drop out and hit the table when fitting as this will chip the corners off.

Either go 7mm wide and say 2mm deep or as Andrew says full depth and come in 1 – 1.5mm.

 

Thats what I did, finished the other side with no movement of the quill this time.  Have orders a replacement 14mm and also bought a 10 and 12mm roughing cutter

Nice swarf?? Mind its bloody dangerous as it went all overe the floor and is very sharp

 

Edited By petro1head on 04/03/2017 14:52:48

[Involute CurveParticipant @involutecurve]

Too true!

The rule of thumb is that if you have a spare cutter you won't break the first one. If you don't you will. The smaller the cutter the firmer the rule.

I've recently made some bevel gears using a 1mm ballnose cutter. In all 20 hours of machining with the same cutter; but of course I had a spare.

Andrew

I made a test piece a few years back for an injection mould tool here's a pic of one half, its quite dirty now and is only used as a paper weight but you get the idea, the finishing path was also around the 20 hrs mark, 0.3mm ball nose cutter these aint cheap!!, the figure is approx 52mm kneeling down, with an eye loop you can see the knots in his boot lases, I remember the split line was a nightmare to draw, bit it did shut off ok with no flash, I later went on to machine 20 odd of these in differing poses and uniforms………..

Pen top to show depth

[petro1headParticipant @petro1head]

Project finished, 6 T nuts made, 2 for the vice and 4 for general work/rotary table

Next job is cutting a large hole in an aluminium front drive wheel cover on the Harley

Guys you have been so helpful, many thanks

[Involute CurveParticipant @involutecurve]

Posted by petro1head on 04/03/2017 17:55:11:

Next job is cutting a large hole in an aluminium front drive wheel cover on the Harley

Grenade…….

[not done it yetParticipant @notdoneityet]

X and Y axes can cause chatter which may lead to a cutter or Z axis loosening and/or moving.

One tip that has been overlooked (I think) is that of machining with the minimum quill extension. Far better to move the table up or head down (as long as the column is not a round one!)

[petro1headParticipant @petro1head]

Posted by not done it yet on 04/03/2017 18:29:04:

One tip that has been overlooked (I think) is that of machining with the minimum quill extension. Far better to move the table up or head down (as long as the column is not a round one!)

Its a Warco WM18 so the table does not move. The head stops quite sort of the table due to the gas ram in the column so I have to use the quill at full reach if I doing work bolted to the table

Edited By petro1head on 04/03/2017 20:52:10

[JasonBModerator @jasonb]

It would be interesting to see how low it goes with out the ram but that would be at the cast of making the head harder to raise unless it could be mounted externally.

I do a lot of work directly on the table be it large sheet/plate work or castings.

[petro1headParticipant @petro1head]

Jason

The problem is the ram is inside the colum, close to the leadscrew, and no way to get at it without re-dismantling the machine which I am not tempted to do,  I had thought or an exteral ram but would be concered about side loading the keyway.

Is there something I could buy to raise the level of the table

 

Edited By petro1head on 05/03/2017 08:59:38

[JasonBModerator @jasonb]

You will get another couple of inches by the time you have your ER32 collet chuck on there which will help plus tool protrusion.

I don't think raising the table would be easy so better to have something to pack the work up with. You could use some bright 12×50 and 12 x 25 bar to make your own, use 1-2-3 blocks and for sheet work MDF does the job.

[petro1headParticipant @petro1head]

Good idea Jason

The only other option is a shorter ram and loose a little on the height which I don't think I would mill as there is at least 350mm Z travel

[BazyleParticipant @bazyle]

If 123 blocks aren't enough there are 246 blocks (note they tend to have annoying UNC threaded holes). Then there are large but pricey machinists blocks in various sizes (the linked one is the biggest I've seen on ebay). A tilting angle table takes up a lot of room – you could set it very carefully flat and make a special spacer/setting block for future easy set up.

[petro1headParticipant @petro1head]

Excuse me for sounding ignorant but what are 123 blocks

[Thor 🇳🇴Participant @thor]

Have a look here. You can also get them in metric version.

Thor

Edited By Thor on 05/03/2017 16:28:50

[Michael GilliganParticipant @michaelgilligan61133]

Posted by petro1head on 05/03/2017 08:57:07:

Is there something I could buy to raise the level of the table

.

… I just saw this on ebay **LINK** and thought of you.

http://www.ebay.co.uk/itm/Vintage-English-made-Versa-Vice-all-steel-construction-Direct-from-Myford-Stuff/201830516881

MichaelG.

[petro1headParticipant @petro1head]

Have ordered some from Warco.

Also got my books today

[Mike PooleParticipant @mikepoole82104]

A box angle plate could give you a small tee slotted table area much higher than the table, Rotagrip do them as do many others on eBay.

Mike

[Neil WyattModerator @neilwyatt]

You might want to consider John Stevenson's 10-20-40 blocks which fit together unlike 1-2-3 blocks…

Neil

[VicParticipant @vic]

Posted by Neil Wyatt on 05/03/2017 19:40:41:

You might want to consider John Stevenson's 10-20-40 blocks which fit together unlike 1-2-3 blocks…

Neil

I bought a set of those with the 20-40-80 blocks but haven't used them yet, they're a bit on the "Dinky" size!

[petro1headParticipant @petro1head]

I agree, too small

I have gone for 1-2-3 and 2-4-6

[petro1headParticipant @petro1head]

Crumbs, the writing in Harold's book is flippin small, had to get my 2x specs out

[Author]

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