roughing and finishing cuts on mill

This topic has 7 replies, 5 voices, and was last updated 2 September 2016 at 13:13 by Douglas Johnston.

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30 August 2016 at 15:36 #8273
BW
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30 August 2016 at 15:36 #253072
BW
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Am an inexperienced mill owner ……….. Rong Fu RF30 2hp motor

I really like the crisp way that a brand new milling bit snicks through the metal and leaves a nice finish – as opposed to an old blunt mill bit that chugs through ………

I've become aware of roughing cutters and other things called "little hoggers" mentioned in a recent thread.

Should I be using things like those hoggers and roughing cutters to remove the bulk of any cut and save my HSS milling cutters for a final fine finishing cut ? In the beginners things I've read so far the concept of a different tool for a final finish hasnt been promoted as much as it is for a lathe.

I have almost finished the final project – Grinding Jig – in Harold Halls milling book and although its all come together reasonably well I still feel as though I dont really know what I'm doing with this machine.

Seems to me that with a 2HP motor and a max speed of 2140rpm this mill has enough power and speed to use carbide effectively whereas my 60 year old 9" Hercus lathe (equivalent to SB clone or old Myford etc) is said to be better off with HSS toolbits.

So – if you could point me to a previous thread, a website or a different book to read I'd be grateful. Thanks.

Bill

Edited By Bill Wood 2 on 30/08/2016 15:38:18
30 August 2016 at 16:10 #253078
Vic
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@vic
I've used roughing cutters on my VMC to good effect but I can't recall what the finish was like, it may not have needed cleaning up with a standard mill? They aren't expensive so worth trying. As for the "little Hogger" set it's just a name as far as I can tell, they look like fairly standard carbide insert mills. They do leave a nice finish though.
30 August 2016 at 20:49 #253127
I.M. OUTAHERE
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@i-m-outahere
Take a look at Stefan Gotteswinter on youtube he did a video on roughing cutters .

If you are just surfacing a piece of plate and taking .010 or so off roughing cutters will not give you any benefit in speed and will give you the same finish as a conventional endmill. if you need to plough out some metal then a roughing cutter is what you want .

You can always leave the piece a little oversize and switch to a conventional cutter to finish to size , it really depends on what finish is called for .

One tip – don't buy cheap cutters they go blunt quicker and usually don't cut as good as a quality cutter .
30 August 2016 at 21:22 #253132
Neil Wyatt
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My mill is just ~0.5hp and max speed 1600rpm and it happily works a 13mm carbide end mill.

I recently took edge cuts 2mm wide by about 7-8mm high in silver steel with a 1/4" carbide end mill – once I realised how daft this was I noticed it was working fine so carried on.

So, yes your Rong Fu will have no problems with carbide.

Neil
31 August 2016 at 03:07 #253161
I.M. OUTAHERE
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@i-m-outahere
Now that is pushing a 1/4 inch endmill to the limit !

Bill i use insert tooling on my C2 seig and my hafco AL50g lathes and have never had a problem , your old Hercus is a better machine than either of those !
2 September 2016 at 12:55 #253616
BW
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Posted by XD 351 on 31/08/2016 03:07:55:

Now that is pushing a 1/4 inch endmill to the limit !

Bill i use insert tooling on my C2 seig and my hafco AL50g lathes and have never had a problem , your old Hercus is a better machine than either of those !

Hey XD,

I do keep finding comments on both sides of this argument I reckon for every 2 people who say I can't do it 1 person will make a comment similar to yours, saying that I can do it – I have used carbide to clean up a cast iron gym weight and it worked fine.

I haven't used carbide on anything small – my top speed is 720rpm and I keep bumping into advice saying carbide must run 2x HSS speed and that it doesnt really cut like HSS does but is more of a brute force tearing.

Have to admit I have neither the experience or skills to really have much of a valid opinion yet, will keep experimenting and see what works for me.

……………….. and thanks to the other people who posted above for your advice and comments

Bill
2 September 2016 at 13:13 #253623
Douglas Johnston
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Carbide milling cutters are less of a minefield than carbide lathe tools since the choice of types is much less. I use both carbide and HSS milling cutters and both types work very well on my Myford VMB mill. The carbide ones keep a sharp edge for much longer but can chip more easily and cost a lot more. I don't tend to run the carbide ones much faster than HSS and they perform just fine.

Doug
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