Using a milling machine to make big holes?

[TheJoker]

What about doing it the other way around: Rotate the work using a rotary table. Then could do any size hole with just an end mill.

This is, so far, my only option. However, it's slow and tedious. Also, if I have a large work piece then I can't rotate it 360 degrees due to a) the small rotary table I have, b) the small milling machine I have. But, yes, it's the option I've got at the moment.

 

[shenion]

Then it looks like an excuse to get the CNC attachments and program some circle patterns

 

[hareng]

I have had a ****** 2" head and use the adapter of choice ie MT2, MT3, ISO or R8 etc all in sub £50 but have MT2 shank and an R8 to use on other millers and tools.
Done serious work for over 10 years (1000's of holes opened up) usually on aluminium 16mm thick, i tension up the locking so that allen key can still move cutter in or out, dont bother locking unless precision jobby. All below on rotary table some may have been around 9 years ago on a Clark miller/driller round column to give you some idea.
http://pic20.picturetrail.com/VOL15/728921/1252422/14584660.jpg
http://pic20.picturetrail.com/VOL15/728921/1243489/297909672.jpg
Offset balloon shaping all bored in.
http://pic20.picturetrail.com/VOL15/728921/1243489/103092209.jpg
Another same http://pic20.picturetrail.com/VOL15/728921/1243489/103092340.jpg

Now for convenience i bought two sets of those ****** 1/2" boring bars, now apparently one shouldnt use carbide with aluminium- decent finish highest speed available and slow feed. Max i would rough out is say 30mm hole opening up to 38mm. Slightest misfead! so tension down feed up which also reduces spindle movement.
Smallest dia you could bore is around 1/4" dia with smallest short bar positioned in the centre.

Have a butchers here though expensive http://www.chesteruk.net/store/boring_tools.htm
Carbide in red cylinder towards bottom either for cast or steels but sharpen properly! Boring bar and shank higher up £90, i paid less than £50 elsewhere.

 

[wyn]

Wyn, could you please explain a bit more for a newbie/daftie like myself? I don't really get it.

You could fit an arbor/adaptor to the milling machine that would be a No.2 morse taper (to replace whatever you have in it at the moment) and would take broaching cutters.

The cutters are available up to around 60mm diameter.

But the arbors only seem to be available with a "tang" on the end of the morse taper and not a threaded hole to take the machine's 10mm drawbar.
Without the drawbar pulling it tight, it might rattle loose.....there again they work ok in a mag drill without coming loose.

 

[Shox Dr]

Wyn you can get them, I have a set, 1/4" 3/8" 1/2" 5/8" for use with straight shank type cutters

 

[wyn]

Wyn you can get them, I have a set, 1/4" 3/8" 1/2" 5/8" for use with straight shank type cutters

That sounds interesting Shox Dr, have you got any pics or links ?

 

[brightspark]

its a nice little machine for hobby use. small engineering parts but it only has a 150 watt motor fitted so would struggle to pull over a boring head the max chuck size for drilling and cutting is 10mm a good power drill is 650 watts geared down on low speed and a good hole saw can make them struggle

 

[Shox Dr]

Bloody typical, I've had a look on fleabay and on Rgd tools site and can't find any. There's usually loads on there, I'll take a pic for you

The largest I had is 5/8" where as the Rotaboarch cutter I have is 3/4ish (just eyeing it up) im sure you can get them though

 

[gavuk]

rough out using cutter and rotary table and finish cut using a boreing head then ?

 

[hareng]

Here you go ready to use if M10 draw bar and MT2
http://cgi.ebay.co.uk/2-inch-Boring...emQQptZLH_DefaultDomain_3?hash=item56385f93bc

 

[hareng]

Just reread and you only have max 255mm spindle to table.

Cant find my MT2 shank but the MT3 attached to same boring head inserted will protrude out of spindle 81.35mm + cutter min 25mm your max = 106.35mm.

You can clamp the work piece to the table, your max 25mm.
So 106.35+25 = 131.35mm leaving only (255-131.35) 123.65mm distance max from bottom of cutter edge to top of work piece.
An 8" Vertex rotary table is approx 130mm high plus chuck and jaws, so 6" or less will be ok without a chuck.

You may even be able to fiddle some extra height out of the miller.

 

[TheJoker]

Thanks very much guys. As I'm quite new to all these techical terms I'm still a bit confused, but you've given me a lot to think about. Especially the broaching cutters and also the boring heads. Need to look into that more.

Thanks again!

 

[graffian]

Boring head would be on my list of "got to have" bit's of tooling.
You can drill a hole with one, I have been using the boring head and
rather than switch to a chuck just stuffed a drill in it and used it to drill the hole. I tend to rough out the hole, if I was making a large hole in ali say, by drilling as much of the material away as possible. I did leave rather a lot on one casting pattern and have to remove just under a half inch on an oil seal bore, with the tool poking out the side of the head I remove about .48 in one go without any problem at all, short rigid tool though.

Here's a pic of a boring head resizing the rocker arm bore in a Velocette rocker cover. Not sure how I would manage without one.

 

[TheJoker]

Thanks for that info and pic, graffian!