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Slot Milling

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Hilton Millar12/06/2009 17:47:38
5 forum posts
I was busy in the workshop the other day making tool holders for my QCTP. While opening up the slot for the dovetail a thought came to me that may be answered by the experienced non-newbies. Is it better for the cutter/machine to open a slot by milling down the extra width or profile cutting the slot to the desired width? I hope my question is clear enough?
Hilton MIllar
Circlip12/06/2009 19:26:32
1510 forum posts
Do you mean use a 6mm Dia. cutter to mill a 6mm wide slot?? If so, no. On a purely PERSONAL note, if you drill the limits of the slot with the required dia. of drill and then machine to width with a 5mm cutter, you ensure (Providing you don't climb mill) that both sides of the slot are clean. If you've tried the size for size method, you already know what I mean.
   Let's NOT get into flamers about "Climb" milling, the newbies have more than enough going against them to start with.
  Regards  Ian.
wheeltapper12/06/2009 21:31:20
424 forum posts
98 photos
I am a newbie and haven't been milling for long but I find that provided I take a very light cut and put a bit of tension on the slide lock I can get a much better finish "climb" milling than the usual way.
just my two pence worth
mgj13/06/2009 11:26:15
1017 forum posts
14 photos
I think a lot depends on the the feed you put on, and the rigidity of your set up compared with the size of the job - and how sharp the cutter is.
Personally I think Circlip has offered very sound advice for the man with a small mill, or one who is using a lathe and vertical slide. If one has a big full sized mill, dovetail column and backlash eliminators, then one is operating in a different league. 
Climb milling without backlash eliminators? Its the tension on the slide that is doing the trick probably, that and the fact that the chip start fat and gets thin - ie a decent bite for the cutter- so the suggestion might be that the cutter is getting a bit blunt for "ordinary milling". ie its riding up and then biting - or there is some float in the spindle? Or you are not feeding fast enough (too low a tooth load) or the revs are too low? Or you are not locking all the unused axes. Climb milling its seeing the full chip width as the edge engages.
Vibration, inherent in milling, is what kills finish, so if one is using a 2 flute slot drill, the 3 flute FC3 type cutters should improve things, because normally you always have one tooth engaged in the job. Being disposable, they are cheap as chips, and double as an endmill too - but tend to be in small sizes.
There's no doubt that climb milling is a better option if you have the right kit, - but it can be really really exciting if you don't.
With many apologies if I am trying to teach my Granny.
Circlip13/06/2009 15:30:15
1510 forum posts
Bet  you've got a "New" miller Roy??  but don't try it on a used and abused one.
  In the words of one of my Japanese motorcycle racing hero's " I Rike Exciting"
   Regards  Ian.

Edited By Circlip on 13/06/2009 15:41:42

mgj13/06/2009 15:57:54
1017 forum posts
14 photos
Rike - exciting - well I don't!!!!
I like to stand back out of range of the coolant spray and drink my coffee to the accompaniment of that gentle brrrr noise that says a milling job is going OK. under power feed. Improves my wah no end.
I don't much like ruined jobs, jammed spindles and busted cutters neither, which is what I find happens if it grabs on the downcut!! Spoils my wah big time - and my wallet.
I have a DoreWestbury, which is very carefully adjusted (and very straight too) and a new Warco super major - bit bigger than I expected, since I don't think in Chinese millimetres. Still same cutter in 2 different machines - finish is chalk and cheese.  Rigidity , mass and damping.
And no, I don't downcut mill on the Warco either, despite it being large (very) and new (very)  -no backlash eliminators that I know of, and I intend the machine to last, and to stay as straight and as well set up as it is (usual disclaimer). 
I'll leave rike exciting to others!

Edited By meyrick griffith-jones on 13/06/2009 15:58:29

wheeltapper18/06/2009 16:48:36
424 forum posts
98 photos
Hmmmm ,power feed......drool drool.
sorry, got carried away for a minute there.
my mill is a Chester Conquest so I dont expect wonderous things but, yes, it is new and I am still learning ( or at least, trying to ).
I wasn't trying to disagree with Circlip, he must know more than me, Hell, everybody knows more than me.
I recently tore all the teeth off a dovetail cutter, shows how new I am.
Ruaidhri Murphy05/07/2009 19:52:27
37 forum posts
1 photos
Sorry to disagree, Roy, but I definitely know less than you!

I have a dovetail cutter - and so far I'm afraid to use it  

See separate post in Beginners Questions.


keithmart06/07/2009 09:06:15
165 forum posts

Hi All


Check this site for free videos of lathe, milling and other machine shop things



Circlip06/07/2009 12:07:31
1510 forum posts
Not advocating climb milling in the least Roy, I just put a comment on what it's rike if you tly it.   Try not to drool for power feeds, a bit like CNC, what yer gonna do while the machine is doing its own thing?? Much preferr to twiddle the wheels, but each to his own.
  If you want to mill a dovetail slot Ruaidri, take as much as you can out with a slot-drill first so you have somewhere for the chips to escape.
    Regards  Ian.

Edited By Circlip on 06/07/2009 12:07:55

Ruaidhri Murphy07/07/2009 11:02:49
37 forum posts
1 photos
Thanks Ian.
At the moment I have a list
Taper attachment from Hemingway
Gearbox (ditto)
Couple more spindles for the Potts
Potts drill grinding jig
Jury rig power feed (thinking wiper motor etc)

Funny thing is that I got the Myford primarily for OT stuff but have gotten sucked in!
Am I the only one whose head is constantly buzzing with (overambitious) ideas?
What makes things really bad is that I bought copy of GMT, Chadock and worst of all Radcliff - I want I want I want .......
Lykle Schepers25/09/2009 08:26:37
7 forum posts
3 photos
I like this thread.
When I was ordering my machines, my wife asked me what I was going to make. I rattled off a list of stuff and after the 6th item she said, that are all more tools!
She was right.
I recently found myself making a tool, to make a tool that will let me make a tool to sharpen my tools. Has anybody out there have a longer chain?
(Between the centres boring bar, to make a over the top ball turner, to make the handles on a Stent, for grinding my end mills)
James Burden25/09/2009 11:20:55
98 forum posts
12 photos
Glad to see it's not just me. I am making slow progress on a Clayton wagon (thanks to help from various people on here) but the workshop projects are building up....
I've got an Adcock & Shipley 1ES mill, and an old bridgeport M type head that I need to get fitted onto the 1ES.
I've also recently bought a very old cast iron linisher ( I believe it is a 'Brooks' ) - was an old three phase machine, a very well engineered machine - but needs stripping, cleaning and rebuilding - paid £40 from ebay, will be a fantastic tool when it is done...
Also bought a Startrite Bandit bandsaw and grafted a reduction gearbox on it to convert it to a metal cutting bandsaw...
I would like to get the Mill, the bandsaw and the linisher operational, so I can make a rivet tool to finish the Clayton chassis... Oh and Harold Halls grinding rest to sharpen the tools used on the above.
If only I didn't have to go to work, I could get so much done...!!!! 
Donald Lunn25/09/2009 13:09:09
9 forum posts
Hi,      Boy am i glad i read these posts,i thought it was just me that is making a tool to make a tool to make a tool.I have made Harold Halls toolrest,and i am now making a QCTP.But i have just rebuilt my Raglan Lathe so i do get some things actually completed.
Peter Tucker25/09/2009 22:22:19
183 forum posts
Lykle,  I made a cross slide mounted table (1) to machine an angle brcket (2) on which to make a V block (3) to suport a slitting saw arbor (4) which was used to slit collets (5) which hold milling cutters used to make other tools.  Is this the sort of thing you mean ?
James, sorry even when you don't work there still isn't enough time.
Falco24/01/2010 00:15:20
65 forum posts
7 photos
what sort of gearing set-up did you put on the Bandit? I have one and the idea of using it to cut metal is very appealing as I am relying on elbow power at present. I built bearing blade guides that run just behind the teeth on sides and back and it worked well on wood. What speed and what type of blade did you find works best with cutting mild steel?
I think the post about the "chain" sums up what our hobby is all about. Few of us can afford to go out and buy all the commercially available tool grinders and other gadgets that we would need to be able to do "that job", but there's that great satisfaction from cheating the system so to speak and getting there anyway by making our own bit of kit. Sometimes the efforts fall a bit short of the beautifully finished specimens we see in the excellent articles in MEW. But sure we all know that our own could be just as good when we get the bits together and build that linisher. And I could build it all the sooner if I could sort out the bandsaw like James and save all that time with the hacksaw........
I reckon that the day you find you've reached the end of your "wants list" you're finished in more senses than one!

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