First Time Milling Cutter Issues Help Needed Please

Tad heavy perhaps

hi jamie,

yes it's possible. file some ordinary BMS then try using the file straight after on your stuff you are trying to mill. you will see/feel any difference straightaway.

when i started this lark 31 years ago there was still a lot of ex-WD WW2 strengthened/armoured plate about - one of my locos has this plate as the frame steel!

cheers,

julian

Edited By julian atkins on 30/05/2014 23:27:35

Simply banging a 12mm hole in metal isn't usually the the correct route, 12mm is quite a big hole

You drill a pilot hole of 3-4mm then take it from there, depending how accurate you want the hole to be

A 12mm drill has a big flat(ish) nose on it which resists the cut, if you drill a pilot hole first then the flutes come into direct contact with the workpiece instead of the nose

A big problem for you is that you have a chunky bit of kit from day one and have not had any experience of what might work and what might fail on smaller machines, cutting speed, torque, feed rate depth etc

It's miles easier to spot your mistakes on a smaller machine because they are more sensitive and less powerful

Edited By Ady1 on 31/05/2014 00:57:45

If a piece of key steel hit against the corner of the plate leaves no marks, then the plate is harder than mild steel.

There are grades of steel plate that comes already pre hardened at about 40 Rc or so. That is very tough going with HSS tooling that is for sure. It should file very easy and be easy to put a ding into the surface. Capcrews are about 40 or so hardness, so it should file a whole lot easier than a capscrew does.

Neil

The problem may well be the drill. I've never heard of Irwin, but I'd be wary of a make that seems to be primarily sold through DIY chains for that market.

For comparison I happen to have bought a 12mm jobbers drill (Guhring) this week from my local professional tool supplier. List price was £12.12p plus VAT. I got a substantial discount on list, but still not cheap.

I'd drill in the following sequence 4mm, 8mm and then 12mm. For the 12mm drill I'd use 500rpm and a feedrate of at least 0.2mm/rev.

Regards,

Andrew

PS: If you send me a sample of the metal I can test the hardness, and try drilling it. PM me for an address.

Metal swapped new block on the mill's bed. Mill head upright with with work clamped flat.

I have set up a butting block and five clamps on the work piece. .

Locked everything down. End mill full in the collect with collet correctly fitted and locked off as tight as I can get it.

Mill speed 300rpm with the mill driving in low gear.

Tried 1mm and 0.5 of a mill. Things feel more comfortable...

BUT... The end mill in still getting pulled out of the collet with the collet becoming loose. I can't tighten the collet any more.

any advice is welcome as to how I can get around this:

set up below

May be a silly question is it the correct size collet? From the picture it looks like the collet is one too big.

Worth checking the shank diameter as some times the shank is a different diameter than the cutter. ER collets are usually 10 to 11, 11 to 12 etc in 1mm steps for larger sizes 0.5mm for sub 7mm. I usual try to use a 12 to 11 for a 12mm shank cutter and not had a problem with them in mill or lathe.

Won't fit in the next size down......

Obvious question but is the spindle rotating the correct way? as something is not right.

Have you got anything to measure the cutter shank with, from the photos it looks like the shank is the nominal size of the cutter so 20mm and your collet is definately marked 20-19 so should fit. Try tightening up the collet without a bit in it and see if the slots close up, it may be there is something stopping the nut going far enough onto the thread.

Hi Jamie,

I'm relatively new to machining as well but have been doing quite a bit of milling recently. I have a slightly smaller machine, the Warco WM-16. I use ER25 collets on an MT2 chuck. (I think your machine would be a match to the Warco WM-18).

Things I would check if I were seeing this problem are :

- For a 20mm end mill the correct size collet would be the 20-19.

- Are you locating any part of a flat on the end mill in the entrance to the collet? (if it has a flat on the shank that is).

- Are you using two spanners to tighten your collet chuck?

- Are you locking the quill before taking a cut? My quill has about 0.8mm vertical backlash if I don't lock it and I've used the fine feed to move it down from its home position.

Pls excuse my input if these are obvious things you already checked.

Regards,
Ed.

Just looking at the photo of Jamies above, if that is a 20mm cutter in a 20-19mm collet there is not a lot of thread showing on the collet holder to be able to close it down to 19mm, compare that with my ER32 with 16mm cutter in 16-15collet.

I wonder if its actually an imperial set with a 3/4" cutter and Jamie's next collet down is 18-17 as its not a full set? Which would mean teh collet is right on its limit for closing down.

Edited By JasonB on 31/05/2014 20:39:20

I see what you mean about the thread length Jason. I wonder if the collet locking nut is unfortunately cracked?

I have just skimmed through this thread again but did not spot the post where someone had commented on too much thread being left exposed after the collet nut was tightened. I did see a lot of thread showing on Jason's milling pictures, Is that what was being referred to?

Looking at some of the photos in the various posts there are some collet holder/mill spindle arrangements that are unusual to me but its hard to see which is the rotating part and which is the quill body.

My thoughts on the original problem (apart from the geometry) is that if I wanted to use a cutter near to the maximum diameter that the mill was designed for, would be to put the ER collet to one side and use a MT3 (or whatever size the spindle is) direct in spindle taper. On some of the setups shown there is quite a lot of overhang to from the cutter to the front (lower) bearing. To my mind some spindles have nowhere near enough spacing between the spindle bearings anyway so doing anything to reduce the overhang will help.

Ian P

When I bought my mill (similar size to Jamie's), I was tempted (by price) to purchase a collet set and chuck. It turns out that it was a sort of half-way between ER25 and ER32. Neither one nor t'other with a taper that didn't correspond to the ER standard. The collets were slightly longer, too! Is it possible that Jamie has a "rogue" collet in a genuine ER collet chuck, or vice versa and that's what's allowing the cutter to unscrew? In my, albeit limited, experience, a proper cutter in a genuine ER chuck will hold tight, with virtually any reasonable loading demands on it. Something has got to be drastically wrong somewhere here.

I have carried out similar operations to the one Jamie is attempting, but on thinner material and I used a smaller diameter milling cutter to excellent effect, with no sign of the cutter going walkabout.

John

Do you have anything other than that piece of plate and that cutter?

If so, try milling the "other" bit of material with a different size cutter because what you have here is just so wrong for a first attempt. I think Jason might be onto something with the Imperial sizes.

Where are you in the country? If you are anywhere near me I will nip round.

graham.

The collet set I have is this one:
ER-40 x 3MT Collet Chuck Set

http://toolco.co.uk/pages/bakery/er-40-x-3mt-collet-chuck-set-467.php

the cutters set I have is this one:

20 Piece End Mill / Slot Drill Set

http://toolco.co.uk/pages/bakery/20-piece-end-mill--slot-drill-set-397.php

Hi Jamie, I have nor read all of the thread but there is for sure lots of good advice, however here is my three penny worth.

Check that the collet is what it says ! I recently purchased a set of ER 16 collets and chuck for a project and found that one of the collets was incorrectly marked for its size. If this is the case for you then it will as others have said make it more likely that the cutter will pull out.

Looking at your set up am I correct in assuming that you are truing up the full depth/edge of the plate ? I.e. Using the side of the cutter to a depth of 20 - 25 mm ? If this is the case then I am not surprised that the cuter pulls down during the cut even if the depth of cut is very small. Hope I explained this well enough. For this type of work it is better to use a Clarkson chuck with screwed shank cutters. ER collets are very good and I use them a lot but only for light cuts and in the situation above would revert to my Clarkson chuck , or indeed for any situation where the depth of cut required it.

Regards John

Cutter problem solved.....

A REALLY BIG THANKYOU TO EVERYONE FOR ALL YOUR HELP AND ADVICE ON MY FIRST VENTURE IN TO USING MY NEW MILLING MACHINE

I problem was a bit of bad finishing on the inside of one of the gaps in the Collet... Using a bit of paper I fed it through all the gaps in the collet to find that one was not as it should be.. Now sorted and cutting well......

Now I have managed to square off the first edge... But I now have a minor issue that I want to address before I unclamp everything to start on the next side.

I have made a number of passes until the edge is squared up. I have then made 3x passes at 20th of a MM to try and ensure a smooth finish but it still looks fairly rough.

Would I be correct that this might be down to all the issues I have had with the cutter and it now might not be as good as it should be to get a really smooth finish I am after? Di I just need to replace the cutter? Or would I be better off doing final cuts with a smaller cutter?

Glad to see you have got to the bottom of the problem/problems

I would try a smaller cutter with a drop or two of cutting fluid.

If I am after a reasonable finish I run one cut as a conventional cut and then without altering any settings reverse the feed direction so that I have a very light pass climb milling.

That said my main mill is somewhat heavier than yours and seems to be happy with light cuts climb milling, only one way to find out...............

Bob