Author Topic: Falling mill? (Read 25431 times)

-steves- · « **on:** October 22, 2011, 02:21:40 PM »

I have recently just started in this making bits and bobs game, and recently acquired a lathe and mill.

What I have noticed is when using the milling machine, it appears to "drop" as I use it. If I start at a position on a work piece, and more noticable where it has parts where it doesnt do anything, then back onto parts that do, then as it moves from part to part, the mill height seems to have dropped slightly without me touching anything, only the x and y axis. If I go back to where I started on the work piece, this can be a significant height difference to what it was when I first started the job. It will only "drop" so far and then not drop anymore, but this can be quite a bit, enough to make 0.5 difference or so, I have not measured it so I am just guessing, but its big.

Can anyone explain why this would do this, yes it is only a cheap mill, but I wouldn't have expected this from even the cheapest mill, or should I have expected this??

more to the point, can I fix it???

Rob.Wilson · « **Reply #1 on:** October 22, 2011, 02:40:02 PM »

Hi Steve

What make of mill ?

What are you using to hold the milling cutter ?

Rob

-steves- · « **Reply #2 on:** October 22, 2011, 02:47:17 PM »

Like I said, it is only a cheapy, well, the cheapest I could find, but this is it. Please dont laught too long

http://www.amadeal.co.uk/acatalog/XJ12-300.html

I am just using a "drill chuck" type thing to hold it, I could understand it moving upwards because of the chuck, just not down

I am intending to get a face mill on an MT3 which I am hoping will be more accurate, but I dont know?

Brass_Machine · « **Reply #3 on:** October 22, 2011, 02:48:46 PM »

The possibilities... We need some more info like Rob stated. Could be anything... quick guesses... 1) Mill is out of tram 2) Not locking the Z 3) Tool holder is worn/broken/incorrect.

Brass_Machine · « **Reply #4 on:** October 22, 2011, 02:51:51 PM »

Same mill as mine. Don't be embarrassed, mine has done a LOT of work (Paid work even). It it does it without issue.

Just noticed you are using the drill chuck to hold endmills. STOP! get the correct holder.

Are you locking the Z?

-steves- · « **Reply #5 on:** October 22, 2011, 02:52:55 PM »

Quote from: Brass_Machine on October 22, 2011, 02:48:46 PM

The possibilities... We need some more info like Rob stated. Could be anything... quick guesses... 1) Mill is out of tram 2) Not locking the Z 3) Tool holder is worn/broken/incorrect.

Erm,

1) No idea what that means?

2) No idea what that means either.

3) It is new, but I honestly don't but I am doubting worn or broken, incorrcet, I would hope not, but again, I dont know

-steves- · « **Reply #6 on:** October 22, 2011, 02:54:37 PM »

Quote from: Brass_Machine on October 22, 2011, 02:51:51 PM

Same mill as mine. Don't be embarrassed, mine has done a LOT of work (Paid work even). It it does it without issue.

Just noticed you are using the drill chuck to hold endmills. STOP! get the correct holder.

Are you locking the Z?

The problem is, is I have no idea if its good, bad or indiffernt, and have no idea on peoples thoughts on buying the cheapest you can find. To me the spec seemed higher than some more expensive ones which is why I went for it. Its nice to hear that it can be good

What is the "correct holder"?

The "Z" ???

sparky961 · « **Reply #7 on:** October 22, 2011, 02:55:18 PM »

Agreed that more info is required, but when I first read it I wondered if maybe you're using an end mill and the end mill is being pulled out of the chuck due to the inherent cutting forces involved. I will admit that I've used an end mill in a drill chuck before, but it is definitely not something you want to make a habit.

-Sparky

Brass_Machine · « **Reply #8 on:** October 22, 2011, 02:57:16 PM »

Sorry... hit post before I finished.

You need to get a collet setup or and end mill holder for you mill. The drill chuck cannot take the forces of lateral movement. It wasn't designed for that.

Something like this

or

Also, are you locking the Z axis when you are making cuts?

I know you are fairly new to machining. When I started, I got a couple of videos from these guys: SwarfRat Helped me a lot! You mmight want to consider getting some. Since they are here in the US, if you have issues getting them, I may be able to help you out.

Eric

Brass_Machine · « **Reply #9 on:** October 22, 2011, 03:05:06 PM »

OK!

Tram. When a mill is in tram, it means the column is square to the table. Left and right AND front and back. A few links ONE and TWO.

There should be a little lever on the side of the mill column. When you tighten it, it locks the head in place. The Z axis is the up and down movement of the mill head.

-steves- · « **Reply #10 on:** October 22, 2011, 03:05:34 PM »

ok, found the Z axis, the vertical. And just been up to look if it had a Z axis lock, it does, and no I have no been using it, I take it this needs to be applied quite tightly. Well there is point number one fixed.

Just to work out these collect things next????

Rob.Wilson · « **Reply #11 on:** October 22, 2011, 03:08:39 PM »

Hi Steve

Nowt the matter with those mills ,,,,,,,, lots of good engineering has been done on them ,,, my mate has one (from the same supplier )and he thinks its great .

As i thought ,, using a drill to hold milling cutters

Best of invest in a collet chuck as Eric has advised

Rob

-steves- · « **Reply #12 on:** October 22, 2011, 03:10:56 PM »

Would this be what is required? Its the one at the very bottom of the page for £96 on MT3

http://amadeal.co.uk/image/sh000000.pl?REFPAGE=http%3a%2f%2fwww%2eamadeal%2eco%2euk%2facatalog%2fCutting_Tools%2ehtml&WD=collet&PN=Sets%2ehtml%23a383#a383

Rob.Wilson · « **Reply #13 on:** October 22, 2011, 03:19:17 PM »

Hi Steve

I would stay away from those ,, they look like old style collets ,,,,,,,, Go for a ER25 collet set ,,more holding rang ,,, then you can in the future get/make a collet chuck for the lathe and use the same collets ,,, like these only a few quid more .
http://www.ebay.co.uk/itm/RDGTOOLS-ER25-3MT-COLLET-CHUCK-SET-16PC-/370501164359?pt=UK_Home_Garden_PowerTools_SM&hash=item5643971d47#ht_1826wt_1185

Rob

-steves- · « **Reply #14 on:** October 22, 2011, 03:22:19 PM »

Quote from: Rob.Wilson on October 22, 2011, 03:08:39 PM

Hi Steve

Nowt the matter with those mills ,,,,,,,, lots of good engineering has been done on them ,,, my mate has one (from the same supplier )and he thinks its great .

As i thought ,, using a drill to hold milling cutters

Best of invest in a collet chuck as Eric has advised

Rob

Another favourable vote for that mill, phew, things are indeed looking up, I thought I had bought a pup, its appears its just down to the user, and I can cope with that as the user does have the ability to learn and get better, whereas tools only wear out and get worse

The lather came from the same place to be fair, it was the 7x14 lathe they do with the 100mm chuck, think it needs an expert eye casting over it, but seems to be doing the job for me so far

picclock · « **Reply #15 on:** October 22, 2011, 03:24:38 PM »

Hi Steves

It's likely to be the chuck. If your mill has the MT3 taper as in the advert you will need something like an ER32 collet chuck. This page tells you a bit about them

http://www.arceurotrade.co.uk/Catalogue/Collets/ER-Collets-Collet-Chucks/ER32-Collets-Collet-Chucks

Although they can be had for a better price. Without a collet chuck the mill will pull itself into the work effectively becoming longer. You can try it by putting a marker line on the junction of the endmill and chuck, then do a few heavy cuts. You should see that the endmill has moved and the line is no longer next to the chuck. As a quick bodge a small endmill <4mm well tightened may just about stay in place but a 20mm endmill will spoil the work and your day.

Although its tempting, try to get a collet chuck with some accuracy even though it will cost more. You only need 3 collet's to start off, 6,10,20 as most endmills will fit these sizes (for imperial you need the whole set).

http://www.ctctools.biz/servlet/the-Tool-%26-Work-Holding-cln-ER-Collet-Chucks/start/73/total/93/Categories

offer very good prices although you may be subject to import and VAT if the goods cost is over £18.

Richontools is a good place to buy endmills from

http://richontools.com/index.php?main_page=index&cPath=15_51&zenid=227ba376fea53d87728a1aa11b4653cd

Good luck with your new mill.

Best Regards

picclock

-steves- · « **Reply #16 on:** October 22, 2011, 03:26:46 PM »

Quote from: Rob.Wilson on October 22, 2011, 03:19:17 PM

Hi Steve

I would stay away from those ,, they look like old style collets ,,,,,,,, Go for a ER25 collet set ,,more holding rang ,,, then you can in the future get/make a collet chuck for the lathe and use the same collets ,,, like these only a few quid more .
http://www.ebay.co.uk/itm/RDGTOOLS-ER25-3MT-COLLET-CHUCK-SET-16PC-/370501164359?pt=UK_Home_Garden_PowerTools_SM&hash=item5643971d47#ht_1826wt_1185

Rob

Thanks Rob, roll on payday, I think a set of those will be coming my way soon. Just need to get some modern day metric end mills as all the ones I have I think are imperial as they came out of the shed and we have no idea of their origin (now where is that blushing smiley again)....

John Rudd · « **Reply #17 on:** October 22, 2011, 03:27:24 PM »

My suggestion would be to use this.....http://www.chronos.ltd.uk/acatalog/Posilock-Collet-System-3-MT-with-4-Metric-Collets.html

I use them on my Chester mill with no issue at all with endmills and slot drills..

Reason being that the ER range of collets are hollow. The Posilock system will prevent the cutter( slot drill) from moving up into the holder...

Rob.Wilson · « **Reply #18 on:** October 22, 2011, 03:37:59 PM »

Quote from: -steves- on October 22, 2011, 03:26:46 PM

Just need to get some modern day metric end mills as all the ones I have I think are imperial as they came out of the shed and we have no idea of their origin (now where is that blushing smiley again)....

No worries ,,,,,, 10mm collet will hold 3/8 ,,,,, 7mm will hold 1/4 excreta thats the good thing about ER collets ,,,,, they have a good parallel closing range ,,and get a dam good hold of the cutter .

Rob

edit cos i cant spell

-steves- · « **Reply #19 on:** October 22, 2011, 03:40:28 PM »

Oh dear, now I am all confused and have no idea what to get, lol ????

Stilldrillin · « **Reply #20 on:** October 22, 2011, 03:56:40 PM »

Steve.
I did say, you'll get lots of advice....... I didn't say we'd all agree!

Go for ER type metric collets. They will hold imperial too, as they have a range of "squash down".

My mill ("same" as yours), but a Chester Conquest, has a gas strut, which pushes the head upwards, constantly......

Yours uses a spring, which doesn't take the weight at all times.

Keep the Z axis lock on, (not too tight), whenever you're not moving the head......

When machining, always keep the non moving slides locked.

David D

Rob.Wilson · « **Reply #21 on:** October 22, 2011, 04:09:55 PM »

Hi Steve

A pozilock chuck is fine if all your going to do is use it for milling ,,,, Small shops need versatility IMOP .

Clarkson autolock chuck ,,,,,, all it holds is 4 metric collets and four imp collets ,,,,,,, thats all it dose .

this is not an ER collet system ,, but close ,,,,,,,, lots of collets

A few additions ,,,,, two holders for the lathe ,, two for the mill all using the same collets and closer

because there they are bored right through long work can be passed through them on the lathe ,, they also fit the dividing head .

On the mill table or angle plate or rotary table

in the mill vice , HZ or vertical say for milling a square on the end of a shaft ,,,,,,, or two parallel flats

I have a hex one that need to be finished

more versatility

Rob

jiihoo · « **Reply #22 on:** October 22, 2011, 05:00:19 PM »

Hi Steve,

If you haven't already found the MIT machine shop videos then you might want to watch them. They can be found here:
http://techtv.mit.edu/collections/ehs-videos/videos.

That should keep you busy for a few evenings

Cheers,

Jari

DaveH · « **Reply #23 on:** October 22, 2011, 06:26:06 PM »

Steve,

If you are new to milling this may help a little. http://madmodder.net/index.php?topic=4678.msg51465#msg51465

DaveH

Ned Ludd · « **Reply #24 on:** October 23, 2011, 10:07:41 AM »

Hi Guys,
Don't we think Posi-lock is a bit old hat these days? Although they were very good in their day, when most end mills had a thread but these days very few do. An ER chuck is a more universal holding method as it will hold both threaded and non-threaded cutters, and has been mentioned they do not need an exact size requirement as they usually grip over a 1mm range. As for which size to go for, well get the biggest you are likely to need, and don't forget that they can be used in the lathe too.
Ned

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Author Topic: Falling mill? (Read 25431 times)

Rob.Wilson

Rob.Wilson

Rob.Wilson

Rob.Wilson

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