New Mill - Starter Tooling

Woohoo!

Never mind aligning it; get the swarf flying. You can always take the time to set it up properly at a later stage once it's settled down.

Andrew

Now how did I know Andrew, that it would be you to tell me to "get the swarf flying" and worry about the rest later..lol

Your quite right of course.

Ron

I thought he would have been saying "get the sparks flying"

Well Andrew will be pleased as the swarf was flying this morning at 6am.

BUT, some good and some not so good. I set up a length of 32mm square ali bar in the vice and made a start getting in some practice. I was using a 10mm 4 flute TiN coated HSS end mill, I meant to order a 3 flute cutter but forgot and ordered the 4 flute. I reduced the top of the bar with two 1.0 mm cuts and then finished with a 0.1 mm finishing cut. I got a really good finish but I noticed that there is a tiny step between the cuts, not much but I can feel it with a finger. Question: is it ok to run the cuts back and forth or should they all be made from the same direction.

I then started to face the end of the bar but struggled here as you can see from the photo. I was up milling not down and I tried numerous spindle speeds/light cuts/heavier cuts but I couldnt improve it. Checked everything was tight which it was, the surface finish shows that the cutter is just not cutting correctly. Is the cutter the wrong type for using on aluminium..?

Ron

Ron

Uncoated cutters are better for aluminium. Look at yours in the picture, the aluminium is stuck to the cutter, so it is not cutting properly.

You can get the residue off the cutter by careful use of a Stanley knife blade, don't take the edges off the cutter though.

Cutting fluid will help, paraffin or WD40.

I would play with the mill as it is for a while. When you decide to correct the alignment it will be best to remove the column and check the alignment of the head against the column first. This is what I did:

With a test bar (or some silver steel held in a collet) in the spindle, push the head along the column checking against the dial gauge. I found that the vertical alignment was good but that the head needed to be rotated slightly for correct alignment.

Once that is done you can mount the column and check that it is vertical correcting it either by scraping or using shims.

Russell

Ron, yes, you can run the cutter back and forth. Sometimes you get a better finish up milling sometimes down. That’s what I’ve found at least. Cutting both ways also gets the job done quicker provided the machine/cutter/material will allow it.

Thanks David

Just tried again with some WD40 and it transformed it, I was assuming with ali it was ok dry.

Thanks Russell, I will give that a go when I come to adjust the alignment.

Thanks Vic, would I be correct in thinking the slight steps between the cuts come from cutting up and down.

Ron

Edited By Ron Laden on 18/10/2018 10:23:48

Welcome to the world of Learner Driver milling!

Your cutter isn't ideal for Aluminium - though they're what I use, you have to keep an eye on them. As David said, Aluminium has stuck to the cutter, which blunts it. Aluminium is a soft metal with a lowish melting point - a blunt cutter, or new one applied at the wrong rpm, depth of cut or feed-rate, or one where the swarf can't escape, will tend to collect Aluminium on the cutting edges and once that starts it rapidly gets worse. Good news - the cutter isn't ruined, but you have to get the aluminium off somehow.

As a beginner I thought Aluminium would be a good metal to learn on. Some Aluminium alloys don't machine well whatever you do, and it's generally a little difficult, especially if you use the 'wrong' cutter. With hindsight, I think free-cutting mild steel is more forgiving. My favourite machining metal is brass - even though the splinters are a pain.

Don't be disheartened, getting the best out of the mill needs practice.

Dave

Ron

Good result, well done!

Much of my machining is by guesswork, and as has been said there is no substitute for getting in the workshop and making swarf, and no shame in asking for advice if it doesn't go to plan!

Hi Ron,

I did exactly the same (tried cutting Ali with a TiN cutter) when I got my mill. Things improved a lot when I got some uncoated HSS cutters for Ali. They cut it like it’s butter.

I tend to take the roughing cuts conventional milling and then take the last .1mm climb.

I’ve found the easiest material to mill so far has been Cast Iron, just it’s not the nicest thing to clean up after.

Cheers

Mark

Hi Mark, thanks for that.

I was looking at that very cutter this morning, I think I will get myself one.

Ron

Well I didnt expect that..? When I set up the mill yesterday I adjusted the X and Y gibs and I did adjust the X a tad tight but it was ok and quite usable. I went out this morning and came back to the workshop a few hours later, the door and window had been closed and the shed had been sitting in full sun. The temperature in the shed was 85 degrees and I guess when I set the gibs it was around 60 degrees. To my surprise the X handwheel was seriously tight, uncomfortably so. At first I thought that something had got caught in the leadscrew but no, it was fine. So I could only put it down to the high temp, I backed off the gib screws a tad and it eased up. I realise that the table and base are largish lumps of cast iron but it surprised me that it tightened that way. I guess if you have the gib screws up close it would only take a couple of thou across 4 screws for this to happen. Unless of course its something else but I cant see what.

Regarding cutting both directions, if you have any backlash in your feed screw then when you are climb milling you risk the job being pulled in by the cutter and taking a big bite, this can break the cutter. Climb milling with a light cut and perhaps a bit of extra drag by lightly applying the axis locks can give a good finish. Backlash can be near eliminated on machines with ball screws or controlled with a backlash eliminator which can be mechanical or hydraulic. Heavy cuts on a normal machine are probably best avoided in the climb milling mode.

Mike

Hi Ron,

I hope you get as much enjoyment using your mill as I do. I have found I’m much happier using the bigger cutters but only taking little bites with them. I’ve got some 1/4” slots to do in some steel soon that I’m not overly looking forward to. These little mills aren’t the most rigid, so you have to take it easy. Having said that, I broke a 4mm carbide cutter on Ali early on, worked out I wasn’t running it fast enough and too slow with the table.

It’s all a learning curve.

Cheers

Mark

Hi Ron

For milling aluminium alloys consider getting some roughing cutters or ripper cutters ,they make a big difference as they put less load on the machine when you have larger amounts to remove , then just use your normal cutters for finishing , the steps between passes you are getting is proof of the misalignment you found while tramming the head , I would think around 2 thou or better total indicator reading over a 5 inch sweep should be achievable with some fiddling , that should be good enough for most model engineering work.

regards Geoff

I was up early this morning and managed to get in some practice on the mill, did a bit of a test piece as per the photo.

All done with 6mm and 10mm 4 flute TiN coated endmills which I now understand are not ideal for ali but with WD40 they seemed just about ok.

I tried different cuts/different speeds, up and down cutting, though most of it was done with up cuts as I read that up cutting is probably best for beginners. Holes I did with the 10mm cutter and I used the vice swivel to produce the angle cut. For a first attempt I am really pleased with the surface finish, its not perfect but pretty good.

I really enjoyed making it and although its a simple part, I learned quite a lot in the 2 hours.

Ron

.

Talk about a 'steep learning curve'

... That's like climbing el Capitan !!

MichaelG.