A few notes:

I normally aim for a thou or less when tramming my mill, over a diameter of 200mm or so.

No idea what happens if I lean on the table after adjusting the gibs; never felt the need to measure it. My manual mill is pretty worn so adjusting the gibs is a compromise anyway. I just do it by judging a slight 'drag' when moving the table.

The manual mill is a knee mill and the column is large by hobby standards. The CNC mill has a conventional column but I've never leant on it to test. I just make parts.

The machining marks are indicative of a blunt or pooly ground cutter. Where did the cutter come from? Is the cutter HSS or carbide? Your speeds are a bit fast for HSS but slow for carbide. If there was vibration and noise something is wrong. As before a worn of poor quality cutter, or the most common early error is feeding to slowly. Rule 1: the cutter needs to cut not rub. Rule 2: cutters are consumsable items, don't try and make it last for ever by pussyfooting about on feedrates.

I wouldn't bother with cutting oil, especially if it isn't flood coolant. If it is applied in dribs and drabs it just makes a s sticky mess which is sure to cause re-cutting of the swarf, damaging the cutter and making a mess of the finish.

Machining a block to an accurate thickness on a mill is seemingly simple, but is much more difficult than it looks. Even if the mill is perfect the results are highly reliant on how the work is clamped and the quality of the machine vice, if used. If I get better than 2 thou on a 6" square I'm happy, and that's on a large mill with a industrial quality machine vice.

Andrew

PS: If I've an edge finder and DRO available I wouldn't bother marking out and centre popping. Just zero the DRO on a convenient corner, move to hole position and drill – quick 'n' easy.

Edited By Andrew Johnston on 07/05/2020 16:37:55

A rule of thumb for HSS cutters in low carbon steel is 100ft/min cutting speed. For a 10mm cutter that's about 970rpm. Slightly slower is better than slightly too fast. A depth of cut of 0.5mm is small, but should be no problem. How do you know it was cutting? I'd be feeding at 100mm/min or more. If you know the pitch of the leadscrew you can work out how many times a minute you need to turn the handle.

The swirls can be produced by several issues. First as the tips wear, or if they're badly ground in the first place, they will cut inconsistently. Second, dragging swarf around with the cutter scores the work as the swarf gets trapped under the cutting edge. Third, the material matters. A 'sticky' steel like EN3 or hot rolled steel is much more prone to this problem than EN1A. The ridges between cuts imply that the cutter isn't cutting cleanly. Assuming the mill is trammed, you shouldn't be able to feel any ridge. Do you know what spec the steel is?

Fair enough on the marking out. Ahem years ago I was taught marking out and centre popping but now I only use it for sheet metalwork, where I'm cutting/drilling by hand. But of course one needs confidence before flying with no safely harness.

Andrew

Amazing, being quoted and he hasn't even posted in this thread. That's definitely action at a distance.

Search for member JasonB.

Andrew

Bother, shouldn't have taken the time to proof read.

Edited By Andrew Johnston on 07/05/2020 17:17:25

If it's blunt then the finishing pass won't be worth doing, even more likely to just ride over the surface.

I would suggest getting a fly cutter as part of your tool collection. A number of people (including me) use insert tooling in them with good results. This has been covered in other threads in the past.

With a fly cutter smaller items can be faced in one pass and often the trailing edge does not reach the workpiece so less chance of the sort of finish you have got.

Martin C

Fly cutting thread

Link added

Edited By Martin Connelly on 07/05/2020 17:56:40

Left hand lathe tool if you want to run insert tooling or the HSS-Co5 tool ARC do cuts well enough, I usually just go with HSS

Inserts should be fine if you want to go that way. plenty of face mills using them and the insert does not know if it is on its own or several in a head.

Not of you are going at it with carbide and going buy the recent comments you may not have much to come off anyway.

There is not much of a machining allowance on some of the surfaces so you will be doing little more than skimming the surface.

The thin sections throw up their own issues with the possibility of being chilled as the small parts, corners and edges cool rapidly and form a hard iron but carbide usually copes with that, at least for the initial milling if not drilling and tapping near corners.

Well I had a pleasant surprise, reading above the tramming of the SX2P I thought I would check mine as is quite some time since I did it last and the mill has done a lot of work since.

Y reading across table edge to edge 5.5" = 0.0002" X reading across 4.2." each side of table centre = 0.0008". I don't think I will complain about those readings.

GMJN, one tool I would recommend for your SX2 is the ARC 25mm 2 insert end mill. It takes coated inserts for steel and uncoated for alu etc, it really is excellent I use mine all the time on parts large and small. Great for facing and reducing thickness and the finish it leaves is excellent. Its about the perfect size for the SX2 and the mill doesn't have any issues driving it, very good price to.

Ron

Edited By Ron Laden on 08/05/2020 10:04:47