What is the maximum tolerance for a DIY Machine ?!

[RobC]

Holding 0.01mm most of the time, often can be on the measurement I wanted. But my machine is far from perfect, I've had to do a lot of tramming and shimming to achieve such, I built my machine using a drill press and a myford lathe which too isn't perfect. The goal is, if you can't make it perfect, make it adjustable!

This is my first build from no knowledge at all to being able to run it without a single problem which has taken me a few years.

[Kitwn]

What a fabulous video! I want to be reborn, work harder at school and go to Cranfield University!

Half a um is the wavelength of blue light. Just measuring to that accuracy is serious science in it's own right and then he says they can make parts accurate to a few nm! One of my colleagues from a past life ('Dr Dave') had got his PhD by 'photographing' the individual atoms in crystal layers without an electron microscope. In effect he was measuring the varying distance between a microscopic metal probe and the surface of the atoms (if an atom can be said to have a surface) as the probe was moved over the crystal . He gave us a talk on how it was done. Nearly 30 years later I still remember sitting there utterly gobsmacked.

[Colin Barron]

Holding 0.01mm most of the time, often can be on the measurement I wanted. But my machine is far from perfect, I've had to do a lot of tramming and shimming to achieve such, I built my machine using a drill press and a myford lathe which too isn't perfect. The goal is, if you can't make it perfect, make it adjustable!

This is my first build from no knowledge at all to being able to run it without a single problem which has taken me a few years.

Machining within 0.01mm (10 microns) sounds a little optimistic with those slideways and what about ballscrew accuracy and vibration?

[JAZZCNC]

Holding 0.01mm most of the time,

Another one who's in La La land with Hanermo.! . . . Thou unlike him you have at least shown us your machine with its nice cheap Chinese round rails which tell us everything. If you are getting those readings then Suggest you get new measuring devices.

[MartinS]

Another one who's in La La land with Hanermo.!

Just to add some fuel....

We used to regularly machine to tolerances of less than 10 microns. But we had to spend £1m on a Swiss machine with a Granitan bed, BUT also had to spend a LOAD of £ on the measuring system and environment to prove it.

A little story:

Years ago we had a customer who produced(s) large diesel engines. They always had problems getting one bearing bore in the block correct. They were working towards TS16949 Automotive Quality Systems approval and someone new to their company who was bringing new systems in, looked at this issue. He discovered that the machining of the bore in the block wasn't the problem, it was the measuring system that was the cause of rejections! He changed the measuring system and the problem disappeared.

Our company was being pushed by this same company to introduce APQP (Advanced Product Quality Planning) systems. Much of what it contained it had good intentions but was "jobs for the boys" (cynical view), BUT a few core elements opened my eyes.

The CAPABILITY of a machine to produce a feature or shape

The CAPABILITY of a measuring system to "know" what a size or shape is.

The "door in the back of the wardrobe" moment:

So, I brought in "Gauge R & R" studies (Repeatability and Reproducibility). This resulted in us better trusting measurements.....some new equipment, fewer micrometers, even fewer verniers (1/10th mics not thou' mics etc), bore air gauges or Bowers in place of internal mics .

Then I had our guys perform "Machine Capability" studies. WOW what did we learn! They pointed us to many changes, some as simple as temperature control of coolant, or larger tanks. Different styles of cutters (tips or grinding wheels), more rigid fixturing, better maintenance of machines etc.

Eventually, our operators bonus earning increased, we re-deployed some of our inspectors (I renamed "Inspection Department" to "Quality Control"), our main customer relied on us feeding him our analysed quality data rather that his goods inwards inspection, and we made more profit. Yeeay win, win, win.

I know, a long story......

Many of us, in the past and now, "know" a machine, ie how much to "adjust", "tap", "nudge" it to get the job right (and part of me hopes that doesn't go away!)

But we have to understand what is ACTUALLY going on.

BTW, as I see it:

A machine does not have a "tolerance" when producing parts. It has a "capability" ie accuracy and precision.

The part has a tolerance which is wrapped around the maximum error that a feature can tolerate whilst still able to function correctly.


Like I said......just a bit of fuel (Dean).......

[JAZZCNC]

Like I said......just a bit of fuel (Dean).......

Martin since when have I needed any fueling. . . . I'm always gassed up with nitro and ready to blow....

People just need to get real and keep the BS in their own little fantasy land. It's like Muzzer said the difference between moving around in fresh air and pushing through a material is light years different and most of those quoting micron tolerances have a machine which couldn't hold the claimed tolerances if pushing through butter..