"Electronic indicator" IP65 400mm 0.5µm

[Milling man]

Dear colleagues, I ask for help.
For a very dirty spot on a grinder, I'm looking for something that looks like an electronic linear encoder with the following features:
-stroke 400+mm (16+ inches)
- resolution 0.5 µm or less
-accuracy is a difficult question The final accuracy should be within 2 μm, but the main thing is stability. If the stability is within 1 µm and the accuracy is 10 µm, then I will simply make a correction table using a laser interferometer
- degree of protection ip65 or so

The device I need should look like this electronic indicator: https://shop.mitutoyo.eu/pim/upload/mitutoyoData/image/bigweb/mit_2332____eps.png
Only with 16 inches of travel Another thing that this indicator should look like is an air cylinder with a linear encoder inside.
I understand perfectly well that this will not be a very cheap device, probably the price will be about $ 5,000
I've almost come to terms with the idea that I'll have to make this thing myself.
Something like a pneumatic cylinder, inside of which a linear guide and a linear encoder are fixed. Attached to the movable side of the linear guide is the linear encoder carriage and stem. Thus, when the rod moves, the carriage of the linear encoder moves, and the linear guide does not allow the rod to turn. The stem seal prevents a cloud of dust and coolant from getting inside and contaminating the linear encoder.
But I really don't want to spend a lot of time on it

 

[neanderthal mach]

Fwiw? No idea just how well this might work for you, but they make ultra thin linear tapes like this https://www.machine-dro.co.uk/high-accuracy-magnetic-linear-tape that might make a good start to what you want. Figuring out the correct signal to marry whatever reader head it uses to a display would be up to you. Yeah that link is in the UK, but there must be others.

 

[Bakafish]

Dear colleagues, I ask for help.
For a very dirty spot on a grinder, I'm looking for something that looks like an electronic linear encoder with the following features:
-stroke 400+mm (16+ inches)
- resolution 0.5 µm or less
-accuracy is a difficult question The final accuracy should be within 2 μm, but the main thing is stability. If the stability is within 1 µm and the accuracy is 10 µm, then I will simply make a correction table using a laser interferometer
- degree of protection ip65 or so

The device I need should look like this electronic indicator: https://shop.mitutoyo.eu/pim/upload/mitutoyoData/image/bigweb/mit_2332____eps.png
Only with 16 inches of travel Another thing that this indicator should look like is an air cylinder with a linear encoder inside.
I understand perfectly well that this will not be a very cheap device, probably the price will be about $ 5,000
I've almost come to terms with the idea that I'll have to make this thing myself.
Something like a pneumatic cylinder, inside of which a linear guide and a linear encoder are fixed. Attached to the movable side of the linear guide is the linear encoder carriage and stem. Thus, when the rod moves, the carriage of the linear encoder moves, and the linear guide does not allow the rod to turn. The stem seal prevents a cloud of dust and coolant from getting inside and contaminating the linear encoder.
But I really don't want to spend a lot of time on it

You haven't explained why a standard glass or magnetic scale won't work, any kind of plunger that long is going to have to contend with spring linearity, stiction, deflection, gravitational droop and a host of other issues. There's a reason you haven't found one. If your worry is about the IP rating, capacitive 'ball bearing' style or otherwise heavy duty units are surely available that can handle that environment. Even adding positive pressurization to an off the shelf unit would likely go a long way.

 

[Bakafish]

China will have something you can use. If you are ACTUALLY in Russia, it would have to be them in any case.

Nobody else can be bothered even researching whether the goods might - or might not - be sanctioned, nor figure out how to get PAID.

Simply too much like work, too much paperwork, uncertainty, and risk.

LOL, good catch!

 

[Milling man]

You haven't explained why a standard glass or magnetic scale won't work

If your worry is about the IP rating, capacitive 'ball bearing' style or otherwise heavy duty units are surely available that can handle that environment.

All magnetic scales that I have seen so far provide resolution 2-3 times worse than necessary. Also, I have my doubts that something like this: https://www.directindustry.com/prod/renishaw/product-5200-1324397.html will work long and well when coated with a few millimeters of abrasive dust.
Let me explain the task a little - this thing will work in a student laboratory. And this means that in 90% of cases it will be cleaned once every 5 years, no one will turn on the compressed air, and sometimes it will be “accidentally” touched by something heavy That is why I need a device that will withstand all the harsh conditions of use without additional assistance (such as compressed air) and without maintenance.

China will have something you can use. If you are ACTUALLY in Russia, it would have to be them in any case.

Nobody else can be bothered even researching whether the goods might - or might not - be sanctioned, nor figure out how to get PAID.

Please, let's at least not get into political disputes here. Consider that I can buy + - any measuring device anywhere in the world.

 

[Milling man]

"Politics" What was it ...?

Once again, I beg you to conduct political demagoguery somewhere else. This topic is about the measuring device. If you have something to offer - I will be grateful, if not - ce la vie.
I emphasize once again - I do not have and do not intend to have anything to do with the production of military equipment in the Russian Federation. Hopefully I'll be living in a different country in a couple of years, but I want to leave the good stuff in the lab where I worked for 14 years (and where the company I'm working at started) - not some thing that the students will break through year.

 

[Bakafish]

You may not be personally culpable, or supportive of what's going on, and I realize that making clear any opposition could put you at risk, but you should at least understand that on principal we won't provide you assistance for anything short of some purely humanitarian effort. I can't imagine you are precision grinding food for orphans. Honestly if I were in your shoes I'd be ashamed to ask... I know there's a lot of Whataboutisum being spouted over there, but this feels like denial of your new reality. I hope you can make things better over there, but you'll be on your own until you do.

 

[Milling man]

I will cover my searches in solving the problem, I think someone may encounter a similar problem. Colleagues suggested feedback sensors from the field of hydraulics: https://www.novotechnik.com/Linear-In-Cylinder/linear-in-cylinder.html#TH1Series The resolution is too high, but this is already something similar to my goal..

 

[Milling man]

mostly sealed with low positive pressure feed to keep dust out?

The keywords are "positive pressure" The pressure will not arise by itself, and the compressor will not be turned on, or it will break, or something else. If only I worked with this thing, then I would just put a good optical ruler with compressed air supply. But, students are a separate type of machine tool destroyers It should be a thing that you can throw abrasive with a shovel, then tap with a hammer and start working with the desired accuracy. Anything that does not meet these requirements is destroyed within a couple of years. So far, I have not lost hope of finding something ready, or almost ready.
If I still make this device from scratch, then I will probably use an optical linear encoder, I have a predisposition to them.

 

[Milling man]

Trust that his students will arrive already expert at wiring AROUND "switches"

Well...you could rig in a pressure switch that doesn't let the machine power on without the air pressure?

In this regard, I am calm:
1. Students are usually not so arrogant as to change something in the machine without permission from the laboratory staff.
2. 95% will still not understand what it is))))) The remaining 5% will turn on the compressor.
I, of course, thought about the pressure relay. But I'm not at all sure that putting air inside "regular" linear encoders will completely protect them from dirt. Yes, I also read beautiful promises in Heidenhain's advertising booklets But I hardly trust them, because I dealt with these sensors in real life.

because training the users to respect and care for scarce resources isn't even considered to be within the realm of the possible.

I have several acquaintances in US and European universities. One of them is at MIT (in the field of lasers). Judging by their stories, students are about the same everywhere)))))
We still have limited funding. I can't even expect any kind attitude towards the machines from the employees when they work for food.....

 

[ballen]

The IP65 part is hard/expensive. Are you sure you can't mount the scale somewhere that is protected? I'm personally very fond of the Renishaw scale materials. Here is a 0.1 micron resolution scale mounted (in a protected area) on my surface grinder: https://www.practicalmachinist.com/...l-axis-dro-scale-on-a-surface-grinder.395769/

 

[Milling man]

Are you sure you can't mount the scale somewhere that is protected?

I guess if I try, I can protect a regular open linear encoder as well. I have several Heidenhain glass rulers that I once wanted to use on this machine.
But from time to time I just run my finger along the machine frame - and I understand that all the dirt that remains on my finger will be on the linear scale

 

[ballen]

I guess if I try, I can protect a regular open linear encoder as well. I have several Heidenhain glass rulers that I once wanted to use on this machine.
But from time to time I just run my finger along the machine frame - and I understand that all the dirt that remains on my finger will be on the linear scale

Gravity is your friend, as are enclosed areas or 'dirt shadows' created by well-placed shields. Grinding swarf and dust move down under the influence of gravity. So does coolant once it has lost its velocity from the wheel. If you compare the design of a grinder to that of a lathe or mill, one of the main differences is in how a grinder is designed to keep coolant and swarf away from the ways. Most of the shielding is based on gravity. (Example: look on the right hand side of a surface grinder, under the moving table. The ways there are completely exposed, but gravity shields them from the mess. That's where I mounted the glass scale for the cross feed of my J&S540 surface grinder.) The rest of the shielding is based on 'shadows' created by shields or shrouds. These are blocking spray and swarf, not light.

With this in mind, look at the photos in this thread. These show two scales mounted on my Studer RHU-450 grinder. One of these is the same Renishaw tape material as in the earlier surface grinder photos, mounted on the underside of the moving table: https://www.practicalmachinist.com/forum/threads/studer-rhu-450-from-the-1960s.343863/post-3348207 . It was hard work to get these mounted, but they have been trouble free since.