Long Horizontal Disk Probe

[[Ow...]]

Tried calling the probe-shop hotline and not getting any answers.

I’m needing to measure some long bores in the X axis horizontal position and a disk probe must be used.
I’ve tried using a 20mmØ x 450mm length (ITP) carbon fiber extension with a metal 50mmØ disk probe (see picture) and using a weighted length equal to it on the other side but, cannot get better than 10 micron roundness on a 99mm XX ring gauge. This system with the adapter plate weighs 560g, well within limits.

I have used this 20mmØ x 450mm length (ITP) carbon fiber extension with metal 50mmØ disk probe vertically (straight down) on a shorter block with no problems (<.003mm roundness) but, measuring horizontally with it becomes a problem.

Any suggestions to make this work or recommendations with something else?

I’m thinking about using ordering an 11mmOD x 500mmL Zeiss REACH CXF-3 extension with a 30mm ceramic ball-disk to drastically reduce the weight and possibly reduce deflection?

[[Ri...]]

It is probably a rigidity issue. I tend to not use aluminum or titanium extensions because they aren't that rigid.

The ThermoFit (now REACH) is really good stuff, and I've built some really crazy stylus systems with it.

If you put a normal stylus on the end of it, how does your roundness values look? Have you tried shortening it (just using the carbon fiber extension)? It is possible to have a head that needs tuning in that orientation as they do ring gauge scans in all three orientations.

[[Ow...]]

Yeah in the same set-up/axis, not moved, a regular 3mm probe on a 75mm titanium extension scans the ring gauge just fine.

I've used a 300mm ThermoFit extension in the past and had really good luck with it but, 500mm is needed and I just need to ensure it works with a 50mm metal disk before spending $430 on it.

It's been awhile since I've ordered from Zeiss, do they guarantee them to work if you tell them what and how it's being used?

I was able to get through to Zeiss but, waiting on somebody to call back.

[[Ma...]]

A 50mm disk seems a bit large for scanning a 99mm ring. Friction may be giving you some trouble. Did you try taking single points on the ring for comparison? Also, check the probe pad for nicks and burrs. This long lever will really show up any weakness in connections.

[[Ow...]]

I do get a little bit better results with single points but, not much and that's why I think it's possibly a rigidity issue.
I need 10mm clearance on each side so, I could use a 40mm disk if I had it.
If we weren't constrained on the budget to help save jobs, I could afford a little trial and error.
I appreciate everybody's advice.

[[Ri...]]

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I'm not certain on your last question, I've never asked.

Right now it's difficult due to people working from home.

I've had great success with the ThermoFit, but never with a disc probe (I just don't use them).

I'm sure you can always return it, but would probably have to pay some sort of fee.

[[Da...]]

You need to drop the probe in Z.
I would make it drop it 55mm to 100mm drop in Z. Had the same problem that is how I fixed it
Not sure why.

[[Ow...]]

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I've experienced just the opposite effect when using drop-downs. This is the first time I've had to use 500mm length but, I used to have a system with 300 length and had to remove the drop to get it to calibrate and function correctly.
I'd guess that every CMM and application have their own recipe.

After discussing this with a few application specialist, the consensus is that what I'm getting now is the about the best they'd expect using this size of disk hung out 500mm.

My options are to reduce weight and go with a hemisphere stylus or a star system to where I can can measure four 90°segments.
I believe (if $ approved) I'm going to try the hemisphere approach where I can qualify it with dynamic tensor.

[[Ch...]]

I use the hemisphere's and I love them. ITP Styli has them for decent price. Last time they price matched them without me even asking.

[[Ri...]]

What benefit is there (if any) in using the hemi-sphere styli? I've never used one, so I'm just genuinely asking.

[[Ch...]]

For me, it is long/deep bores where you need a thicker shaft. It just stops the thicker shaft from shanking out. I only use them as a last resort when a normal ruby probe won't work. That and you can qualify them as a normal probe and not like a disc.

[[Da...]]

Weight could be one.
The other is calibration you get more data points to verify your center point.

[[Ri...]]

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Are they typically only ceramic though?

[[Ch...]]

All of the hemisphere's I have bought were ceramic. I have a one inch steel ball probe that weighs a ton that I suppose one could use. But I don't recommend it. I've used the one inch steel ball probe more as a counter weight than an actual probe.

[[Ow...]]

Thought I'd follow-up with what I ended up using.

They didn't want to spend the $2,200 for the special made 40mm ceramic hemisphere probe before trying other/cheaper options.

I ordered a 40mm Disk probe which weighed 11g less (was using a 50mm) and also ordered a full-length 20mm x 500mm thermalstable carbon fiber extension.

Verified and qualified the bending parameters of the probe using a ring gauge and the 'gauge correction qualification' option and along with good size accuracy, got a 0.002mm roundness on the ring gauge, which was good enough.
Weighing each section for balance was imperative.