DIY Sonic Testing

[200cfm]

Well I invested in one of those ebay sonic thickness meters and it arrived yesterday afternoon. It's an import like everything else and hopefully it can serve the research efforts here. Model is TM-8811 that they discussed some on speedtalk. Got a reading on my wifes iron frying pan last night. And played around with my cut up head chamber some. Does fine if the surface is flat. Not so fine if there is casting or arching anywhere on the surface. Not sure of the real accuracy until I can mic and compare some things. I've got a chip from a cylinder block around here somewhere (it was always in the way and now I can't find that sample). Once I know more on the useage I'll share the pros and cons. Was hoping to use it on my PRt and SSR, bowl etc but the probe is much bigger than I anticapted. Total length of the touch probe is wider than the wall to wall on my port so that is a serious problem that I didn't think about. My heads are still off the block so will try a cylinder wall reading this afternoon. If I can't get a wall reading it will be a bad day here. Anyone used or have experience with this model?

tom

[bruce]

Tom, I read on ST that they were buying extra probes and shaping them to suit their needs?

I sent you an email the other day about some things must have gotten caught in your SPAM filter? Give me a shout sometime via email or PM

[Scott H]

Tom,

Could you provide a link to the vendor or the name of the unit? I haven't been able to find anything on e-bay so far.

You might try using petroleum jelly instead of baby oil to couple the probe to curved or rough surfaces. Note I don't know if this will work for certain, my last ultrasonic contact experience was nearly 30 years ago, using old Krautkramer equipment with a oscilloscope display. The idea is to completely couple the probe, iow, no air gaps.

Scott

[106-1194218389]

Here is the link for the $179.99 ultrasonic tester - never mind nothing worked so If you do a search for ultrasonic thickness tester - they have all price ranges - I tried doing our link but it wouldn't work
John

[200cfm]

ebay vendor cares the name: emovendo. I tried to read some cylinder walls this afternoon. Does fine on any flat surface. Sort of touch and go on getting a wall reading. I think the probe is too wide for the cylinder wall arch radius to offer me the accuracy needed. And I can't get it into the port areas between the walls.

[Scott H]

Thanks Guys,
I'll have a look.
Scott

[200cfm]

Did some sonic measuring today. Have concluded the meter is accurate on materials that are flat and when the probe and surface area are well oiled and wetted. On the curvature of the cylinder wall it is more of a contact problem to obtain a reading. Appears I need to subtract around .030 or .040" from any reading to correct for the curvature of the bore. If I could find a probe transducer that was half this size it would be ideal for the ports. Here is a picture of the probe end. Probe end is .403" diameter and length is 1.075" Anyone know the probe sizes used on cylinder walls by shops that provide sonic testing on blocks. How are they correting for the arch or wall radius.

[106-1194218389]

I noticed on one of the sonic testers on ebay that it had a 4mm and and 8mm end. The 8mm end would be .315" and the 4mm would be half of that and would be .158" and would probably work better on cylinder walls. That was an expensive unit.
John

[200cfm]

That's nice to know, so a smaller probe end would be the solution. Knocked out a wall piece from my busted block and the gap between the probe and curvature of the wall is a good .020". Measuring the piece with calibers and then with the sonic probe shows a needed .030 to .040" correction factor. The probe reads on the high side so I am thinking of factoring in a correction factor of -.035" from the sonic readings. Tested several miked flat pieces and the sonic tester can hit it dead on within .001" so there is no error from any smooth flat surface readiangs. It is just the curvature that is limiting the useage on cylinders.

[Greg]

My sonic tester has exactly the same probe as in the photo above. I shaped the end to measure bores. If you sand back the metal shroud, you can sit a piece of 240 grit or so wet and dry in the cylinder and rub the probe up and down the bore to get a decent radius on it. Mine is done like that and had been working fine for 4 years or so now. Also, make sure you keep the batteries replaced regularly, they read all over the place with flat batteries.

[200cfm]

Well that solved the problem. Gave the probe end a slight arch to match the cylinder wall. Used 3 in 1 oil and got good repeatability readings and much more accurate. Did a complete mapping on two cylinders using code 10. I am happy.

Now if I could only get it inside the walls of the port to measure that Pushrod turn thickness.

[Greg]

You can get ultrasound gel from most vets, they will probably be happy to sell you some in a specimen jar or similar. Physiotherapists etc.. use it as well.