Probe for sonic tester

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dualquad
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Probe for sonic tester

Post by dualquad » Tue Mar 13, 2018 10:20 pm

I just got this sonic checker off ebay. It works well on flat surfaces, but it does not work well at all checking the port wall thickness in cylinder heads. Does anyone know of a probe that would work, and where to get it? I only have one bbc 781 practice head, and I have ground through one of the (good) ports already. So, I have one more good port learn on, lol.

Thanks, Kenny
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Re: Probe for sonic tester

Post by ProPower engines » Wed Mar 14, 2018 12:43 am

I have seen those advertised on ebay out of china. Why not just ask the manufacture if they have a smaller diameter probe???
If you figure out how much smaller you will need that will help.
All so I have heard of some guys sanding the probe to allow for checking curves better with some success. But you may go too far and need a replacement regardless but for the very small cost of the unit to start it may be worth looking for a different unit with a small probe that will suit your needs as the probes are most times an expensive piece by themselves.
but where that one is from I bet they are cheap enough it is not an issue with cost :D
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Re: Probe for sonic tester

Post by Prostreet Racer » Wed Mar 14, 2018 7:33 am

Hi Dual Quad, i have the same sonic tester and probe.
I modified my probe and works fine in cylinder bores.
The line in the centre of the probe don't touch but radius either side till you get a curvature that fits a 4" bore nicely.
I have used this modified probe from 4" to 4.7" bores, works better in ports once modified also.

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Re: Probe for sonic tester

Post by k-star » Wed Mar 14, 2018 12:43 pm

I have a bit older version of the same tester. I put the radius on mine by hand, works like a charm.


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Re: Probe for sonic tester

Post by SupStk » Wed Mar 14, 2018 1:08 pm

What these guys suggested I've done on the recommendation from KKB.
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Re: Probe for sonic tester

Post by groberts101 » Wed Mar 14, 2018 2:21 pm

these guys are spot on. I have the C version of that same tester, whatever difference that makes?.. and the only issue I see after radiusing the probe is that it's tougher to close in on actual thickness since any slight deviation in true perpendicular placement to the surface being tested results in thicker than actaul readings. I believe the square head just dumbs it down so we get consistent readings on truely flat surfaces, is all.

Tons of other probes out there too if you don't want to fiddle with it.

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Re: Probe for sonic tester

Post by racear2865 » Wed Mar 14, 2018 3:22 pm

Can I intercede here. I too have a couple of these and I have purchased several for friends. For their cost, they work quite well. O have a $1200 unit that doesnt work any better than this. Really a shame. But back to question at hand. I have 2 sets of probes, one for flat surface and another for curved (cylinders). As per the answer above, rework for curvature, but keep center section within certain limits of the metal to be checked. The curvature has to be almost perfect to stop any "rocking". I did mine on a mill and used a router bit with curvature that I hand sharpened to fit 4 inch curvature. It worls pretty well up to 4.5 in and then begins to rock. So find a piece of plastic or wood or (not magnetic) and slide over outside and cut larger curvature si u can slide the transducer up and down inside the plastic. This will keep every thing straight.. here is where I got my extra probes
https://www.ebay.com/p/5mhz-8mm-Probe-T ... 7675.l2644.
Also I think a 2Mhz transducer does better on cast iron--I think. Ill let u know when it arrives. I have one on order.
reed

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Re: Probe for sonic tester

Post by Ericnova » Wed Mar 14, 2018 3:56 pm

While we are on this subject, how does the MHz rate effect measurement capability??

I see 6mm probes, but listed at 7MHz and description says ***for use on thin wall tube and "small curved " pipe***.
At a glance, seems like this would be the ticket for cylinder head port work, once modified to a face with a radius on it??
Or does the higher MHz rating cause a problem with accuracy??

Also, instead of just a single curve radius on the face, what about an actual full dome type of radius?? Or will that just ruin it??

Thanks to anyone who help on this.

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Re: Probe for sonic tester

Post by dualquad » Wed Mar 14, 2018 10:31 pm

Thanks for all the response. It is easier to modify this probe, knowing that it has been done successfully! I will also get a couple more probes, just to have.

Now I'm curious about the 2MHz transducer. Also the 7MHz ,since it is 6mm, does seem like it would be better for port work.

Can I use these transducers with my unit? Since it came with a 5MHz transducer, I thought that was what I had to use. If I can use others by just recalibrating or something, that would be nice.

Kenny

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Re: Probe for sonic tester

Post by jsgarage » Thu Mar 15, 2018 2:58 am

DQ, are you using a coupling agent between the sensor and the curved metal wall? When I was testing things using a sonic sensor, I slobbered a gob of silicone grease on the sensor base and stuck it firmly to the surface being checked. Not only did it work, it was consistent. Beveling a sensor's edges is risky as they are hollow with electronics inside, and you can't really match much of a curved contour.

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Re: Probe for sonic tester

Post by dualquad » Thu Mar 15, 2018 6:13 am

jsgarage wrote:
Thu Mar 15, 2018 2:58 am
DQ, are you using a coupling agent between the sensor and the curved metal wall?
Yes, I've been using white lithium grease.

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Re: Probe for sonic tester

Post by clshore » Thu Mar 15, 2018 1:34 pm

jsgarage wrote:
Thu Mar 15, 2018 2:58 am
DQ, are you using a coupling agent between the sensor and the curved metal wall? When I was testing things using a sonic sensor, I slobbered a gob of silicone grease on the sensor base and stuck it firmly to the surface being checked. Not only did it work, it was consistent. Beveling a sensor's edges is risky as they are hollow with electronics inside, and you can't really match much of a curved contour.
This^^

If you've ever seen an ultrasound done , they smear the skin with coupling jelly, same deal.
Lithium grease might work, but silicone is probably better.
Validate whatever goop you choose using a piece of pipe, and don't forget to add a fudge factor that accounts for the gap.

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Re: Probe for sonic tester

Post by clshore » Thu Mar 15, 2018 2:48 pm

I guess 'coupling jelly' could be interpreted a couple different ways ;)
But in fact, KY does work well, it's just that it's water based, so rust could be an issue ... with iron or steel anyway.

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Re: Probe for sonic tester

Post by gmrocket » Thu Mar 15, 2018 8:09 pm

I've tested white grease against the recomended coupling against on the measuring standard block.

No difference..then I found out the manufacturer recommends white grease if the coupling agent is not available..

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Re: Probe for sonic tester

Post by racear2865 » Thu Mar 15, 2018 11:29 pm

The higher the frequency, the thinner metal it will measure, but at our thicknesses, we need to be between 2 MHz to 5 MHz. Ultrasound coupling is best but will leave rust if u dont remove all. Ive used Vaseline and seems ok but I use the jelly 90% of the time
reed

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