Updated Edge Finder Function - New TouchDRO Video (and new build)

Inferno said:
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OK, I have a dumb question: how can ANYONE make this probe with enough margin to
1. Sell it for $9
2. Pay AliExpress fees
3. Ship it all the way across the world
4. Have enough margin to cover losses and warranty replacements

Oh, and this same probe is also listed for $36, and $51, and $68, and $103 on AliExpress. I'm no genius, but this looks weird.


Update: I think I know. The listing is for the stylus. If you look at the three reviews, two were for "6mm Probe and wire" and one for "Tungsten ball needle". Other sellers have the stylus listed for even less. Like this one https://www.aliexpress.us/item/3256805149835667.html

So, in this case, either a seller mistake, or scam.
 
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ycroosh said:
OK, I have a dumb question: how can ANYONE make this probe with enough margin to
1. Sell it for $9
2. Pay AliExpress fees
3. Ship it all the way across the world
4. Have enough margin to cover losses and warranty replacements

Oh, and this same probe is also listed for $36, and $51, and $68, and $103 on AliExpress. I'm no genius, but this looks weird.


Update: I think I know. The listing is for the stylus. If you look at the three reviews, two were for "6mm Probe and wire" and one for "Tungsten ball needle". Other sellers have the stylus listed for even less. Like this one https://www.aliexpress.us/item/3256805149835667.html

So, in this case, either a seller mistake, or scam.
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Thanks twice, Yuriy. I was looking at the linked probe and after navigating away for the initial page I back tracked and the same item (including questions & review) was US$49, so apparently the price depends on chance.

“Similar” probes are on Amazon & eBay for ~$75. While I don’t have issues with purchasing some items from China, I’m more than willing to pay more to directly support small businesses that really care about what they are doing (like TouchDRO).

If I upgrade to a larger mill I will seriously consider the DrewTronics unit, but for my Mini-Mill and the work I do I will continue with my mechanical (Fisher style?) edge finder, wiggler and fine-point “probe” (works great picking up scribed lines & center-punch marks):

Center Pointer.jpg


All of these methods work well as long as you understand the potential for error involved in each. The Indicate Workpiece function makes it easier to use the edge finder & wiggler, taking a couple of steps out of the process.
 
Good catch on it being the stylus only. I don't like it when sellers do that. They trick you onto their sales page by showing you a small component and you have to click something else to see the actual item.
Ebay and Amazon do it too.

As for the seller being from China or local. It's a matter of the buyer what they want to do.

(this next part is in jest)
If you buy something made in the USA, a person gets fed. If you buy something made in China, 10 people get fed.
 
ycroosh said:
I have a box of these, ranging from "$10" (really, $60) to $300. The two I use are DrewTronics and SlavTech.
Almost all "hobby" grade probes use the design with three mechanical connections (a dowel pin makes contact between two balls). As far as I know, this is an old Reneshaw design that is now out of patent protection.

DrewTronics probe is very simple - a resistor and an LED, that lights up when the circuit is opened. SlavTech has some circuitry, but works on the same principle. Both give me repeatability under 0.001" (I have "alarm" set to 8 microns, and rarely see the warning). Both are very well made. I talked to both owners (Andrew for Drewtronics, Slavomir for SlavTech) and they both were knowledgeable and responsive.

I don't know about $10, but Chinese probes in the $80 range (that I own) are "OK" if you get lucky. Cheaper parts, a bit slippy built, etc. but mostly functional if you get a good one. Out ot 5 Chinese units I have, one was dead on arrival (missing solder joint on the connector; an easy fix), and one has weird "jitter". The contact spacing is uneven, so the stylus doesn't make solid contact. Repeatability is a bit worse (I often get 0.0016" spread on the "best" one).

As far as side-by-side comparison goes:
  • DrewTronics - made in the USA by a small business, and is objectively better quality than the Chinese probes I own. Has warranty, and the owner of the company picks up his phone and talks to you when you call.
  • SlavTech - made in EU by a small business. Quality and "presentation" about the same (I like the connector and longer cable, but the body is not anodized). The owner answered my email right away when I had questions.
  • $10 Chinese probe - haven't tried
  • $80-ish eBay probe - made in China, QA doesn't exist, works if you get lucky. Support for the two that had problems was along the lines "please send pictures; please send a video; there is no problem; you're just using it wrong; send it back to China and we will look at it; please remove the negative feedback and we will give you $5; please close the eBay case and we will refund you."
On a personal note, I get questions along the lines of "why do you charge $130 for your DIY DRO adapter; I can get a whole unit from China for $80" almost daily. The short answer is "Because I don't use slave labor, Chinese government is not subsidizing me, I've spent a lot of time and money on R&D, I pay for good quality parts and assembly, I inspect and test each board, and I stand behind my product".
I suspect the answer to your question about $10 Chinese probe, vs. DrewTronics is about the same.
Whether or not it's worth the difference in price, is a personal question.

Regards
Yuriy


P.S. I am not affiliated with either company, and bought both probes for full price.
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@ycroosh Thanks for the video, I learned some things! Thanks also for your thoughts on the various probes.

I have been thinking that some sort of an electronic probe is in my future but I haven't made time to investigate so your info is valuable to me.

Last, I too have experienced the song and dance from AliEx sellers with requests for photos and video, all stalling tactics to get you to cancel the intervention my AliEx. More bad faith being shown by AliEx sellers these days. I knew the item was not high quality but it was defective on receipt.

Cheers,
Dave
 
Yuriy,

I reviewed both probes from Drewtronics and Slavtech. What is involved to connect the probe to your board?
 
JFL4066 said:
Yuriy,

I reviewed both probes from Drewtronics and Slavtech. What is involved to connect the probe to your board?
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I don't have it in front of me, but if I recall right, DrewTronics works best when connected between signal and ground pins on the board, with the LED forward biased (i.e. when the probe is triggered, LED lights up).
SlavTech needs 3 wires: Ground to ground, Vcc to Vcc, and signal to signal.

I'll double check next time I'm in the garage.

Regards
Yuriy
 
ycroosh said:
I don't have it in front of me, but if I recall right, DrewTronics works best when connected between signal and ground pins on the board, with the LED forward biased (i.e. when the probe is triggered, LED lights up).
SlavTech needs 3 wires: Ground to ground, Vcc to Vcc, and signal to signal.

I'll double check next time I'm in the garage.

Regards
Yuriy
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Thanks Yuriy. I'm inclined to solder the wires to the board and put a strain relief on the cable to enclosure. In lieu of installing a cable socket to the board. Would this be ok? Also, I'm assuming the cable will have shielding, should I attach it to ground? Or just clip it off?
 
JFL4066 said:
Thanks Yuriy. I'm inclined to solder the wires to the board and put a strain relief on the cable to enclosure. In lieu of installing a cable socket to the board. Would this be ok? Also, I'm assuming the cable will have shielding, should I attach it to ground? Or just clip it off?
Click to expand...
I'm not a big fan of permanently soldering things to the board, but there is no inherent problem with that. Just less flexibility.
It's always a good idea to ground the shielding on one side.
Regards
Yuriy
 
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