Dial indicators?

Hey folks,
Seems like it would be useful to have a dial indicator, especially for checking flatness of waste board in connection with milling pcbs (which I’m just now starting to play around with). Just for example, I see a lot options here:

https://littlemachineshop.com/products/product_related.php?RelatedID=161701030&Source=SOTW

Other than that I like to work in metric, I’m not sure how to evaluate the quality of the offerings. Also, am I likely to be kicking myself for getting a $25 one when a more expensive one might have lasted longer/given more useful results?

Recommendations appreciated!

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I have a Habor Freight digital (comes in very handy) and a Teclock analog (I got that one used on eBay for next to nothing). They’ve both worked very well for me.

I picked up an inexpensive Test Type dial indicator ($28) from eBay and also purchases a Dovetail adapter ($10). It’s great for (1) tramming in the router square to the table, and (2) indicating holes. (and a small Mag Base ($12).

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I cant find one rated for 30K rpm…

:thinking: oh wait…:scream_cat: I can’t get around my 3XXL that fast…

I think “Do’oH!” is the appropriate response…as there is no face palm emojy…

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To the precision of these machines, even the inexpensive harbour freight, LMS, or equivalent are fine. If you are in a place where there are a lot of yard sales or flea markets, you can do well that way, as well, for the indicator itself. The other cost is mountings and accessories, and what you need depends on what you are doing. I make a lot of my own mounts, and PhilG shwed his recently ( Nomad 883 Pro Carriage Dial Indicator/Accessory Mount ).

For checking level and flatness of a setup with the Nomad or shapoko, 0.001" (0.025mm, roughly) is fine, and a mechanical (not digital) unit is prefferable, since you can see fine movements of the needle. You care about seeing change, and even cheap ones show that to better than the precision of the machine. For checking PCB setups milled with a 90 degree vee bit (a common setup), with trace width and separations of 0.25mm (0.010"), such as with components with 0.50mm lead spacing, you need to be flat and level to within roughly 0.1mm (0.004") worst case, and and that might need to do some post milling repairs. 0.05mm (0.002") is what I shoot for, and that is quite within the capability of a cheap indicator, as long as the mount to the spindle carriage is rigid.

Most plunger type (standard dial indicators, drop indicators, the type at the top of the page you linked to) in the USA have a 0.375" (3/8") stem diameter, and this is the preferred mounting for greatest rigidity and best repeatability. In the rest of the world, the diameter is generally 8.0mm OD (5/16" + about 0.07mm). The lug on the back plate that many have is handy, but can be more difficult to get a rigid setup with.

For checking level for PBC work, I mount the indicator to the carriage and scan a few different lines across the work, maybe 10mm apart. If everything is within 0.05mm, I set my Z zero to the midrange and call it good. The one I use most on the lathe is a $2 import I picked up at a yard sale, since it is good enough to center a part to 0.005mm (0.0002"). The one I use most with the Nomad for setup is a 3mm range from the GDR I got for $5 at an estate sale. I keep the calibrated units for hen I really need them, since they cost real money and cost more if they go out of calibration.

The test indicator (lever test indicator, dial test indicator) shown by RichCournoyer can be somewhat more precise, but the price is much higher, even for a cheap unit. The range is much smaller in many cases, as well. For the Nomad of the Shapoko, this is probably overkill, unless you have a need otherwise (says the man with about a dozen in different configurations and sensitivities).

If all you want is to check level, and you are in the US, PM me your address and I’ll drop one of my spares in the mail to you. I need to start lightening the stock a bit. Making a mount isn’t a big deal. It doesn’t even need to be dead perpendicular to the surface you are measuring, since all you care about is the changes. At 5 degrees form square, the error is only 0.4% anyway. At 2 degrees (quite achievable by eye), the error is 0.06%. Rigid is key for leveling. Dead square is not.

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Nice vid on dial indicators. Shows the real difference between “awesome” and “chinesium” (not much)

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Good summary - I have both a standard dial indicator and a lever test indicator and the extended travel (1.5 inches as I recall) of the standard dial indicator means I can run the Z axis up and down relatively quickly without fear of slamming the needle, bending or breaking the lever test indicator. If you are only concerned about flatness I would go with the standard. I spent a whopping $25 on mine and it does the job pretty reasonably. Can buy quite a few to make up the cost of a single (exquisite) Starrett.

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Wow–thanks for the info everybody, and thanks for your generosity @enl_public!

Much appreciated!