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Multimeter info
« on: May 14, 2016, 12:59:45 AM »
if im going to redo my mill control (knee mill currently fed 240 single phase) im going to need a decent multimeter.  i copied a photo of a $20 one that looked pretty nice and showed it to the shop electrician.  he said uh uh, you need to get a cat 3 or cat 4 meter.  you guys are the ones who have installed servo and stepper controls with mach3.  what say you?

thanks!

ken

Offline Hood

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Re: Multimeter info
« Reply #1 on: May 14, 2016, 04:01:21 AM »
Just use a cheapo myself, a dual trace scope however is also sometimes useful.
Hood

Offline Davek0974

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Re: Multimeter info
« Reply #2 on: May 14, 2016, 06:15:48 AM »
Anything by Fluke will last you a very long time - nice kit.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives
Re: Multimeter info
« Reply #3 on: May 14, 2016, 07:39:41 AM »
Fluke 88 automotive for me, had it ~10 years
But it would be overkill for bog standard use.
And a Philips (fluke) scopemeter 97, under utilised.

Really you want:
Ac, DC, ohms, diode test.

I'd suggest autoranging (that way you are less likely to kill something by using it on the wrong voltage range)

Current reading is not really something that gets used much.

Beep continuity test is useful too (testing fuses, identifying cable cores etc)

Fluke is a top brand and it will likley last a lifetime as not a trade everyday use, but can be pricey.

Rob

Albert Einstein ― “If you can't explain it to a six year old, you don't understand it yourself.”

Offline mc

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Re: Multimeter info
« Reply #4 on: May 14, 2016, 03:19:26 PM »
Even a cheap meter will do most things. The big issue with cheap meters though, is they're not usually the most accurate, however in terms of machine conversion, you don't usually need much accuracy. You're typically more interested in if there is power and it's at roughly the correct voltage, or if you have continuity. You rarely need to know with certainty an exact voltage or resistance.
Re: Multimeter info
« Reply #5 on: May 14, 2016, 03:32:11 PM »
Yeah I've been hunting test equipment on Ebay. Got a Fluke 289, 773, and a 789, real pricey if new. We have a real use for it all though, not just collecting nice toys.
Re: Multimeter info
« Reply #6 on: May 15, 2016, 06:58:07 AM »
Hi,
I work for a company that repair welders and I use a multimeter ALOT!! Tig welders produce HF and that is fatal for any miltimeter
Fluke or otherwise. I uses a Tenma (Chinese or Taiwanese I think) which cost about $60US, Cat III.
It will measure 20A but the shunt is unfused so be careful. I don't use Temp, Capacitance or Frequency very often. Volts,Ohms,Current and Diode
I use ALL the time.
Fluke is great but expensive and to my thinking provides little better than low to mid priced units epsecailly when one moments inattention
can allow HF into the meter and its a throwaway thereafter.

Craig
My wife left with my best friend...
     and I miss him!
Re: Multimeter info
« Reply #7 on: May 15, 2016, 10:48:02 AM »
thanks all.  i believe monday i am going to order this one:

http://www.amazon.com/Mastech-MS8268-MS8261-Digital-Multimeter/dp/B000JQ4O2U?ie=UTF8&psc=1&redirect=true&ref_=ox_sc_act_title_1&smid=A127S1ML5E6NGI

gets decent reviews in a few places, should be suitable for my task i think.

Offline RICH

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Re: Multimeter info
« Reply #8 on: May 15, 2016, 11:35:17 AM »
Going to expand this thread a little......

GENERAL ADVICE:
 
Unless you are going to use all the functions and desire accuracy of higher end instruments I would suggest
one don't spend a lot and be practical on intended use of what and why you buy something. There are many
different "toys" available, some worth buying new because of todays technology and associated cheap price.
I will add that a specific tool even if used once a year purchased at "steal" price could worth it's weight in
gold when your doing something. Any electronic used "toy" should be considered faulty, but, an attachment
may worth the chance. Know the instruments you are buying, be patient and you can have a lot of practical use  
"toys".


SO, that said and it's just my opinion,

Volts,Ohms,Current,continuity Multimeter................
Have a Fluke 87 & 77 and mostly use the 77. Another cheapo one is in the auto tool box. One can get a lot for
your money these days.

A dual trace scope can come in handy and you can find some used ones reasonably priced. Functionality,
bandwidth, sensitivity, etc all add to the cost. Have two of them 20 & 400 Mhz, don't use either of them
often.

Then you have temp measurement........
You can get probes which work with the higher end multimeters, but, individual
digital hand held infared or thermometers with probes are nice also. All depends on what
one is going to do with it. An infrared nonconctact with emissivity adjustment is a very usefull item.
There are manny available today resonably priced.

Then you have RPM measurement........
This is one thing that you should have. There is nothing wrong with contact speed indicators ( Biddle,
Hassler, etc ) because if you can't shut the rotating item off it may be the only way to measure rpm and they
are quite accurate. The digital tach's are just great to use and you can get one for cheap!


Then you have inductance and capacitance measurements.........
Comes in handy if you want to know some characteristics of the unknown stepper, but, the average guy
won't be interested or use one, and yes some of the higher multimeters provide these functions.

Then you have you AC amp measurements.......
A clamp on meter is usefull to measure current draw.

So there are a lot of "toys" out there and can find some real bargains if they take their time.

Here is some prices and toys and most are handheld:

RPM MEASUREMENT:
- Digital Tach DT-2234C ~ $11 on EBAY today ~ very accurate and just great for checking or setting rpm.
  I modified a contact strobe attachment from a high end but broken digital tach $3 from flea market
  so it can be used on contact.
- Biddle, Hassler or other mechanical brands - why bother when you can buy the above today

Multimeter:
- Fluke model 77 - $10 from a pawn shop ( I usualy have  a few batteries with me so i can test stuff when
  looking for stuff. )

Dual Trace Scope
- B&K 25 Mhz with probes - Flea market and could check the trace before purchase ~ $50

AC CURRENT CLAMP METER
- Sperry digital with leads/case - and also has typical multimeter function ~ $12 ( took a chance
  didn't have a battery with me to test, the leads were worth the money ) like new and works fine.

TEMP MEASUREMENT
- Whal - digital infrared nonconctact with emissivity adjustment ~ $15 Garage sale
- VMR Taceable Digital - Data logging with probe and case ~ $5 flea market special and like new!

TORQUE MEASUEMENT
- Look for In oz torque wrench, beam type is ok 0 to 28, or 1/4" drive adjustable say 20 to 100,
  but my best find  was an actual small calibrated Gauge 10-120 in oz / reversable and very accurate.
  That's what's used to find  the affect of bearing preload or gib adjustment on min axis torque and backlash.

In summary you can have a lot of use full toys for under $100.

FWIW and may your dumpster diving adventures be fruit full,
  
RICH




 
« Last Edit: May 15, 2016, 11:38:42 AM by RICH »