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oxford
11-25-2012, 06:12 PM
Is there an affordable digital rpm gauge for spindle speed on a lathe? I am doing a vfd conversion and it would be nice to see what speed you are running at. I am not sure if my drive can support an rpm function or not but it will be in an enclosure so I would need a remote readout anyways. I would also think it would not work when the lathe was in backgear. I need a speed range from 0-2000 rpm and would like it to display to at least 5rpm intervals. I am thinking of something like this. http://www.ebay.com/itm/andytach-digital-rpm-tachometer-for-diesel-/251150233438?pt=Motors_Car_Truck_Parts_Accessories&hash=item3a79b86f5e&vxp=mtr but this one looks like it reads in 60rpm intervals. Most of what I search brings up pages of car tachs, I am not sure if I use the correct terminolgy to finf what I am looking for.

jmarkwolf
11-25-2012, 06:17 PM
I bought a hand-held unit from Harbor freight awhile back. Worked well enough for my applications.

Can't remember the actual cost but I think it was something like $39.

Forestgnome
11-25-2012, 06:35 PM
http://www.machtach.com/

sasquatch
11-25-2012, 06:49 PM
I think "Little Machine Shop" sells them.

lakeside53
11-25-2012, 07:49 PM
Just engrave or laser print sticky scale for your speed knob. Got 8 gears? Easy - 8 concentric scales.

flylo
11-25-2012, 08:17 PM
A bicycle Speedo works, but you have to use a certain one that only cost a few bucks on ebay. My laptop is on the fritz & I'm using a tablet and it sucks!

Evan
11-25-2012, 09:03 PM
I just bought a tach from DX for $20. I guess I should try it out.

MaxHeadRoom
11-25-2012, 09:09 PM
The majority of VFD's have a analogue output for a moving coil meter, its not digital or high tech, but cheap and simple, you can scale it by parameter for calibration.
Someone like RedLion may have a digital analogue meter you could also use.
Max.

bborr01
11-26-2012, 11:12 AM
I bought one of these and it works well. Comes with reflective tape. My machines all have a piece of this tape on the spindle now.
It is surprising how far off the dial of a V/S B'port can be on rpm's.

http://www.ebay.com/itm/Handheld-Digital-Laser-Photo-Tachometer-Non-Contat-RPM-Engine-Motor-Speed-Gauge-/290768687377?pt=LH_DefaultDomain_0&hash=item43b32a1111

Brian

bandsawguy
11-26-2012, 11:18 AM
Most VFD's I have worked with have a display that instead of showing freq can use a multiplier to display the rpm.

lakeside53
11-26-2012, 11:18 AM
You can also just use a 4 1/2 digit panel meter (<$10 ebay). Scale the analog output of the vfd to suit, and put in a multi-positon switch with simple resistor dividers for gear positions. Works well.

rode2rouen
11-26-2012, 11:44 AM
The "MachTach" looks to be a pretty decent unit, too bad it's a kit.
I'd be all over it if it was available as "plug & play".


Rex

Scottike
11-26-2012, 12:27 PM
I used one of these on my var speed Rockwell lathe:
http://www.ebay.com/itm/RED-LION-CONTROLS-DT3D0500-USED-/230797443741?pt=BI_Control_Systems_PLCs&hash=item35bc99829d
along with an Amplified Magnetic Pickup mounted to sense one of the gears on the back of my head Stock. It reads rpm from 0-2000
http://www.ebay.com/itm/RED-LION-CONTROL-LMPC0000-USED-/321014873476?pt=BI_Control_Systems_PLCs&hash=item4abdfa3d84

lakeside53
11-26-2012, 12:38 PM
Most VFD's I have worked with have a display that instead of showing freq can use a multiplier to display the rpm.

But.. you would have to change the multiplier for each gear/belt change, or factor it in your head. With a VFD you'll still be using gearing unless you install a mighty big motor.

lakeside53
11-26-2012, 01:38 PM
I've also used a Shimpo DT5. These are expensive but come up on ebay all the time. Very versatile and can take just about any input device.


This one is "reasonable".

http://www.ebay.com/itm/Shimpo-DT5RL1-Panel-Mount-Tachometer-Accepts-only-TTL-input-signal-/200848100192?pt=LH_DefaultDomain_0&hash=item2ec37acb60

Evan
11-26-2012, 02:06 PM
I tested the new portable tach last night and it works fine. I ran it up to 8000 rpm on the mill. It is rated to 99999 rpm and has memory for highest, lowest and last measurement. It autoranges. It runs on two AA batteries and draws about 60 ma so they should last about forever. It comes with reflective tape for marking spindle etc. Cost was $17.50 from DX with no shipping charge.

http://dx.com/p/2-5-lcd-digital-led-laser-tachometer-rpm-tool-3-x-aa-66751

http://ixian.ca/pics10/tach1.jpg

http://ixian.ca/pics10/tach2.jpg

kc5ezc
11-26-2012, 02:19 PM
Evan, Thanks for the testo-testo. I've been needing one of these.
The DEX ad says 3 AA batteries. No problem just different than you reported.
Got it ondered. We'll see how long it takes. Other items from DEX have been
10 days or less.
Thanks again.

Evan
11-26-2012, 02:41 PM
It is three batteries. I confused it with some other toys I ordered. Works great though. I showed it to wife measuring ceiling fan and her comment was "Why didn't you get one of those a long time ago?" I didn't have a good answer for that...

MrFluffy
11-26-2012, 02:53 PM
Ive got the meter above, but on my mill I have a revmaster built from a kit at ls caine. Its got a nice display and I have it in the same case as my yadro dro board. It just seems to be less temporary and nicer to use for this than the chinese meter which I use in other places.
http://medw.co.uk/wiki/index.php?page=Tachometer

Willy
11-26-2012, 03:09 PM
Yeah the hand held tachs are great, so many uses around the shop and on outside equipment.
All one needs is just a spot reading of the rpm you're working at, not really any need of a continuous readout.

The reflective tape isn't really an absolute necessity if one runs out. I've used mine on so many different applications over the years all I do now is to put a dab of white paint from a metal marking paint pencil on as a target. All the tach needs is reflective white target and it's happy.

By the way they are now $10.80 including shipping here (http://www.aliexpress.com/wholesaleproduct/wholesaleProductDetail.htm?productId=640461991&productSubject=Freeshipping-Digital-Laser-Photo-Tachometer-Non-Contact-RPM-9852).
At that price you can't afford to not have at least one.

MaxHeadRoom
11-26-2012, 03:39 PM
By the way they are now $10.80 including shipping here (http://www.aliexpress.com/wholesaleproduct/wholesaleProductDetail.htm?productId=640461991&productSubject=Freeshipping-Digital-Laser-Photo-Tachometer-Non-Contact-RPM-9852).
At that price you can't afford to not have at least one.

I picked up one of those, mine has a 9v battery, I found that the battery goes flat in around 3 weeks with the unit off.
From the discussion I had in another forum, I was not alone.
Its a nuisance to have to remove it each time it is used!
Max.

rowbare
11-26-2012, 03:53 PM
LMS sells the Tachulator which like Mach Tach can do SFM display as well as RPM.

bob

lakeside53
11-26-2012, 07:48 PM
Yeah the hand held tachs are great, so many uses around the shop and on outside equipment.
All one needs is just a spot reading of the rpm you're working at, not really any need of a continuous readout.

The reflective tape isn't really an absolute necessity if one runs out. I've used mine on so many different applications over the years all I do now is to put a dab of white paint from a metal marking paint pencil on as a target. All the tach needs is reflective white target and it's happy.

By the way they are now $10.80 including shipping here (http://www.aliexpress.com/wholesaleproduct/wholesaleProductDetail.htm?productId=640461991&productSubject=Freeshipping-Digital-Laser-Photo-Tachometer-Non-Contact-RPM-9852).
At that price you can't afford to not have at least one.



Even with no paint a hex bolt head works. I can point it at the drawbar on my BP. Of course, you have to mentally divide by 6!

oxford
11-26-2012, 08:02 PM
Thanks for the replies. Maybe one of those handheld units would be the ticket. As far as using the VFD, mine will be in a box where I won't be able to see it. I would have to run some sort of remote readout for it, so it seems just as easy to hook up a dedicated tach that wouldn't change with gearing changes.

oldtiffie
11-26-2012, 08:03 PM
I have a digital tachometer similat to/same as Evan's - they are really good.

Buy a good (cheap) hand-held digital thermometer to go with it. They are very good.

You might get a few surprises as regards real and presumed temperatures around the shop and the property.

Evan
11-26-2012, 08:53 PM
We went to Kamloops this last summer for a medical appointment. It gets real warm there as it is in the central desert. We were parked in the hot sun beside a jet black luxury car of some sort so I whipped out the digital thermometer to read how hot the metal was. At the same time the owner, a middle aged woman with a couple of friends walked up. I asked her if she wanted to know how hot it was and she scowled at me and said "NO". I told her anyway, 152F. Even luxury car air conditioning doesn't work when it is parked. http://ixian.ca/pics9/biggrin.gif

Forestgnome
11-27-2012, 09:57 AM
[QUOTE=Evan;811123]I tested the new portable tach last night and it works fine. I ran it up to 8000 rpm on the mill. It is rated to 99999 rpm and has memory for highest, lowest and last measurement. It autoranges. It runs on two AA batteries and draws about 60 ma so they should last about forever. It comes with reflective tape for marking spindle etc. Cost was $17.50 from DX with no shipping charge.QUOTE]

Wow! Can't beat that deal with a stick. Looks like I suddenly need one too.

BillTodd
11-27-2012, 03:15 PM
Most VFD's I have worked with have a display that instead of showing freq can use a multiplier to display the rpm.

Yes. The ABB one I'm using for my mill has the option of using one digital input as a frequency counter. I'm driving the input from a sensor on the spindle with the result scaled to show spindle RPM.

If I could de-cypher the ABB manual I'm sure it could even be adjusted to show SFM etc.

Oldguy
11-27-2012, 04:28 PM
Here is a link to using a bicycle cyclometer as a tach:

http://www.machinistblog.com/inexpensive-diy-tachometer-for-a-mill-or-lathe/

Glenn