# Digital tacho



## firebird (Jan 8, 2011)

Hi

I just bought this digital tacho from ebay

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=390238842077





At the price I couldn't resist having a go. It arrived today so I just had to have a play with it. It comes without a battery (pp3) so I had to buy one.

Basically you stick a bit of reflective tape, supplied in the bag, to your machine.

On the mill





On the lathe





Then point and shoot.





My X1 mill has a design max speed of 2000rpm. The tacho gave me a reading of 1960rpm.
My X3 mill has a design max speed of 2000rpm. The tacho gave me a reading of 2126rpm.

It seems to be fairly accurate.

I have a Myford ML7 lathe. It has 6 speeds, 3 ungeared and 3 in back gear.
In the Myford manual the quoted speeds are in the left column and the speeds recorded by the digital tacho are in the right column.

1  35rpm        39rpm
2  62rpm        68rpm
3  110rpm       117rpm
4  200rpm       227rpm
5  357rpm       390rpm
6  640rpm       670rpm

Cheers

Rich


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## Blogwitch (Jan 8, 2011)

Rich,

If you have strip flo lighting, try it first with the lighting on, then with it off, and see if there is any difference between the readings.

Some of these types of units are affected by the frequency of the strip flo lighting, and give an over reading with it on. Mine does it, but it is a different model to yours.


John


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## firebird (Jan 8, 2011)

Hi John

Yes I do have strip lighting, I'll try again with the lights off and compare the results. Thanks for the tip.

Cheers

Rich


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## deere_x475guy (Jan 8, 2011)

Guys, what is "strip lighting"? Is it what we call fluorescent on this side of the pong?


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## shred (Jan 8, 2011)

I think so. Any fluorescent (including the new CFLs I believe) may show this-- it's not obvious, but they flicker on and off 50-60 times a second (or maybe 100-120, I can't remember). That can play hell with tachometers and the like, though I have seen calibration disks on various bits of equipment to match them. Somebody posted some for pasting on a lathe chuck long ago, but I could never get them to work very well. I have one of the little digital tachs too.. it lives in a drawer most of the time, but comes out every so often to check speeds on things.


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## deere_x475guy (Jan 8, 2011)

Thanks Shred...I just didn't want to assume that's what was meant. Looks like an interesting gadget anyway. I think HF has something now that you can hold against your rotating part. I haven't seen it in the local store yet though.


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## Noitoen (Jan 8, 2011)

New compact fluorescent work at higher frequency.


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## firebird (Jan 9, 2011)

Hi

I have just done another test with the lights off and the readings are almost identical. I do have a lot of natural light in my shop though, all my machines have windows behind them. In a closed shop with just strip lights the readings may be different?

Cheers

Rich


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## krv3000 (Jan 9, 2011)

well its bin a good by then


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## wheeltapper (Jan 9, 2011)

Hi
Ibought one of those to calibrate my mill, it only had slow and fast on the speed knob. ???

mine also has a spindle that takes various tips so I can measure by direct contact, it even has a setting to show surface speed.

tacho






attachments





I can't remember what I paid but it wasn't much.
got it on fleabay.
Roy


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## Blogwitch (Jan 9, 2011)

Try it at night Rich, and compare to the notes you have already made. That way, the bright daylight won't be affecting the readings.

I have to do all my checks outside or by the open door because there are no windows in my shop.


John


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## firebird (Jan 9, 2011)

Hi

I'll give that a go John, it will be later on in the week now though.

Cheers

Rich


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## d.bick (Feb 4, 2011)

Ive just received my digital taco from a seller in china advertising on ebay. Its the same as Firebirds (the first entry in this thread) and I used his link to ebay to buy it. The cost £3 plus £5 post. It took 19 working days to arrive to the U.K.
 It seems to work O.K. They do tell you to paint shinny things black or use black tape around the revolving item. I went for the black tape option.
Thanks Rich for the link 
        Dave Bick


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## firebird (Feb 4, 2011)

Hi Dave

For the money they are really good aren't they.

Cheers

Rich


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## Tin Falcon (Feb 5, 2011)

Rich thanks for the thread. 
This is one tool on my wish list for a long time , a couple years anyway. I have seen them for about $30 and just never got around to getting one. 
Well with the trying to get the cnc making chips and wanting to hook up the spindle control or even setting speed with the pot . I ordered one hope to have it soon it came from Hong Kong, coming to east coast of the USA. 
tin


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## mklotz (Feb 5, 2011)

Amazon has them...

http://www.amazon.com/dp/B000I5LDVC/?tag=skimlinks_replacement-20


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## Tin Falcon (Feb 5, 2011)

Yep and mine cost about half that with shipping. but have to wait for the slow boat from china .
Tin


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## Twmaster (Feb 7, 2011)

I've got one of those the OP bought. Works like a champ and was very cheap.


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## Tin Falcon (Feb 13, 2011)

tried out my tach .It finally got here. Seems like it reads higher than the published numbers of my machines.
But since They rely on quartz timing i would think the accuracy is built in . 
Any Ida how acurate these things are. ??
Tin


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