Tachometer

I guess my search capability is limited – I have looked for the prior thread on the really good tach and cannot find it so …. Could someone point me in the right direction to get one?

Thanks

LAST EDITED ON Oct-01-03 AT 03:49 PM (CDT)
 
Cary,

Unless you are a *rokkit injinier* (read Brett Buck) you can just get yourself one of those Hobbico tachs.

They now use regular AA (or AAA?) batteries and have an automatic shutdown (When they used those expensive watch cells they didn't have this feature!

I'm sure Brett will frown at one of those, but they are good enough for me, and cheap.

If you want a high-class-100%-precise tachometer and are willing to spend 80 bucks ask Brett Buck (the pun is non-intentionally intentional...)

In Christ,

Ion

EDIT

I found the thread! There you are...
http://www.clstunt.com/cgi-bin/dcforum/dcboard.cgi?az=read_count&om=3696&forum=DCForumID1

...

>If you want a high-class-100%-precise tachometer

If you don't care about accuracy, why buy a tach?

LAST EDITED ON Oct-01-03 AT 06:36 PM (CDT)
 
>If you don't care about accuracy, why buy a tach?
>
>Preston

Preston, my man! Surprised to see you make such a statement.

Unless you are proposing an International Tach-Your-Motor contest whereby we all do our testing at a set time of day on a date certain and then post the results on the net, why do tachometers have to carry a high degree of accuracy? Along with the higher price such units command.

All we really need is an instrument which is easy to read and is consistent. If off by 150 rpm, but always off by this amount, one can still gain good information. Especially with Stunt motors. Most especially with pond scum four-strokes.

Dan Rutherford

Ooops. An edit because I forgot to mention that my GloBee tachometer has given good service. At least after I fixed the switch. And the things are cheap enough that if some miscreant Combat flier makes off with it, no huge loss.

>Preston, my man! Surprised to see you make such a statement.
>
>Unless you are proposing an International Tach-Your-Motor
>contest whereby we all do our testing at a set time of day
>on a date certain and then post the results on the net, why
>do tachometers have to carry a high degree of accuracy?

Perhaps they don't. I was merely reacting poorly
to reverse snobbism in the previous post.
I like to measure things, as accurately as I can,
and study the results. Gives me a lot of pleasure.
Sometimes I even learn something

Preston,

you got me wrong.

It ain't reverse snobbery, it's simple as this: I don't need a $80,00 tach.

I also don't need a PA.61 with a Werwage pipe on the nose of an Impact or a Trivial Pursuit.

If, though you want to give me as a demonstration of your love for me a fancy tach, a PA, pipe and a super duper stunt ship you'll find out if I'm snobbish or not, be it reverse or whatever...

In Christ,

LAST EDITED ON Oct-02-03 AT 03:54 PM (CDT)
 
>you got me wrong.

I apologize.

>It ain't reverse snobbery, it's simple as this: I don't need
>a $80,00 tach.

Ain't it?

Perhaps you believe you don't need good equipment,
don't need to filter your fuel, don't need to wipe your lines,
or don't need to attend to any other other myriad details
that Brett at al. are so good about showing us,
but perhaps you're wrong.

I understand your implication, that you don't fly well enough to
need to bother about all these things. I don't fly that well either.
Losing because I'm a beginner doesn't embarrass me;
but losing because of some simple problem I could have easily avoided!
Quite another thing...

Wrong again, Preston...

I use two fuel filters, my lines are always clean, all my gear is double checked before and after each flight, I use a magnetic prop balancer, I was the first guy in the whole country to use a safety brace on my handle and I never had a failure due to carelessness.

About the tach that started our friendly debate, the thing Brett complains about is the fact that them Hobbicos take 2 or three seconds to show a variation in the revs. The 80 buck tach shows any variations on "real time", the Hobbicos are always 3 seconds late.

They are precise, I assume, since when I turn mine on against a light(60 hz) it displays 3.600 on 2 blade mode and 2.400 on three blade mode.

OH, they are 10 rpm quantized, which means that if your engine is runnin' at 9,005 they'll display either 9,000 or 9,010.

Still good enough for me.

You also forget, my beloved fellow modeler, that taxation in Brazil for stuff like that is 60% of the value +shipping costs.

The $80,00 tach ends up costing me something like US$120,00. The Hobbico cost me US$30,00 at a local hobby shop.

I don't need a tuned PA on an Impact. I need a light, straight and rigid ship, and that doesn't cost me no money. Just time, patience and careful building.

At last but not least I hate loosing, begginer or not!

Ain't you gonna give me a PA and a laser cut Randy Smith Kit?

I'd love it!!!!

I hope you got my point. Let us not argue, let's be friends.

God bless you!

In Christ,

Best tach available can be found here <http://www.bktsi.com/>
They are however very expensive.

I have one of those Hobbico type tacs and used it hundreds of times for about 12-15yrs with excellent results. Batteries last a long, long time but it needed them once around 1995(the nickle size watch types which were big bucks) but otherwise never let me down. If memory serves right the accuracy can be checked with a light bulb. I checked this tach against my full scale plane's tach and it was right on. It picked up the 64" prop from the cockpit which was at least 4'away. I'll buy another Hobbico when this one quits.
Bill P.

the latest Hobbicos may not be as good as the old ones. I have one a couple years old(uses to AAA batteries). After bringing it to the field for a couple of months every day the last year, it quit. New batteries didn't help. It just flicks on and then off right away.

>the latest Hobbicos may not be as good as the old ones. I
>have one a couple years old(uses to AAA batteries). After
>bringing it to the field for a couple of months every day
>the last year, it quit. New batteries didn't help. It just
>flicks on and then off right away.

One thing you NEVER should do is let the LCD be exposed to sunlight. Let the sunshine on it for 10 minutes and you can kiss it goodbye!

God bless you!!

In Christ,

I'll second the use of the TNC Tach. One of the good things about it is that it uses a standard grocery store 9 volt battery, so you can get steal one out of your TV remote in a pinch.

Thanks all!

I have a tach but it is one of the cheaper ones and in bright light it will not read the carbon glass props that I run on the Nelson. Also won’t pick up the read on the ½ A props. Probably the big problem is that they pass some light? Anyway it is a tad frustrating and I thought the better tach would read these props.

Almost threw my old Hobbico tach in the woods yesterday but, didn't want to litter. It worked ok for a while but, now it only works maybe if conditions are perfect. I tried new batteries, waste of money.

E-mailed Skyborne they have the PT10 for $110. Worth every penny for racing engine/prop development.

Very frustrating to have a highly tuned expensive racing engine screaming itself to death while you try the tach at different angles to the prop and, still don't get it to work.

Buy high quality stuff and take care of it, that's how you save money.

Giffy

LAST EDITED ON Oct-02-03 AT 03:46 PM (CDT)
 
>Thanks all!
>
>I have a tach but it is one of the cheaper ones and in
>bright light it will not read the carbon glass props that I
>run on the Nelson. Also won’t pick up the read on the ½ A
>props. Probably the big problem is that they pass some
>light? Anyway it is a tad frustrating and I thought the
>better tach would read these props.

Some tachs have trouble reading black props.

Black props become invisible above a certain speed (rpm's)

Paint the tips white or yellow.

I reccomend this procedure not only to help your tach, but for your own safety.

You don't wanna know with which authority I'm speaking, unless you delight in hearing bloody stories...

In Christ,

>Black props become invisible above a certain speed (rpm's)<

You mean invisable to the eye? I would think a black prop would be the best for a tach.

Giffy

Get a black prop, a clear wooden one and compare.

Let me know the results.

In Christ,

>>Thanks all!
>>
>>I have a tach but it is one of the cheaper ones and in
>>bright light it will not read the carbon glass props that I
>>run on the Nelson. Also won’t pick up the read on the ½ A
>>props. Probably the big problem is that they pass some
>>light? Anyway it is a tad frustrating and I thought the
>>better tach would read these props.
>
>Some tachs have trouble reading black props.
>
>Black props become invisible above a certain speed (rpm's)
>
>Paint the tips white or yellow.
>
>I reccomend this procedure not only to help your tach, but
>for your own safety.
>
>You don't wanna know with which authority I'm speaking,
>unless you delight in hearing bloody stories...
>
>In Christ,
>
>Ion

Ion,

If you want a tach that will read a black prop then go ahead and spend the money for the TNC and it will read it with no problem. I have been using mine for that past seven years and it will not only read a black prop but it will read it from four feet away and in light at near sundown. You get what you pay for.

>Ion,
>
>If you want a tach that will read a black prop then go ahead
>and spend the money for the TNC and it will read it with no
>problem. I have been using mine for that past seven years
>and it will not only read a black prop but it will read it
>from four feet away and in light at near sundown. You get
>what you pay for.

Bill,

it's cheaper to paint the tips of the black props. Also, as I wrote, if you paint the tips white or yellow you can see them a lot better.

I use wooden props, and last time I used s Master Airscrew I realized
I just couldn't see it as I can see a wooden one.

The black props just get kinda hard to see...

I never had to stick my tach into the prop. If I have trouble gettin a reading from behind, for example, I just repeat the procedure from the front.

God bless you!

In Christ,

The other really safe thing about the TNC is its functional stand-off distance. The thing will read in bright sunlight from 20 or thirty inches away.

Ever see anyone stick a tach into a prop trying to get a stable reading--not even funny!.

And the TNC is very stable--no need to mentally average the display.

FWIW

Like already posted maybe the new Hobbicos don't work like the old ones. Mine is a Tower brand which I figured is the same although prices back then were almost the same as now. Low light definitely makes a difference on black props but 99% of mine are wood and reflect well. Higher rpms may be harder to detect at distance too as mine easily picks up 600-2900 rpms through a plexi canopy from 4'on the 64" wood prop. Also, my tach has the clear lens "photo eye protector" removed and if memory serves right I took it off to make it pick up better. This was so many years ago I don't remember for sure but it has been off the tach for years and no problems with the photo eye uncovered...it looks like a tiny circuit board.

Lets hear it for the old vibra-tach!

(My tach is a TNC)

My dad had a vibra tach, I remember that thing. I think it went up to 15,000 but never saw those short wires vibrate with a Fox .35 stunt. Anyone have a picture?

Giffy

I had a Vibra Tach, or something similar, kind of a handle with a series of wires, sorta looked like a paintbrush with about 6-8 wires.
Then a Zim-Tach. It would stop a TD .049, and must have been at least 3k rpm off. Next came a Heathkit Thumb-Tach. Not bad, but I loaned it out and it never worked again. When returning to models, I bought a Glo-Bee tach, and it worked good on lightbulbs, but otherwise NOT. Then came the TNC tach. Nice unit. I opted for the extra digit readout and the memory switch. I have apparently pushed the memory switch on zero rpm reading before, which caused a bit of an issue. And the DRO panel has come loose inside the case. Should I fix it myself? Steve

And
>the DRO panel has come loose inside the case. Should I fix
>it myself?

Yeah, that happened to mine, too after one too many falls of the back of the test stand. Just push it back into the socket.

> Lets hear it for the old vibra-tach! :) :) ;)
>
> (My tach is a TNC)
>
> George

Ron B.
F4Fguy

Don't knock it!The Vibratac is very accurate within it's calibration range.It will readily read revs in our range and ,if you take the time to make markings "between the lines"with a calibrated source,it will read +/-20 rpm,which is,forgive me accuracy freaks out there,as close as you can repeatedly set any model engine.It doesn't need batteries,it's easy to use,and you can make your own with little effort.
One other thought,what most of the replies to this thread are talking about is not accuracy,it's measuring increments.Repeatability is the name of this game.What we are interested in is comparative data;does this engine turn this prop faster/slower than another;is my setup the same as it was last time,Etc?
Re the +5/-5(first of all you're kidding yourself)this is the price you pay for digital instruments,analog instruments never have to make this distinction.But no matter how you cut the baby,true accuracy=$$$$$.

Bah! It ain't got any buttons, digital display. 2 or 3 blade modes to play with...

No fun...

God bless you!

In Christ,