More instrumentation.

[BobL]

Been meaning to do this one for a while but only just go around to it.


The blue do-hickey is a temp gauge (I got it from an RC hobby site).
48F - that's cold morning for where we live

The temp probe is located in a small gap between two cylinder fins, just on top of the exhaust port. See red arrow.


I started the 880 and let it idle until the gauge read a constant temp - that took about . You can see 2200 rpm idle is a touch low. That took about 5 minutes but I don't think the whole saw had reached it's equilibrium temp.


Cranking the throttle immediately drops the temp indicating the cooling air is reaching the probe tip. I am reluctant to block the gap the probe sits in, any ideas of where else to place the probe?

Then I cut a slab - so it sure reached operating temp. The probe has a "hold max temp" facility which is nice - max temp reached was 182F

Then I let it idle to constant temp again - see the idle is now 2400 rpm - which is where it should be


Why did I do it - because I could and because I hope to assess saw load when I'm cutting some big slabs.

 

[dave k]

Nice Bob, the tach is very much like the Stihl EDT which I have, you would wonder if they make them for Stihl ? I put mine on little rubber suckers so can be used for tuning on various saws.
The temp meter is a good idea as you could try the mix ratio ,40-1 50-1 etc as the mixes should give different temp readings ? I use a lazer temp reader for the bearings on my large stump grinder and have found the use of different grades of grease can give a 2/3 degrees in temp which on bearings that cost around $1000 US each is important in the long run !

 

[Rookie1]

Very nice Bob. You sure are a handy man. I think the temp gauge is a good idea. Shows me that you care about your equipment. Did I say nice job already?

 

[Hddnis]

Other locations to try might be the downstream side of the exhaust or the downstream side of the jug if you can get the probe down between the fins.

You are starting on a project that I have dreamed about for years; a small electronic recorder that monitored vital signs. I had hoped to get one about the size of a wrist watch that would be powered by the magneto and would use bluetooth to upload the data to our servers every time the machines were put away.

For a half dozen saws it might not make a huge difference, but in our operation it could add up. We're down because of the economy, but just last year we had dozens of hand held power tools running every day. If we had predictive indicator of failure we could swap a machine out before it failed and hurt productivity of a crew sixty miles away from the shop. The goal was to reduce the spare machines carried on each truck. This would reduce inventory and allow us to make the same revenue with a lower capital investment.


Mr. HE

 

[BobL]

Thanks Guys.

Other locations to try might be the downstream side of the exhaust or the downstream side of the jug if you can get the probe down between the fins.

Good idea - the probe/sensor wire is not very long and it just reaches the middle of the space between the top side of the exhaust outlet and the cylinder. I could mount the display on the shroud to get more length out of the wiring but part of the idea behind having it on the wrap handle is to reduce vibe. I will try to make the wiring longer.

You are starting on a project that I have dreamed about for years; a small electronic recorder that monitored vital signs. I had hoped to get one about the size of a wrist watch that would be powered by the magneto and would use bluetooth to upload the data to our servers every time the machines were put away.

The RC car market has multifunction input devices that send data by radio that are pretty small but nothing that stores data.

 

[Hddnis]

Thanks Guys.


Good idea - the probe/sensor wire is not very long and it just reaches the middle of the space between the top side of the exhaust outlet and the cylinder. I could mount the display on the shroud to get more length out of the wiring but part of the idea behind having it on the wrap handle is to reduce vibe. I will try to make the wiring longer.



The RC car market has multifunction input devices that send data by radio that are pretty small but nothing that stores data.

Any way you can make the wire longer?


I have looked at the RC products and some of them are close. I just need to pay one of those guys with the time and know how to design one for me; put it on one truck and see how it works.



Mr. HE

 

[LAndrews]

Most likely extending the wire will require use of thermocouple wire. www.omega.com

I'd bet that silver-filled epoxy would glue the thermocouple down to the top of the exhaust port casting and move heat just fine for your needs. I can't reccommend a specific adhesive for sticking to aluminum castings...sure that someone in the business can. Have always had good results using Lord MD-80 to glue thermocouples to circuit boards and have learned that a thin coat of clear paint keeps the junction from acting weird when it touches silver.

There are a lot of really good data acq systems out there. One of my favorites for 2/s motors is the mychron stuff - not expensive and very reliable. Probably a little more money than people are thinking, but $150 from fleabay for a basic system will give 2 temps and RPM. A little more money could give chain speeds with a small magnet on the chain somewhere.

 

[demographic]

Some of the tachos built for racing carts are very good, with several temperature sensors and all sorts of stuff.

Admittedly I doubt you would be paying extra for the laptimer option though.

 

[BobL]

Most likely extending the wire will require use of thermocouple wire. www.omega.com

I'd bet that silver-filled epoxy would glue the thermocouple down to the top of the exhaust port casting and move heat just fine for your needs. I can't reccommend a specific adhesive for sticking to aluminum castings...sure that someone in the business can. Have always had good results using Lord MD-80 to glue thermocouples to circuit boards and have learned that a thin coat of clear paint keeps the junction from acting weird when it touches silver.

Thanks for the ideas. I have a roll of TC wire in my hand right now. I will try some silver epoxy and see what happens. First I will to set up a plug and socket so I can remove the gauge.

 

[Ted J]

An exhaust temperature guage will give you a more accurate reading. There are two types:Exhaust Gas Temperature and Cylinder Head Temperature.
The CHD will give a more average reading. The EGT will be more accurate as you rev the engine. You could actually use it to tune the engine if you wanted.

http://c-brookperformance.com/yahoo_site_admin/assets/docs/moto_16KOSO.271123826.pdf

Ted

 

[wavefreak]

Dude.

You're hard core.

 

[Ted J]

Thanks for the ideas. I have a roll of TC wire in my hand right now. I will try some silver epoxy and see what happens. First I will to set up a plug and socket so I can remove the gauge.

Bob,
There is a sensor that slips on around the base of the spark plug like a washer, but whether it would fit your sensor?

Ted

 

[BobL]

Thanks - All good ideas guys.

I'm now thinking a small 3 or 4 way switch that can redirect input from several temp sensors studded strategically located all over the saw?

And how about a wood grain dash with polished ally frame?

 

[LAndrews]

US Ebay item - 110358657079 Not a bad price for a basic EGT gauge, and the analog readout gets bonus points too!

I'm a big proponent of EGT as a way to keep tabs on carb tuning and current motor conditions - it's saved my bacon more times than I can count. And if you're trying really hard to track down some weird behavior, the fine-wire exposed TC probe from the seller above is probably one of the best ways I know of - probably even better than an oxygen sensor.

CHT is a nice backup. It's slow, but it never lies unless one of the wires breaks and then it just pegs the meter so something's obviously wrong. Aircraft spruce had some cool dual analog gauges...

 

[Kupreanof]

I would love to see this done with stock muffler vs. dual port vs. modded, then with mix ratios, with different tunings (carb set for different max rpms), different chains etc... It would be good to dial in the best set up for milling and verify the claims of cooling via these various avenues.

I've been thinking a lot about this lately.