Dyno

[Ronie]

So I've been wanting to build a saw hydraulic dyno for awhile and have finally decided to get busy on it. I'm up in the air about using a scale or just going off the flow rate. On the kart forums it seems like there is the flow crowd and the other crowd that say using a scale is better. That scale crowd says that the fluid will get to hot and the other crowd says that it won't get hot enough to make a difference, anyone have any real life experiences with the two that can shed some light on this? I've ordered most of the parts and something like the pic is what I'm planing, it would be simpler without the scale.

 

[Dieselshawn]

I have both scale and fluid gauge. Both tell me how much is being loaded. Everyone has their preference. I use both to make sure the number is accurate. This much Psi always seems to be this much Lbs or Kg. Doesn’t change. But if the scale acts up, the fluid gauge will verify that it’s not reading right and then I can fix it.

I’ve found no difference in dyno performance between cold and hot oil. The oil gets thinner when it gets hot, but I’m still closing the needle valve as I load the saw more.

If I leave the saw loaded and not touch the needle valve, the oil getting warmer will get thinner and the load will drop until I close the valve more.

My machine doesn’t have a radiator. I use 20 litres of oil to make it take time to warm up. Even after an hour of running, the oil is just hot to the touch.

I have found the numbers to be closely consistent through out the year which makes it very reliable. I’ve been very happy with my machine. I’ve also tested saws, one after another for over an hour, even full tanks to empty. The dyno works consistently.

Since I’ve got no wood to cut, I can use the dyno to clear all my saw’s throat and keep fresh mix going through it. Or put in true fuel or something for storage.

The machine does allow me to listen to the saw running under load which I like

 

[Ronie]

I have both scale and fluid gauge. Both tell me how much is being loaded. Everyone has their preference. I use both to make sure the number is accurate. This much Psi always seems to be this much Lbs or Kg. Doesn’t change. But if the scale acts up, the fluid gauge will verify that it’s not reading right and then I can fix it.

I’ve found no difference in dyno performance between cold and hot oil. The oil gets thinner when it gets hot, but I’m still closing the needle valve as I load the saw more.

If I leave the saw loaded and not touch the needle valve, the oil getting warmer will get thinner and the load will drop until I close the valve more.

My machine doesn’t have a radiator. I use 20 litres of oil to make it take time to warm up. Even after an hour of running, the oil is just hot to the touch.

I have found the numbers to be closely consistent through out the year which makes it very reliable. I’ve been very happy with my machine. I’ve also tested saws, one after another for over an hour, even full tanks to empty. The dyno works consistently.

Since I’ve got no wood to cut, I can use the dyno to clear all my saw’s throat and keep fresh mix going through it. Or put in true fuel or something for storage.

The machine does allow me to listen to the saw running under load which I like

Thanks for helping me out, using one to verify the other is a great idea.

 

[Woodpecker]

Nice thread @Ronie looking forward to seeing what you come up with.

 

[Ronie]

Nice thread @Ronie looking forward to seeing what you come up with.

Thanks, this may take a little while to get done and I'll update the thread as I go.

 

[Woodpecker]

Thanks, this may take a little while to get done and I'll update the thread as I go.

Sounds fun. Planning on making it a build thread then? I’ll make the

 

[Ronie]

Sounds fun. Planning on making it a build thread then? I’ll make the

Originally I wasn't but if some are interested I'll post up the pics, problems and cost. There's not a lot of info on building one out there so maybe it will be a little help to someone else that's thinking about building one.

 

[Ronie]

This is what I've spent so far, I'm sure I could have cut the price down some if I'd shopped around.

Updated 8/19/2022
Prices include the shipping

 

[Ketchup]

Originally I wasn't but if some are interested I'll post up the pics, problems and cost. There's not a lot of info on building one out there so maybe it will be a little help to someone else that's thinking about building one.

Very interested. Subbed.

 

[wcorey]

On the kart forums it seems like there is the flow crowd and the other crowd that say using a scale is better.

Flow or pressure?
Using flow rate I could see temp causing some variation due to viscosity change but with pressure there should be negligible effect.
Using scales, bounce/oscillation is obviously most of the issue...

 

[Ronie]

Flow or pressure?
Using flow rate I could see temp causing some variation due to viscosity change but with pressure there should be negligible effect.
Using scales, bounce/oscillation is obviously most of the issue...

I decided to use pressure but I'm also going to put a tachometer on the pump sprocket, that way I can also use flow and compare the two.

 

[wcorey]

If your pump is rated for side load (as in can be pulley/sprocket driven) you can simplify the design and construction and also make it considerably more compact by just hanging it off the output shaft as in the pic.



This one was post brake dyno and a preliminary very basic set up made with stuff I had on hand to test a couple different pumps and flow rates, so minimal plumbing and such.

 

[Ronie]

If your pump is rated for side load (as in can be pulley/sprocket driven) you can simplify the design and construction and also make it considerably more compact by just hanging it off the output shaft as in the pic.

View attachment 340128

This one was post brake dyno and a preliminary very basic set up made with stuff I had on hand to test a couple different pumps and flow rates, so minimal plumbing and such.

Nice, do you have some more pics?

 

[wcorey]

Nice, do you have some more pics?

Tons, I'll post some up after work.

Anything in particular? I tried a lot of different drive lines, torque arms, saw bar mounts, sensors, valves, cooling, damping, etc...

 

[Ronie]

Tons, I'll post some up after work.

Anything in particular? I tried a lot of different drive lines, torque arms, saw bar mounts, sensors, valves, cooling, damping, etc...

Great, anything you got would be appreciated. Thanks for helping out.

 

[Ronie]

If your pump is rated for side load (as in can be pulley/sprocket driven) you can simplify the design and construction and also make it considerably more compact by just hanging it off the output shaft as in the pic.

View attachment 340128

This one was post brake dyno and a preliminary very basic set up made with stuff I had on hand to test a couple different pumps and flow rates, so minimal plumbing and such.

I like how compact yours is, I want mine up on a table and was thinking about mounting the pump and scale under the top to make it smaller.

 

[wcorey]

I went with a small fluid reservoir and ran it through a cooler/radiator rather than using a large tank, so I could really take advantage of a compact portable size. I was told the larger tank is necessary not only for cooling but also to help eliminate the aeration bubbles caused by cavitation but for whatever reason it didn't seem to be an issue.

 

[wcorey]

Same frame and "drive cube", different pump, this one needed to spin in the opposite direction from the other one so had to swap sides. Again just temporary plumbing to test function. Gearing was something around 3/1 IIRC, was 1/4" pitch stuff I had kicking around and seemed sort of marginal so I doubled it up. I was trying to make everything I could in somewhat modular form to make swapping stuff around easier.
I used those particular bearings because MRO Supply had them stupidly cheap, like three bucks or something.
In the interest of compactness I sort of folded the torque arm into two pieces, it pushes on a load cell.

 

[Ronie]

Same frame and "drive cube", different pump, this one needed to spin in the opposite direction from the other one so had to swap sides. Again just temporary plumbing to test function. Gearing was something around 3/1 IIRC, was 1/4" pitch stuff I had kicking around and seemed sort of marginal so I doubled it up. I was trying to make everything I could in somewhat modular form to make swapping stuff around easier.
I used those particular bearings because MRO Supply had them stupidly cheap, like three bucks or something.
In the interest of compactness I sort of folded the torque arm into two pieces, it pushes on a load cell.

View attachment 340196

I like the idea of two bars welded together to get it to taper down to the small sprocket.

 

[wcorey]

It's actually reversible, k095 on one side and d025 on the other. I adapted a clutch drum/hub for the driven shaft so to use a standard rim, making chain pitch changes easy, just pop off an e clip a la stihl.