Would appreciate some advise

[wa8dof]

Hi Guys

I have built several simple engines (wobblers) but would like to build something a little more complex. I have been looking at Elmer's #6 Slider and feel that it would fit the bill, however I think it is a little too small for me to build comfortably. I do not have any # 3 taps or hardware, and I do not see as well as I used to, although I do pretty good if I take my time.

I am toying with the idea of simply doubling all dimensions and using # 4 or even #6 hardware.

Any of you guys have any experience doing this to a set of plans? Are you aware of any "pitfalls" or reasons this would not be advisable?

Thanks for reading and hope you all have a Merry Christmas.

Dave

Dave

 

[stevehuckss396]

I have scaled many engines both up and down. It's as easy as you are thinking. Just look up the diameter of the original bolt and double it and see what bolt you come close to.
A number 3 is .095 to .099 diameter so .190 to .198 diameter. Number 10 is .184 to .190 so a number 10 is just about double. I would go with a number 10.

 

[wa8dof]

Thanks for the advice Steve. That was what I was hoping to hear.

Davfe

 

[tractor162003]

Dave
This is what I did.

 

[abby]

Not sure what you mean by a "slider" but from the gist of your first post I am thinking a slide valve steam engine , is this correct ?
Slide valve engines are more advanced than "wobblers" in so much as they are able to utilise the fact that cooling steam expands.
This introduces the concept of "cut-off" where-by the steam is admitted for only a short period of the power stroke thus allowing full use of the available energy in the steam.
In both full size and model steam engines , especially in locomotives , provision is made by the valve gear to vary the steam admission length , so for example starting to move a train of trucks will require a different admission setting to that required when the load is moving at speed.
For smaller scale models , again I am thinking steam locomotives of 1/32 scale or gauge 1, it would be difficult to have and operate variable valve gear , although some do have such operated by radio control.
Getting to the point of your post ; In a simple model with no timing adjustment the port timing is often arranged for a 50% cut-off , ie.the steam is cut off halfway into the stroke.
The port timing is controlled by the length of the inlet port/exhaust ports , the throw of the eccentric which moves the slide valve and the length of the valve faces.
Now if you simply double the size of a drawing to make a bigger engine you will alter the running characteristics , because when you double areas you are actually squaring them and this goes for bolts and screws too .
Hope this makes sense!
Dan.

 

[vederstein]

have built several simple engines (wobblers) but would like to build something a little more complex

I've designed and posted several engine designs here on this forum:

https://www.homemodelenginemachinist.com/threads/swashplate-engine.33125/
The plans for this engine didn't really work out. I highly recommend you read the build log before trying the Rotary Engine.
https://www.homemodelenginemachinist.com/threads/rotary-engine-design.19381/
https://www.homemodelenginemachinist.com/threads/t-head-engine-plans.32917/
https://www.homemodelenginemachinist.com/threads/coomber-engine-ideas.32117/
https://www.homemodelenginemachinist.com/threads/sun-planet-engine.31854/page-2
https://www.homemodelenginemachinist.com/threads/two-cylinder-double-acting-steam-engine.30980/
https://www.homemodelenginemachinist.com/threads/plans-camgine-a-k-a-spherical-bearing-engine.31416/
That is all...

Ved.

 

[wa8dof]

Thanks for the input Guys. I think I will just double the dimensions of the engine I mentioned and see where the journey leads. If nothing else, I may learn what doesn't work, which is a step towards learning what does.

Since I am in the midst of a long cold winter here in Northern Michigan, I should have lots of time to play. Machining keeps me off the streets and out of trouble (mostly).

Thanks again for the sage advice.

Dave

 

[Bentwings]

Not sure what you mean by a "slider" but from the gist of your first post I am thinking a slide valve steam engine , is this correct ?
Slide valve engines are more advanced than "wobblers" in so much as they are able to utilise the fact that cooling steam expands.
This introduces the concept of "cut-off" where-by the steam is admitted for only a short period of the power stroke thus allowing full use of the available energy in the steam.
In both full size and model steam engines , especially in locomotives , provision is made by the valve gear to vary the steam admission length , so for example starting to move a train of trucks will require a different admission setting to that required when the load is moving at speed.
For smaller scale models , again I am thinking steam locomotives of 1/32 scale or gauge 1, it would be difficult to have and operate variable valve gear , although some do have such operated by radio control.
Getting to the point of your post ; In a simple model with no timing adjustment the port timing is often arranged for a 50% cut-off , ie.the steam is cut off halfway into the stroke.
The port timing is controlled by the length of the inlet port/exhaust ports , the throw of the eccentric which moves the slide valve and the length of the valve faces.
Now if you simply double the size of a drawing to make a bigger engine you will alter the running characteristics , because when you double areas you are actually squaring them and this goes for bolts and screws too .
Hope this makes sense!
Dan.

Interesting comment. Being hot rider thus very cam and timing aware. I observed the sliding piston ports. These motors were originally not a piston but an actual flat plate the opened and closed ports. The first thing is timing these next is optimizing flow. While calculating displacement I occurred that maybe the sliding piston applies som power to the crank shaft . Since there will be some pressure both ways I’d guess this would in turn be applied to the piston both bays. In this engine timing is fixed by location of the crank slid valve bearing position. I just got a book on various steam engines and I goes on to show hoe some of the adjustable linkage was laid out . There are optimum angles but linkage can can and does. optimize it . This still leaves optimum port shaping which only race car people might consider. It would take some real intensive dyno testing and computer software. The usual solution is to just apply more and hotter steam pressure. Kind of like supercharging if you want more power you just turn up the boost Flow will take care of itself. It’s almost to where the automotive camshaft would work there is variable cam timing today so nothing new here. Just a whole bunch more complicated . I’ve already made this hobby complicated it will be just fun to see it all operate smoothly . I’d rather it not pitch a rod out or breake the crankshaft. I’ll be more than happy if I can look at bearings after time running and see no wear . If the boiler works and doesn’t leak and operates as designed I’ll be very happy. I’d like to see the little dynamo put out some power for lights then the dyno brake can show me torque and I’ll enter on the spread sheet.
Byron

 

[Bentwings]

Interesting comment. Being hot rider thus very cam and timing aware. I observed the sliding piston ports. These motors were originally not a piston but an actual flat plate the opened and closed ports. The first thing is timing these next is optimizing flow. While calculating displacement I occurred that maybe the sliding piston applies som power to the crank shaft . Since there will be some pressure both ways I’d guess this would in turn be applied to the piston both bays. In this engine timing is fixed by location of the crank slid valve bearing position. I just got a book on various steam engines and I goes on to show hoe some of the adjustable linkage was laid out . There are optimum angles but linkage can can and does. optimize it . This still leaves optimum port shaping which only race car people might consider. It would take some real intensive dyno testing and computer software. The usual solution is to just apply more and hotter steam pressure. Kind of like supercharging if you want more power you just turn up the boost Flow will take care of itself. It’s almost to where the automotive camshaft would work there is variable cam timing today so nothing new here. Just a whole bunch more complicated . I’ve already made this hobby complicated it will be just fun to see it all operate smoothly . I’d rather it not pitch a rod out or breake the crankshaft. I’ll be more than happy if I can look at bearings after time running and see no wear . If the boiler works and doesn’t leak and operates as designed I’ll be very happy. I’d like to see the little dynamo put out some power for lights then the dyno brake can show me torque and I’ll enter on the spread sheet.
Byron

Sorry for the spelling I just missed it it’s getting late and cold
Byron