Member postings for richard orr

To the moderater:

Jason, I should probably start a new thread ,but, do you care to explane the double eccentric valving on the grasshopper .

Took a look at your grasshopper build. Beautiful work. Cannot figure out how the multiple angles are acheived unless your milling machine has a swiveling head that is hooked up to a computer.

Indeed a very accurate observation about the inexorable allure of steam and the creative force.

Oops on that last post.

Question to Bill: what's delrin rod?

Jadoson, good advice. Perhaps there is a rentable hone of that size , If not , making an iron ring sounds like the second best choice. Do you have a pic. or two of that grasshopper on line?

Jadoson, good advice. Perhaps there is a rentable hone of that size , If not , making an iron ring sounds like the second best choice. Do you have a pic. or two of that grasshopper on line?

Am familiar with balanced D valves, having built one for my double acting 5 x 8 - simple and self seating. Question I am wondering about is weather they leak or how much they leak ( as I've been told they all do to an exent. ,. Probably neglible in most high pressure applications. Am feeling though that the success of the low pressure, large bore grasshopper will partially have to do with maxamising vacume and so I'm casting about for the best seal for the least machining. Also feel that there is less friction and better seal in the stuffing box when valve rod is designed to rotate rather then reciprocate. Of cource the over riding part of the formula is that I just want to do something different.

In starting off, ...a little background: The engine I am building is a large bore , low p.s.i., (40 p.s.i.) low r.p.m. grasshopper steam engine, .using dry steam but no superheat.

Regarding porting design, the inlet steam will be seperate from the exaust steam. I am using the pre existing D slide valve port surface as the base to build a type of spring tensioned swing valve that seats against the outgoing exaust pressure rather than seating inline with the exaust pressure. In this way it will do double duty as a water-slug relief valve..

In order to attain the most effective sealing against vacume loss and because steam temperatures will be well within the opperating limits, I am thinking of using metal backed viton rubber for the valve material. Anybody caring to take pot shots at that idea, opinions invited

The packing that I would prefferably use is some sort of graphite empregnated woven square yarn.. The idea is to make a piston with a removeable top. Packing could be replaced from time to time without having to remove piston from cylinder. I happen to have some woven 3/8ths. square packing that I bought 10 yrs. ago that is so tough that I could not cut it with a knife. Can't remember what it is called , but it may be tough enough to to burnish cylinder by simply running it in.

Cylinder was bored out some years ago and has been stored with a thick coat of grease.Perhaps lapping may ultimately be unnesessary.

On a slightly different, but related note, I believe the leather packing rings in some of the earlier steam feed pumps were set with a loose fit so that steam pressure could get in back of the ring in order to expand and snug them up against the cylinder. Am wondering weather that is the practice also with yarn packing rings in larger bore applications?

To answer Jasonb: Cylinder dia. is12 inches (twelve). Steam at 40 pds. 80 to 120 r.p.m.

O.K. That sounds reasonable. The question is how then would a c.i. cylinder be polished? I have thought about making a graphite impregnated leather piston ring and initially breaking the engine in with it, using it to burnish the cylinder walls.

Am wondering about an effective and simple way to lap my large cast iron cylinder. Am thinking about using a polishing wheel and compound hooked up to a hand drill.

Am wondering about an effective and simple way to lap my large cast iron cylinder. Am thinking about using a polishing wheel and compound hooked up to a hand drill.

The engine is indeed a 12" bore. double acting steam cylinder. ( Quite a story to my finding it ) It is going into a large sidewheel steamboat that I have been building over the past 14 years. The primary power will come from pressure rather then vacume. However, with a cylinder of that diameter, there is a ot of power to be gained from vacume also

I cut off the steam box and will use the D valve port face to make a type of poppet valve for the exaust that will also serve as a water slug relief port . Intake will be through bored out water drain valves. Intake pressure will be 30 p.s.i.g. expanded down to 10 p.s.i.g. R.p.m. will be from 80 to 120.

The cylinder I am using to build up a grasshopper steam engine is 12" bore dia. Am wanting to get as good a seal as possible in order to maxamise condensing vacume. O rings seem prefferable but would they hold up in a cast iron application? Will be steaming with graphite introduced into the steam line.Also, I am thinking graphite packing would tend to burnish cylinder where as am thinking o rings might score cylinder if particles in steam are taken up.

Edited By richard orr on 18/09/2013 03:37:05

Have read that it is ill advised to use graphite rope packing for piston rings when used in a cast iron cylinder. Am wondering if this is true in all applications across the board or weather it's use is possible in a large , low pressure , low r.p.m. steam cylinder application where the cast iron cylinder could be highly plished?