Honing cylinders

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gcarsen
Posts: 575
Joined: Sun Jul 08, 2007 7:39 pm
Location: Tigard, Oregon

Honing cylinders

Post by gcarsen » Wed Mar 24, 2021 7:27 am

Honing Cylinders,,, this always seams to be an interesting topic and conversations with people! this give our final size in our cylinders, very tight tolerance, and roundness and straight. plus our crosshatch finish for sealing and lubrication.
i have had a set of cylinders sitting on the bench for my Allen Ten wheeler project. they had been sitting a while and had gotten damp somewhere, probably some collant splash or something and had a little surface rust. built to all the new allen updates on my fixtures, really helps on time and quality of the parts!! first thing to get them completely cleaned up first I have a large Ultrasonic cleaner, my poor mans hot tank! , filled with simple green. set the pair in there at full bore and let them ultrasonic clean for about 20 minutes!! they come out pretty clean but with some funny black spotches on them , next into the wash tank that has heavy duty simple green, its kinda purple but does a fantastic job of cleaning, you can see the castings and machine work clean down to bare metal very nicely!
Ok, for Honing I use a regular comercial Sunnen Hone, picked up a unit fully loaded with all the bars , stones and external hones you would ever need! this is a pretty universal unit and handy. you can hone upwards of a 6 inch hole and the outside of shafts upwards of 4 inches i believe! so we pick the bare and we want one longer than the cylinders. that way we can go full length plus a little to control belmouth or barrel shape, load the bar up, get the proper truing sleave, this trues the full length of the stone's to the rear of the bars guide shoes. this helps control straightness and taper in our bore as we are honing.
once everything is ready we slip the cylinder on the bar and adjust our cutting preasure on the stones. using the foot pedal and the size knob we spin the bar, and slide the cylinder back and forth lightly as we increase the cutting preasure, takes a little getting used to the machine, you need to constantly take the cylinder of and spin it around while doing this process, back and forth swapping ends and stroking away! becarefull you dont take to much out to quickly!!! i use a dial bore gage that i have set to the size i want. ruff pretty hard to about .001 from target , then use the truing sleeve and touch up stone if needed! and go to size. the nice thing about the dial bore gage is its set up using a .0001 dial indicater to show size. preset with a micrometer to 2.0000. my target that i was shooting for was 2.0005 to 2.001 , 5 tenths window and straightnes in the bore within .0004. i wanted to be able to slip over a 2.000 mandrel if i ever had the wants or need to. i hit 2.0007 and maybe a .0001 varience along the length of the bore, measure along 2 axis, pretty dang good! but to digress a bit, todays chevy small block, the stand by 350! and millions have been made! its production bore tolerances is 3.9995 to 4.0025 (.003!) and within .0007 taper from the factory floor! and its goes through a ton more HP, Torque, Rpm's, heat ! and a lot of other factors. our little engines are way over built in comparison in scale wise. plus once being run at steam heat with the way the cylinder walls and body is cast who knows where that bore really measures in use!! so best thing to do is just keep the bore as true as posible with no taper or belmouth being our first priority, and size second importance.
once we are very close, we want to be carefull and stroke the cylinder back and forth along the bar at a fairly fast rate, our target is to get the hone marks to meet at about a 45 degree angle! this gives the cylinder walls a good lubrication surface.
when doing parts like this , its a good idea to use the support rod, if the bar grabes the cylinder, its spinning in your hands!! think cuts , slices ,broken bones!! then a good cleaning with the purple simple green, then wash with hot water and give a good dousing of WD40 to keep rust away till assembly!
Grant
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gcarsen
Posts: 575
Joined: Sun Jul 08, 2007 7:39 pm
Location: Tigard, Oregon

Re: Honing cylinders

Post by gcarsen » Wed Mar 24, 2021 7:29 am

more pictures,
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gcarsen
Posts: 575
Joined: Sun Jul 08, 2007 7:39 pm
Location: Tigard, Oregon

Re: Honing cylinders

Post by gcarsen » Wed Mar 24, 2021 7:30 am

more pictures
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Pontiacguy1
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Location: Tennessee, USA

Re: Honing cylinders

Post by Pontiacguy1 » Wed Mar 24, 2021 10:09 am

Some very fine looking bores. I agree with trying to get as close to size, straightness and roundness as you can when you are building something new. How much clearance do you plan on giving the piston, and will you be using Bronze or Cast Iron for the piston?

I have seen some of these Allen cylinders with a lot of pits and scratches, that were given a light hone to help with the surface, then put back together, and they worked and ran pretty well also. Like one friend told me, and as you also alluded to, There have been literally hundreds of locomotives built and running that used Allen's cylinders, and you know that they weren't all machined correctly. However they all still seem to run well enough to get the job done. The steam locomotive seems to be able to tolerate a good amount of slop or imperfections in certain areas and still perform decently. Most people say that they run the best when they are half worn out!

BClemens
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Location: Gloucester, VA (Sassafras)

Re: Honing cylinders

Post by BClemens » Wed Mar 24, 2021 1:29 pm

I bought a Sunnen Hone many years ago (mine is red - old!) when I was building miniature internal combustion engines (still have a few untouched casting sets). It is an indispensable machine for a 'perfectly' sized and finished bore. The bluish photo of the cylinder finish that reveals the 'cross hatch' is what is needed to seat a set of properly fitted cast iron rings with correct wall tension. If a bore is too smooth the rings will never seat and in internal combustion the engine will be next to impossible to start and have no power when and if it does due to lack of compression. But if the bore is too rough the rings will wear out before seating... Steam is much the same except that piston travel speed in the bore is considerably lower than short stroke internal combustion engines but ring seating is just as important or blow-by will be excessive.

Another beauty of a Sunnen Honing Machine is for super finishing a rod journal for a bronze or light metal bushing - internal or external for example. I found this machine when an automotive engine machine shop went out of business. Also found a 'Quickway' cylinder boring table and valve grinding and seating equipment. That stuff hasn't seen much use like the Sunnen Machine has.

BClemens

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Bill Shields
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Re: Honing cylinders

Post by Bill Shields » Thu Mar 25, 2021 6:19 am

Now...are you going to polish lap the valve mating surfaces?
Too many things going on to bother listing them.

BClemens
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Location: Gloucester, VA (Sassafras)

Re: Honing cylinders

Post by BClemens » Thu Mar 25, 2021 5:33 pm

That is a different machine Bill (trick question?). A hone is for round and a lap is for flat surfaces. I use a cast iron surface plate for lapping the valve mating surfaces using non embedding lapping compound such as Timesaver - Green Label for the iron and Yellow Label for the bronze. Wring them together like gauge blocks to test sticktion - if your eyesight is bad..

BC

gcarsen
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Re: Honing cylinders

Post by gcarsen » Thu Mar 25, 2021 5:43 pm

Hello Bill, i am planning on dealing with the valve surface last, right before assembly so that its fresh that way!. i was going to deal with it one of 2 ways , 1 just load it up on the surface grinder and kiss that area, or as Bclemens states lap it for finish. need to find me a pice of iron to make my self a nice lapping plate.
but on other hand if i have time i am looking at doing a quick piston valve conversion. i got a concept that will drop inside the stock valve chest and covers. and use the existing ports. just got to see if i have time before the next trianual!
Grant

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Bill Shields
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Re: Honing cylinders

Post by Bill Shields » Thu Mar 25, 2021 7:21 pm

Not intended to be a trick question...just wondering what tools are available out there for fellow steamers.

As much as I like piston valves..slide valves have served me very well on many models.

Would really like to feel dedicated enough to do capriotti.

Doubt I will live long enough to even consider it
Too many things going on to bother listing them.

BClemens
Posts: 468
Joined: Sat Oct 08, 2016 10:04 pm
Location: Gloucester, VA (Sassafras)

Re: Honing cylinders

Post by BClemens » Thu Mar 25, 2021 8:22 pm

A surface grinder is the ultimate answer to 'D' valves for sure. Piston valves are the best but five times the work. Whenever I think of piston valves I remember what some of the old timer steam fans had to say...And the way they 'hid' 'D' valves in a piston valve housing - Little Engines and others too.

I bought a used surface grinder and tried my best to make it work but could never get the darned thing to give a clean finish. It was too far gone and the desire is there to purchase one but they get more and more expensive. That's why I do the best finish I can on the mill and then lap - and lap...and lap. There is only one other person around here that I need to convince...and that scares me!

Poppet valves and cams are too much, just too much!

BC

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Bill Shields
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Re: Honing cylinders

Post by Bill Shields » Thu Mar 25, 2021 9:49 pm

Never had pleasure of a sunnen... and have made do with cylindrical lapping of bores.

Good friend taught me how to do it using brass lap and toothpaste to make cylinder lubricators... this when I was a teenager and he has been gone for 11 years.

All downhill from there..
Too many things going on to bother listing them.

BClemens
Posts: 468
Joined: Sat Oct 08, 2016 10:04 pm
Location: Gloucester, VA (Sassafras)

Re: Honing cylinders

Post by BClemens » Fri Mar 26, 2021 6:17 am

Yes the Sunnen is a bit more rapid than cylindrical brass laps... I had forgotten about those - they're on a shelf in a cabinet where they barely get any light -

Now it's time for Bill Shields to pass on all that keen knowledge to some deserving young folks. That will take things back up the hill.

BC

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