cylinder liner press

Hi, A question on the press fit size of the cylinder liner into the cylinder block on my 2in scale D & NY traction engine. I've bored out the cylinder block and am now turning down the cylinder liner. Both are cast iron. The bore size is 1 5/8. (1.625" I've worked out the press fit size for the liner as being just over 1 & half thou .001625" using .001" per 1in is this the right size please, or have I miss calculated. Thanks

My engine also has a cast iron liner and block but is bigger than yours in 6" scale. But iInstead of a press fit, I used a shrink fit using a H7 fit on the bore and a u6 fit on the sleeve.

Note that the tolerance is dependent on the diameter of the hole and you have to refer to a table of limits and fits. My cylinder bore is 3.5" and the H7/u6 fit resulted in an interference of approx. 0.1mm [.004"]

The bore for the liner was made slightly larger on the front side than on the rear side.and the cylinder OD stepped to suit each of the block bores. Done so I did not have to press the liner all of the way thru, just where it seals with the block walls.

The block was heated in my BBQ to approx. 240 deg C for over an hour. The liner then inserted into the block while hot and anly required a light push with my press ot push in.

The boiler testing requires that you take it to twice the working pressure. I took mine to 2.5 x WP and there were no leaks.

Paul

Edited By Paul Lousick on 29/07/2020 08:59:08

Gary,

I did the same as Paul on my last block also 6" - shrink fit. It's kinder to everything and it doesn't take any force to assemble. Unlike Paul I used the same rule of thumb as yourself 0.001" per inch diameter.. Heated the block on top of a wood burner checking temp with a infra red gun and put the liner in the freezer. It fell in although I did have it set up under the press just in case! I know it's not coming out again as the bore nipped in about half a thou at both ends, quick lick with a home sorted that.

Paul.

Thanks both of you. I'm going to go along with the hot & cold idea. That does away with over stressing of the parts while pressing them together at room temp.

Garry

Much the same fit using 001" per 1in of bore diameter. With a 3.5" bore = 0.0035"

Using limit and fit tables for a shrink fit = 0.004"

Paul

Not Loco related, but recently, wanting a 0.001" intereference fit, I obtained permission to use the domestic facilities for a "heat and freeze".

The steel shaft spent the night in the freezer, falling,. hopefully, to -18C.

The cast iron base spent a couple of hours in the oven at gas Mark 6.

The parts slid together easily. As I watched the frost vanish from the steel bar, it became fixed in the cast iron..

A successful method.

Howard