Hi All,

The photos shows one of two part machined main bearings for my jepson engine.

It is 5/8" dia cast bronze in two halves, soft soldered together. It has been waisted and the two holes are 8ba clearance.

I need to cross drill/bore a hole around 6.1mm diameter on the join line. The hole has to be parallel to the underside and also square to a centre line through the two holes. The hole position on each bearing has of course got be exactly the same.

I'm struggling with a 4jaw or face plate set which will give me the accuracy I need.

Any ideas anyone? the two outer faces will be machined later using a small expanding stub mandrel.

cheers geoff

Hi Jason,

Thanks, I may well have to go with a vertical slide and in my case angle plate set up.

Would prefer a to do it the other way so I can cut the oil groove in the same setting but as things stand now your suggestion looks the best way forward.

Yes the 7/16" dia will be tight, possibly slightly under but as it's not critical not really a problem. (Both my bearings will have a face width of 3/8&quot

cheers geoff

Hi Gents,

A question if I may on the slide valve for this engine.

The last photo in this thread shows the ports in the cylinder block.

The outer dimension across the two inlet ports is 1/2". The ports are 3/32" wide so the inner dimension is 5/16".

From what I have read (M.E. tyro articles by W J Hughes issue 2666 and 2670) the length of the cavity in the slide valve should be the same as the inner dimension (5/16&quot. This would seem to me to be fundamental as with the side valve in a mid position both the inlet ports will be closed. If the slide valve cavity is any longer then both inlet ports will be open with the valve in the mid position, even if only by a small amount.

The drawings for the slide valve on this engine show a cavity length of 3/8". Is this fundamentally wrong, does the length have to be 5/16" or am I missing something?

If you are a "Tyro" like me gents I can recommend the articles by Mr Hughes which also explain clearly the principles of lap, lead, angle of advance etc.

cheers geoff

Neil,

A fair point.

When I bought my Myford/drummond M type I spent 6 years doing nothing except renovate and make parts/accessories for it plus two other drummond M's a flatbed drummond and ……… a super adept ( now you didn't know that did you?).

This year I decided it was time to make something, the whittaker firefly 46 and now my second the jepson engine which is nearing completion. I now consider myself to be a model engineer but still a tyro.

I had the jepson running today and I'm pleased to say it ran very well. The only problem is keeping it going for an extended period. I ran it off the airbrush compressor which is fine for a small oscillator but the jepson gulps in air like a drowning man rising out of the sea. 15 seconds and the pressure has dropped and the tank has drained. I need a bigger compressor!

geoff

Hi Ian and ndiy,

Thanks for your comments.

Sold the adept Ian, big mistake, I now have small indoor model room where I do much of my assembly work. The adept would have been perfect in there ideal for some "little bits".

The jepson is now on youtube, not complete, an early test run which went quite well. It's leaking here and there and needs a bigger compressor than the airbrush one being used. If I could keep the pressure up this engine would be a real high speed "fizzer"

You tube "1947 jepson vertical marine steam engine". Sorry not worked out how to upload videos, I'm rather hoping Jason or Neil will do the honours and add it to this post.

cheers geoff

Edited By JasonB on 21/12/2017 13:36:26

Hi All,

Took a day of today from usual activities to prepare the Jepson engine for steaming.

Added the home made displacement lubricator to the valve chest, then the three oil cups.

The oil cups hold oil to lubricate all the external moving parts. the two main bearing ones also lubricate the big end and the eccentric via oil channels in the crankshaft. The other one carries oil via a down pipe to the cross and the small end.

Bought the cups on ebay, "cheap as chips", £1.50 for 10, why bother making them!!

Also added an additional flywheel. The engine runs fine with the combined flywheels/crank but better with the added flywheel.

I bought some PTFE sheet to make gaskets. Really impressed, only .004" thick and very easy to cut and shape with a sharp modelling knife and gives a perfect seal.

It would appear to me that I have an internet world exclusive on this engine. I've searched and can't find a single example, apart from mine of course.

Best to all Geoff

Hi Emgee,

Thank you for your comments and also thank you, somewhat belatedly to Jim Nic for his earlier post

This is the first steam engine I have made but with it being an obscure design I have found it difficult to assess how well it actually runs, apart from a "gut" feeling that it seems ok?

Therefore feedback from experienced modelers like yourself is much appreciated.

Thank you again Geoff