Oilite bushes

I a building a PYRTE traction engine & have now started the cylinder. The spec calls for brass ( which I have) bored & then lined with phosphor bronze bush for the cylinder liner.

i am lucky enough to have a stockist of oilite bushes very near & can purchase 1 inch bore oilite bush of the correct length & diameter requiring a moderate amount of external work to press fit into the brass.

The cost , along with the bushes for the con rod, & eccentric, is little more than the postage for the raw phosphor bronze

Can someone advise if one can use oilite bushes, which would not need internal machining, for a cylinder liner, or is this a big no no

Thanks

Sintered bronze bushes are porous, so that they retain lubricating oil. The porosity is usually around 20% or so. If you are using steam, I expect the oil will rapidly wash out and you will be left with a porous bush and no lubrication beyond the bronze itself. The normal lubricating oil these are impregnated with is only rated for something like 120C or so. I know from my own experience that you can get higher temp oils that are good for 150C but they are expensive.

No experience with steam cylinders as such but perhaps someone else here does.

Murray

The oilite is porus so you may get some steam trying to pass through it, not quiet sure of the Pyrte cylinder design but if like other TEs where the liner has a steam passage round it you could get steam passing from passageinto cylinder and bypassing the regulator which would show a drop in pressure and fail the boiler test.

I suggest (in the absence of responses from others) that the porosity will present problems. The seal of a piston ring on the cylinder face relies on pressure behind the ring, and if this leaks away via the porous metal the power will drop.

But let's hear from anyone who has actually tried it ...

Regards, and seasonal wossnames

Tim

I wouldn't bother, anything you do to an oilite bush to stop it leaking will ruin it as a cylinder liner. Get a plain bush instead.

Neil

Why don't you use a glass cylinder ?

http://www.aimer.co.uk/glass_tube.html

.

Failing that he could do something totally obscure like doing the tried and trusted method of following the drawing to the original design.

Nick

Thank you Jason

That was something I did not know & the reason I asked the question

Sorry if I upset the "experts" but I did not know that oilite bushes were porus & thought that I would at least just ask the question as it seemed an obvious way of saving quite a lot of money.

But perhaps I should keep quiet & make mistakes & learn that way !!!!!

Edited By Sam Longley 1 on 02/01/2017 07:59:04

Edited By Sam Longley 1 on 02/01/2017 08:01:47

Sam, it is possible to buy hollow cast Bronze which may work out a little bit cheaper than solid as you are not paying for the swarf that will get thrown away. Have a look at College Engineering and M-Machine to see how the prices work out. If you are going to Alley Pally you could collect from College or maybe find an offcut on their stand which would save postage.

Another thought would be to use a CI liner, I have done this on a CI cylinder but should be OK on your brass one.

You could still use the oilite on some of the axle bushs as like you say it is a lot cheaper than solid.

Edited By JasonB on 02/01/2017 08:10:16

.

Sam,

No ... don't do that, Sam

Here are more answers about Oilite than you even knew there were questions ...

**LINK**

http://www.bowman.co.uk/products/oilite_technical

MichaelG.

I am not one of the experts,don't be afraid to ask any questions someone will answer and help to resolve ones problem.I have had a lot of help and am grateful for this site

Frank

Sam, I think you only upset one 'expert' so please carry on asking questions, not only will you get an answer but so will the rest of us.

Brian

The so called "upset expert "is nothing more than a pratt . the whole purpose of this type of forum is to exchange ideas and further knowledge.The OP should ask as many questions as he likes, and those with the appropriate knowledge ,I am sure,will be only too willing to help, in order assist the OP.

Hi Sam, a fair while ago I asked an uncle of mine some advice, as he was an expert in his job of very many years. He couldn't give me the answer I was hoping to hear, instead he advised me by pointing out some important questions that I should ask about the advice I was seeking. After I had accepted what he told me, he said to me "even the experts are not always right", I assumed he had experienced this aspect. So don't be afraid of asking questions that you do not know the answer too, as there is a wealth of experience on this forum which sometimes surpasses so called expertise. Nobody knows everything, even in their own trade, remember, everyday is a school day.

Regards Nick.

Edited By Nicholas Farr on 02/01/2017 09:45:50

I feel this is too significant a point to be dismissed lightly. Learning on the job can be expensive and frustrating, and it's particularly wasteful when the answer is already known.

As a beginner myself I can confirm that it is NOT a good idea to go off piste too soon. Once a certain level of competence is reached, that's different.

Top marks to Sam for asking about Oolite in this application. I've learned something. Top marks also to Nick for highlighting an important basic engineering principle: don't deviate from a proven design without good reason.

Of course what constitutes a "good reason" is for you to decide, not me!

Cheers,

Dave

Here in Oz, bronze bushes such as these **LINK** are readily available. I have purchased bearings from this company - always top quality. Once when some bearings came in later than quoted they actually drove out and hand delivered them at no extra cost.

Surely equivalent items are available in the U.K.

* Danny M *

.

That I can assure you is not what I meant.

Especially as I myself am fairly new to this game and would not have the projects under my belt that I do if it were not for members help from this site.

An 'expert' I certainly am not. And TBH never will be.! - Besides my flippant tongue in cheek remark was not aimed at the OP. However he seems to have interpreted it to have been so. 

Nick

Edited By Nick_G on 02/01/2017 10:56:03

Its very hard to find any "non sintered" bushes or bearing online in the uk, loads in the uS etc..

Would something like this not do. Needs machined but price seems reasonable.

**LINK**

That is a B....r because I have already bored the brass to 33.3mm (as per the instructions Nick G )

But thanks for looking any way

So I think I will have to start on another part of the project until Alexander Palace.

Edited By Sam Longley 1 on 02/01/2017 11:45:02