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by Bill Shields
Thu Sep 06, 2018 8:14 pm
Forum: Milling Machines
Topic: Bradford Milling Machine
Replies: 5
Views: 553

Re: Bradford Milling Machine

even if they are the 'same machine' be careful about expecting parts to be 'interchangeable'.

Some of these critters start out as the same casting(s) but have no guarantee that all (or any) of the other parts are the same.
by Bill Shields
Thu Sep 06, 2018 8:11 pm
Forum: Riding Scale Railroading
Topic: Small Diesel engines for motive power
Replies: 26
Views: 1521

Re: Small Diesel engines for motive power

another way to 'eliminate the lawn mower effect' is to put steam through the exhaust :shock:
by Bill Shields
Thu Sep 06, 2018 8:02 pm
Forum: Live Steam
Topic: Re-facing Slide Valve & Ports
Replies: 53
Views: 1646

Re: Re-facing Slide Valve & Ports

You have it.

In REALITY, if you can work it out, you want the 'leading edge' of the valve to ALWAYS be 'peeking over' the edge of the groove at all used cut-offs.
relief 3.png
another picture....for others who may be just 'getting in the groove'....
by Bill Shields
Thu Sep 06, 2018 7:48 pm
Forum: Live Steam
Topic: Re-facing Slide Valve & Ports
Replies: 53
Views: 1646

Re: Re-facing Slide Valve & Ports

thought you would ask this. relief.png relief 2.png the 'inside edge' of the relief should be just under the overlapping edge of the valve with the valve gear in FULL TRAVEL. basically the edge of the valve 'peeks over' the cliff created by the relief groove. What you DO NOT WANT is for the internal...
by Bill Shields
Thu Sep 06, 2018 7:30 pm
Forum: Lathes
Topic: How does one polish a thread?
Replies: 19
Views: 2978

Re: How does one polish a thread?

As for what you originally asked - the acme thread for an injector...I have to agree with Harold on the pig / lipstick although I usually think purse and sow's ear. After you have machined a good fitting thread, pack the gland with graphite ribbon and forget about it. The graphite will flake off ont...
by Bill Shields
Thu Sep 06, 2018 6:52 pm
Forum: Live Steam
Topic: Re-facing Slide Valve & Ports
Replies: 53
Views: 1646

Re: Re-facing Slide Valve & Ports

no no no no....bronze bushings are just fine. Don't panic here..just think things through. changing the sliding surfaces with cast iron is a real undertaking. It is best if you design things that way from the get-go. these cylinders are a silver soldered assembly of steel and phosphor bronze (on the...
by Bill Shields
Thu Sep 06, 2018 4:25 pm
Forum: Live Steam
Topic: Re-facing Slide Valve & Ports
Replies: 53
Views: 1646

Re: Re-facing Slide Valve & Ports

I am saying that bronze is low on the list of materials from which you should make a lathe - but the LEAST of the concerns is the sliding surfaces. Stop and think WHY CAST IRON is used (or Meehanite if you are familiar with name) as opposed to Bronze. Young's modulus of CI is almost 2X that of Bronz...
by Bill Shields
Thu Sep 06, 2018 4:16 pm
Forum: Live Steam
Topic: Understanding types of copper?
Replies: 26
Views: 927

Re: Understanding types of copper?

Extraordinary lengths is when you order it from the UK...as I do for 5" and above tubing...and 7/16" OD thick wall tubing for flues. Be CAREFUL about tubing sizes as Harold mentions. In many places they still use SWG for wall thickness. There WAS a time when 3/8 tube was 3/8 OD because tube was tube...
by Bill Shields
Thu Sep 06, 2018 4:09 pm
Forum: Live Steam
Topic: Re-facing Slide Valve & Ports
Replies: 53
Views: 1646

Re: Re-facing Slide Valve & Ports

Giggle...

Not using bronze for a machine tool frame (or any sizable component there of) has very little to do with its suitability as a bearing surface.

Think about the mechanical properties of bronze and all the reasons why it is unsuitable for anything much larger than maybe a small toaster.
by Bill Shields
Thu Sep 06, 2018 12:46 pm
Forum: Live Steam
Topic: Re-facing Slide Valve & Ports
Replies: 53
Views: 1646

Re: Re-facing Slide Valve & Ports

There is bronze and there is bronze..some combinations are quite good for bearing applications.

Aluminum Bronze and /or Phosphor Bronze on 'other bronze' actually makes quite a good bearing combination for our application(s).
by Bill Shields
Thu Sep 06, 2018 6:24 am
Forum: Live Steam
Topic: Re-facing Slide Valve & Ports
Replies: 53
Views: 1646

Re: Re-facing Slide Valve & Ports

80 hours is not a lot of time. What materials are used (cylinder / valve)? If you don't have a lapping plate, you might consider using a fly cutter on the cylinder surface just enough to remove the wear / grooves, then polish the surface as best you can. If a surface plate and abrasive paper is all ...
by Bill Shields
Wed Sep 05, 2018 4:18 pm
Forum: Riding Scale Railroading
Topic: Small Diesel engines for motive power
Replies: 26
Views: 1521

Re: Small Diesel engines for motive power

Perhaps a really good, sound deadening exhaust system and enclosure that make the engine quiet....and a really cool electronic sound system to make it sound like a big diesel...????