Machining techniques for castings

[lensman57]

Hi,

I have at least 8 air-steam engines of bar stock construction under my belt and I was considering a Stuart engine from castings for my next project as I wanted to use sream rather than air to power it. Despite having reservations about my ability to machine the castings the real deal breaker was the price of the Boilers, either ready made ( astronomical ) or in kit form ( quite expensive ), so I think that I would stick to bar stock designs running on air for a long time to come.

Regards,

A.G

 

[Tin Falcon]

LM you can always run a casting engine of compressed air and add a boiler later.

Double expansion and triple expansion engines pretty much need steam and a boiler. other that that no worries.
Tin

 

[MuellerNick]

I mill dedicated soft jaws for the vise out of Ureol. That leaves no marks at all. Even on painted parts.
Yes, paint, then mill, with the vice closed with 4 tons pressure!

You might try MDF, cheaper but maybe will give in and not so good if you work with coolant.

An other option for intricate parts to clamp is -as I call it- a cast able vise. Wood's or Rose's alloy. Heated up, part stuck in and mill. You can even mill trough the "vise". Collect the chips, melt them and skim off the chips.


Nick

 

[trumpy81]

An other option for intricate parts to clamp is -as I call it- a cast able vise. Wood's or Rose's alloy. Heated up, part stuck in and mill. You can even mill trough the "vise". Collect the chips, melt them and skim off the chips.

Nick

Nick that is an excellent idea and not one I had considered before. I have a little bismuth here so I will definitely try this the next time I have trouble holding a part.

Thanks for the great tip!

 

[MEM]

I have found that when casting a part it is best to leave a "Turning leg" that can be screwed to a base plate and held in place for drilling and milling. After the part is assembled I can then cut the leg off the cast part leaving a clean finished piece. Oversizing the casting is also a good idea as you can always either turn, mill or drill the part and file it to the desired size. Hope this helps. I find trial and error not to be the best teacher. -Mike

 

[gus]

Hi,

I have at least 8 air-steam engines of bar stock construction under my belt and I was considering a Stuart engine from castings for my next project as I wanted to use sream rather than air to power it. Despite having reservations about my ability to machine the castings the real deal breaker was the price of the Boilers, either ready made ( astronomical ) or in kit form ( quite expensive ), so I think that I would stick to bar stock designs running on air for a long time to come.

Regards,

A.G

Hi AG

Castings are expensive and so I stuck to building engines from bar stock.But
when I get over procrastination stage,may build a simple mini LPG Fired Aluminium Furnace to cast parts for Slide Valve Engines.I live in a "walk up flat with limited space.As for the cylinder ,I may have cast insitu or press in the cylinder sleeve. The flywheel have to come from bar stock.
Will try building "Stuart" engines when I get over procrastination.

 

[Dusty1]

I usually set castings up to the areas that don't get machined.
Then I go back and check the cores and machined areas to be sure they are properly placed and will clean up.

On train wheels/flywheels setup to the cored spokes so they will run
true and in balance.

We used a surface gauge on a surface plate for large castings
but with small castings
merely scribing a line will knock the casting out of line.

It is good to rough them all out because that will eliminate distortion
and show the areas that may not clean up.

This is a Goldman locomotive casting,

checking the core locations prior to boring.

Next is axle box castings Little Engines

ready to bore Goldman

bored and skimming the saddle. Goldman

Kap

 

[Dusty1]

train wheels:

 

[Dusty1]

Here's a handy tool for working on castings,
This is a mini wall caliper.

It is used by woodworkers, pattern makers
and machinists.

This double ended caliper can
measure the thickness of a casting to check
the core location, or thickness to see if your cut
will break out of the casting.

We had these up to 36 inch depth back in the day
when I worked in a heavy fab shop.

Kap