Cast iron or steel or maybe ally

[lee hawkins 1Participant @leehawkins1]

Hello All,

I am going to build up a Lathe cross slide and carriage, I have lots of steel plate and aluminum but do not have any cast iron plate thick enough, in my mind a cross slide and carriage should be made from cast iron, or does it really matter?

thanks

lee

[lee hawkins 1Participant @leehawkins1]

[Ian S CParticipant @iansc]

The main advantage (in my mind) of cast iron for machine building is the damping effect it has, where as steel tends to resonate. Many machine parts are castings. Cast iron contains free graphite which is a lubricant. Cast iron can be run as a bearing surface against either cast iron or steel.

I don't suppose you are going into mass production in a factory, I'd go for the steel option, if it's going on an existing cast iron lathe bed it should be spot on, if it is a home built lathe with a steel bed, use a good supply of oil on it, and it should be OK for many years of use.

Just my ideas.

Ian S C

[Ady1Participant @ady1]

cast iron has good compression and wear properties and is used by all lathe makers because of this

its not so good under tension, good vices are sometimes made of steel because of this

[Ady1Participant @ady1]

It can be tuff stuff, disc brakes for cars for example

[lee hawkins 1Participant @leehawkins1]

The bed of the lathe is a 65mm diameter hard chrome hydraulic shaft and one the same at 40mm being used as to say a stabilizer either spaced underneath or spaced at the side, either this **LINK** with support at the end, or like **LINK**

I was thinking on maybe I could make some cast iron bushes pressed fit for the carriage to run on the chrome shaft, Bronze being too soft ?

[BazyleParticipant @bazyle]

Nothing soft about bronze. For centuries after iron was discovered it was still the preferred material for knives snd weapons. Also brass. Look how often gib strips are made of brass and they then form 25% of the bearing surface.

You could also look up Moglice – homemade versions. Make all the structure out of steel or even cast some aluminium but arrange for bearing surfaces to be something else.

You could also consider something more complicated with ball/roller bearings Your choice of bed makes this viable whereas the point loading would be too much for a CI or plain steel bed.

[lee hawkins 1Participant @leehawkins1]

Yes, Brass bushes might be the best bet, just thinking on the thickness of the bushes, would it be good idea to mill in some oil retaining grooves like thats whats used on lathe spindle bearings

[Bill PudneyParticipant @billpudney37759]

There is another reason why cast iron is used. One of the reasons that casting things out of iron was so popular was that the process enabled shapes to be made that were otherwise not practical. It also enabled simple and even complex shapes to be made cheaply.

Everything that has been said so far is true, about the vibration damping etc, but never forget the cheapness of the process.

Also have a look at "Russian" lathes at everyones' favourite resource, I have one of these lathes and it is a really robust small lathe.

cheers

Bill

[Ian S CParticipant @iansc]

Lee, you could probably get bronze bushes "off the shelf" to fit the bed shafts.

OT I'v got a pair of motorcycle front forks (straight, and unwarn), been thinking for some time of making a lathe using them.

Ian S C

[lee hawkins 1Participant @leehawkins1]

Than you those who have replied with advice,

Ian,

Yes I know , I have checked them out, but it seem to me the wall thickness of the bearings could be a bit thin to me, with the ones I have looked at, outside diameter only goes to 70mm that would just give me 5mm wall, I would need to get them at 63mm inside diameter and bore them out to get a nice precise snug fit at 65mm

Recon those motor bike fork shafts could make a cracking little lathe, if you do decide to do it , be warned though, it do become a bit of an obsession, I been thinking on this project for months and months, when I bought this hydraulic ram on ebay over a year ago, I new the rough dimensions , the person said they measured the shaft at under a meter long, when I pulled the shaft out it just kept coming , it ended up at 2 meters, straight away I thought this would make a excellent lathe

[Ian S CParticipant @iansc]

Lee, you could press the bronze bushes into holes in the cross slide.

Ian S C

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