Hi Sean,

If I understand you correctly you want a tool holder that doesn't mount on the top slide, but directly on the cross slide. Some time ago I made a tool holder that mounts directly on the cross slide of my small lathe, I used mild steel, it has worked well.

Thor

No need to limit yourself to steel Sean – you can buy pieces of cast iron too.

Norman

Cast iron would certainly be easier to machine, as long as the material you use is of reasonable quality – otherwise it may have inclusions of casting sand etc which will do your nice sharp tool no good at all. Other than that, it is dirty stuff to work with, because of the carbon it contains, which will fly to your hands (face, shirt, etc) as though magnetised. But it washes out OK.

Of course, as soon as you have a tool holder made up, you can get on with making your own proper toolpost. Cast iron again, I suggest.

Cheers, Tim

I have a cast iron block i use with my t-slotted table as the topslide won't fit to it.

Don't live in fear of cast iron, it is messy but if you get the good stuff it is beautiful to machine (although it turns your snot jet black if you breath it in).

Neil

I,v been machining a cylinder for a IC engine today from some cast iron obtained by another ME in Christchurch a few years ago, I'm not sure of the grade, it machines more like mild steel, and reasonably clean, which is more than can be said for the next job which will be making the piston, which will be the cast iron from an old window weight.

Cast iron when used on machinery has the advantage of dulling vibration.

Ian S C

> Iron Carbide particles which should not be too detrimental and reasonable easy to clean up. Graphite is a fairly good lubricant.

Graphite is a lubricant, but carbides are abrasive.

Neil

Iron castings tend to have a "skin" which consists of sand and chilled cast iron, both of which are hard, granular and therefore abrasive which tends to both blunt HSS tools and cause an increased rate of wear if left on machine slides. Sections of cast iron as bought from the trade (such as meehanite) have had the skin removed and are pretty benign to machine, if somewhat messy since the iron and carbon tend to come off the tool as powder rather than curly swarf. For what it's worth, my view is that a machine is made for cutting metal and I'm happy to machine anything that comes along, cleaning up as necessary afterwards. There is an argument that cast iron, since it has very little coherent crystal structure, is better at absorbing vibration than steel and is therefore better for the manufacture of machine tool components.

Cheers,

Rod

Work lathes are like rental cars, they will do things that your own won't – like machine cast iron without a worry.

I made my "semi-Gibraltar cum rear toolpost" out of pieces of black mild steel bar welded together and machined in the lathe to suit the existing four-way toolpost I scrounged up for nothing in a box of junk at a garage sale. I very rarely use the topslide these days. Pretty much only for screwcutting.

So yes, any old block of mild steel you find lying around the yard of suitable size should do the job, or a stack of pieces of flat plate or flat bar welded together also. Just make it good and solid, so 3" or 4" square is ideal. The clamping bolt down through the middle of mine is from memory 7/16 UNF high tensile, machined to fit the T slot at the bottom and  to fit the 3/8" T slot. Tool clamping screws are 5/16" but 1/4" will do the job if you are using 5/16 or 1/4" square HSS blanks instead of the 3/8 tool bits I use.

If you just make a big square block with one slot milled in it for the tool bit, you can mill it in your own lathe by setting the block in its operating position, but packed up with spacers as needed and hold the milling cutter in the lathe chuck and away you go. I made another four way toolpost  that way. The whole thing was milled from solid like this:

Edited By Hopper on 13/09/2016 08:54:57

Some years ago, I made a four way Rear Toolpost for my lathe. The raw material was a 3 foot length of 3" x 1" BMS, (declared scrap by R & D). It was made to match the four way front toolpost.

Each of the five laminations was machined differently, and clamped together, internally, by three long Allen capscrews. The fourth position was used for a dowel to locate each orientation. It carries a parting tool and two chamfering tools (front and back chamfer).

1/2" bar was ideal for making the M10 Tool clamp screws.

The base is clamped onto the rear T slot of the Cross Slide, with two small dowels to locate it against the back of the Cross Slide.

Have also made two other 4 way toolposts, for friends from lumps of mild steel. One is on a Little John, the other on a Chester Cub.

As far as I know,like me, they have had no problems. So Mild Steel will do the job.

When machining cast Iron, I position a magnet under newspaper beneath the chuck. Aftrerwards, removing the newspaper allows the dust to be disposed off quite easily, and the lathe needs almost no cleaning up.

Howard