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[Kerrsy]

 I wrote the reply above on my Mobil
You would think in day and age it would know the difference between a b and d !!

[ooyah/2]

Hi Allen.
No the tool has to be set by the following.

Dia of the bar was .470" dia, it had to be as the cast hole was quite small and I wanted to finnish with a .625" dia hole.

Measuring over the tool tip and the O/D of the bar was .540" , so if you take away half of the bar dia it gives .305" which will give me a bore of .610".

This allows me to use a .625" hand reamer mounted in the 3-jaw and as hand reamers are smaller at the tip I was able to ream straight thro' the casting.

The tool is held in with a socket grub screw and if slackened of the tool can be tapped thro' to give a different bore cut and then tightened up for boring.

Not very technical but it worked.

George.

[frazer heslop]

Nice going George, just a wee tip. I stamp 1/2 the dia on the boring bar it just saves my fuddled (addled) brain from forgetting
I will take a pic of my boring tool so you can see the mods
cheers

[southsteyne2]

Hi George nice work I had an old south bend lathe and always wished I had those t slots on the cross slide
Cheers
John

[ooyah/2]

To make the jig for holding the castings I had a centre to top slide dimension of .874", so after taking the 4mm ( .161" ) plate I was left with .713" to make up.
I had a length of Ali bar 2" wide x 5/8" thk , I cut of 6" of the bar and then cut it down the middle with a haksaw to give me 2- pieces of Ali to make the slips from.
I wanted to finnish up with the jig about .050" lowere than the lathe centre to allow me to pack it up to match the lathe centre, I started to mill the Ali but I was not having much success as the cutter kept clogging up even using W.D. 40 as a lubricant so they were mounted in the 4- jaw and machined to size.

The 4mm  steel plate has 4- holes drilled to match the "T" slots and the slips have matching holes to go down thro" the Ali into 4- "T" nuts in the slides.
When it was all bolted up it was a very solid base to which the casting was to be bolted thro' the lugs with 6-B.A. bolts into tapped holes in the 4 mm plate.

I now had to get the exact centres of the cast holes in the trunk guide,  with a 1/2" round rough file I cleaned out one hole to smooth the sand cast holes and fitted a brass plug turned up to a push fit with the centre marked on.

The casting and the mounting plate were now all boltted up and with a centre finder in the chuck I packet up the casting with shim brass to get the centres within about .005 0f the chuck centre.

When I was satisfied that all was well I ran a D.T.I. across the face of the flanges that I had already filed to a good finnish to square the job to the cenre line of travel to the lathe.

All that remained was to set up the boring bar and as a last proceedure tightened up the Gib strips in the cross slid to prevent movement.

Now was the big question , would it all work, started up the lathe , engaged the Auto feed and stood well back, to my great delight the tool started cutting away with no trouble so on the same tool setting I gave it 3- passes and then removed the tool. my 5/8" reamer being hand held the stem was parallelI  fitted it into the 3- jaw and at my slowest speed reamed out the hole, it was bang on 5/8" bore, so all that was required was to slacken the Gibs , wind the cross slide across by the drawing centre dimension, lock up the gibs and repeat the process

You can imagine how pleased I was at the result, having never attempted such a machining process before and for it to turn out as it was I was "well pleased"

Just a few pics to let you see how it was all set up.

Thanks for looking in and I hope that it will be off help to anybody who has never done this before, if I can do it so can you..

George.

[ooyah/2]

OOPS, forgot to post some pics.

George.