I tend to start reducing the depth of cut earlier than that and would go from 10 to say six then 4 then 2 and finally sneak up with a thou or less by which time all the spring should have worked its way out of the tool.

Reverse cutting can catch you out if gibs on the saddle are slightly loose and you end up with more taken off than you expect. The last thou can also be uncertain if the tool is not really sharp and rubs rather than cuts. You then put a little more depth of cut on and this time it cuts but then takes too much off.

Doug

The other problem is that the spring builds up as each cut is taken so does need to be run out now and again. Often run through several times to get rid of it completely.

One saving grace is that if some depth of cut is taken and then reduced to hit size there will be less spring so it wont reach it. The bore can then be picked up again with the tool, get close and then take trial cuts of some order until one is actually taken. It's a bit like the usual idea of getting a 1 thou clear fit. If you get close and then switch to 1/2 thou cuts and at some point a gauge goes in the fit has to be 1 thou or better.

Another way is to have say 1/4" of the bore that doesn't matter too much. Take a cut for that depth measure it and adjust if needed. Done correctly even the bit that doesn't matter will come out correct even accounting for a certatin amount of spring if the adjustment is small.

Loose gibs can cause problems working the normal way if the tool isn't wound back far enough away from the work.

John

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Danny

Been there; done that; worn out the T-shirt.

For critical dimensional boring I utilize my Myford top slide fitted with an Armstrong boring tool holder and gibs a little on the snug side; tool set to a few thou above center. I set the top slide scale so the handle is between 1/2 to 1 degree on the Y+ side. I bore to within 8-10 thou using the cross slide. I repeat the final pass 4-5 times to hopefully eliminate any residual spring. I then lock up the cross slide gibs and finish with the top slide. After locking up the cross slide, I always check, by advancing the apron, that the tool is still just barely touching the work. With the top slide set at 1/2 to 1 degree, an advance of 1 increment (.002 at 90 deg), I can feed a few ten thou at a pass. Works most times unless Mr. Murphy comes to call. For less critical applications, I use my tailstock boring tool holder.

Cheers

Bill