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gambler
06-22-2009, 04:02 AM
what determines the angle that the compound is set too? and also, after setting the compound what angle should the tool be in relation to the work and the compound?

BadDog
06-22-2009, 04:11 AM
Compound angle depends on personal preference and operation to be preformed. It can be perpendicular to bed ways for improved rigidity or incremental offsets without disturbing cross dial setting, parallel to allow measured depth (often not available on saddle long feed), or at 29.5 off perpendicular for reduced load thread cutting. Compound angle can also help keep hands and hardware out of the way of obstructions.

Tool angle depends on the particular grind and how it is to be presented for the cut. It's the cutting edge angles that are important for the cut. Generally the angle of the bit is irrelevant as long as it holds the cutting edge in correct orientation. However, for some cuts, holding the bit at some optimal angle can more readily handle cutting forces and may be a factor in reducing chatter, or possible keeping the tool post (etc.) out of obstructions.

oldtiffie
06-22-2009, 07:48 AM
That was as good an answer as I've seen in quite a while Russ - all pertinent points covered clearly and precisely.

I realised that it was a general response to a general question.

For the OP: did you have a particular need or was it a general question?

If it related to the compound off-set for screw-threading, there was a very comprehensive thread on that topic not so long ago. If I recall correctly, it was raised by "Hwingo" (Harold Wingo).

To paraphrase "BadDog" (Russ): if you have the tool at the angle to the work that you require, you could loosen the compound slide and the tool-post (while holding the tool-post steady), then swing the compound to where you require it, then secure/tighten both the tool-post and the compound slide. All that will have changed is the angle of the compound.

Bill Pace
06-22-2009, 09:00 AM
Please excuse the drift off topic for a moment to give Russ (baddog) a couple 'attaboys' for his response to the OP's question - you managed to give a very good description to a, what can sometimes get into a long discussion (ie: tiffies mention of the other thread), and yet kept it short and to the point.

Oldbrock
06-22-2009, 04:25 PM
Mine lives at 29 1/2 degrees from in line with the cross slide unless needed at some other angle. Ready for screwcutting and out of the way of the cross slide handle. If you need to take a few thou off the face just double the amount you want to remove. Peter

Peter.
06-22-2009, 04:34 PM
Deos anyone set their compound at a particular angle to provide a finer in-feed for creeping up on critical dimensions? For instance, a shallow angle to use whereby putting 5 thou on the compound would be tha same as a thou on the cross-slide? Is there a particular angle/forula that's commonly used?

ammcoman2
06-22-2009, 07:54 PM
On my Std Modern I leave the compound at 60 degrees to the cross slide (or 30 to the bed). This way you get 0.001" reduction in diameter on a part with 0.001" infeed on the compound dial. - sine 30=0.5.

A benefit is less chance of smacking the tailstock!

Geoff

BadDog
06-22-2009, 09:10 PM
Thanks for the kind words fellas...

Peter: I've seen comment on that practice, and have tried it myself, but I find it questionable, at least for my purposes.

Basically, targeting tenths is mostly in the domain of grinders. With a lathe, you generally need at least a few thou in-feed to get even a sharp HSS finishing a bit to cut decent. So to hit sizes in the "tenths", you still need to stage your final cuts to hit size. I haven't seen where adjusting by 10ths using the compound would help me, unless maybe using a tool post grinder or something...

tattoomike68
06-22-2009, 09:16 PM
Please excuse the drift off topic for a moment to give Russ (baddog) a couple 'attaboys' for his response to the OP's question - you managed to give a very good description to a, what can sometimes get into a long discussion (ie: tiffies mention of the other thread), and yet kept it short and to the point.


Amen he does keep if informative and to the point.

Most home machinist with smaller tools use the compound to thread but some time when running a big machine, high dollar tooling you just use the cross slide to thread and dont mess with the compound till you get to doing 5 TPI or less.

On smaller work the compound will help you get tooling close to a center and chuck as already stated so it gives you so some room to work.

on large work peices, on big lathes with bigger tools its much less of a factor.

lane
06-22-2009, 09:53 PM
It all boils down to you can put it any where you want to . You the one doing the job at hand.Their is not a right and wrong way.

gambler
06-22-2009, 10:56 PM
thanks very much for the replys gentlemen. my next question will probably have a pic attached. I always wonder if I'm doing something the hard way.:)