- Joined
- Sep 22, 2010
- Messages
- 7,223
1) Standard lantern with rocker.
Advantage :- can use Armstrong type holders with cheap square tool-bits, one tool the right shape for every job becomes affordable, small size.
Disadvantages:- probably the least rigid type, tool can move in approximately 64 directions simultaneously to around 128 million distinct positions when the bolt is loosened. Repeatability approximately zilch, tool has to be set each time. Realistically can't use carbide insert tooling.
Use:- Boat anchor (small) but occasionally handy when you absolutely can't get at the job any other way. Don't mention parting off!!
1a) Standard lantern with flat washer instead of rocker.
Advantage :- can use Armstrong type holders with cheap square tool-bits, small size, stiff enough for light use with carbide insert tooling.
Disadvantages:- tool can move freely rotation to around 100,000 distinct positions when the bolt is loosened. Repeatability approximately zilch, tool has to be set each time.
Use:- Generally considered the quick'n dirty first step improvement to the standard lantern whilst you make / wait for delivery of something better.
Although rarely seen the improved variant with a thicker washer slotted to locate the tool (preferably an Armstrong holder) having some means to stop it rotating, such as a pin in hole arrangement locking it to a longer tee nut, is effective. Especially when used with a decent tool height gauge so the tool bits can be changed whilst the holder stays fixed. Also easy to arrange more than one rotation location angle. Part off with care.
2) Four way holder.
Allegedly the classic Brit alternative but really requires a 45° rotation ratchet for proper exploitation. Perfectly acceptable ones can be screwed'n glued up from stock sections.
Advantages:- rigid, holds multiple tools, designed for forged shank but welded tools but just as good, maybe better, with carbide inserts, can accept T type and carbide bit parting tools.
Disadvantages:- porcupine effect from multiple tools, unless fitted with a good ratchet tools still need to be set after rotation into place, shims needed to set tool height after sharpening, relatively large.
Uses :- SouthBend Tee slot compound isn't the ideal base but it does make it easy to interchange complete posts and sets. I always had 3 or 4 kitted out complete with tools, locking handle and Tee nut for rapid slide in / out changes and found the results, although not ideal, good enough not to embark on a different system. Pretty much never set up more than two tools tho'.
3) Quick change system.
The fashionable favourite. Every bodies safe recommendation. Crusty ole Clive says over hyped, over-priced and unnecessarily everywhere, especially since they invented positive rake carbide inserts which don't over-stress a small lathe.
Advantages:- can accept Tee type and carbide insert parting tools, easy height setting after regrinding tools, extra weight helps combat chatter.
Disadvantages :- expensive, needs enough holders to prepare a complete set of tools for the forthcoming job (preferably without disturbing your standard set) seems to be agreed that 10 or so will do (I have more), extra joints mean less rigidity even if your post is of high quality, poor quality post is a nightmare, tool has to divine its support at considerable distance and often ends up overhung relative to the slide ways.
Uses :- developed for forged shank butt welded tools where the height adjustment really helps (but slower in use than a proper ratchet four way) so probably the best choice if that's what you use. Pointless with carbide inserts which are fixed height.
4) Two slot block.
What I'd go for if starting now.
Advantages :- smaller than a 4 block so tool axis can be pretty much over slide ways for rigidity, easily made by screw'n glue from stock sectons, holds longitudinal and facing tool ready to be swung into place, easy slide in / out interchange for sets e.g. another one for boring tools, ideal for carbide or Armstrong holders, easily takes T type or carbide parting bit holders.
Disadvantages :- needs shim adjustment if used with forged shank tools, simple version is free rotating so needs either a locating system or has to be worked with in fixed position.
Uses :- In my view best bang for buck, ideally combined with a rear-mount parting tool. Make at least three, one for turning, one for boring, one for parting. If happy to sharpen tool bits and, most important, to make the angle jigs so each one comes back to the same shape, then use a fixed position block with two Armstrong holders. Bent to right one for normal turning, bent to left for facing (straight holder is for when you just gotta have that clank-clunk-clank experience of the tool eating the chuck and the chuck eating the compound). Make a decent tip height gauge, optical type is easiest and best, and simply swop tips as required.
If you don't want to sharpen go straight to positive rake carbide and make blocks as needed to permanently carry the holders, rotation angle location is probably essential. Theoretically you can arrange repeatable swopping of holders in a fixed block but I'm unconvinced.
Advantage :- can use Armstrong type holders with cheap square tool-bits, one tool the right shape for every job becomes affordable, small size.
Disadvantages:- probably the least rigid type, tool can move in approximately 64 directions simultaneously to around 128 million distinct positions when the bolt is loosened. Repeatability approximately zilch, tool has to be set each time. Realistically can't use carbide insert tooling.
Use:- Boat anchor (small) but occasionally handy when you absolutely can't get at the job any other way. Don't mention parting off!!
1a) Standard lantern with flat washer instead of rocker.
Advantage :- can use Armstrong type holders with cheap square tool-bits, small size, stiff enough for light use with carbide insert tooling.
Disadvantages:- tool can move freely rotation to around 100,000 distinct positions when the bolt is loosened. Repeatability approximately zilch, tool has to be set each time.
Use:- Generally considered the quick'n dirty first step improvement to the standard lantern whilst you make / wait for delivery of something better.
Although rarely seen the improved variant with a thicker washer slotted to locate the tool (preferably an Armstrong holder) having some means to stop it rotating, such as a pin in hole arrangement locking it to a longer tee nut, is effective. Especially when used with a decent tool height gauge so the tool bits can be changed whilst the holder stays fixed. Also easy to arrange more than one rotation location angle. Part off with care.
2) Four way holder.
Allegedly the classic Brit alternative but really requires a 45° rotation ratchet for proper exploitation. Perfectly acceptable ones can be screwed'n glued up from stock sections.
Advantages:- rigid, holds multiple tools, designed for forged shank but welded tools but just as good, maybe better, with carbide inserts, can accept T type and carbide bit parting tools.
Disadvantages:- porcupine effect from multiple tools, unless fitted with a good ratchet tools still need to be set after rotation into place, shims needed to set tool height after sharpening, relatively large.
Uses :- SouthBend Tee slot compound isn't the ideal base but it does make it easy to interchange complete posts and sets. I always had 3 or 4 kitted out complete with tools, locking handle and Tee nut for rapid slide in / out changes and found the results, although not ideal, good enough not to embark on a different system. Pretty much never set up more than two tools tho'.
3) Quick change system.
The fashionable favourite. Every bodies safe recommendation. Crusty ole Clive says over hyped, over-priced and unnecessarily everywhere, especially since they invented positive rake carbide inserts which don't over-stress a small lathe.
Advantages:- can accept Tee type and carbide insert parting tools, easy height setting after regrinding tools, extra weight helps combat chatter.
Disadvantages :- expensive, needs enough holders to prepare a complete set of tools for the forthcoming job (preferably without disturbing your standard set) seems to be agreed that 10 or so will do (I have more), extra joints mean less rigidity even if your post is of high quality, poor quality post is a nightmare, tool has to divine its support at considerable distance and often ends up overhung relative to the slide ways.
Uses :- developed for forged shank butt welded tools where the height adjustment really helps (but slower in use than a proper ratchet four way) so probably the best choice if that's what you use. Pointless with carbide inserts which are fixed height.
4) Two slot block.
What I'd go for if starting now.
Advantages :- smaller than a 4 block so tool axis can be pretty much over slide ways for rigidity, easily made by screw'n glue from stock sectons, holds longitudinal and facing tool ready to be swung into place, easy slide in / out interchange for sets e.g. another one for boring tools, ideal for carbide or Armstrong holders, easily takes T type or carbide parting bit holders.
Disadvantages :- needs shim adjustment if used with forged shank tools, simple version is free rotating so needs either a locating system or has to be worked with in fixed position.
Uses :- In my view best bang for buck, ideally combined with a rear-mount parting tool. Make at least three, one for turning, one for boring, one for parting. If happy to sharpen tool bits and, most important, to make the angle jigs so each one comes back to the same shape, then use a fixed position block with two Armstrong holders. Bent to right one for normal turning, bent to left for facing (straight holder is for when you just gotta have that clank-clunk-clank experience of the tool eating the chuck and the chuck eating the compound). Make a decent tip height gauge, optical type is easiest and best, and simply swop tips as required.
If you don't want to sharpen go straight to positive rake carbide and make blocks as needed to permanently carry the holders, rotation angle location is probably essential. Theoretically you can arrange repeatable swopping of holders in a fixed block but I'm unconvinced.