CL430/500 Lathe Tooling size

[Gary LynchParticipant @garylynch39491]

HI All
What is the best tooling size to use in a Clarke Cl430/500 Lathe?

Thanks Gary

[bernard towersParticipant @bernardtowers37738]

usually the largest one that fits the tool post and able to be on centre height

[Howard LewisParticipant @howardlewis46836]

Yes, as Bernard says, the largest practicable, to maximise rigidity.

Howard

[JasonBModerator @jasonb]

I’d say the opposite in most cases. Why spend an age grinding a bit of 1/2″ square HSS when for most jobs a 1/4″ square will do. It is only really when you can’t avoid excessive tool stickout that bigger helps. keeps the costs down too

likewise with inserts no need for a really big cross section holder when say 8mm will do, many a modern benchtop machine won’t have the power to need the rigidity of a larger tool and will just flex elsewhere particularly the jacked up CL500 . Smaller holders also tend to take smaller inserts so again a cost saving.

 

[BazyleParticipant @bazyle]

100% Jason. ‘fraid it rather annoys me to read some new users thinking they must use the biggest that will fit the toolpost gap then complain it is above centre.

Although I’ve not used anything bigger than 24in swing (at work obviously) I have never needed anything bigger than 1/4″. While I have some 3/8″ and even a bit of 1″ that is only because they came as freebies with something else. Often better to make a holder if you need more stick-out. I do have some Armstrong holders designed for that purpose but they don’t actually fit any of my lathes! Used to use them in the B&S at work where they just didn’t waste money on any HSS larger than 1/4″. Defence contracts were so tight (not) we had to save every penny.

[Howard LewisParticipant @howardlewis46836]

Whatever size you use, it needs to be held rigidly.  Assumes that the tool has been ground properly.

For most of our work, clearance angles are not too vital. A lot of the time, anything between 5 and 10 degrees seems to work for me. I avoid large angles, since that removes metal from behind the cutting edge, that could be used to conduct away heat, prolonging tool life

If it is flexing, surface finish and accuracy will suffer. The least that you will get is chatter.

As to not being on the centre height, unless it is, the tool will not cut properly (If at all when above, just rub)

Have done a lot of work with 1/8″ ,1/4″ and 5/16″ toolbits in holders that are as hefty as possible, and carbide tips, again in holders that are as rigid as possible.

Howard

[duncan webster 1Participant @duncanwebster1]

This thing about being bang on centre height needs to be qualified. When I worked a centre lathe as part of earning my crust, we had 4 way turret and a pile of packing, then thinnest being about 16g, so the nearest you could get was 1/32″. If you’re a tad off centre height it changes the front clearance angle, how much depends on the workpiece diameter. It also affects the accuracy of the infeed. In short, small work needs tool to be nearer centre than large, but if you’re near enough it will still work.

[old martParticipant @oldmart]

At the museum, we have a large quantity of lathe tools, almost all are insert type. Having qctp would not be affordable and as the insert height pretty much stays the same per tool, even with different makes of insert fitted, it pays to buy 20mm square tools and mill the bottoms to as close to the centre height of 17.53mm as possible. Of course, boring bars from 6mm upwards need shims which are kept in with the bars in their tubes. When I made the longer cross slide for the Atlas, the tool height was made the same as the Smart & Brown to share 90% of the tools. We also have some 12mm tools with shims in case the size suits small work. One advantage of the larger sizes is that they are longer and stiffer should the work require greater length of stickout.

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