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Lathe tools


chrism
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Hi

Im after some decent tools for my lathe

At the mo I have been using carbide tipped ones which are fairly worn. With the auto feed taking about 0.2mm off im not getting that great a finish and when i stop the auto feed and wind the bed back without pulling the tool away from the work piece it still takes a cut off. Sometimes it just leaves a line on the surface but most of the time it wants to take more, about 0.2mm

Would this be down to worn tools?

The lathe is in good condition and there doesnt seem to be much play

Would the tools which have replaceable tips be the best, they are fairly pricey though from what i have seen, such as the sandvik type.

Where is the best place to get them from, i have seen a few sets on axminster. I would like to get a set really of the different types.

My lathe is a colchester student, without a q/c toolpost and the tool height is 7/8" which means i need about a 16mm shank so i can pack it up a bit

Any help appreciated

Thanks

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Oh I am with you on this :(

My Lathe is only a Small Boxford, nothing huge n chunky, as such I need sometimes

to cut / turn down stuff bore stuff out and not taking huge bites at a time as its not that powerful.

I have a "Wide selection" of tooling bits mainly from car boots, tried shapening and

frankly the cutting isn't that great on any for too long, in the end I bit the bullet and

bought a tool that takes disposable inserts - christ on a bike what a difference :)

The one I bought was a STELLRAM (www.stellram.com - 01225897100 brochure is worth having :) )

The 1st tool holder I bought was :

STELLRAM SELPR1212F08

this has dimensions of the main body of the tool of 12mm wide and 12mm high

They do bigger ones - instead od 1212 in the part number you can have 1616, 2020, or monster 2525

This takes a disposable tip, although square ish only able to use 2x of the 4 cutting edges as the shape fits only on way, but

I have also bought a :

STELLRAM SESPR1212F08

This then allows me to use up all 4x cutting edges

The tool I have takes cutting tips EP_083M3 (same on all the toolings above) and can be bought in a variety

of roughing cutting (lots of metal off in a pass) down to fine finishing grades,

tips are aropund £5 each so not cheap but wow makes life so much better. with all 4 used almost £1 a tip :)

I bought a box of tips in mixed cutting grades, but have quite a number of 2Mediums"

these are :

EPMT08M302 73 SFZ

These will be fine for most general cutting, with the excpetion of Ali which has a slighty different part number, these will do

ali at a push but for big ali work buy a suitbale tip for ali only

HTH

Nige

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Hi, you could try looking on www.cromwell.co.uk - they sell lots of tooling (as well as just about anything else you might need).

Their catalogue is highly recommended for passing the time in the 'small room' :lol:

Cheers, Al.

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PH Horn tool and insets are amazing imo but very expensive.

having the tool set to centre height or just below is crutial to surface finish.

I'd also really recommend a q/c toolpost. Even if you basically only use one tool, it makes setting or adjusting centre height a doddle. I have a Chinese one in the style of Dorian but it seems really good. If I have something really heavy to do I just put the original toolpost on.

Nigel

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I would buy some hss, you often need form tools or just a very sharp tool.

I never really worry what grindstone I use, but I tend to touch up hss on

my valve lathe, which has a very hard fine stone. I always stone edges

with a fine carbonudrum stone . Try and buy small blanks, I have quite a few 3/4 square

bit's and it is a right waste of time and steel carving a tool out of them.

Keep the speeds low with hss, I often switch to a hss tool to chamfer a corner and forget to drop

the speed, eats hss.

Carbide inserts are fantastic. I have always used them, but on my old lathe with 600rpm

they gave a rough finish, when I got a lathe with a 2500 rpm spindle the finish is often like chrome.

Getting enough speed can often be a problem. You will find cuts less then 20thou often

leave pretty poor surface finish[depends on the insert]. I have rarely had the luxury of picking a grade I get whatever

is cheap, I would guess the polished inserts for ali can be used on everything, I use them on en24 and

they work really nicely.

Get small nose radius inserts.

I have a lot of CN tools[that's an 80 degree diamond] I use them for general turning and boring, I

have a holder that uses the 'other' corner for facing so I manage to use all 8 corners of the CN inserts.

I dug around in a quid box at a local place and took all the CN inserts, they mean't a quid an insert

but I managed to pay a quid a box for them. Some of the inserts are really light, they are quite

amazing, they chomp thru hardened steel! They also do strange things like the worpiece stays cool[ish]

but the swarf comes off seriously hot. I do use other shapes but the majority of my tools take CNXX12 inserts.

You can braze old chipped inserts into steel blanks and sharpen as you would a chunk of hss.

It would be well worth your while making a quick change toolpost if you don't have one. I had never used one but

my CVA came with a tripan toolpost. it'a simple enough thing and I wouldn't be without one now.

Somthing I keep meaning to try is a circular saw blade for a parting tool?

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A lot to read through there!

I will start at the top...

I cant seem to find a catalogue or list of products from stellram, what sort of prices are the tool holders?

cromwell looks pretty good but how many toolholders do you need to choose from! I will have another look later but the chances are I will have a look through and have a couple of those. I just need to see which would be ok for general turning

The warco stuff looks good value compared to the above, what makes the difference between them, just quality? are the tips not as good quality? I cant decide whether to just get a set of 5 tipped tools from there or not

I dont mind spending the time setting a tool up and dont change over too often so im not too fussed about a q/c toolpost yet

Integerspin, what are cn tools? I need to turn an internal circlip groove, am i best shaping an old boring bar to do this?

Do you mean cut a strip out of a circular saw blade so it goes in a tool holder? I like the sound of that!

My lathe has a max speed of 1200rpm, and when using carbide tipped tools i have been using 500rpm, do you think with carbide tips i should be running a nearer 1200rpm for finishing then? What sort of speed would you use for general roughing with carbie tips?

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Volumes have been written about speeds and feeds - but in general I think most people find their own way that suits their machine.

In general, carbide needs to work - high speed and/or deep cuts and/or high feed rates. HSS needs to be treated more gently.

If you cut in one direction then wind the tool back, it will usually take off more material. Cutting in one direction is effectively cutting a very fine screw thread. reversing the direction is cutting across the threads.

You generally get the best finish by retracting the tool a bit before winding back. It also means that you are only cutting on the face of the tool that is intended to cut. Not all are intended to be reversed.

The other issue if you reverse the feed is that whatever flex there is in the tool, toolholder, machine is being reversed and may not move the same amount - leading to a different cut depth in opposite directions.

Si

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The CNXX inserts are 80 degree diamond[shape], the N is negative rake.

The first letter indicates the shape.

S; square

R; round

W; trigon;-)

V; is a pointy diamond, I can probably remember them all but thats enough.

Take a look at the sandvik site they have all the catalogues online.

There are quite a few other makers, I think the sandvik catalog is the best

you will find online. There is someone on this forum that works for Kenemetal.

No idea what holders cost new, try barretts tools. They are up north somewhere and I have had

really good sechonhand tooling at a fair[ish] price.

The spring cut is like simon said. When you made the cut the tool was pushed down/away and when

you moved the tool over the surface, that had been turned, the tool had 'sprung' back to it's original

position so took another light cut. There are a few ways to get round this, either withdraw your tool at the end of the

cut, or make the final cuts light enough to eliminate or nearly eliminate the sping cut. If your using hss it's not a

problem to take thou or less off so you can creep up on the final size and make a light last cut, eliminating the

spring cut. Carbide often leaves a pretty bad finish when you try and whip off that last thou.

If you are newish to this work out surface speeds a few times to get some idea, the speeds quoted for carbide

are very high, they quote a speed that gives max metal removal and a very short life. I just guess at the feed and

speed.

What I was thinking of with a circular saw blade was mounting it on my rear toolpost, which is bassically a big solid

toolpost, I was thinking it would be fixed with a large bolt thru the centre hole into a block in the toolpost with some

way to index it, so you could lock a tooth on the centreline and then turn it to use another tooth when that one was

shagged. I haven't taken a good look at a saw blade so it may not be possible.

Parting tool holders that take narrow hss blades are OK.

I would have thought the cheapness of the toolholders doesn't matter a lot, I have a lot of home made toolholders

which are just milled from whatever is at hand and they work great. As to quality of inserts you would have to ask a pro

that uses lot'sof them, I have never found anything wrong with any but have never had anything but the well know brand names.

If they are not to expensive buy the set you were on about, I woudl go for triangles. But you can't really be without some

HSS.

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