Thread sizes for little screws on Glanze 10x10 and Myford 12x10??
|Neil Wyatt||01/07/2014 16:08:32|
16277 forum posts
It's interesting to read the Wikipedia page on cutting tools, it explains why carbon-steel and HSS tools are sharp, and why carbide are 'blunt' and the different ways in which they cut.
Which goes a long way to explaining why these 'orses suit different courses.
|384 forum posts|
I've dipped my toes in this murky water before. To my mind Its probably best to buy inserted tooling from a supplier that advertises to the model engineering fatuity, as the grade of carbide and tool shape they supply will be a happy half way house that will preform well in a variety of different applications.
To try and get industrial style inserted tooling to work in a hobby environment is only at best a get out of jail option.
When I worked in industry I use to favor the double side triangular style of tool holder, but had different inserts for just about every material I machined on a regular basis. If the inserts were placed side by side its virtually impossible to see the difference between, but difference there is when machining, a stainless steel insert will preform poorly when cutting cast iron and visa versa, cast iron inserts preform badly when cutting anything but cast iron.
|Adam Harris||01/07/2014 18:25:47|
|391 forum posts|
As the person who started this thread and also the person who likely knows the least on the subject, it is very frustrating to read all these lengthy opinions that obviously come from experts but offer in reality no practical help to anyone! It is common sense that different tips will offer different performances on different metals (however slight or great), and common sense that HSS may work well in many circumstances, but what WOULD be of practical help is if someone could list which tips they personally recommended on model engineering lathes for which type of cuts (roughing out, medium or finishing) for which materials.
|Oompa Lumpa||01/07/2014 21:27:59|
|888 forum posts|
So Adam, there you have it. This is the problem you have and as Ian points out it can put you off for life. I was given a couple of tips to "try" recently and I destroyed them before I had actually made one full pass on the material I was working on!
There is no one single magic answer and the range of tips and styles is just bewildering. Even using the reference guides I get totally confused sometimes. However, this was some advice given to me and it has worked so far: Buy some Glanze holders from Chronos and buy some Sumitomo tips from Arceurotrade. This combination is by far and away the most reliable. So far I have yet to wear out or break (this will happen tomorrow) the first Sumitomo tip I fitted to one of my holders for roughing out of Aluminium. Sure, they may appear expensive, but if you go through half a dozen £3.50 tips and one £6.50 tip in the same time...........
I use the CCMT style tips and would not hesitate to recommend them. I also use HSS tools but for Aluminium and Brass/Bronze I wouldn't use anything other than Indexable. It has worked well for me for a while now. And the lathe I use them on is quite small, not an industrial machine at all.
|Adam Harris||01/07/2014 22:02:28|
|391 forum posts|
Thanks. So Sumitomo TCMT/CCMT tips from Arceurotrade for Aluminium and Brass/Bronze roughing (and finishing?) cuts, and maybe steel, but HSS also good for steel. Would you bother to choose a Sumitomo CCMT specified as "Finishing" for finishing and "Roughing" for roughing or do you use "Finishing " inserts for everything from roughing to finishing?. What about stainless steel and cast iron (roughing inserts and finishing inserts)? For CCMT inserts do you follow the standard material speeds as recommended for HSS bits or do you run the lathe at maximum speeds regardless? Ideally I would like to make myself a simple matrix for 5 materials (Steel, stainless, cast iron, brass/bronze and aluminium), vs recommended index tips for each , vs best material speed for each, vs 3 types of cut (roughing, medium and finishing). Then I would be finished bothering our patient forum members!!
|Bodge it, Bodge it, Leg it & Hide||02/07/2014 07:25:08|
|44 forum posts|
In the last 12 months I have started using CCGT tips , which are generally listed for use with aluminium and brass, and they work incredibly well on those materials. However the also work superbly as a finishing tool on steel. I have been able to make controlled cuts of 0.5 thou using these inserts and the finish is very good.
So I now have 2 right hand knife tools, one set up with a CCMT 06 insert which easily takes 20 thou a side and one set up with a CCGT 06 insert which I switch to when I get within 10 thou of finished dimension.
I should add that I generally do not try to cut more than 5 thou a side with the CCGT insert on steel
|384 forum posts|
Well Adam, the only inserted tools I use on a regular basis on my Myford are a couple of Glaze right and left hand profiling tool holders and a rear mounted parting blade. I have a couple of screw cutting tool holders on a 20mm squ. body, which, when mounted on a couple of 5/16'' strips directly to the compound slide base gives centre height. The rest of the industrial tool holders I have acquired over a working lifetime remain in the tool chest.
|Andrew Johnston||02/07/2014 11:35:25|
4719 forum posts
Well, that's charming innit. Since I haven't done exhaustive tests on all types and makes of insert and different materials, and I don't have what might be termed 'model engineering' lathes I can't help.
Out of interest I've just measured the surface roughness of the inner bore of a bronze (SAE660) bearing I machined a couple of days ago. Finishing cuts were with a CCGT insert, 540rpm, 4 thou per rev and doc 1thou; the result was an Ra of 1.45µm.
15773 forum posts
A lot will depend on what you term a "model engineering lathe" I know someone who ises insert tooling on a little Cowells lathe and they also have a Colchester Master in the shed and several other lathes in between, all used soley for hobby model engineering.
This is what I'm currently using on my Warco WM280, which is a bit bigger than a myford but if you believe what you read about imported lathes not as tightly made!!
Aluminium, Brass & the Bronzes CCGT tips, I'm still on teh Chronos ones I bought about 2 years ago but do have some Sumitomo one for
Steel for most general work I'm using Kennametal CCMT 060202LF inserts which have a small 0.2mm radius tip and as the LF (light Finishing) signifies are good for lighter cuts, I can easily take 0.001" depth of cut off steel with these unless its very long and slender. They will still quite happily take 0.050" cuts as well. I always have these set up in the following quick change holders, R/H, L/H and two boring bars
For roughing out I don't use a specific insert but I do have one of teh holders that allows you to use the two "spare" corners of the CCMT inserts, as these are an obtuse angle they are a bit more durable and it allows you to get your monies worth out of the inserts, one always ready to go in a holder for the QCTP
For chunky iron castings I do have some similar CCMT 060208 again by Kennametal which are a bit more durable due to their 0.8mm tip radius though not much good on my machine for fine work
For parting in all metals I have a Glanze holder and thats still on their standard 2mm GTN tips. Have also recently bought one of the Mini-thin holders which are great for small grooves such as those needed for "E" clips Both in their own QCTP holders plus two other HSS parting tools
I also have a 6mm button type tool again from Glanze with the original bits but don't use it a lot
And for getting into tight spots I have a reversible L/H & R/H holder for the more pointed DCMT tips
Plus a load of HSS and some Brazed carbide only one R/H tool thats permanantly in an extended holder and ready to go, others used as needed
Unfortunately I can't quantify the finish like Andrew as I don't have a surface comparitor but here are a few shots to show what comes straight off teh tool.
And the ringlets of swarf from the 0.050" DOC, notice how they have been thrown away from the finished surface which I believe is a sign that the tip is working correctly
Bit of Ali done with a CCGT
Iron Casting done with 0.4mm radius CCMT
Edited By JasonB on 02/07/2014 13:35:57
|Adam Harris||02/07/2014 13:27:25|
|391 forum posts|
Jason that is really very helpful of you. Many thanks indeed!
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