SillyOldDuffer:

Sorry to hear about your setback.

Did you try putting in a new insert to see if the problem lies with the existing? I have no experience of this blade but is there an aluminium-specific insert for it?

That said, it does look as though the blade has yielded under the dig-in. What about the other end of the blade, assuming it is double-ended? I guess they are made this way because the blade pocket does not last indefinitely.

It would probably help to run the tool upside down in forward, the idea being that the chips then fall away from the cut (I don't think you should be aiming for a continuous ribbon, by the way).

Finally, can you mount the tool with minimum overhang in the Z axis?

Edited By ega on 13/12/2017 17:41:00

I run mine upside down in forward no problem plus i cannot under stand why you do it that way the reason for running upside down is to push the main spindle down to reduce pressure on the bearings regard norm

Are you sure that the insert is the correct one for your blade? the lower front edge is not in line with the blade holder, else the slot has been opened up due to poor blade quality. Similarly when (upper photo) the insert does align with the lower edge the top edge does not line up with insert. The extractor tool needs to be able to touch at rear so the upper photo is more correct.

Hi Dave

Just looked at my part of tool (looks identical to yours) and my insert has also been pushed back also. I removed the insert and put it in the reverse end which has never used and it dosn't go in so far and is flush with the end. If the tip is pushed back, because of the angle of the slot the centre height will drop and probably chatter. I have reset the tip height and parted of a piece of 25mm silver steel with no problem but the tip is pushed right back and resting on the bottom of the slot and has a lip like photo of yours. It cut well and so I will continue to use my part of as is.

David

And how many amateur size lathes have they tested with indexable tips to come to that conclusion I wonder?

On this subject I prefer the empirical evidence of my own experience…

Is that bumble bee flying past?

Neil

Well they got that wrong then

The video is of 30mm Aluminium but I use the same tool where appropriate on silver steel, stainless steel, brass and bronze, feeds and speeds are more the key than rear tool posts or extremely expensive QCTPs.

In the video I'm using an RDG Dickson copy with a home made tool holder in a QCTP holder, the sideways overhang is far more than would seem ideal but it simply works on a well set up Myford Super 7

Edited By Nick Hulme on 13/12/2017 22:41:06

You can get uncoated inserts for parting and grooving aluminium, although you have to look for them. I have some Korloy GTN type uncoated inserts (grade H01) that I got from Cutwel (see the last page of this catalog extract).

And the shape of the chipbreaker in these GTN inserts is designed to reduce the width of the swarf to clear the slot so it doesn't bind. It is then intended to coil up and periodically break off / drop out of the groove. Gravity is not required.

The only issue I've had recently was when the work slipped in the chuck and I had a major jam due to the power feed continuing with the work almost stationary. Shattered the insert but my pants retained their integrity on this occasion.

The MGT and KGT type parting / grooving system has a bigger choice of uncoated (and coated) inserts in various widths and profiles. They are available from people like APT Tools, Cutwel etc. Again, the uncoated inserts are "H01" grade in the Korloy system.

Here's a vid of the Korloy system ("Sawman" 3mm width – using the "GTN" type inserts) in my amateur Colchester Bantam. As you say, they seem entirely unsuited to our little machines.

Murray

Edited By Muzzer on 13/12/2017 23:13:38

Kerosene or WD-40, and at 5", a bit slower, by the time your in about an inch then the 450rpm would be ok. How close to the chuck is the cut, you want to be as close as you can. I only have a very limited experience of TC parting tools, enough to know that the one I got for a dollar isn't much use to me, it's 4 mm wide, and I only have 1.5hp, so HSS does all I need.

Ian S C

Should be possible to get uncoated parting tips for Al.

The uncoated carbide end mills work like a dream on aluminium alloys.

Neil

Hi chaps, it might be appropriate to point out that all coated grades of throw away tips have a radius over the edges, otherwise when the coatings were applied a sharp edge would push through, to see the difference one only has to fondle the exaggerated angles & ground all round with razor sharp edges displayed by tips for fine finishing on Aluminium, no coatings there then.

Where parting tools are concerned & I speak here from personal experience, when confronted with a component that calls for a flat parting off face after parting through hexagonal EN24T, to obtain an uncoated tip we would merely get a used tip out of our private collection, put it in a holder made from a short piece of part off blade attached to a small block of metal then show it to a diamond wheel, both sides, front & a tichy little chamfer on both corners no more than say 0.015", the work of one minute, problem solved. We used this technique for many years & sad as it may seem even kept records of their performance due to the mild form of OCD we suffered from, note that I can't speak for other brands but Mr. Sandviks part off blades would accept 2 adjacent sizes ie 3 & 4mm would fit the same blade, this came in useful if called upon to cut an O- ring groove in a face where a draughtsman had dreamt that it would it would be a suitable embellishment, look that one up in a dictionary as I just did, its description is bang on!

I will now shuffle off & post the last few christmas cards & let you chaps get on with some workshop time.

cheers Bob H