1.2 mm Insert tip radius

I use CCMT/GT inserts which I believe (could be wrong) only come in .04 and .08 tip radius. I have a job where a 1.2mm radius would be ideal but are inserts available at that size, I appreciate if they are available it would probably be another type of insert which would need a holder to suit. I have been searching but havnt found anything unless I,m looking in the wrong places.

Ron

Hi Ron

I've not seen inserts with 1.2mm radius and always prefer an 04 or even 02 radius so when turning to a shoulder there is not too much cutting length that may cause chatter.
Good luck with your search.

Emgee

They do come in 1.2mm radius, but a bigger size than is common in the ME world:

CCMT 1.2 radius

Andrew

If I want a bit bigger to form fillets on "cast" parts I use these quite often which give a 1mm radius, any bigger than that then I have a couple of the brazed carbide inserts and then its upto HSS or a RCGT with 6mm dia insert

J

PS CCMT & CCGT 06 size also come with 0.2mm radius

Thanks guys for the links.

Jason the APT inserts are new to me not seen those before, there is some interesting tooling there. I see they do a 3mm (1.5 rad) which would suit the job better than the 1.0 mm going up on the 1.2 mm size rather than down.. Would you happen to know the holder for the MRMN inserts, I see holders for the MGMN inserts listed but not the MRMN or are they the same holder for both. A pity min qty is 10 off but so be it they will last me a lifetime.

Thanks Ron.

p.s. Me been a bit slow Jason I think they are the same holder, G = Groove  R = Radius. 

Edited By Ron Laden on 13/02/2022 07:43:40

Yes same holder for both. A bit of web searching may find the inserts cheaper

Well the MRMN 1.5mm radius inserts and holder arrived, unfortunately the inserts dont fit the 8 x 10mm holder I ordered. Apparently the holder I have only takes inserts up to 1.0mm rad, for the 1.5mm inserts the smallest holder has a 16 x 16mm shank which is too large for my lathe. So I could get the larger holder and reduce the shank to 10 x 10mm or try to modify the small holder which would need the insert seat increasing in width by 1.5mm or drop down to the 1.0mm radius inserts though I would prefer to go with the 1.5mm.

Decisions, decisions.

Ron, I have cut down the holders, and I cut from the underside. On some of mine, I extended the cut to the under body bulk of the tool by about 6 to 8 mm or so. I did this to reduce the overall over hang of the tooling. As I have a Dickson toolpost, the closest it can get to the long work piece is the clamp plate of the boring bar tool block. Yeah some holders are tougher going than others. What really did annoy me, was to find that there are industrial tool holders for small machines that are all in 12mm shank holders for most of the insert tooling, including TNMG16040XX inserts and for holders like you may be looking for. Mitsubishi Carbide, may well have a holder for your insert. I just checked , and they don't do that insert type in the 10-12mm holders. 16mm is the smallest for the MRMN inserts I could find. Some do a cast iron grade insert in the narrow 2mm insert. It is basically flat or inclined with no pressed geometry. These can and are used to make Special radius inserts, and can be shaped with a diamond file, or diamond mounted points with a rotary tool, or on a suitable grinder for grinding carbide. So you could create your 1.2 or 1.5mm radius. Just hold the insert forward a little , then you do not need to modify the tool holder in any way.

I can recomment APT they are very good and fast. For home shop people they have a common range of inserts available singly, so you can buy an assortment to test out rather than a box of 10 which might be unsuitable. They also sell carbide threading inserts singly if you only have one job for them.

Thanks Neil and Mart,

The holder and inserts I got from APT unless I missed something the MRMN 1.5 rad inserts came as a minimum 10 off. I must admit I was a bit surprised that the smallest holder shank size is 16mm for these inserts I just assumed that the 8 x 10 shanked holder would be correct. To be fair APT were very good on seeing my order they emailed to point out that the holder wouldnt fit the inserts but it went into my junk mail and I missed it.

I am going to try and modify the holder which will need the bottom seat lowering by 1.5mm using a carbide cutter I,m thinking it should cut ok. The seat is V shaped so after removing the 1.5mm, angle cuts each side should re-produce the V, well thats the thinking.

A lot will depend on the individual holder, some I have milled down without too much trouble other s have taken the corner straight off a set of inserts.

You could always rig something up to clamp the tool holder straight to the top of the compound slide and do away with the toolpost, have a look at some of the photos of myfords to see the clamp arrangement.

Thanks Jason, I will see how it goes modifying the holder if it doesnt work out I will get the 16mm holder and work out a method of clamping it to the compound, thanks for that I hadnt thought of it.

The lathe at the museum has a tool height of 17.53mm and I buy 20mm tooling and just mill the 2.47mm off the bottom of the tool. No shims are required, so using 2 and 4 way toolposts is easy. I would steer clear of modifying the insert seat.

Mart, I have considered getting the 16mm holder and reducing the height but with the holder I have only needing the bottom seat lowering by 1.5mm I think it worth giving it a try. Providing it cuts ok it shouldnt be too difficult to do.

Ron

Well the holder was easy to modify and impressed with the insert whilst cutting the 3 degree tyre angle on a test piece.