Member postings for old mart

I agree, the tang is purely for extraction purposes.

First, I am assuming that your tool size is 12mm square, from your other thread. You could probably get WNMG 06 inserts for this shank size. They are trigonic, with 6 edges per insert, which is very economical compared to the 2 edges on the CCMT 09 in your other thread.

I have just looked for 12mm tooling for this type of insert, and unfortunately, the smallest size was 16mm square. With a mill, that size could be reduced to 12mm in height.

Edited By old mart on 14/09/2020 13:54:11

Looking for CCMT 09 on the unnamed auction site, there are sets of 12mm square tools all using this size of insert for extremely good prices, which include a box of ten inserts.

Piaggio marketed this type years before anybody else, the bike cranks over like a normal bike with a clever linkage keeping the front wheels parallel, but the inside one goes up, while the outside one goes down. The concept is to attract people who might be wary of holding up a normal two wheeler.

CCMT 09 it is then, you can get the cheap Chinese inserts readily which are pretty good quality now, and also the CCGT09 for aluminium which are good for stainless steel and for fine finishing cuts on steel. Only experiance will tell you what depth of cut and feed rates to use, these inserts have two edges only, unless you get hold of tools which use the obtuse angle for roughing.

Edited By old mart on 13/09/2020 17:47:58

It is certainly single sided, and looks to me to be a CCMT12, the CCGT12 for aluminium would also be useful. The size is the inscribed circle diameter in mm, with this shape, just measure across the flats in mm.

This chart from the Carbide Depot is useful for identifying inserts:

www.carbidedepot.com/formulas-insert-d.htm

Some of the older Haynes manuals used to have a very useful scale of sizes showing the various spanner sizes along it.

What I noticed about your shell mill inserts are the inserts are not a matched set. Sone have 8 indexing notches, and others have 4. WNT and Cetatizit both make the particular insertsfor these shell mills, likely RPHX12 if they are 12mm diameter, RPHX10 if 10mm.

The advantage of mine is that it takes half a box of inserts to fill it, but yours can run balanced with 2, 3, 4 or the full six inserts.

Edited By old mart on 11/09/2020 19:59:23

I just hold boring bars in a milling vise on parallels making sure the line contact is a safe ammount below the top of the jaws. First you need to measure the height of the tip above the bar base to find out whether your toolpost/ toolholders minimum height call for any modification. Then measure the thickness of the bar relative to the clamping height. When the bar has had its height/thickness adjusted, hold it in the toolholder and check whether the clamping depth allows the screws to hold the bar securely. If the bar looks like it is not held securely, then a little milled off the back will allow it to seat deeper.

That 63mm shell mill has exactly the same type of inserts as my Ceratizit, the cutouts on the rear of the inserts are the indexing positions. You have to slacken off all the screws, and then hold each insert in turn while further slackening off the screw until you can turn to the next position. Remember to turn them all the same way. As soon as the insert is re indexed, fully tighten it. When you run out of slack screws, you know you have re indexed and retightened the lot.

I have just noticed that the inserts in your shell mill are not a matched set.

Edited By old mart on 11/09/2020 18:26:04

I usually mill down the shanks of indexable lathe tools with a 50mm Ceratizit shell mill which has 5 inserts of 12mm diameter. They are economical as they index 8 times, but I would only expect to get one index when milling a 20mm turning tool shank to 17.53mm. This is partly my own fault as the inserts are for stainless, and the steel I use it on is harder. It can be cut with a hacksaw, but it's hard work. The cheap APHT type shell mills would do the job with Chinese inserts. I would not recommend using a solid carbide cutter as the average person cannot sharpen them.

It has got noticably more difficult to illustrate something when the link used conflicts with the commercial aspects of the forum, their sponsors and advertisers.

Boring bars are sold by their diameters, but it is most common for a bar with an indexable insert to have flats top and bottom. Having a mill in your workshop has its benifits as oversize boring bars can have their flats increased slightly. I have milled a little off the backs of 20mm bars so they fit better in the limited toolpost depth, (not height).

The 25mm Sandvik bar that I bought recently is round shank and will have 1.5mm taken off the top and bottom, and 2.5mm off the back to fit perfectly in the large four way toolpost which will be attached to the Smart & Brown model A cross slide. The toolpost height will be set to 17.53mm to match the existing one. The big Sandvik won't need any shimming.

The ebay 10mm solid carbide bars seem to be ok, I bought one to try it out. I would recommend a shim above the bar to reduce the screw loading on the brittle shank. I have made several myself, by getting carbide ground rod and silver soldering the end of a similar size steel bar on. I have 3 different 12mm bars and also a 7mm one. I had a pile up and broke the end off the 7mm one at the silver solder joint. I have also made threading and boring bars out of Densimet, which is a tungsten alloy, not carbide. This is not as hard, so milling and threading can be carried out, avoiding a steel end. I recon Densimet is not as brittle as carbide, which makes it better, I have 1/2" and 12mm stock.

Very interesting, I am not a good enough mathematician to have ever thought of it.

That depends whether you are lucky enough to also have a mill and a rotary table with a tailstock.

What I fail to see is how the average lathe owner would ever be able to make substancial modifications to his machine without first having the use of a much bigger one to make the parts. An interesting project for anyone simply wishing to tinker with machines, but I have yet to see any of the OP's projects actually being used for their original purpose.

I was refering to the tip height relative to the bar height. There is an example of a Glanz 12 mm bar from Chronos with the tip height about 6mm from the base. Ebay 333281987078. The 25 mm Sandvik bar I have has the tip height at about 12mm. I have shims to fit under all my 20mm bars, wheras all the 20mm turning tools are reduced to 17.53mm to use without shims.

For an 18mm deep bore, it would be best to have only 20mm of the bar projecting and set the saddle stop to prevent the toolpost from hitting the work. As the nornal indexable boring bar has the tip height much lower than turning tools, a 16mm bar would be a better choice. The gibs on the saddle if adjustable and the gibs on the cross slide and compound should be checked. If you can change the insert for another grade, it's worth a try.

I am currently modifying a 25mm boring bar to fit in a larger toolpost which will be attached directly to the cross slide of the Smart & Brown model A which will greatly stiffen up the boring of holes bigger than 40mm. Even at 25mm diameter, the Sandvik bar is marked at 100mm for maximum depth.

Edited By old mart on 06/09/2020 15:59:27

Welcome, Reggie, I have looked at the Randa lathes on the "lathes" website, not all of them have backgear, although if yours has parts missing, at least the large gear next to the chuck would be present, as it is harder to remove. Finding detailed specs on an old machine like this could be very hard.

Edited By old mart on 04/09/2020 18:17:24

Most of the VFD's used for small motors from domestic mains also output 240V three phase. I set the connections in the motor i bought to delta to suit that. If the motor had been left in star, it might have run, but at reduced output, as star usually used 415V.