Member postings for richardandtracy

Nick,

What bits of a lathe will it not support? As far as I can see, the following:

1. Threading
2. Lathe specific canned cycles in the G7x range.
3. Spindle encoding - used for threading.

Is there more I have missed? The majority of a lathe's work can be simulated by 2 axis movement, which is well within the scope of a milling controller. There will be milling specific canned cycles that I'd have to avoid, but with thought it's not hard to imagine most lathe functions simulated as 2 axis mill functions. It should be relatively simple to work through a G1 command linking the spindle rotation axis (which I'll call 'A' and the lathe bed axis (usually called 'Z' with a command like 'G0 Z-20 A7200' to create 20mm of 1mm pitch thread - obviously having to repeat several times to get the correct depth of cut.

I have never used a CNC lathe, and am not totally sure of the full operation of one, or which codes are most useful, but I have studied the list G an M codes for each, and made a basic assessment of the possible viability of the idea.

I am looking for specific cases that I may need or have not considered. Sweeping statements and no specifics will not persuade me one way or the other.

John,

That was the sort of thing I was thinking of. Apart from being slightly crippled in its use, have I forgotten something obvious? I well know the thing hiding in plain sight is the bit you don't see..

Regards

Richard.

Edited By richardandtracy on 12/05/2018 23:10:15

I am in the process of building a CNC lathe to make pens with. I want to be able to engrave the outside of the pen as well as make all the usual 2 axis lathe stuff.

Now, my workshop is unheated and is a killer forPC's, so I want to avoid the usual Mach3 route and use a standalone controller. WinXP PC's are getting less & less reliable as time passes and becoming less available to act as replacements, and I hate the faff of setting up a new PC every 6 months. There are quite a few milling controllers on the market, some of which are both cheap and capable. The problem is that 3 axis lathe controllers seem to be like hens teeth, a bit rare and disappear when you start looking harder for them.

A gent suggested I used a 4 axis milling controller instead. Used the x & y axes for the 2d bit of the lathe work, then remove the main drive belt and hook in a stepper motor onto the spindle for the thread cutting and engraving and then use X,Y and A. It sounds like it could work.

Has anyone tried a system like this? And can anyone see any drawbacks that I may have missed? I can write programs to generate code that would make up for the lack of a G76 thread cutting canned cycle, if that's the only drawback.

Regards

Richard.

If it is really cast iron, as opposed to cast steel, then the strength will be very much less than expected.

At the turn of the 1800's to 1900's, the max tensile strength for cast iron was considered to be 2000 psi, and anything stronger was cast steel. In modern units, this is 13.8 N/mm^2. So, the shear strength is 65% of that at 9 N/mm^2. This goes a long way to explain why Victorian machinery was so huge for its output.

Regards

Richard.

In conclusion, then, it's highly probable that, if other causes have been eliminated and the finish from these Bang good style cutters is still inadequate, then different inserts should be investigated before condemning the cutter as rubbish. That is good to hear, but doesn't help those who've found the taper on the mandrel to be wrong.

What has surprised me,though, is their sensitivity to insert geometry. It is much more sensitive than lathe tools seem to be.

Regards

Richard.

I have to confess I have no idea what inserts came with my cutter apart from the fact they were AMPT1604's. The insert box does not give any further indication (pot luck I got good ones, I think - it is typical of many of the Chinese inserts). Getting the right designation means it's possible to get the right ones again in the future - though not necessarily direct from China.

Regards,

Richard.

Maybe you have it, HasBean. The steel -M2 side looks not too sad at all.

Regards

Richard.

I doubt if Delrin would be great. It's soft with a lowish melting point, so will wear fast and may melt. I always remember a time when my dad melted his bicycle brake blocks on a long hill - the old fashioned rubber on rim type - so am always wary of low melting point brakes.

Many early locos used timber as the pad. Could a little bit of beech do you? Does the kitchen chopping board need changing - the boss may be pleased with a new one.

Regards

Richard.

Ah-ha. The web Chronos website has spawned a Glanze site since I bought the holder, knowing TPAN as an acronym means I can now find the inserts. Thanks Jason.

Maybe that's the difference, the inserts I got from cskwin2015 do actually feel quite sharp on their edges. Not quite as sharp as the little ccmt06 lathe tool inserts, but not far off.

Regards

Richard.

Jason,

Can I ask where you get tips for the cutter in the last photo? I have a 32mm end mill with similar tips but one fell out after the screw loosened a bit under the initial vibration on starting a cut and is now lurking somewhere in the workshop. I have been unable to source a replacement - possibly because I have no idea of their acronym - how could one find a CCMT06 without putting the name in?

But.. Surely those tips are horrendously blunt compared to the AMPD1604's where the edge is shaped and thinned to present a chisel edge rather than a scraper.

Regards

Richard

Takes us about 5 years to get through a bottle of sherry. No worries with it. The one that goes off (solid) is Baileys Irish Cream. Given up on it as we don't drink it fast enough. Even a bottle of wine lasts 3 weeks at home. The last glass is usually a bit sour.

Regards

Richard.

I have a similar cutter bought from cskwin2015 on e-bay, and was using it this afternoon without problems. I do not have power feed available, and was using it at 1600 rpm, and approx 50 mm/min, maybe a little faster, one turn of the feed handle every 2-3 secs and 2.5mm per turn. Why such high rpm? Well I had the belts set up for a 6mm cutter and figured the tips could be worked very hard on a CNC machine, so could stand high heats, which meant fast speed if the feeds were low. And I was too lazy to change the belts. The chips came off blue.

I think Jason has it right in suggesting you check for concentricity in the machine. Also, put it cutters down on a flat surface and see if it rocks between 2 cutting tips, that would be a good indicator if one insert was too low and doing all the cutting. Check if the insert is over size, change if it is, but if not, consider complaining to banggood or remedial work with a Dremmel on the tool holder. Shouldn't be needed, but could save the day.

Regards

Richard.

What is the toolholder design?

Is it one with a common insert holder and an interchangeable taper? If yes, investigate the tightness and fit of the joint between the two bits.

Regards

Richard.

I will be the first to admit I've not had a lot of experience milling, but I have used Weldon, Clarkson, MT and ER 32 collets. I now use ER32 almost exclusively. I had tool edge out in MT tapers - I wasn't really willing or able to tighten it enough. Weldon worked well, but the expense to cover each and every size I was likely to use was excessive. I already have ER 32 collets to hold pen making materials from 6-20 mm, so the choice was a no-brainer. The results I get are acceptable commercial quality, meeting Ra1.6 standards without trouble. This with mills bought direct from China, in a collet holder also bought direct from China, using collets bought one at a time from Axminster. All using the milling head of a Warco WMT300, a Clarke CL500 clone. According to some of the more opinionated authorities here, everything about the equipment I use should make the achievement impossible. As it isn't, I'd suggest you don't get too hung up about perfection and think more about what is acceptable to you in your situation.

At work, until he retired in March, our machinist used ER50 collets on the works mill and never had a mill edge out. If he had, the whole factory would have known. He was not one to hide his feelings.

Regards

Richard.

With me, I ordered from Chester tools on Tuesday, received a despatch e-mail Wednesday, only to find it had arrived half an hour before the e-mail when I got home from work. Quite amazed at the time machine technology available these days.

Regards

Richard.

Absolutely agree on this. If you start with the -S10 there's less to turn down and the holder's cheaper than the S12 too. Think I got my -S10 for under £4 last year, but without inserts (of which I already had enough) from cskwin2015 on E-Bay.

Regards,

Richard.

That looks amazing.

I am always astonished when someone uses one of my programs. I am further astonished when the results look quite as they do. I am amazed at the results. You have done a remarkable job.

Regards

Richard.

Edited By richardandtracy on 30/04/2018 21:45:57

Unless the thread is fit & forget, always helicoil aluminium. In for a world of grief otherwise.

Regards

Richard.

Always amuses me when I see the BA series described as non metric. The whole definition is metric - not one bit of imperial in it. It's just not an 'M' series thread.

The pitch of BA thread n in mm is P = 0.9^n rounded to 2dp. The major diameter is 6 * P^1.2. The head size is 1.75 x major diameter. ( **LINK** .).  .

Regards,

Richard.

Edited to get rid of spurious emoticon

Edited By richardandtracy on 27/04/2018 11:24:52

If you are really concerned about ham-fisted machining shattering the spokes, heat up & flow soft solder into the recesses between the spokes, machine the spokes free and then melt out the soft solder.

The chances are that if you have a really sharp tool and take tiny cuts, you'll get to the point where you have foil between the spokes and it will deflect out of the way. At that point a penknife blade will act as a deburrer to cut the last bits away.

Regards,

Richard.

Used excel & the brute ignorance & force method.

Regards,

Richard