[russellthackray]

I have a right angle (already milled) 200 x 200 with a 7 mm rad in the corner on 27mm thick plate i need to put a 16mm chamfer around it problem is to get a tool big enough to do it i cant achive the 7mm rad is there a way i can do this with a small cham mill and blend the cuts ? simple job just got me stuck, any help would be great,thanks
ps any advice on programming chamfer on siemens would be great help , all the jobs im doin lately seem to have a chamfer of some sort and i havnt really found a consistant easy way of doing it yet ,thanks

[christinandavid]

As standard practice I find it easiest to set the radius at the nose of the chamfer tool as my cutter compensation - I use insert tools that are 32mm or 20mm diameter at the nose, so I use 16 or 10 as my cutter comp, regardless of the major diameter size. A cutter ground to a point would therefore have a cutter comp of zero, regardless of the cutter's major diameter, O/D or shank size.

So, to achieve a size chamfer it is then simply a case of running the same contour you used to cut the profile out, using cutter comp, and adjusting the Z-depth until correct chamfer is achieved.

I am not being patronising here. I have seen people setting up chamfer tools in many different ways, and you end up with either an illogical cutter-comp value, an illogical contour, no cutter-comp at all, or a combination of the lot. If you then need to use different cutters, or, in your case, cut the chamfer in more than one pass, it turns into a nightmare.

Now then, programming what you are after would be tricky - I know little of Siemens - what I've seen in the manuals is reminiscent of Heidenhain, so failing the control having an actual 'Chamfer' Cycle, you will need to define your radius offset and Z-depth on each pass to achieve your goal, correct? If I needed to do this on a Fanuc I would alter the tool length and radius wear offsets (it can be done within the program). On Heidenhain I would use DL and DR (an 'extra' offset than can be defined in the tool table AND the program). Maybe your control has something similar?

Failing that you could even define an individual 'tool' for each pass, but with a pointy chamfer tool chunking out a 16mm chamfer this would be just asking for trouble....this approach would only be feasible if you actually have a large tool to do the top of the chamfer, and follow it up with the dinky one.

Another way would be to use 2 variables, redefining their values for each pass and somehow using them in your contour routine. Your contour would comprise of a Z-move to the work surface position (minus the value of variable 1). X(or Y)-move with cutter-comp onto the contour-edge(plus the value of variable 2), linear move to the Y(or X) intersecting edge(plus the value of variable 2) with a corner rounding function of 7mm(plus(the value of variable 2 minus variable 1)) and a final linear move clear of the job.

I apologise for having no idea of the correct syntax/format you need for your control. Hopefully my post will clear things up for you regarding a consistent strategy, and maybe trigger a post from someone who knows the control's capabilities.

DP

[russellthackray]

Thanks for that, at the end of all that this morning when I got to work our customer said to leave the chamfer and that they were going to do it after assembly!

As a rule I use the dropping z depth method like you first said.

I'm a self taught miller and have worked for the same company since leaving school and sometimes it's helpful and interesting to hear how others do things, thank you for your help.

[christinandavid]

My current job is only my second - and coming half way around the world and doing work that is at the opposite end of the spectrum in every respect is a bloody eye opener, believe me....

DP

[russellthackray]

We are so busy if you ever fancy working in sunny England get in touch!

[christinandavid]

Ooh, don't tempt me...it's absolutely bucketing down at my end at the mo.

'Course, if you fancy covering my petrol and lunch money I would be more than happy to nip over for an interview...


I would have thought there would be no shortage of labour over there at the moment? How did your place do during the downturn?

DP

[russellthackray]

Even though there are tonnes of people out of work nobody seems very interested in taking up engineering,

At 26, the next youngest person at our place after me is 41 there is that gap where in my opinion half the kids leaving school have gone to uni to study sports science or art or some other waste of time and the other half gone off to try and earn a fortune being a plumber!,

Its a massive problem round our way (east midlands) and from what I can see the whole country.

Our small factory employed 18 men at the height of the good times our numbers went down to 12 men when it was at its worst and now we have 14 men on the shop floor. We have enough work for about another 2 cnc millers, but we cant find anybody.

Anyway how about you and your end of the world?

[christinandavid]

We have enough work for 2 cnc millers...

It must be fate then...that's exactly the amount of work I am usually expected to do! Sign me up!

But seriously, the company I work for is the only large scale machine shop in town, and probably for the next 60 miles in any direction. They have had a hard time finding skilled machinists, and the "jobbing shop" environment is usually enough to put off your basic operator type, so new recruits are mainly apprentices and foreigners like myself...

After a few layoffs in the downturn, we are now in full headless chicken mode trying to keep up with the upturn. I'm lapping up the overtime...

DP

ps What happened to the all the Poles? Thought you'd be fending them off with a big stick by now!

your end of the world?

Hey, it's not that bad! Really!

[johnny cd]

I have a 1020 vmc from xyz machine tools with the 840 d controller on it.Chamfers also messed me around abit to begin with, but now have it sorted out.There is a dedicated chamfer option, if you keep on clicking after you have changed from rough to finish, you get chamfer and you get finish wall.I have a 12mm chamfer tool set up in the tool library as a bevelled end mill with a 45° tip.Tip of said tool is measured length wise as normal and i have it set up as having a 12 diameter.You can do most small chamfers with this, the only thing that messes you around is the safety distance, something no one has really been able to give me a reasonable answer to.You need to drop it down to next to nothing otherwise it tells you allsorts of stories about tool being too small, or insertion depth too big.

With large chamfers, its easier to use finish wall and tell it that its a 2mm diameter straight cutter, when in actual fact it is a 12mm chamfer tool.Use contour mill, draw your contour as being two 205mm perpendicular lines connected with a 7mm radius.In stock removal(finish wall) connected to this contour use a depth of say z-1.Now use the yellow input button to insert a line of g code into the program.Type in g90.Go into transformations and go into offset.Offset z by -1 and x and y also by one.Depending on how you have drawn it, you will have to see if the x and y values need to be offset +ve or -ve. Set mark 1 before the contour and mark 2 before the end of progam line.Now go back into transformations and use program repeat with say 3 repetitions and repeat between mark one and mark two.Use the yellow input button again to input a line of g code just before the end of program line, and type in g91.That should get you a large chamfer, cut in 4 passes.

Bit of trail and error, but you can work out how many repititions you need for the desired size of chamfer.You can work it out with trig also..Hope this is of some use to you

Johnny

[maximusek]

DP

ps What happened to the all the Poles? Thought you'd be fending them off with a big stick by now!

do you have something against Poles???

[christinandavid]

Well, regarding Poles, there are indeed some positives and negatives....

Me being an Angle, I can sometimes be very acute, but as you may have noticed I am usually quite obtuse....

DP

[maximusek]

Well, regarding Poles, there are indeed some positives and negatives....

Me being an Angle, I can sometimes be very acute, but as you may have noticed I am usually quite obtuse....

DP

Well, regarding Brits, a lot of them say Pole is always drunk because they have seen one idiot from Poland sleeping on the sidewalk but... they don't see their country men (groups of 20-30 people) throwing up in the middle of 1000 years old city Krakow in Poland... maybe next time you and your friend would pay more attention to cnc subject instead of suggesting crap about other nationalities on the public forum... welcome to Euroland

[christinandavid]

... suggesting crap about other nationalities on the public forum... welcome to Euroland

What exactly have I suggested (I take it my last comment was too dry...)?

Just stating to russell that the last I knew there were plenty of people migrating to Britain from the Eastern Bloc to fulfill a labour shortage and try to attain something better for themselves in the process. There should be plenty of applicants.

I have nothing against this practice or the people involved in it, wherever they hail from. Having tried it myself I now know exactly how difficult it is.

DP


ps I'm also not over here because I fear a European superstate...I was just getting tired of my hometown (also over a thousand years old) being sprayed in the projectile vomit that you mention...you got me there!:drowning:

[toy4mud]

Try using the tool type "face mill." If you have an accurate od measurement of the tool, and the chamfer size, it cuts correctly and shows in simulation correctly.