Face Milling Experiment

[JasonBModerator @jasonb]

You can always e-mail it to me and I'll get it up onto Youtube.

[JellyParticipant @jelly]

I'm just sorting out a box of suitable size and sturdiness to send it over to Andrew…

Will be most interested to see the results.

[JellyParticipant @jelly]

The eagle has flown, (or being that it's from northern Sweden and extremely heavy, should that be "The walrus has left the beach&quot.

Taken just before I packed it up to go…

[JasonBModerator @jasonb]

Andrew kindly took another pass with the 80mm head and took a video which I have put onto YouTube for him. Quite a difference to the SX2.7 mill's rate of metal removal when a powerful and solid machine is driving the cutter. Some nice warm chips judging by the slight blue tone. More details in the video description.

Edited By JasonB on 08/12/2022 19:14:22

[Anonymous]

Posted by JasonB on 08/12/2022 19:13:44:

…nice warm chips judging by the slight blue tone.

The chips range from royal blue to a rather pretty gold colour:

Andrew

[SillyOldDufferModerator @sillyoldduffer]

Anyone up for making a video of the same cutter being spun by a Myford Super 7 into a slab of metal held in a milling slide?

I confidently predict the lathe and slide aren't powerful or rigid enough to work the cutter effectively! I'm sure the set-up could be made to work, but only with such light cuts as to be not worth the bother. A smaller cutter would do a better job and they're cheaper.

A small cutter suitable to milling on a lathe would also work OK on Andrew's monster Adcock, but using it slows metal removal down because the machine has to take more passes. Selecting the optimum tool is a balancing act. It matters most in production because time is money and competition cut-throat. Man in shed has far more leeway, and hobbies are all about pleasurably wasting time and money!

Dave

Edited By SillyOldDuffer on 09/12/2022 10:25:48

[Anonymous]

Posted by SillyOldDuffer on 09/12/2022 10:25:20:

…small cutter suitable to milling on a lathe would also work OK on Andrew's monster Adcock…

…hobbies are all about pleasurably wasting time and money!

Small cutters don't work well on my horizontal. Highest spindle speed is 1200rpm. On the Bridgeport I will be running a 10mm carbide endmill in steel at 2200rpm and for cutters less than 6mm on the CNC mill between 3000 and 24000rpm. I rarely use endmills or slotdrills on the horizontal, but when I do they are around 1" diameter. The horizontal mill was designed tor use with relatively large diameter HSS cutters, which dictates the available spindle speeds and feedrates.

Building engines maybe a hobby, but for me it is all about making parts as efficiently as I can. I hate wasting time and/or money.

Andrew

[JasonBModerator @jasonb]

I would think a Myford could handle similar cuts to what I showed in the other thread with the 80mm facemill and APTK inserts. as it is belt driven all the motors power will be available so plenty more than the SX2.7 and although I only have a Myford Vertical slide and not the actual lathe I would say the setup would be as rigid as the benchtop mill. Again same would apply with it still being the fastest option compared to a flycutter or milling cutter.

Myfords are certainly capable of turning 80mm dia work so why would they not have the power for an 80mm cutter ? The metal and inserts don't know which is stationary and which is moving.

The main problem is likely to be lack of cross slide travel

 

Edited By JasonB on 09/12/2022 13:02:10

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Andrew Johnston on 09/12/2022 09:41:35:

Posted by JasonB on 08/12/2022 19:13:44:

…nice warm chips judging by the slight blue tone.

The chips range from royal blue to a rather pretty gold colour:

.

All working in perfect harmony

… Thanks to all involved, for the demonstration

MichaelG.

[BazParticipant @baz89810]

Worked for quite a few years in an aerospace Toolroom, we had a vacancy for a miller and after all the interviews were over the job was given to a bloke from the machine shop. Foreman gave him a job to do on his first day but after about an hour the foreman went over to him and had a word in his ear, “we are the Toolroom,you don’t make coloured swarf in here”.

[Anonymous]

I have finally got around to testing out the 160mm diameter face mill kindly lent to me by Jelly:

Material is hot rolled steel. I dropped the spindle speed to 210rpm, about 105m/min surface speed. Width of cut was 150mm. I initially kept the feedrate at 430mm/min for a chip load (10 inserts) of about 0.2mm. However, I got some chatter. This may be because the cutter body is held to the spindle only with 4 1/2" BSW SHCS into the face of the spindle. So, despite my efforts, it is running noticably eccentric with consequent variation in chip load. I am also not sure that the inserts are consistently located in the pockets. I dropped the feedrate to 285mm/min for a chip load of about 0.13mm/min and that cured the chatter. Chip width measures 0.15mm, which is about right, as chips tend to be slightly thicker than the feedrate would suggest.

I have sent JasonB two videos which I hope will be posted in due course. The first run was with a depth of cut of 2mm. Changing units that is about 5.38 cubic inches per minute. The mill had no problem with this. I then increased the DOC to 2.5mm (6.72 cubic inches per minute) and stalled the cutter. I think that the squeal towards the end of the video is the motor belts slipping. I did some tidy up passes and have run the mill in a range of speeds and it all seems fine. I'd be pretty niggled if it wasn't. The stall was quite gentle and an industrial machine should be designed to survive that without damage.

When I stalled the cutter it chipped one insert so the next task is to order another batch of inserts from Ebay.

Andrew

Edited By JasonB on 08/01/2023 20:10:46

[Michael GilliganParticipant @michaelgilligan61133]

Wow !!

MichaelG.

[SillyOldDufferModerator @sillyoldduffer]

Nice! Andrew removed more metal in his video than I have this year. Admittedly a small job, but it took longer to set up in the lathe and mill than it did to turn, mill and drill, about 40 minutes total. I doubt I removed more than 3/4 of a cubic inch of metal, including sawing the blanks.

Must get into the workshop more often…

Dave

–

[Neil LickfoldParticipant @neillickfold44316]

When you get to that size cutter, they take alot more power to run. Not sure on the insert geometry, but the positive inserts do use less energy , but are also alot more fragile. We used to have a big heavy Cincinnati Mill for roughing die plates for bolsters, back in the days when standard bolsters were not available. The 20 hp or so for the head was enough to run the cutter to a depth of 5mm, 0.2 inches at full cutter width. 180mm mm diameter Sandvik cutter head. 180 to 210 rpm but forgotten the exact feedrate but thought we were running around 18 to 20 inches per min. If I blew air onto the cutter, got a lot more life out of the inserts, compared to the water making a big splashing mess. Be were mostly cutting Pre Hardened P20 at 28-32 Rc steel. I remember cutting a very large cast iron piece, and were taking max depth of cut the body could take, which was 10mm or 0.4 inches. Clamping the job securely enough was the biggest problem with most pieces . We had new then clamps that held by the sides and pulled the piece down to the table. Great as there was top clamps to clear or reset again etc.

[JellyParticipant @jelly]

That was a substantial amount of metal moved right there.

The cutter looks very at home on your A&S Model 2 mill too, despite being designed for machines with slightly more horsepower (which is not something yours lacks!)..

Posted by Andrew Johnston on 08/01/2023 19:57:39:

This may be because the cutter body is held to the spindle only with 4 1/2" BSW SHCS into the face of the spindle. So, despite my efforts, it is running noticably eccentric with consequent variation in chip load. I am also not sure that the inserts are consistently located in the pockets.

I realise now you've said that, that I had the exact same issue with eccentricity when I last ran this and had the thought "I should make up an arbour as a locating feature if nothing else" but then forgot by the time I came to lend it to you… Sorry Andrew!

As far as the insert location, I did give the pockets a good clean when I got it and they're all in pretty good shape, so If you were pushing them home as you tightened the wedges I would expect they were consistently located, the way those Dolfamex cutter bodies are made everything should always line up properly when assembled.

Posted by Andrew Johnston on 08/01/2023 19:57:39:

The first run was with a depth of cut of 2mm. Changing units that is about 5.38 cubic inches per minute. The mill had no problem with this. I then increased the DOC to 2.5mm (6.72 cubic inches per minute) and stalled the cutter.

That does tie up nicely with the rule of thumb that in mild steel / annealed carbon steels generally you can take about one cubic inch per horsepower.

It really did seem like it was struggling before it stalled on the second pass, you could see the cutter slowing slightly more on the "deep" side where the eccentricity of the mounting was pushing the cutting edge slightly further towards the workpiece.

[JellyParticipant @jelly]

Posted by Neil Lickfold on 08/01/2023 20:47:33:

Not sure on the insert geometry, but the positive inserts do use less energy , but are also alot more fragile.

That head takes SPAN or LPKN inserts for roughing, and SPKR inserts for finishing, and there's no back-rake to the seats, the vertical axis is dead in-line with the spindle axis.

I've only ever set it up with the the SPAN type as they're more available and inexpensive, which is what Andrew is running there.

Not really sure if the chip-breaker setup on an SPKR is sufficiently positive to make a meaningful difference to horsepower as compared to the Neutral inserts, but it might be worth a go if I can find some at a reasonable price.

[Anonymous]

Posted by Jelly on 08/01/2023 23:43:47:

It really did seem like it was struggling before it stalled on the second pass…

I wasn't at all surprised that the mill stalled. The motor was struggling more and more as the width of cut was increasing, as can be heard. It's a plus in a sense, as I now know where the limit is. So I can run the machine hard but without overdoing it.

Andrew

[DiogenesIIParticipant @diogenesii]

Thanks all for taking the trouble; it's always informative to see what you don't have the resources to experiment with yourself.

[Author]

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