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View Full Version : How to f**k up a bridgeport



aboard_epsilon
12-21-2008, 09:26 PM
This guy has no idea

enjoy

http://uk.youtube.com/watch?v=wMaq2QaYUEE

http://uk.youtube.com/watch?v=geTJsmNhtkE

All the best.markj

torker
12-21-2008, 09:59 PM
Oh...must be time to start a new mill/drill thread :D I do that...

Carld
12-21-2008, 10:03 PM
both video's failed to finish. They were so dark I couldn't tell what he was really doing. In the first it looks like he is using a multi insert head and we ran them at 1000 to 2000 rpm with a .050" to .100" DOC all the time so what is unusual about what he is doing?

In the second video it looks like he is making a cut with a flycutter and says it's .100" DOC. I normally run my flycutter at 1000 to 1500 rpm with a DOC of .050" with no problem.

When I worked for a hydralic shrinker/expander co. they used flycutters exclusively and we always ran them as I described. The cutter has to be carbide with a leading edge angle of about 45 deg and it will cut steel like butter.

aboard_epsilon
12-21-2008, 10:22 PM
in the first video ......he's cutting with blunt inserts ...you can hear the motor straining, he even turns the sound down to disguise it, its straining its balls off, all he's doing is burnishing ..no cutting taking place ....using it like an angle grinder.....way too fast as well.

in the second again you can hear the motor straining .......i posted the wrong one there ...there is another vid where he cuts less and you can really hear the motor ..about to burn out ..if he was to do that for a few more Min's it would burn out.

for a another giggle have a look at his lathe vids...

i think he's just taking the piss .and is trying to destroy that bridgeport ...some other vids he's made are ok.

oldtiffie
12-22-2008, 05:32 AM
Nope.

I think that is may well be Kosher.

If the chips are blue or hotter you will or may not see them glowing in the lighting used on a mill most times, but it is quite possible that you will see the occasional "glow-worm" in the dark - just as it the posts here show it. Perhaps if he pushed harder you might see them in normal lighting.

That being the case it may well be a good example of a BP trying to emulate an average Chinese mill-drill (possibly "round-column") again.

And failing.

Again.

Now if he were using "Chinese" cutters instead of "made in USA" cutters he just might do better on a BP.

torker
12-22-2008, 09:00 AM
I had to narrow the small ends on some connecting rods for a guy here awile back,
Them things really suprized me how hard they were. The "spark show" off them was pretty spectacular.

gnm109
12-22-2008, 01:30 PM
Oh...must be time to start a new mill/drill thread :D I do that...


I'd like that. Maybe one about round-column machines....heh heh. That should get some nice comments. :)

lazlo
12-22-2008, 01:53 PM
in the first video ......he's cutting with blunt inserts ...you can hear the motor straining, he even turns the sound down to disguise it, its straining its balls off, all he's doing is burnishing ..no cutting taking place

in the second again you can hear the motor straining.

Yeah, he doesn't know what he's doing. In the first video he's running about a 3", 5- or 6-tooth cutter at what looks like 1200-1500 RPM. That's around 1,000 - 1,200 SFPM (!)
You can't see what DOC he's taking, but like Mark says, the machine is straining so badly once it gets in the cut that he turns down the volume :rolleyes:

I'm guessing this is an American tool dealer: "Lee Machine" -- the other videos look like he's trying to sell the machines.
The comments on the second video (with the flycutter taking a .1 DOC at 1,000 RPM or so), are pretty funny:

".100?? WTF! Dude you have no clue what you are doing do you? That depth of cut is so wrong! and the feed was too fast. You are going to trash the quil bearings and god knows what. Sell your sh!t before you f*ck it all up, if you have not already doing dumb sh!t like this."

Carld
12-22-2008, 02:15 PM
lazlo, with a 45 deg angle on the leading edge of the cutter .100" DOC @ 1000 or more on steel works fine. At one company I worked for we did it all the time at .050" and a few times at .100" DOC. They had been doing it that way for years and when I left there three years later the mills still had good bearings. We ran the multi insert heads at about the same rpm but faster feed and the chips came off red or white at times.

We used brazed carbide in the flycutters and they had to be sharp. If they dulled at all they began to hammer. The inserts have to be sharp as well and any sign of loading the motor, hammering or mostly white chips is a sign to rotate the inserts.

As stated by others, he is not using sharp cutters and maybe not even using a BridgePort. The videos are to poor to tell for sure.

derekm
12-22-2008, 02:51 PM
lazlo, with a 45 deg angle on the leading edge of the cutter .100" DOC @ 1000 or more on steel works fine. At one company I worked for we did it all the time at .050" and a few times at .100" DOC. They had been doing it that way for years and when I left there three years later the mills still had good bearings. We ran the multi insert heads at about the same rpm but faster feed and the chips came off red or white at times.

We used brazed carbide in the flycutters and they had to be sharp. If they dulled at all they began to hammer. The inserts have to be sharp as well and any sign of loading the motor, hammering or mostly white chips is a sign to rotate the inserts.

As stated by others, he is not using sharp cutters and maybe not even using a BridgePort. The videos are to poor to tell for sure.

a 1000 rpm on a 100mm cutter is at the upper limit but is not really above it...
you can get 1100 sfm for steel inserts

aboard_epsilon
12-22-2008, 03:54 PM
I feel sure, that whenever people here quote sfm here ...they are the cnc guys ..who operate machines with 15 hp motors , built like a brick outhouse...and flood coolant.............and the info is not relevant to a bridgeport............or smaller machine.

well only relevant if your doing a final facing pass

all the best.markj

lazlo
12-22-2008, 04:58 PM
lazlo, with a 45 deg angle on the leading edge of the cutter .100" DOC @ 1000 or more on steel works fine. At one company I worked for we did it all the time at .050" and a few times at .100" DOC.

Carl, you're a pro machinist, so I'll defer to your experience, but any speed/feed table (http://www.whitney-tool.com/html/calculatorSpeedFeed.html)says that coated carbide inserts on mild steel is 700 - 900 SFPM, so that guy is running at least 50% faster than that. And like Mark says, the speeds and feeds tables assume an infinite power, infinitely rigid machine, and a Bridgeport is neither.

But, like Mark, I was mostly referring to the sound of the machine -- it's definitely not happy.

Peter N
12-22-2008, 05:24 PM
I agree, that guy doesn't have a clue what he is doing, and is giving the machine some serious grief, it sounds 'orrible.

However, I run an 80mm 6-insert facemill in my Bridgeport (I also ran it in my 6x26, but it *really*clattered in that!), and with experimentation I've managed to find a sweet spot where it works very well.

The pictures below are of a block of 2085 (pre-hard) stainless, although it does have a small sulphur content for easier machining, and the swarf it produces when run at a 0.040" DOC.
I run the facemill with SEHW inserts, and it runs at 1100 rpm on the Bridgy, and cuts really sweetly at a DOC anywhere between 0.005" - 0.040". I tried going a bit deeper, but it didn't like it at all.
It doesn't hammer, and gives that lovely swiiisshhhh sound when it's cutting. As soon as that sound changes, you know that the edge is blunt on the insert and it's time to change.
The finish has to be seen to be believed, the photo doesn't do it justice.
I'm probably a little bit conservative on the feed if anything, and TBH I don't have a clue as to how fast I'm feeding it, I just know when it sounds and feels right.

http://www.btinternet.com/~p.neill/Swarf2.jpeg


http://www.btinternet.com/~p.neill/Swarf.jpeg

Peter

oldtiffie
12-22-2008, 08:22 PM
Good post Peter,

and well and truly "on target" in "reality land" response.

Other than counting the RPM of my lead-screw (either with a digital tacho - or more often than not just "counting") and relating it to "numbers" on my auto-feed unit, I have no idea how fast my feed (rate) is.

My machines are not CNC-ed. If they were, I'd adjust my feed-rates "on-screen" until they "felt right" - as before.

"Tables" are OK as a guide, but really, the best results are machine and/or job and/or cutter and/or set-up dependent.

I do exactly what you do. I just "try" it on each job and when it "sounds and feels right" it is just that - right - and optimised. I usually try it "by hand" first and see how it "looks and feels" and set my feed rate to that hand feed rate. Its all very unscientific - but it works!!

If it seems that I am abusing or "thrashing" a machine, cutter or tools/accessories etc. and if I can't "adjust it out", then I stop and "re-think" it all.

I am not and never have been in the business of "bashing and/or thrashing" a machine or tool or accessory at all, let alone for the sake of "making chips" or "hogging" or "flogging" my machines. That applied when I was employed to use other peoples machines etc. and certainly on my own. "Push" the machine? Sure? But sensibly.

As regards multi-indexable TC milling cutters, I'd doubt that they were dead accurate as regards equally sharing cutting loads. I'd be inclined to (re)sharpen them on the T&C grinder as an assembly to optimise life and performance. The only error would be in my mill quill taper and not anywhere on the cutter assembly other than a possible small amount on the T&C grinder spindle bore.

I suspect that anyone who is flogging a hand-wheel while on a machine is busy flogging himself when he is off the machine.

http://en.wikipedia.org/wiki/Wanker

Its surprising (perhaps not) the number of people who seem to be either "in orbit" or having an orgasmic climactic experience when either flogging a machine and/or themselves. In the vernacular, they are "wankers".

What I think those wankers think of themselves:
http://i200.photobucket.com/albums/aa294/oldtiffie/Funnies/Rambo1-1.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Funnies/machine-gun-cat-animation.gif

And what I think of them:
http://i200.photobucket.com/albums/aa294/oldtiffie/Funnies/pumpkin1.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Funnies/Life_in_oldies_after_all.gif

Liger Zero
12-22-2008, 08:28 PM
I'm not an expert. I don't try to be one. All the advice on here is wonderful but you either develop a "feel" for how the machine is cutting or you don't. I got lots of advice on how to machine plastic, good starting point, but what "actually" works is quite a bit different than what my mentor suggested I start at.

gunbuilder
12-22-2008, 11:36 PM
Hi,
It seems if I were to push one of my machines too hard I can about guarantee I will break an endmill or pop the part loose. Neither of which makes me happy nor gets the part done right.

I probably dull more endmills by running them too slow or too shallow a DOC. But I break fewer of them.

Oh well.

Thanks,
Paul

torker
12-22-2008, 11:57 PM
Peter...geez, I like that cutter you have there. Those curly coil chips are lookin good!
Russ

Carld
12-23-2008, 01:19 AM
Peter, the multi insert head we had used a similar insert and at the right speed and feed it does just hum along and it sure does tell you when it's time to change the insert or if your running to fast. We used the flycutter much the same way because we could cut a wider path. Also, the inserts are more expensive than a single cutter in the flycutter. The flycutter will tell you when to sharpen it and you have to experiment for the speed and feed. We had power feed on the mills but I don't at home so I feed slower most the time because I'm not in a hurry much now.

Normally we used a .050" DOC as a max. for the flycutters and I didn't run the multi cutter head much so I don't remember much except it sure cut a nice finish.

I never have used a speed/feed chart. I just start cutting and speed everything up untill I know it's getting to fast and then back off. I guess I just prefer the seat of the pants method.

tattoomike68
12-23-2008, 02:14 AM
This guy has no idea

enjoy

http://uk.youtube.com/watch?v=wMaq2QaYUEE

http://uk.youtube.com/watch?v=geTJsmNhtkE

All the best.markj

both videos stink. I dont see anything.