homemade pneumatic bar feeder

[Ztiggi]

Today i finished my homemade pneumatic bar feeder, it's activated by M-code, M81 for push, and M82 for return,

there is no reason for the special type of cylinder, it was just something i had laying around, but the great thing with it was that the stroke became adjustable.

this is a very cheap solution, and can be built in one day

here is a video:

YouTube - Homemade pneumatic bar feeder

YouTube - Homemade pneumatic bar feeder

i'm using 3seconds dwell time twice here, maybe i could use a little less, but it works

[Delw]

Thats Pretty cool and I am not trying to be an ass,

but get that off the machine Immediatly.

NEVER hook a barfeed directly to the machine especially the accutaor, if you get any vibration you just wiped out your machine not to mention you can kill someone pretty close.

A barfeed MUST Have some sort of Stand, and be completely separated from the machine. think of your machine as being a giant propeller just waiting for ignition.

[Geof]

Originally Posted by Delw Thats Pretty cool and I am not trying to be an ass, but get that off the machine Immediatly. NEVER hook a barfeed directly to the machine especially the accutaor, if you get any vibration you just wiped out your machine not to mention you can kill someone pretty close. A barfeed MUST Have some sort of Stand, and be completely separated from the machine. think of your machine as being a giant propeller just waiting for ignition.

This is absolutely correct; the only thing missing is all CAPITALS, BOLD, and UNDERLINING

GET IT OFF THERE, IF NOT FOT YOUR SAFETY FOR THE SAFETY OF ANYONE ELSE WHO MAY BE NEAR IT..

You should never have barstock protruding beyond the end of the spindle a distance more than a few bar diameters and even with this it should be supported to run true in the spindle. You should never attach anything to the chuck actuator.

When something is spinning unsupported if it starts to go out of balance a little bit it goes further very quickly and ends up flaying around like a big whip. Have a look at the first picture and see how the machine housing has been formed in: This was done by the previous owner of the machine who ran a piece of 1" brass barstock sticking out the back end about 4 feet. In your case the chuck actuator would probably be destroyed also.

Have a look at the second picture; the machine, all 9000 lbs, sits on a big frame and the bar feed is attached to the frame. The barfeed tube, which comes out of the spindle and disappears out the hole in the machine enclosure, is supported by two large bearings on the barfeed support and by a collar in the chuck. It does not touch the chuck draw tube which has to be free to move.

[Ztiggi]

hmm, i think there's a misunderstanding here, nothing is spinning unsupported,
the bars is only 1.5meters long, and is allways inside the spindle tube, with a plastic bearing at the end to prevent vibrations,
and the cylinder with the plastic piston retacts before spindle starts.

the only danger i can mention is if the whole actuator starts spinning for some reason, then the 5pcs of M5 bolts that holds the cylinder would brake off pretty easy i think.

did you misundersand this thing or do i misunderstand you?
i dont think this thing is dangerous at all...

[Geof]

Originally Posted by Ztiggi hmm, i think there's a misunderstanding here, nothing is spinning unsupported, the bars is only 1.5meters long, and is allways inside the spindle tube, with a plastic bearing at the end to prevent vibrations, and the cylinder with the plastic piston retacts before spindle starts. the only danger i can mention is if the whole actuator starts spinning for some reason, then the 5pcs of M5 bolts that holds the cylinder would brake off pretty easy i think. did you misundersand this thing or do i misunderstand you? i dont think this thing is dangerous at all...

Okay I will tone down my comment but ask the question does the bar stick out behind the spindle by more than 40 cm or so? This can still consitute a hazard.

Also what happens if your piston hangs up and does not retract before the machine starts? Do you have some form of interlock?

I know this may all seem a bit extreme and nit picky, but Murphy Rules. If something can go sideways someday it is going to go sideways.

[Delw]

It doesnt make any difference if nothing is spinning, it all has to do with harmonics and vibration.
What is spinning is inside that tube that is what is dangerous.


Heres an example.
hitachi seiki 20s II
no bar feed
bar length 6" shorter than the spindle tube to the back of the machine,
jw preessure on 3 inch long chuck jaws max
bar size was 1/4" less than spindle tube ID.

Vibration at 5000 RPMS enough to pick up machine and move it at a 45 degree angle, throwing nickle alloy (Inco 718 or it was stelite) bar 20 feet up into a 4" thick concrete ceiling and poking a hole in it.
took the bar and bent it like a prezel as it shot out of the back of the machine.
lift of the 7000lb plus machine was said to be easy 1 foot off the ground

this was a bar that was inside the spindle tube not sticking out like yours is.

point is your set up will kill someone, destroy the ceiling of the shop due to chains and destroy everything and anything with in 50 feet.

[Ztiggi]

I'm ok with the critics,
it may be helpful to get others' point of view,

no the bar is never outside the spindle,

there is no interlock if the piston fails to retract, but the piston is attatched with a ball bearing, so it would spin free,
but make a little vibration to the cylinder, i have tried this.

[Ztiggi]

Originally Posted by Delw It doesnt make any difference if nothing is spinning, it all has to do with harmonics and vibration. What is spinning is inside that tube that is what is dangerous. Heres an example. hitachi seiki 20s II no bar feed bar length 6" shorter than the spindle tube to the back of the machine, jw preessure on 3 inch long chuck jaws max bar size was 1/4" less than spindle tube ID. Vibration at 5000 RPMS enough to pick up machine and move it at a 45 degree angle, throwing nickle alloy (Inco 718 or it was stelite) bar 20 feet up into a 4" thick concrete ceiling and poking a hole in it. took the bar and bent it like a prezel as it shot out of the back of the machine. lift of the 7000lb plus machine was said to be easy 1 foot off the ground this was a bar that was inside the spindle tube not sticking out like yours is. point is your set up will kill someone, destroy the ceiling of the shop due to chains and destroy everything and anything with in 50 feet.

sounds like a new james bond movie to me...

my bar is never outside the spindle, and is supported by a plastic collar that is
slightly smaller than the spindle bore, but has got O-rings inside that holds it in position at the end of the bar all the way.

what you see on the picture is not the barstock, it is the piston rod, i had t attach one onto the cylinder, because this is a special "rodless" cylinder

[Delw]

Oh I kow yours isnt outside of the spindle. and the bar doesnt show, I have seen ones just like yours ona few machines.
I been trying to think of a way to describe it cause I suck with words.

But I think I figured out one to use.
its about Containment.

your bar tube (any barfeed) is basically containing the vibration, small bars are easy to contain vibration from gettng out of hand, we have all done it. need to chamfer a bar end on a 12 foot bar 3/16 stock on a hand lathe, you grab someone give them a pipe slide it over the material and hit the jog button on the hand lathe to chamfer the bar.
since the material is small and the person holding the long bar is pretty stout compared to the bendability of the bar the whipping effect is contained in the pipe so it doesnt go out of control.

we used to use a 55gallon drum with a piece of V cut would stock to cut 1/4" bars. as I am sure that you are aware that 1/4 bars have flex and they don't need to be 100% alinged to run smoothly. if the Wood V block is 1" to low and off center a tad it still runs smooth on a 1/4" bar. the wood V block is basically containg the vibration. put in a bigger bar and you will have some major problems. Because the bar doesnt bend that easily and the vibration gets worse onces its spinning.

now in your situation any vibration you get is transfered to where it is bolted to. Compound that by the 5-6 feet sticking out of the back end of your machine and that vibration is putting a big strain on those bolts.
one comes loose or breaks then it pops another and another and in a matter of a few seconds all the bolts are gone and its free. which in turnes mean the bar sticking out of the spindle( the one you are cutting) is free to whip around.

with bigger stock you neeed something bigger to contain the vibration before it gets out of control

Aside from it being dangerous or potentually dangerous, your putting stress and weight and vibration into the actuator. this will cause failure in the actuator.

if you were cutting 1/4 bars all day it would be no biggy except for the stress on the actuator.

you also need to figure in leverage.
I am betting it doesnt take very much pressure to push the back end of that tube 1" past were its sitting. think of a 1" dia bar being 1" off center spinning at 2000 rpms the wiping action will start and the vibration will get worse and worse. it only takes a matter of seconds not even that.

Once the whipping action started you couldnt shut your machine off fast enough to stop the damage.

Always better to be safe than sorry, at the very least put a stand bolted to the floor in the back of that bar and the to save your repair bills unbolt if from the machine and put a stand in the front as well.

if you can make that you can easily make a pair of stands.

one other note if what you were doing was safe, Machine builders would have been doing that for years. I know cause it was asked by many people who owned lathes to do something like that.
it always came back with the same reply No its not safe and will damage the actuator and spindle system

[Ztiggi]

Originally Posted by Delw now in your situation any vibration you get is transfered to where it is bolted to. Compound that by the 5-6 feet sticking out of the back end of your machine and that vibration is putting a big strain on those bolts. one comes loose or breaks then it pops another and another and in a matter of a few seconds all the bolts are gone and its free. which in turnes mean the bar sticking out of the spindle( the one you are cutting) is free to whip around.

if the bolts break, the whole cylinder would drop down on the floor,
and the bar i'm cutting would still be inside the spindle, supported by the plastic collar, and clamped in the chuch, dont't think we understand eachother here....

but i do agree that it is probably unhealthy for the actuator and it's bearings,
and think i will make a couple of stands for the cylinder, and bolt it to the floor.

[Ztiggi]

placed the cylinder on a stand today...
it still works perfect

[holbieone]

i had a 1.5" bar ,sticking out the back of the spindle 18" ,bend 90 degrees when the spindle cranked up 2500 rpms

the wight of the bar flapping danced the machine off its bed and took out a coworkers tool box

nice setup