Planer Mill - Table Speed Limit?

We are developing a cutting process and plan on running some tests to determine cutting forces. We have an old planer mill that has been updated with CNC controls that we use on a regular basis and it would serve as the perfect test bed for the cutting tests except that the Table drivetrain is designed to top out at 150 IPM.

We can easily update the drivetrain to make it go faster, but I don't know how fast we should push it. I am thinking that we would optimally run at 40 ips (2400 IPM) but we can settle for something between the 150 IPM and the 2400 IPM . . . what is a reasonable maximum speed to aim for without risk of damaging the bed ways? (We will take into consideration accel / decel / stopping distances - we have 19 feet of travel and will only be using 12 feet of travel for the tests)

the problem is stopping that behemoth. I don't think I'd have the table inline with that air tank...... looks it could almost reach it at 2400 ipm....that thing got air brakes?

That looks more like a converted planer, than a planer mill.

Point being i don't know what rapids on a planer mill might be considered normal, but on a "modern" planer, the table speed is designed to be high, constantly reversible, and run all day long with high durability.

Whitcomb Blaisdell advertised in a 1920's catalog that their planers were operated in plants in this and other countries at "extremely high speeds" and that where brass, copper and other soft metals were being machined they were routinely operated at "100 feet cutting speeds and more" I think the limit they saw was the new HSS for which the new machines were designed to take full advantage of.

Depends on the machines and lube system but I doubt 120 fpm would hurt the ways. As others mentioned, can you accel/decel with good control and minimal wear?

The faster they run the more oil the old ones sling up on the ways. The table will start to float if it is a roller lube type. If there's a pump, you may have to do some testing, and maybe use a lighter oil.

smt

I just worked on a retrofit bridge mill with a big ass table. Max rapid was 800 IPM. It looks slow on such a large machine, but it's plenty fast.

This was an Ingersoll with hydrostatic ways. It does not use a ball screw in X. It's a worm drive. That also limits rapids.

Momentum and energy come to mind. If you don't use some kind of regenerative braking you'll need one large cooling system...

Also think strain gages on some critical parts. I can visualize something like a railroad siding stop made of main line rail set in concrete...

We will not have any problem setting up regenerative braking - high power positioning drive systems are what we do for a living.

120fpm / 24 IPS should be doable. We will place a limit switch in the center of travel and locate cams 3.5 feet from each end of the table. At 2 ft/sec, the decel distance = the decel time in seconds so if I decel in 3 ft, that will take 3 seconds . . . 2 ft/sec / 3 sec = .7 ft/sec2 = .02 G's . . . if the table weighs 5000 lbs, that is only 100 lbs of accel / decel inertial force which is easy to manage. Likely friction will be all of that and more.

I don't know of any box way machines running more than 1000 ipm. The fast stuff all runs on linear ways.

Can't you find a better suited machine to do your testing?

I need 138 inches of cutting at speed . . . this is the only machine we have with enough travel. My options are to run this fast with a temporary oversize drivetrain and drive, or run at slower than real life speeds or come up with a different configuration.

I ran a purpose built (not a conversion) 4 head GA gray planer mill off and on for years. The table was 4 ft ax 16 ft and thinking about it, I seem to recall the table in rapid traverse took about 5 seconds for the full 16 feet. That's what? 3.2 ft per second. The traverse motor was a 3 HP shunt DC motor that started full field current accelerated under field weakening to max RPM is less than a second. It stopped under dynamic braking in about a half second. Considering the table weighed tons is was very responsive.

I know a little about the electrics of this machine because I was buds with Paul White the electrician and its DC controls were often troublesome. The general plan was a Ward Leonard drive for the 15 HP feed motor which had a very wide range of feeds from less than 1/4 IPM to over 40. The table feed and the traverse motors were clutched to the table drive shaft by a single lever with neutral in the middle. The direction, start, etc was controlled by a push-button pendant with a wand stop switch extending from the bottom of the pendant enclosure. Traverse push buttons were momentary

The machine in your image looks like a GA Gray originally intended for a press brake die shop. Narrow table long travel, open side, small rail height.

I think you could solve all your table motion problems with a 1150 RPM GP three phase motor of about 10 HP running under closed loop control coupled directly to the table drive input flange. However rated motor RPM depends on the table drive ratio. A general purpose DC drive planer of the day took about 11 turns of the input shaft per foot of table travel. There were options for 8 and 16 depending on customer preference. Table drive backlash acceptable in a planer is probably a no-no in a CNC conversion. Has a ball screw been installed? A double motor rack drive is a possibility as is a zero backlash single motor transmission. $$

Gonna put real milling heads on that machine in place of those tinker toys? I once looked at the Rambaudi milling heads; the ones that look like big Bridgeport heads but with 5" quills and 50 tapers

But hey, it's your project. I sometimes bubble over with ideas. I love tinkering with and modernizing machine tools. Especially the other guy's where I don;t have to do the work.

Motion, would you stick with one unit for velocity? You are making my head hurt with ips, ipm, fpm, fps. And I think your design speed of 150 IPM you cite in your first post should be 150 FPM.

Another point of reference: If it has V ways like a planer, it is analogous to a surface grinder. Quick poking around on the web reveals table speeds on surface grinders from around 80fpm on up to Okamoto advertising 150fpm (listed as rpm, but pretty sure given the description and ad copy, that it is fpm.)

smt

This is a Cleveland and it's nickname is Grover . . .

We have a 50 taper Yancey head for this machine but it is generally used for light cuts / drilling and tapping so the Bridgeport J-Head gets the most use.

we will rig it up for 150 fpm and see how it goes.

How about a gearbox with a VFD / vector drive coupled to the machine.
With the right motor you could over speed and brake as a unit.
Figure a gradual start to get oil to the ways or a pressure lube system.

If you figured your metal removal rates & HP the drive could compensate.

Regardless, physics and number crunching is the next step. Got to do the pencil work so the thrust to accelerate, power and ratios optimize and performance is maximized/ . You settled on a speed and know the length of travel. I suppose it all starts with the mass of the table. Screw it up and you will be cursed at every button push.

I once worked out a hydraulic cylinder linear deceleration buffer where 3000 lb force decelerates a 3000 lb table from 80 ft per minute to zip in 3 inches but don't count on my figures. It was more of a SWAG than a calculation. Motion Guru's problem is force and time to accelerate so there is a force squared or time squared function in there somewhere.

Have fun

I've worked on a few planers in the past. They were mainly 1950's era machines and they were set up to run around the 200 feet per minute area for long periods. Some would do a bit more, some would do a bit less. Obviously lubrication is critical at high speeds.

Standing next to a big planer table running at high speed on full stroke is a bit awe inspiring.

Regards Tyrone

Tyrone Shoelaces said:

I've worked on a few planers in the past. They were mainly 1950's era machines and they were set up to run around the 200 feet per minute area for long periods. Some would do a bit more, some would do a bit less. Obviously lubrication is critical at high speeds.

Standing next to a big planer table running at hide speed on full stroke is a bit awe inspiring.

Regards Tyrone

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Yup. Been there. Ever run the table off the bullgear? I ran the table of E11 off the bullgear so it slid out about 6 feet to block the door of the time booth. The time clerks had to climb out the window to go to lunch.

Forrest Addy said:

Yup. Been there. Ever run the table off the bullgear? I ran the table of E11 off the bullgear so it slid out about 6 feet to block the door of the time booth. The time clerks had to climb out the window to go to lunch.

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Not me personally but that used to happen pretty often in the shops I worked in. Just a question of shoving a bar through the rigging holes in the bed. Attaching a chain block on either side of the table to the bar and carefully winding the table onto the screw. Of course you needed to synchronise the trip dial at the same time.

One machine I knew was being converted into a Plano Mill but the Planing facility had to be kept. When the " Futurmill " guys were commissioning the machine they had the table ( 20ft by 8ft by 1ft ) running empty at 200 ft per minute on the maximum stroke of 20 ft.

All of a sudden something went wrong and the table flew off the rack and went straight out through a pre-fabricated wall at the back of the machine !

I was away from the job at the time but when I got back all I could see was a table shaped hole in the wall and the back of the table outside the building.

We were lucky it went out that way, if it had have gone out the other way into the shop a large vertical boring mill was directly in line of fire.

Regards Tyrone.

It would be far simpler to build a live fixture

Couple of profile rails ,some trucks,a ballscrew ....

Or you can strip your pinion/rack and see how far down the shop the table will slide.

No worries - we regeared and have a 5HP motor spinning 1750 rpm = 175 fpm with a 15HP vector drive running in closed loop control. Takes 3 feet to accel and 3 feet to decel and the dynamic braking resistors are barely warm. Now to mount the new cutting head / spindle and we will be in business.

Can you post a video of this thing in motion? I desperately want to see this!


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