Deckel Z Axis Power Feed Problem

I recently purchased an FP 2 circa 1970.
The Z axis power feed works in the down direction only. If you try to engage the up feed, it is like there is nothing there? To manually bring the table back up, is nothing short of a workout. It is extremely difficult to turn the handwheel, and it remains difficult to turn until the top 3 - 4" of travel. All other feeds work perfectly. If this has been discussed in another thread, please point me in that direction. If not, any help would be appreciated.

It sounds like the down-and-no-up behavior is a symptom, not a cause. Try to find out what is causing the stiff movement. Could be gib adjustment, gunk, who knows? The down-and-no-up may be due to a broken shear pin. The pin's remains can provide enough torque to lower the table, but just slips when trying to raise the table.

When I select the down movement, I think I am feeling the engagement of the mechanism. There is a defintie mechanical feel to it. Trying to engage the up, there is no feeling of anything. its like there is nothing there. On rare occasion, i can discern the slightest amount of rotaion of the z axis handwheel. I will investigate your suggestin of it being really dirty. Would that be the gib area, the lead screw or both?

Better to clean everything, starting with gibs and ways. If the screw was so dirty it was causing your problem, I’d be worried.


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Sounds like two issues to me.
First off like Rick suggests likely the shear pin is no longer providing a positive drive, but rather friction from the pin remains are allowing the
down feed to sort of function....
Test:
Engage the down feed at a relatively slow feed rate....engage the hand wheel for the "Z" and attempt to restrain the slide from moving by holding the hand wheel.
If you can stop the movement then the shear pin is no longer really working, and needs replacing...

Now for the other problem:
Because the effort to move the vertical slide (Z) is high till you get to the last 2-3 inches to height where it seems to free up and get easier...this would indicate to me
that one: the ways are worn...and two: the gibs are adjusted too tight so that when the slide moves to the unworn portion everything tends to bind and get tight....
Wear on the vertical ways is most likely at the top where most machines get used the most....Past owner perhaps adjusted up the gibs to be sung in the worn range of movement....where they were most using the machine.
Leaving the slide too tight when moved to the less worn portion of the vertical travel....
To have acceptable movement over the entire range you have to average the gib adjustment so as not to be overly tight in the unworn portion.

Could easily explain why the shear pin might have failed. High effort with the slide low and doing a rapid to raise the table ,especially if a heavy part was mounted ,could have required enough force to make the pin fail.

Now that said, a failed shear pin will also prevent the other axis from moving ...again easy test is try to restrain the move of the slide by holding the hand wheel engaged....

NOTE: If this is a new install....be sure the main motor is rotating in the correct direction...if the drive motor is running in reverse the feeds will not work properly....Spindles should be running right hand....
both horizontal and vertical....

Cheers Ross

Firstly, thanks for the detailed explanation.
I set the feed to its slowest setting and tried to restrain the handwheel, after engaging the selector to feed down. I could not hold it.
With the selector set to feed up, and the power feed still engaged, I can rotate the handwheel in either direction, moving the table up and down.
I have a couple of questions. What differentiates the up and down feed. Is it a separate gear train for each? Is there a gear in the drive that might have broken a shear pin and is spinning on a shaft? Where might it be?
I will have time this weekend to check the gib. Your suggestion that it is too tight seems to make sense to me. The motor is turning in the right direction.

The switching of up versus down is done with a dog clutch that engages one of two gears inside the support. You can see the mechanism if you look at some of the photos in this thread. For example the second photo in this post shows part of the clutch mechanism.

http://www.practicalmachinist.com/v...wn-reassembly-277534-post2192135/#post2192135

Some more photos can be found here: http://www.practicalmachinist.com/v...own-reassembly-277534/index2.html#post2196281

It could be that there is a simple explanation for what is wrong and it can be easily fixed with no surgery. But if not, you will have to lift off the support as documented in the thread above, and fix it. The good news is that these machines have a robust design and are well built. So if something is broken inside, it is probably a sheared pin or shaft key or a stripped gear, which can be easily fixed.

Cheers, Bruce

What might couse the problem is a broken tapered pin that holds the dog clutch
That way the clutch can be pushed down and you have no feeling in the clutch handle at all

The problem then is to get the broken tapered pin out Thats in 3 pieces now
I did have a few

Peter

My apologies for my recent absence on this thread. A family situation rquired may attentions elsewhere. A friend and i have finally gotten to the issue with the with the Z axis. A shout out to Peter who correclty sent us in the right direction. It was in fact a broken taper pin on the dog clutch gear that controls the down movement.
We measured the pin and have been unsuccesful in ordering a replacement. Can anyone tell me the correct part number or source of this pin.
On anothe note, the likely cause of the breakage may be that the main shear pin, seems to have been replaced with a drill bit? It is not likely to ever shear before breaking something else. What is the correct replacement?
I would apreciate any and all help with these questions. And as always, thankyou to everyone who has taken the time to offer help.

Taper pins usually go by number, which denotes the size. I would expect that they are all pretty much standard. McMaster sells taper pins, so another hardware place should be able to get them for you. At least you can compare your pin's dimensions with stock size pins in the McMaster book to see if a stock pin would work for you.

Careful....metric and imperial taper pins are different....rate of taper is not the same.
That pin should be at the metric taper.....
Believe McMaster has both flavors....Buy a pin that has the small end at the needed size or slightly smaller and longer than you need ...Lightly test fit the pin, shorten the ends to suit...
Cheers Ross

In regard to the sheared taper pin; the hole likely needs to be reamed to repair it. Should be 100% contact (the shaft and both sides of the gear collar) for full strength and holding purposes. I would just buy a standard OS long pin (sold 5" or 6" length) and a suitable taper pin reamer and open up the hole to fully clean it up, install the new pin and trim to length. I use a punch and a small hammer to seat those pins and never had one loosen or fall out. Machinery's hand book has a section covering taper pins and standard sizes.
That Z axis should be easy to crank up and down, hopefully that is the only thing you need to get it up and running.
Dan

PS I have a little bag of the shear pins, were included with a machine I bought. Singer in Germany should have some but if you have any trouble I'd be happy to send one for the cost of postage.

Thanks everyone. Seizing upon Danny's advice about using a reamer. Should that advice hold for all the taper pins i removed to get the broken one? I beleive there were three.