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Thiel 159 duplex HELP! Power Feed Not Engaging

Benwalker048

Plastic
Joined
Jun 22, 2020
Hi guys

Bought a 159 duplex a few months ago having never seen one before and not knowing how the feeds work.. once I figured it out I realised that the feeds are just not working at all.

What I find odd is that the rapid feed still works, but the normal power feeds don’t. Having no experience with these machines I’m wondering where to start looking for the potential causes? Could it be a broken shear pin? If so where could it be? Also could it be the clutch for the power feeds isn’t engaging? Is there a separate motor to engage the feeds?

There is very little documentation on the internet of these machines and how they work, so I’m hoping someone on here can share some knowledge!

Thanks in advance
Ben
 
Definitely check the motor rotation before you do anything else.

You can be misled by the rotary controls for the feed gearbox. They can sometimes appear to engage a gear when in fact you have a false neutral. I always turn the spindle by hand when selecting spindle or feed gears to ensure that the gears are properly engaged. The electric clutch engages the rapids fairly forcefully - this can have the effect of fully engaging a feed gear if you have not correctly selected it. Using heavier oil than specified in the gearboxes can make this effect much worse, especially when cold. Since you have recently bought this mill, I would have a good look at the oil in the gearboxes anyway, irrespective of any other work needed. If the previous owner tried to quieten down noisy gears with heavier oil you should change it. The upper spindle gearbox can get coolant in it so it is worth doing an oil change on both gearboxes just on a precautionary basis.

There is no separate motor for the feeds on an unmodified 159, although I have heard of examples where modifications have been made to add a feed motor. Such a modification should be really obvious - just have a look under the rear cover.

The feeds gearbox is driven from the spindle gearbox via a chain to two feed gearbox input sprockets. The upper sprocket carries the normal feeds, the lower smaller sprocket the rapids via the electric clutch. The chain wraps around some roller guides to get good engagement with these sprockets. I suppose it just possible that the larger sprocket is just running free on its shaft (it does have a key), in which case you would get feed movement only when the the rapids are selected. To check this, remove the outer cast Aluminium cover, then slacken off the motor mount, remove the upper pulley and the three belts. The chain drive is under an inner cover which you can now remove. You should be able to check the chain and sprockets with this off. This is an easy check to make and you need to do some of this in order to check the oil levels via the sight glasses and change the oils via the fillers and drain plugs.

There is an electric clutch for the rapids, but the feeds for the individual axes are engaged manually by individual dog clutches engaged by the three different feed control levers. The rapids feed goes through those same manually selected dog clutches, the electric clutch simply connects the whole feed gearbox at a higher speed. The individual dog clutches can be adjusted so it is just possible that you have one of these that is not quite fully enaging due to poor adjustment but is bumped into full engagement with the shock of the rapid engagement - but that is very speculative.

The rapids use mostly the same transmission path as the ordinary feeds, so if you get rapids but not feeds and have checked all the points above, more investigation is required. You should get both rapids and feeds or neither. See if you can get feeds on any of the axes. If you get them on some but not others that would be a big clue to diagnosis before you strip it down any further. It needs a fair amount of torque through the transmission to rapid the Z axis upwards (consider the weight of the saddle and table), so if you can get this axis to rapid up it is a bit unlikely that you have a sheared key early in the transmission path (apart from the input sprocket mentioned above), but I could easily be wrong.

These are very well designed mills, so provided it has not been badly abused I supect you will find a simple solution.

Let us know if you need more detail.
 
Hi guys.
I have a similar issue with my new Thiel 159.
My machine was poorly looked after, and had alot of dried out oil all over. It doesnt look like it got any maintainence at all, and it hadnt been much used the last years either.
All the axes were pretty hard to move, but with some cleaning of the slideways and daily oiling and moving the Z and X axis are back to normal. However the Y axis is still very hard to move, and the rear locking handle on the Y axis is stuck. I have a theory that this has been stuck fore some time, and the mill has been run with the powerfeed anyways, and this has worn something out?

Question one: How to I get this loose? I have tried to semi-gently loosen it with a hammer, but based on the front handle this particular pair of locking handles cant rotate 360 degress like the others that can be screwed all the way out, but stop in both directions?


The "fast" feed works on the X and Z axis, but I havent tried the Y axis as I dont want to damage anything. The fast feed is very slow. The normal power feed doesnt work in any axes, but I can see the vertical axle underneeth the table rotating slowly when the feed handles is in neutral (center) position. If I move it in any of the directions it stops. This leads me to think that some gears have a sheared pin / key, so once the torque increase the gear stops.

I have added some videos and photos here: Shared album - Magnus Myklebost - Google Photos
The video of the ruler / scale shows the power feed in fast mode, where I have to hold the feed handle and push the lower control button. Could the cluch be worn?

thanks for your time!
 
Last edited:
Hi Magnusrm-

Thanks for your PM regarding your Thiel. I will answer as best I can here rather than via PM just in case the information is useful for any others who come here.

Starting from the top of your message, all the axes should move easily with a very smooth feel. Disengage the dials on the handles so that you can be sure that the stiffness is not in the dial mechanism. The Z axis is heavier of course, but that is just the weight of the table. The Y axis should be the easiest to move, if not there is definitely a problem.

The locking handles used throughout on the Thiel are 'KIP' handles. The good news is that these are easily found if you have worn out or broken handles. The two locking handles for the Y axis should lock and unlock easily, turning through a small number of degrees. They do not turn through 360 degreees (although you can put the actual handle anywhere you like). If yours are not freeing easily, at least one of the locks is probably engaged and that will make the axis hard to move. I can see that you have removed the Aluminium KIP handle, but the splined centre is still in place. That centre is actually part of the standard handle.

It has been a while since I did anything behind the Aluminium cover for the Y axis, but as I recall, the small socket head cap screw at the front of the cover is actually a pin that engages with a groove on the front Y axis lock barrel. If you remove this screw, the entire handle and barrel should just pull out of the mill. The small slotted head screw at the rear has a similar function for the rear locking handle, but looking at the drawings I think there is a rod behind the screw which engages with the rear Y axis locking barrel. If you take out the screw and then wiggle the rear locking barrel, it should push this out of engagement and allow you to withdraw the locking handle barrel. I have to admit that I don't really recall all the details of this part. I suspect that this is what is causing your problem with removing the cover. Please don't use a hammer, you have a good chance of breaking the cover or worse.

The actual lock plungers are in the cast iron body of the Y axis. It is possible that they are rusted in, but if they are I think you will need to remove the Y axis slide to get at them. That would be a big job, and I have not done this myself. I would try to get plenty of fresh oil into the whole area, especially along the gib before thinking about that.

You have already removed the hand wheel assembly. I expect you have the metric only hand wheels, so imperial/metric gearing inside the handle. Let me know if this is the case. I do not think anything else should prevent the removal of the side cover.

------------------

For the rest of your queries, the rapids should be fast. You should hear the clutch engaging when you press the button. The vertical feed shaft should really speed up when you select rapids. You should not need to hold the feed lever in for any axis to get rapids. Just select the axis with the lever (let go of the handle)then hit the rapids button. If the feed lever is kicking out when you do this there is something badly wrong. I agree that your obsevations suggest that you may have a sheared key somewhere, but I would leave this alone until you have the Y axis freed up.

I assume that you have checked that the motor is rotating the correct way? This is important!

These are very good mills and although yours has had a hard time it is well worth sorting out. The quality of the design is impressive and generally fairly easy to work on.

If you can't make progress, I will dismantle that area of mine for comparison, but obviously I would rather not. I use this mill frequently.

Let us know how you get on - don't hesitate to ask.
 
magnusrm,
Please ignore my query about geared dials. After looking at your photos more closely I can see that you have metric only dials.
 
thank you very much, billmac. Will test this ASAP when I get back to the mill. So there are locating plungers on the cover similar to the rear cover? I will try to squeeze in a multi spray 556 (rust remover / oil) tube and spray it down on the inside.

Are there any special precautions I need to make when removing the lower panel? I guess this is where I access the gear box? My plan is to rotate all handles as far clockwise as they go, take photos and then remove them.
 
magnusrm

thank you very much, billmac. Will test this ASAP when I get back to the mill. So there are locating plungers on the cover similar to the rear cover? I will try to squeeze in a multi spray 556 (rust remover / oil) tube and spray it down on the inside.

Are there any special precautions I need to make when removing the lower panel? I guess this is where I access the gear box? My plan is to rotate all handles as far clockwise as they go, take photos and then remove them.

I'm not sure what you mean by locating plungers on the cover. If you mean dowels on the joint between the Aluminium cover and the main cast iron frame, I think it is quite possible but I don't remember. Some penetrating oil is a good idea.

The outer Aluminium panel covering the two gearboxes is easy to remove. It is a good idea to put the handles into a known position before you remove them. You will find that there are two further cast iron covers behind the Aluminium panel closing each of the two gearboxes. To access the actual gearbox internals you will need to remove these. (Drain the oil in both boxes first!) The gearbox internals are simple and well made, so unless you have reason to strip them down further I would resist the temptation.

The gearboxes have quite large oil flingers and when the mill is running oil goes everywhere inside these boxes. Make sure that you protect the joint faces on the covers from damage. Some jointing compound is probably a good idea when re-assembling. I did this and have not had a leak.
 
The inner gearbox covers have dowels that locate them to the main casting. However, from memory I think there are tapped extractor holes close to the dowels to aid in taking them off. Have a look for these and if possible, use them to remove the covers; that way you avoid damage to the joint faces.
 
Hi. Just a short update.
I got the upper cover of the power feed end stops / Y axis locking handles off.

The issue was caused by the rear locking handle was locked, and it turns out that the locking screws located on the front and back of the cover wasnt working in the same way. Both screws were identical, but the rear one didnt push directly into the groove, but had a extension pin that entered the groove. This pin must be removed with a magnet if the cover is to be removed without removing the locking axle.

The issue with the rear locking axle is still persistent, and I am not sure how to best try to loosen this. I have tried to turn the handle both ways with quite some torque. I have also tried to pull it out with quite some force.

Im not sure what would be the best way forwards here. I could add a large nut, where I drill a 5mm pin through the axle and nut, and thereby getting a easier way of getting torque / force on the axle?


Shared album - Magnus Myklebost - Google Photos
 
Further update:
I took the gear box cover off, and did a visual inspection of the the internals. The main chamber looked decently clean, but the front chamber where the crown pinion gear is located doesnt drain to the normal oil drain and this recess was filled with crap. I will purchase an oil extractor to get this out, as it was a larger volume than I expected. I cleaned the main compartment with some clean rags, but the pinion gear area was very dirty, and I did not want to drag these particles into the main area.

When I manually rotate the belt drive, every gear turns ok. When I activate the normal power feed on the X axis it seems to work, but I feel that the movement speed is pretty fast compared to what I expect. 13 turns of the upper belt wheel corresponds to 1 turn of the X axis handle (3mm). All gears are in the most counter clockwise position. My untrained eye cannot locate any issues this way.


Shared album - Magnus Myklebost - Google Photos


So... What do to next... Im kind of tempted to start up the mill, and see if I can see any issues when using the power feed that way. I know its not optimal to run that gear box without oil, but could i be OK for a short period of time without any load? The gears are well oiled now, but I expect that the oil will be slung off pretty. fast.
 
magnusrm -

You are definitely making progress. As you say, the long pin behind the small screw at the rear of the cover was causing your problem getting the cover off.

The rear lock should not require a lot of force to unlock. I have not stripped down the internal locking mechanism, so I only have the parts drawings to help here. It looks to me as if the rear locking axle is similar if not identical to the front; it just has an eccentric on its end that moves a locking plunger up and down in the body of the mill. It might possibly be pulling down on the Y axis gib. The locking plunger is spring loaded, with the spring below the vertical locking plunger. You should be able to feel the spring compress a little as you lock the handle. There should not be anything preventing you from pulling out the entire rear locking axle, unless it is totally seized up or possibly broken internally.

If you look at the Y axis casting vertically above the rear locking handle and close to the square drive used to move the upper slide, you will see an oil nipple. This looks at first as if it is just for the adjacent way close to it, but on my mill at least, there is an oilway that goes down to the Y axis way on that side. If you pump oil in that nipple you should be able to develop significant pressure and you will see the oil oozing out along the edge of the satin chrome Y axis rule from the Y axis ways. The oil also makes it way (or it should!) into the rear locking plunger bore. On my mill, I can see the oil pumping out as I move the rear locking plunger. I suggest you get as much oil as you can into this region and see if that helps - it is just possible that someone has used grease on these nipples, in which case everything will probably be gummed up and you will have a longish job cleaning it all out.

If that doesnt help, I would suggest gently trying to move the Y axis as you apply a little torque to the lock, and see if you can feel anything. You could also see if the Y axis gib is free to move. It is just possible that the gib is galled and that this is what is locking up your Y axis and the locking plunger. If so you don't want to make this worse; in this case, I think you will need to strip the Y axis to get at the area and clean it up. That would be a fairly big job, so I would keep trying with the oil first.
 
So... What do to next... Im kind of tempted to start up the mill, and see if I can see any issues when using the power feed that way. I know its not optimal to run that gear box without oil, but could i be OK for a short period of time without any load? The gears are well oiled now, but I expect that the oil will be slung off pretty. fast.

I have run the mill with that cover removed for a short time. You will need to cover everything near and wear overalls and face mask. The oil will go everywhere. The oil flinger really works well and will throw drops of oil a long way. So long as you make it brief and keep the load down you should be OK. Of course, don't try and engage the Y axis feed. You can put the handles back to change the feed gears.

I have a similar photo of my feed gearbox somewhere. I will try and find it and post for comparison.

Incidentally, if 44 is the production mumber for your mill it must be quite an early one.
 
I finally managed to get the rear locking handle axle loose!!! I used the small M4 bolt and jacked it out slowly. Once I got it out, the Y axis now runs smooth as butter, what a relief!
Since the handle locks in both direction, i thought it was a safer bet to try to pull it straight out rather than trying to turn it loose. The locking axle slides easily back in now that the locking is disengaged.

I have used some clean rags to get all the oil out of the rear of the gear box, so the oil flinger shouldnt be that much of an issue. However, there is of course oil on all the gears, so will expect some splashing! So I should use the slowest possible feed to start with?

I have made a shared album, which I will update as long as progress. The last photo at the bottom shows the way I got the axle loose. Doesnt look too professional, but didnt have a correct tube to make a better support sleeve.

Thiel Duplex 159 milling machine - Google Photos
 
Magnusrm -

Nothing wrong with that. I can't imagine how someone managed to get it so tightly locked, but nothing is broken so all fine.
 
Magnusrm-

I found the photo of my feed gearbox from a similar angle to yours.

attachment.php


I think you have had a little water in your gearbox at some time - you can see some slight rusting when you compare to mine. If you look closely I have a little bit of wear on one of the gears, but your gears look good.

It must be just the gear selection, but I can see more gears in my photo. Have you tried moving the gear selectors to make sure they are all there and engaging properly?
 
magnusrm -
I have looked at your later photos of the gearbox internals and they do seem to show a full complement of gears. I think it would still be a good idea to check all gear selections just to make sure that there is nothing preventing engagement anywhere.
 
Hi guys. Sorry for the long pause. After some tinkering we found out that the issue lied in the biggest gear on the longest axle. This gear has a one-way drive inside to allow the power feed to function. It looked to be a nightmare to disassemble, and we did some brainstorming. After a while, we figured out that the issue really lied in the wiring of the motor. The electrician who did the wiring had swapped two of the phases so the motor ran the wrong way. We found out because of the arrow on the belt drive wheel. When we did the manual turning of the motor, we turned the correct way and the power feed seemed to be working. When we ran the motor, we just checked that the spindle was turning the right way, not the actual motor.

Stupid mistake, and a simple solution. We just flipped two of the wires and everything works as a charm. It was nice to open the gear box anyways, as there is oil pool that isnt drained by the plug. This had a lot of dirt / rust in the bottom of it that needed to be cleaned with a oil sucker and rags.
 
This happens sometimes with this type of mill. The symptoms can be mysterious and it is an easy trap to fall into. No harm done and you have a much better understanding of how your mill works now. You must have had the spindle reverse selected on the upper gearbox - don't forget to change that to the forward setting before you start to use the mill.
 








 
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