Electronic leadscrew pitching error

[paulg 1Participant @paulg]

Hi, I’m a new member with a new Amadeal lathe.

Amabl250ex550.

It has an electronic leadscrew

It’s not pitching properly when the distance is input through the screen.

 

I’m wondering if the machine requires a tweek with the step motor pulses and encoder pulses.

It may be something much simpler!

Any ideas?

Paul.

[JasonBModerator @jasonb]

The first thing to check is that you have not inadvertantly altered the pitch in the settings.

Hold the far left “FN” button down until it beeps twice. After a moment the screen will display the settings, use the “FN” buttom again to move from one setting to the next until you come to “pitch”

I’m not 100% sure what the 250 needs it setting to but you should be able to measure the leadscrew pitch which is probably 3mm but may be 2mm. You also need to check the pulley ratio between stepper and leadscrew which can be seen by taking off the cover on the side of the headstock, it is likely to be a smaller pulley on the stepper and larger on the leadscrew  such as 1:2

From that you can work back and get the pitch that one turn of the stepper will produce.

Based on the 210 lathe which has a 2mm pitch leadscrew and 1:2 belt ratio the pitch is set at 1mm as 1 turn of the stepper will move the leadscrew half a turn = 1mm

Hold “FN” again for a double beep to exit settings

 

[paulg 1Participant @paulg]

OK, many thanks fir the detailed reply.

What and where is the pitch?

If this helps:

The leadscrew is set to 2mm. Which looks about right.

The encoder pulses are set to 2000.0

And the step motor pulses is set to 1600

With a ‘move’ distance of 2.5,  the carriage is moving about 1.5.

No idea what the difference is between encoder and motor.

 

[JasonBModerator @jasonb]

If you keep clicking the FN button then the pitch (lead screw) comes up just after the two pulse settings which are the same as I have on the 210E.

As I said take the cover off the end of the headstock and look at the bottom right which is the stepper motor and that is belted to the leadscrew . A quick count or measure should give enough to work out the ratio

You then need to look at the lead screw and check what pitch that is, hopefully some will be exposed on the right side of the carriage before the spring cover starts. If not just pull the cover to one side and measure over 10 turns and divide that measurement by 10 to get the leadscrew pitch.

[JasonBModerator @jasonb]

Also make sure you have taken any backlash out of the drive train before you zero as movement may be less than expected if you fail to do that. though 1mm sounds too much for backlash.

[paulg 1Participant @paulg]

<p style=”text-align: left;”>Many thanks Jason. Very helpful indeed.</p>

[JasonBModerator @jasonb]

Any luck sorting this one out?

[paulg 1Participant @paulg]

Thank you for asking, Jason.

So, I have asked Amadeal to contact the supplier so they can send default settings. I’m hoping to hear from them in a day or so. I’m surprised, with the settings being so easy to access, that a list of default setting is not supplied.

The ratio between spindle and stepper pulleys is 2:1 the stepper having 20 teeth and the spindle pulley having 40.

The Leadscrew pitch is 2mm.

Entering the setting on the digital panel, the leadscrew is set to 2mm. I set this to 1mm and it brought the pitch to within .25/.3mm over 10mm, which is still very poor. I was careful to maintain pressure on the carriage hand wheel, to minimise backlash.

This leaves the encoder and stepper pulses as methods of adjusting?

As you have a similar machine, can you tell me if you have a machine ID plate? I can’t find anything to identify the machine/ date of manufacture or link it to the manual.

The machine also has what looked like cast iron swarf in the carriage tee slots and under the headstock. Even the drip tray was clearly marked by the lathe having been bolted to it. Is this usual for this type of machine ? I am new to the model engineering side of things, where so much is sourced in China, but have bought many new industry cnc and manual machines over the years and they have all been pristine.

 

 

[Tony Pratt 1Participant @tonypratt1]

Definitely up to Amadeal to sort out this problem, you contract is with them!

Tony

[JasonBModerator @jasonb]

Entering the setting on the digital panel, the leadscrew is set to 2mm. I set this to 1mm and it brought the pitch to within .25/.3mm over 10mm, which is still very poor. I was careful to maintain pressure on the carriage hand wheel, to minimise backlash.

 

No what you really want to do is engage the half nuts and then use the electronic feed to bring the tool close to the end of the work, then use the topside to touch the tool onto the end of the workpiece. This is your zero. Enter the length of cut or thread from there.

All the threads I have cut with it seem fine when offered up to a thread gauge, lengths set are what it cut when in auto and it stopped the right distance from shoulders when threading to a shoulder.

Drip tray on the 210 was pristene, I even put some paper on it so that it is not marked when it goes back. No signs of swarf apart from what I have made. But don’t expect the same fit and finish from the far cheaper imported machines there is a reason they are cheaper

[paulg 1Participant @paulg]

Jason,

 

The setup is very different.

Amadeal will be in touch in a couple of days and then I’ll decide what to do.

 

[JasonBModerator @jasonb]

Yes as the change gear 250 machines have a basic gearbox where the stepper is now located the leadscrew is shorter so the stepper is mounted the other way round so it’s pully lines up with the one on the shorter leadscrew.

 

Similar 2:1 between stepper and leadscrew . I will look at the encoder bullies tomorrow and let you know what they are but my pulses are set the same as yours

[Robert Atkinson 2Participant @robertatkinson2]

Is the error consistent? If it’s not consistent it’s possible you have an interference issue or bad connetion. This changes the amount of spindle rotation “seen” by the ELS controller. This result in incorrect movement.

Robert.

[JasonBModerator @jasonb]

I have a suspicion it is something else but need to get a couple of things confirmed first. I read Paul’s last post quickly on the phone last night but having read it again there are a couple of points.

The ratio between spindle and stepper pulleys is 2:1 the stepper having 20 teeth and the spindle pulley having 40.

Firstly the spindle is not mechanically linked to the stepper. The lathe spindle drives the encoder (small round item in your photo) The stepper (big black item bottom front) drives the leadscrew. Can you confirm if the stepper to leadscrew ratio is 1:1, 2:1 or something else. Don’t worry if you can’t easily see it, there is another way to check my theory.

Secondly your comments seem to suggest you are turning the diameter down to a length and not getting the expected result. Are you using the feed lever which is the short one that goes both up and down for along/across or are you using the longer lever that engages the half nuts?

[paulg 1Participant @paulg]

Thankyou again for all your input. Apologies for my lack of understanding and terminology. I see that the stepper drives the leadscrew but cannot see anything to determine the ratio.

By the way, incorrect turning tools were sent, so I cannot turn anything at the moment. I have been trying to understand the digital programming.

I’ve been using the MOVE command to precisely translate the carriage.

It was then that I noticed that the distance programmed does not related to actual distance travelled.

The movement is pretty consistent.

But I await Amadeal to tell me what there supplier says, including why the machine has no ID. This is a new machine and I should not be having these problem. If not resolved I will reluctantly have to return it.

Re the swarf found, it’s shape tells me it’s been created by screw cutting. I wondered if new machines are tested for accuracy in the way. I’m afraid Amadeal have no technical knowledge or support to offer

[paulg 1Participant @paulg]

<p style=”text-align: left;”>Btw, I’ve been using the longitudinal/ crossfeed lever, not the long lever. I reserved this for screw cutting.</p>
Re the id number, looking at our Colchester at work, the serial number is stamped on the bed at the tailstock end. Photos of my model on the Amadeal site, also show it stamped in the same place, so will check my Amadeal lathe tonight.

[JasonBModerator @jasonb]

Btw, I’ve been using the longitudinal/ crossfeed lever, not the long lever. I reserved this for screw cutting

I feel that is where your problem lies.

Based on the way the gear train 250, 280 and 290 machines work then the lead screw also acts as a feed shaft, You should be familiar with industrial machines that have more than one shaft across the front – a lead screw, a plain feedshaft with a keyway and a control shaft.

The “feed lever” on the front of the machine takes the drive from the keyway and through a set of gears and either moves the carriage via a pinion that engages with the rack on the front of the bed or by another set of gears drives the cross slide lead screw. In both cases the thread and therefore pitch of the leadscrew does not really come into play and those internal apron gears will reduce or increase the number of handwehel turns relative to the feed slots rotation, usually giving a finer feed per spindle rev when facing to turning*.

For the Auto turning (lengthways) to work correctly the Leadscrew thread needs to be used so the half nuts need to be engaged, backlash taken out by using the electronic feed to move the carrieage, tool position set and then the cut made.

 

* I suspect this is why you first got the incorrect movement as the feed shaft driven gears within the apron move the carriage at a different rate to what a leadscrew would move it. So the 2mm pitch that was set at the factory may well be right. Reducing the pitch setting actually just reduced the error.

 

 

My suggestion would be to check that the pitch is set correctly is to reset the leadscrew pitch to 2.00mm in the settings. Engage the half nuts and move the carriage to the left a little. And take a measrement of it’s position from a fixed point. Better still if you have a plunger type indicator then move the carriage upto that and set the dial to zero. But make sure you are only moving the carriage to the left which eliminates any backlash.

Then use the FN key to select “automatic turning” and follow the prompts to set a known distance say 10mm or 12.7mm if using imperial measuring tools and to “stop” at the end not return. Then start the spindle turning and click run. The carriage will move to the left and stop at the set distance. Measure how much it has moved and report back. If all is OK I’ll explain how to make cuts using teh feeds, if not we can look again at the numbers.

This should give you an idea of what to engage and what buttons to press. As I was using an imperial gauge I set the distance to 12.7mm (0.500″) and got five turns of the dial at 0.100″ each.

[JasonBModerator @jasonb]

The 210 has a serial number and date on a plate fitted to the belt cover 03/2025.

If you are looking at the plate on the far end of the bed on teh Amadeal site photo then that is about the hardened bed. My old Warco 280 has a number engraved on the far right edge of the bed but not the 210.

[paulg 1Participant @paulg]

Jason,

Thank you for that great description of feed and screw cutting gearing and also the method of testing. I followed your instructions and found the lathe to be working perfectly. The serial number I found as I mentioned above, at the end of the bed. Amadeal also confirmed this, kindly emailing me a photo of its placement.

You mentioned a process for taking cuts using the feed?

[JasonBModerator @jasonb]

Good to know it is all working and that the machine was fine.

 

I’ll put something together in the morning about using the feed lever.

[JasonBModerator @jasonb]

Hopefully this will give you a good idea of how to use the feed lever for general turning.

I show the setting up of the ELS – Function, feed rate, direction, etc. Once the spindle and leadscrew are rotating I use the 210 machine’s halfnut lever but you will be using the feed lever. Engage lever to get things moving, back to neutral to stop the carriage or cross slide and then wind back to the start and put on another cut and off you go again.

Speed can be changed at anytime on the fly as can direction. Though if using a high feed and high revs I would suggest pressing “RUN” again to stop the screw, change direction and then “RUN” again to get the screw turning the other way. This can also be used to return the carriage/cross slide back to the start but is a slower way of doing it than disengaging the lever and winding back by hand.

When finished or if you want to check the dimension of the part just wind the knob to zero. To start again with the same settings just wind up the knob.

At the end I have used my lathe to show the feed lever in action and the way I remember which way to move it. I have a separate drive shaft but that is like the slot in your leadscrew that is going round out of sight under the telescopic cover.

* The displayed feed rate per rev will not apply when using the feed levers. It could be worked out but best to go by feel, start with a low rate and then wind it up to find what suits the job in hand.

One other thing if the screw is rotating slowly you may need to feel the lever into position as it may take a while for the slot to come round. You can see I was having a job with the half nuts but was also watching the camera and did not have both hands available at all times add this to a slow spindle and fine feed and it looks like it is hard to engage but is fine in normal use.

[paulg 1Participant @paulg]

Jason,

Thank you so much for taking the time to provide a video. Helpful and appreciated.

With my lathe having two methods of moving the carriage (through the lead screw thread and the key way) I feel less concerned about wear and a decline in accuracy over time. I see your lathe has one lever and yet still has a rack attached to the bed. Without separate levers for feed and screw cutting, I’m assuming this does not get used?

I have taken a look at some of the engines you have machined, which roused my appreciation of the beauty of Victorian engineering. You are clearly very skilled.

Thanks again.

Paul.

[JasonBModerator @jasonb]

I have a simple gearbox on the headstock. One of the levers will transfer drive to either that shaft you see turning or to the leadscrew.

 

So for feeds I run the shaft and use the up/down lever. There is a worm gear that can slid eon the shaft that is driven by a key in it’s keyway. This then turns gears withing the apron that either move the bed along via a pinion that engages with the rack or the cros sslid ebut the gears driving it’s screw.

If screwcutting then I alter the gearbox to drive that and have the screw rotating and have a similar lever to you which engages the half nuts that then allow the carriage to be pulled along by the leadscrew.

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