Member postings for Martin of Wick

Managed to get one of Lidl's bandsaw offerings with the idea of hacking it to make a compact light duty vertical band saw for fine cuts etc ( already have a CY90 which I have fettled to cut bar very accurately)

Irrespective of the useless vice arrangement and awesomely poor build quality, it was very disappointing - in fact if I was being generous I would describe it as total carp, with a useless uninformative manual included .

I am considering whether to persist and attempt to fettle the product into some sort of usable condition or return from whence it came.

So have the following questions for guidance from those with more experience of the product...

Out of the box, I don't seem to be able to get any real tension on the blade - with the red cam lever is in the fully locked position and the blade correctly located in the guides, the blade set is very flabby with an inch of sideways play and a distinct curve. As a consequence the blade stalls frequently. Surely this cant be right- I would expect to tension to about the musical equivalent of C flat. Does anyone know if there is any other adjustment possible of the jockey wheel to increase the blade tension? If not , do I get blades made up 5mm shorter to mitigate the issue?

Fault two - as set up on the pivot, the blade ends up angled about 5-7 degrees off vertical (as reported by someone else in this thread). Can't see any obvious adjustment to mount or the blade guides - they appear to be a single unit locked into one position - does anyone know any different ? It may be possible to shim these blocks closer to vertical.

The thing can be made to cut metal (just) but only where no real cut accuracy is required. I am doubting if it is of sufficient quality to become a useful tool either as a vertical bandsaw or as a rough cutter.

Thanks.

Paul,

The 'made for myford special chucks' do not have a backplate in the conventional sense, what you are assuming is the backplate is in fact an integral but threaded part of the chuck, as shown in the picture below.

You take it apart by undoing the socket screws and splitting the two parts with a hide mallet.

if inconsistent or large TIR is an issue for you the easiest route is to purchase a new chuck (of the non integral variety) and new unmachined backplate, machine said backplate on your lathe to mount your new chuck. dont expect less than 3-6 thou TIR as a repeatable error (you might get better - just don't expect it!).

Your other more time consuming choices are:

determine the cause of the error -

is it badly worn jaws - if so you could attempt a jaw re-grind to minimise the runout, you should be able to reduce it slightly but not remove it entirely (google / utube is your friend here)

worn or damaged scroll - you are stuffed - you can tell by inconsistent runouts at differing diameters if runout is a problem you will need a new chuck

deformed , (ie bent off axis) chuck mount (hard to believe but entirely possible- that was the problem with the one in the picture) - you can tell by putting a dti on the back of the chuck and check for axial wobble - you may be able to effect some sort of correction by shimming the downside on the rear chuck part.

Greg,

If it is truly an AT4, you should have no trouble setting P0 to default 380v and usually they arrive correctly programmed anyway. Check the boards as Andrew suggests. Usually AT1 have the earth on the incomer side and NOT on the control side as with the AT4 - but there could be variants.

I strongly suggest before you resort to resetting, that you fully work your way through the manual and parameters and understand the important ones that relate to your intended operation. A full reset may result in some very strange parameter conditions and unintended consequences (in my experience).

Set up on the bench and go through all of the significant parameters as stored in the device and write them down. try to check and change the ones you want again and check the running. Try to understand the manual - most of the info is there, just not in a helpful form.

If you really want to do a full reset have regard to Parameter P77 and the associated reset condition 54321. but take heed, you are likely to get some unexpected consequences and may need to re enter some of the parameters you wrote down from interrogating the registers. In my case I was able to restore most functionality except for the ramp times which now requires dividing the required Hz/s by10!

Take very, very great care with these AT4 devices, they output very high peak voltages at high currents.

If it is of any comfort, my devices all bear that label, but I wouldn't set any great significance to that. I doubt the QA extends to identifying the numerous production variants. Once the box has left the factory, you are on your own and up the creek.... Just sayin!

Until you really know if you need to modify the torque curve, best keep it linear as per the defaults. Shovelling more amps and volts into the motor at its most vulnerable (reduced RPM) is a good way to shorten its life.

wouldn't worry to much about the indicated currents as long as the motor isn't overheating. I doubt this device samples or filters the values so you are seeing the peaks.

Strange that one of the phases is 20% out. If true, and happens on all motors, that is quite significant and could be a cause of rough running. Not encountered this problem before.

You could see if making small changes to the carrier frequency P22 on VFD1 makes any difference ( no more than + or - 5 from the default value of 10 in either direction). Beware that increasing the frequency significantly will increase the running temperature of the motor (but make it quieter as somebody has pointed out). And vice versa.

Sometimes you just have to fiddle and even that doesn't always do the trick!

Edited By Martin of Wick on 26/05/2020 18:26:11

And just for further information,

If you set P73 at 31000, I think you may get the external pot to control between 0 to 65Hz (if you have set 65 in P06)

BUT when you switch back to panel control you will find that you can control the frequency OK (0 to 65) but only over half the span of the panel pot!

To restore full span control on the panel pot, you have to bring P73 back to 61000 and probably the source of my confusion - panel and external don't set up the same way on this device and the manufacturers supply on the assumption that the panel pot will be the primary control, but don't bother informing you of the parameter changes needed for external control.

Further tests.... I am beginning to doubt my own sanity...Some apologies due.

Something Dave said made me think.. Managed to find a 25k pot to replace the 4.7 and set up Result Max Hz 31 !!! How could that be? I was expecting 0 to 65 Hz but controlled only over half span.

So looked at P73 setting and reduced it to manual setting of 31000 as a trial - low and behold the full range of 0 to 64 Hz restored.

So apologies for misinformation - Bad to rely on my memory, but I would have sworn when I tested months ago I had to have P73 at 61000 for full speed and left the parameter in that state for later installation, obviously I was not paying attention at the time.

Suffice to say, have a go with the info sheet values input in P73 and 74 and see what happens.

Rough running of motor - is that at low speed? sometimes too high a value in P72 torque compensation will cause 'cogging' of the motor.

Edited By Martin of Wick on 25/05/2020 11:49:19

Andrew,

lashed up an arrangement with the AT4.

Voltage across the VR (5V to Com) was 5.1 volts

Potential on earth (PE to 220v mains incomer) 0.02V max

couldn't find my 10k pot but with 4.7k I get about 0 to 29 Hz across the range which is about right as I set the max frequency at 65Hz in the table.

James, it is always useful to see what parameters others are using in their set ups.

Edited By Martin of Wick on 25/05/2020 11:20:36

Just to avoid tail chasing,

we are sure that it is a new and/or tested 10k Pot and that P10 is set at 2 with P11 set at 2?

Edited By Martin of Wick on 24/05/2020 14:02:38

Andrew,

Some mistakes in my original post - I referred to P74 and P75, when I should have said P73 and P74.

Originally out of the box, P73 was set at 61440 and P74 was set at 4096.

And P75 was set at 4196 with P67 at 45000.

I don't know what P75 and P67 do but have recorded the fact that they appear to change the reported output current and voltage on the VFD display.

I checked and confirmed with a clamp on that changing P75 did also appear to change the output current very approximately inline with the observed variance in the VFD display. Couldn't check the voltage as I don't have a filtering voltmeter.

As you see, all supplied values differ from the info sheet. Clearly the thoughtful manufacturers have provided a generic info sheet and couldn't be a***d to amend it for different products.

When I did the unit reset, all values returned (approximately) to those on the info sheet, but the AT4 was definitely not working as it should. Normal function was only restored when I re-entered the 'as supplied' parameter values as above.

On set up, I only checked to see if there was a voltage from the PE terminal ( you can actually just see it marked in your photo) to the mains earth and there was no potential, but then I wasn't expecting any - maybe I should check again because all may not be well if there is a voltage present.

I didn't ever record the voltage across the VR as it didn't seem to be an issue at the time. Unfortunately, my unit is not on the bench at the moment pending works to the drill for which it was purchased for. I will see If I can cobble something up tonight and let you know.

Hmmm....

just seen your latest post... will be most interesting to see if reducing your P74 75 parameters to manual values actually gives you back full frequency control on the external input - It would then be the exact opposite of what happened in my case! Go figure!

P67 is another parameter you may need to have regard to as it is often different from the one listed in the info sheet.

I didn't detect any voltage between device and mains earth when I set up

On my AT4 version, after some head scratching, I found the earth was located on the outer left-most terminal of the of the left hand green block above the 220v power input on your picture above- it is marked PE in minute lettering obscured by the casing (WTF!....yeah I know! …. don't start.), but don't take my word for it, check to ensure there is connection to the cooling plate.

On my device, parameter 74 is 63500 and P75 is 4200 basically the span and offset values for the external control.

Originally I noted these values along with other obscure parameters prior to use of the device (and a bloody good job too) seeing they were different from the 'manual'. As a test I input the values quoted in the 'manual' that were about half the 'as supplied' values and had similar half F issues.

I then did a reset (bad mistake - don't ever be tempted to do one). The reset resulted in the same low values replaced in P74 and P75 (among a whole lot of other unwanted changes).

I suggest you check what P74 P75 contain. If the stored values appear to be about 31000 and 1100, you could try the higher values quoted above and see if that helps and experiment from there until you are getting the range of control that you want.

Above all take care, this thing is a pretty scary device to have floating around on the test bench.

Edited By Martin of Wick on 23/05/2020 23:14:06

John,

you can use either momentary or latching, depending on what parameters you program to the multifunction inputs P50 to 55.

The supplied 'manual' lists the switching types available, but has been so badly translated that the terms are meaningless in English and utterly unsatisfactory. Originally I worked out what they might be from the supplied description, but then experimented to prove the hypothesis.

See thread titled AT1 inverter 3 wire control, I think the very last post in that thread has a detailed description and practical descriptive use of the listed parameter functions (as determined by me on the examples that I have worked with). If you cant find it, let me know and I will PM you a copy.

Should at least get you going but you can always run a test setup to experiment with the switchgear of your choice to find what works best for your application.

Remember, AT1 multifunction inputs are all LOVO stuff so you don't really need expensive 600v /20A switchgear or to shell out Farnell/RS etc. Reasonable quality stuff from the usual eastern sources will do.

The answers for my WM16 in order of questions are:

Yes up to about 6mm in steel but you have to go slooow if you have any mechanical sympathy

In steels yes, but not in one hit - after roughing out, I generally do one side then t'other, never tried very small slots at one pass,' spect they would be oversize though.

Don't know - I expect it would be doable but slowly to respect the mechanical limitations of the mill

Yes

Nope

Not yet

Table too big, column too small, motor too noisy and no taper eject on the spindle not happy with slow heavy cuts.

The new fangled carbide tooling has been a boon for this mill and I have changed technique to suite - set RPM to maximum possible, shallow depth of cut, calculate a suitable lightish tooth load and twirl the handle to approximate the required feed. Basically treat as a manually operated high speed CNC mill hi speed lite cut repeated often until your arm gives up.  Much less shake rattle and roll.

Edited By Martin of Wick on 27/04/2020 18:01:03

Edited By Martin of Wick on 27/04/2020 18:04:01

In the past, I used to leave the open spools (PLA) on the printer for months with a feeble attempt to cover/protect from sunlight with old box, paper bag etc.

However, recently noted two issues;

Where the filament run to the hotend had been exposed to sunlight, it had become brittle and snapped like cheap spaghetti, the stuff on the spool that had minimal protection was OK, I just determined the extent of the brittle section and cut it off.

When changing to a fresh spool of PLA of the same make, I noticed that the print made with the fresh stuff was notably better in overall quality than the old material that had been exposed for months.

Unless I intend to be using the printer on a daily basis, I now remove the spools, pack in airtight bag with silica gel and store out of the light.

It seems a bit of a faff at first, but you soon get the removal technique sorted. I did have a free demo reel of PLA that was completely shattered, couldn't even be unwound without disintegrating into tiny fragments. PLA from reputable suppliers has been generally fine unless abused as above.

Uh-hu...

you can cycle between rpm/ amp/ volt/ hz/ hrsrun/ temp by pressing the function/data key P62 just sets what comes on the display at startup.

Check how you have set P06 that sets the max Hz I would recommend no more than about 75Hz - that is 50% inc on design freqency. While it may be OK to run the motor at 2500 RPM, the torque will not be as expected, approx 50% relative to the higher speed.

The overspeed will be fine if you are wanting a speed boost for using a very small drill or some other low torque operation. However, if say using a large forstner in wood, there would be insufficient torque to maintain the set speed, so you may not gain much in that case, or by going to much higher frequencies (unless you are regularly using sub mm drill bits).

Looks like your display current is more accurate than some, which is good. I could have suggested another way to set trip current for real world practicalities. Get a large chunk of gnarly steel about 2 in thick and your largest drill (I assume 1/2- use an old bit you don't care about) set machine gearing for approx. RPM for material and start drilling like you don't give a **** while observing the indicated current, then set that or just above that as your trip current - as being defined by the nastiest job you are likely to do!

Edited By Martin of Wick on 03/04/2020 11:45:16

Edited By Martin of Wick on 03/04/2020 11:48:40

A) In my limited experience of these simple devices, the display voltage and current is probably not a true indication of the actual RMS voltage and current taken by the motor. However, the indicated display is what the overload current setting will cut out at.

This makes setting a meaningful overload current cut out problematical. Ultimately it will depend on how bold you are or how much you think your motor will take. A reasonable quality induction motor is fairly tolerant, so here is what I would do as a start.

check current draw indicated at no load - say it was 2.0A the real current load should be closer to 1.1A divide 2/1.1=1.8 now say you will tolerate 1.5A for a short run overcurrent ( say 3 seconds set at parameter P24) then multiply that by 1.8 which will give you 2.7A as a possible overcurrent setting. If it was me, I would set it at 3, but be prepared to check the temperature rise in the motor if working it hard.

B) There is not enough information on how you have set up for your drilling operation. At half frequency, the power being delivered in your system is only about 110 watts. depending on how hard the steel is and how sharp your bit is and whether you are using the correct RPM, that may not be sufficient to maintain speed/Hz relationship so the VFD pulses open up delivering additional voltage and current until the trip is activated (or not, in which case the motor will potentially overheat if care is not taken).

In the first instance, leave the motor at the full frequency and set the pulley system to give somewhere in the region of 800 -1000 RPM for 1/4 in steel ( we are in the home workshop here, not industry). With a low power system, if you have to use the VFD to reduce spindle RPM by as much as 50%, to trim to an optimal setting then consider setting up with pulleys for a lower than optimum spindle speed, but use the full motor frequency (50 Hz). That way you will get the maximum power to the bit.

A VFD is not a substitute for the correct motor gearing.

I cant believe you are getting no torque at the 50% setting, but if you are, check that P02 is 110 and P03 is 25 with P04 P05 both zero.

Edited By Martin of Wick on 02/04/2020 21:39:19

Edited By Martin of Wick on 02/04/2020 22:07:15

John, check carefully, is it one of these? If not, you will need to post the relevant part of your manual.

**LINK**

If so set P1 to P11 as per listed defaults for your voltage system (220v, I assume)

If P78 is listed as Main current overload on your instructions, set as 2000 for 1/3Hp motor to start with.

You do not need to repeat this for P79 to P85 unless you intend to use pre set operating conditions selected by a rotary switch.

P34 Main Rising Velocity can be set to your desired ramp start speed. At 10 Hz/s, run up to full speed at 50Hz will be about 5 secs (i.e. 50/10). For example, if you changed it to 25, run up to full speed will take about 2 sec.

Find a youtube video on how to use the shift key to rapidly select the digits you want to change rapidly with the arrow keys.

Bruce,

I simply don't know. In most cases where I have replaced bearings, there have been two thin wavy washers. However, I have encountered an instance where there was only one, but whether by accident or design I couldn't say.

These spring/wavy washers can usually be obtained at modest cost from on line bearing factors.

Edited By Martin of Wick on 29/03/2020 10:00:12

the wavy spring washer goes between the end housing and the bearing.

The dimpled steel washers were used with unshielded bearings and helped keep the grease on the bearing. They are fitted behind the bearing on the inner part of the shaft and retained by shaft shoulder or circlip (ie trapped between the shoulder and the bearing).

The dimples should be facing the bearing so the washer is slightly stood off the outer bearing shell slightly to avoid rubbing.

sequence is:

Housing- spring- bearing- washer- rotor+shaft- washer- bearing- spring- housing

Thanks to all those that helped, I will post here as a sort of build thread in future and put some photos in the album as I progress. Might be helpful for anyone else contemplating such madness.

The material for the job was approx. £30 as only about 800g copper was required when using vendors wire data and correct stripped diameter. Decided to have a go as a learning experience.

Quite difficult to determine the original winding pattern from the old motor, as not quite what I expected. Eventually worked out it was : 2 No. phase groups, each with 3No. concentrically arranged pairs of coils (1 pair coils per phase). So need to wind a nested coil pair x 6, arranged and connected appropriately to generate the 4 alternating poles.

This is where the 3d printer comes in - to produce a demountable double former to generate the concentric coil pair. Haven't got as far thinking about the winder yet - probably on the lathe faceplate with some Heath Robinson arrangement using the small cheap mechanical counters commonly available .