[Paul_J]

Hi Folks,
Firstly lots of really great information on this forum and many great CNC builds so thank you to all who contribute as this info is invaluable to a newbie

Unfortunately its out of desperation that I turn to everyone on the forum to help me. 10 months ago I ordered a promica HM kit, double ball nuts the lot to allow me to carry out a cnc conversion of my SX3. It was all bought and paid for via bank transfer from the UK a not insignificent amount of money. To date I have not received any part of this kit, many times it has been promised to me to be delived by x and then nothing, Marc has recently stopped responding to E-Mails.

Does anyone know the status of this company and whether it is still in existence. I decided on the promica kit as I liked the design of the kit and the aftersales service appeared to be excellent

Many Thanks Paul

Any help or information would be great, I just want the kit

[fretsman]

I hate when I hear stories like this.

Is this the same company you're referring to?

PROMiCA - CNCKits Contact details

Paul, have you called them by telephone?

[Paul_J]

Thanks for your reply, Yeah thats the one,

I'm totaly surprised by lack of response as everyone was raving about the support but all feedback on their customer forum is many months old

There may be some totally plausible reason behind the lack of communication but 10 months is a bit long for any order, No I've not tried to call recently, As this forum has members round the world I thought I'd put out the feelers

Regards Paul

[GusBiz]

Paul,

Have you recieved your kit?

I live 15 minutes drive from Marc, I have a kit and he doesn't return an email or phone calls.

[Paul_J]

Just got a note that the kit from PROMICA has arrived, got to admit I was worried I would never see it, So thankyou to mark, The fun begins

Regards Paul

[Bluey76]

Just a follow up on this tread guys, Ive been looking at CNC ing a Sieg X3 and seeing this guy had good feedback here I thought Id give it a go but cant find any info at all. Does anyone know if he is still in business? I haven't got the mill yet so Im open to suggestions....ok, just searched further and of course Ive found the bad news.
So, still open to suggestions as to where is a good place to search for the electronics side of a cnc kit, Im completely ignorant of what I need. Could possibly be interested in a 2nd hand unit complete???

cheers
David

[charris1950]

Hello all,

I bought one of Mr. Huett's CNC mills a couple of years ago and I have never managed to get the damned thing fully operational. Fully operational in the sense that I can achieve any kind of repeatability when sending the same toolpath file to it multiple times. Like most others who have tried to contact Mr. Huett, I have been unable to do so. There may be a perfectly valid reason for his withdrawal but it would have been good form to let his customers know if he was discontinuing services.

So, I have a very lightly used mill that I can't get to work properly and no way of contacting the person who built it. Most annoying.

Perhaps there are CNC operators on this forum with more knowledge than I, (which would include almost everyone) who may feel inclined to shed some light on the peculiarly vexatious problem that exists either with me or the machine.

When attempting to mill wooden gears for instance, the machine seems to be digesting G-Code satisfactorily and moving smoothly in all three axes in the manner I would expect them to move whilst producing the appropriate variably pitched sound that I presume all stepper motors make when rotating at variable speeds. However, every now and then during a milling operation, either the X or Y axis seems to pause momentarily before continuing. The pause is accompanied by a change in sound from one of the axis stepper motors which I imagine could be equated to a 'grunt' in human terms. At that point the cutting head skips from the path it is supposed to take by anything from a few to several millimeters in the X or Y axis before continuing and completing the operation. This aberration occurs irrespective of what G-Code post processor I use to convert toolpaths from either the ArtCAM or Aspire programs.

I am inclined to think that the problem might be with the stepper motors but as my knowledge is more in the line of analog electronics rather than digital, I hesitate to begin dismantling the table assembly to investigate for fear of introducing a misalignment, thus further complicating matters.

The mill is an MX3 controlled with Mr. Huett's Promica IC3A controller.



Any assistance with this irritating condition of partial operation or communication with persons suffering the same or a similar problem will be met with my most effusive appreciation.

Regards

charris1950

[Preso]

Charris1950,
I have a Promica kit fitted to my X3 and it has performed well for several years now. The condition you are describing sounds like the X and Y stepper motors are losing steps. This could be because the gibs are too tight, inaccurate alignment of screws or ball nuts, lack of lubrication of the ways or possibly overloading of the tool by having feed rates set too high. If the machine is tracing out the tool path accurately when it is not actually cutting material, then you can be fairly sure the gcode is good and the controller is doing it's job properly. I am curious as to how you are cutting wood with metal cutting bits. This could be the source of your problem. Wood cutting should really be done with router bits which have a different geometry to end mills and slot drills designed for metal. Router bits should also be running at a much higher rpm than the standard X3 motor can provide. If the tool is binding up with waste material it will produce enough drag to overcome the limited amount of power the stepper motor can provide to move the axis. When that happens the stepper just stops turning but the gcode doesn't know that so it will continue to send pulses to the motor until it unloads and moves again. By now the controller will think the cutter is somewhere else along the tool path which explains why you are getting tool path errors of several millimetres. The change in sound you describe is probably due to overloading. If you always get that sound before tool path errors then I would be looking at what might be causing overloading at that point.
Good luck.
Regards,
Preso

[charris1950]

Hello Preso,

Thank you for taking the time to reply. I spent several hours last night working through possible reasons for the mill's erratic behavior and came to the same conclusion as did you. The programs I use generate and simulate toolpaths and the G-Code generators generate the appropriate codes for the mill as far as I am able to determine. However I only checked the first couple of dozen lines or so. The controller seems to be outputting motor controls to the stepper motors so I thought to myself that perhaps the bearings or ways might be binding in such a fashion as to temporarily overcome the torque of the stepper motors. So I bit the bullet today and dismantled the X axis. The bearings on the belt driven end of the X axis ball nut drive shaft were dry and not turning smoothly which may account for part of the problem.

I spoke with another helpful bloke who has had similar problems and he said that I am probably on the right track.

So, suitably revitalized by the help and advice received so far, I shall investigate further. Once again, thanks for replying.

[charris1950]

"When that happens the stepper just stops turning but the gcode doesn't know that so it will continue to send pulses to the motor until it unloads and moves again. By now the controller will think the cutter is somewhere else along the tool path which explains why you are getting tool path errors of several millimetres. The change in sound you describe is probably due to overloading. If you always get that sound before tool path errors then I would be looking at what might be causing overloading at that point."

As an addandum: What you described above, is pretty much what is happening Preso, but I do not think that the 4mm cutter is causing the problem. The ply was only 7mm thick, the feed was extremely slow, I didn't have any foam or spare aluminium and I was watching it like a hawk.

Before dismantling the X axis I traversed the X & Y axes to their plus and minus limits several times with the Z axis way up out of the way. The gibs were slightly tensioned with an allen key prior to this (and the table was easily slid off the ways when the drive shaft was later removed.)During the traversing operation both the X and Y axes seemed to momentarily drag at random points. This dragging was accompanied by noisy vibration. I am inclined to believe (as you pointed out above) that the increased torquing caused by the ways dragging / vibrating is causing the motors to over torque and miss a number of steps, causing the G-Code to think that the motor is further along the axis than it actually is.....

I appreciate your diagnosis..... And I will buy some router bits.

[Preso]

Charris1950,
If you are using 4mm cutters and 7mm ply then the problem probably does lie somewhere in the mechanical setup of the mill. If it is any comfort, my machine does not always home the Y axis without binding. I have tried lots of times to get the Y axis to move smoothly throughout it's entire range but I suspect that the dovetails are not completely parallel. I have given up homing the machine since I rarely run the same job more than a few times so I just reset the home point for each job without bothering to use offsets. If your X and Y axes are binding at random points it could be that your ball nuts are dry as well. I always thought that they were sealed and didn't need any lubrication. I actually retrofitted my axes with double ball nuts since I only purchased the single ball nut Promica kit. When I dismantled the machine prior to fitting the extra ball nuts I found that after nearly a year and a half of use, the ball screws and the ball nuts were quite dry. I sprayed everything with lithium grease and it has greatly improved movement of all the axes. Another thing to try is to remove the drive belts from the stepper motors and try turning the screw pulleys by hand. You will be able to feel if there are any tight points. If it binds every revolution the ball screw is probably bent. If the tightness is random then the issue could be to do with contaminated ball nuts or lack of lubrication somewhere.
Regards,
Preso

[charris1950]

The more I think about this the more convinced that the problem relates to the mechanical alignment and condition of the moving components.

I was down in the shed staring gloomily at the disassembled X axis lead screw, thrust bearing, Thomson Ballnut and a pile of its ball bearings stuck to a magnet. The bearings are now in the bottom of a jar of cloudy grey petrol. "This", I was thinking, "Does not bode well". The Thomson ball nut has no seals and I was further thinking "Anything could get into that thing" and it probably has. The thrust bearing also looked a bit parched and dusty as did the caseless bearing that was mounted beside it.

I also rotated the shaft by hand before removing it from under the table and it felt like it had been lubricated with very small bits of glass because it made a faint crackling noise as it was rotated. That also did not bode well.

And I said as much to my wife's pet magpie who was watching inquisitively if uselessly from the doorway.

I'll clean the bearings in an ultrasonic bath then re assemble the thing, force feed the bearings with lithium grease and see if there is any improvement.

The Y axis is probably in a similar state of disrepair. Don't know what to do about the ways. Perhaps a long polishing session with some 800 grit wet and dry on a suitably shaped wedge might help a bit. But It might not come to that. We shall see.

In the mean time, thanks again for your interest and suggestions.

[charris1950]

Not happy with Mr. Huett. He does not answer his phone or reply to text messages. Thinking of taking the matter further. But on the positive side, I have learned quite a bit about installing and aligning the axes on a CNC milling machine.