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Vinyl Cutter Z axis Broke!!

Vinyl Cutter Z axis Broke!!

Postby Rob366 » Mon Aug 25, 2014 5:16 pm

Hello. I've just joined the site. Hope you don't mind my first post
and asking for help.If I have broken any board rules please accept my
apologies.

I'm a retired vinyl sign maker, but I still like to keep my hand in
and do the odd job from home.

The problem I'm having is with my old Roland PNC1100 vinyl cutter.
The Z axis has stopped working so the knife does not come down to cut
the vinyl. The magnetic servo has been checked and is in good order, all connections
are good too.

I've been in contact with Roland but they can't help the "machine is too
old", 1990s vintage.

Ive just about exhausted all my options, no one I've asked can help.
I can not afford a new machine, or a good second hand one. It was a fantastic
machine when working and I would like to resurrect it. I'm lost without it.

My son is good with electronics, builds his own ECU's and other equipment.
If anyone can help, my son will probably understand better than me, and will
help with identifying what might be at fault, with your help.


Thanks Rob
Rob366
 
Posts: 12
Joined: Mon Aug 25, 2014 4:33 pm
Location: Durham, Englang, Great Britain.
CNC Machine: Other

Re: Vinyl Cutter Z axis Broke!!

Postby joelaw » Tue Aug 26, 2014 1:12 am

Rob, where are you located? Maybe someone close by can take a look.

Joe L.
joelaw
 
Posts: 99
Joined: Wed Apr 21, 2010 8:46 pm
Location: Upper Marlboro, MD
CNC Machine: BlackToe v4 2x4

Re: Vinyl Cutter Z axis Broke!!

Postby Rob366 » Tue Aug 26, 2014 7:16 am

Joe, Thanks for replying.
Sorry I should have given more information.
I'm actually in the UK, Durham area.
I was advised to try here by someone on a sign forum.
Any help will be greatly appreciated.

Rob.
Rob366
 
Posts: 12
Joined: Mon Aug 25, 2014 4:33 pm
Location: Durham, Englang, Great Britain.
CNC Machine: Other

Re: Vinyl Cutter Z axis Broke!!

Postby joelaw » Tue Aug 26, 2014 1:00 pm

Sorry Rob, I am in Maryland USA. I am an electronics guy like your son. If it doesn't work, ther is always a reason. It just takes patience, time and luck to find out why. If it mechanically is ok then must be the drive circuit so I would just start with running it and seeing where the signal stops. Your son should be able to find out and if you are lucky find the part to replace or juryrig a fix.

Joe L.
joelaw
 
Posts: 99
Joined: Wed Apr 21, 2010 8:46 pm
Location: Upper Marlboro, MD
CNC Machine: BlackToe v4 2x4

Re: Vinyl Cutter Z axis Broke!!

Postby Rob366 » Tue Aug 26, 2014 5:54 pm

Thanks Joe, I really appreciate you taking the time to reply.
I will ask my son to have another look bearing in mind what you say.
He's a smart lad I'm sure he will get to the bottom of it.

If I could just pick your brains.
The fault seemed to develop over time.
The servo on the Z axis holds the blade, the down force can be
increased or decreased by moving a slider switch on the side of the
machine, from 0g to 200g. every time I turned the machine on over
a period of weeks I had to increase the down force by a few grams
until one day no amount of force would work.The slider switch
checks out ok, all other functions work as they should.

If you can help in any way I'll be very grateful.
Rob.
Rob366
 
Posts: 12
Joined: Mon Aug 25, 2014 4:33 pm
Location: Durham, Englang, Great Britain.
CNC Machine: Other

Re: Vinyl Cutter Z axis Broke!!

Postby joelaw » Wed Aug 27, 2014 2:25 am

Rob,

Are you saying that there is a servo motor that drives the head down? Do you really have a motor or is it a solinoid (relay) coil that when triggered forces the head down? I wouldn't think that they would use a "servo" motor just to move the head/cutter up and down. If it is a motor maybe your son can see if it is drawing enough current to move the head. Even if it is a solinoid it needs enough current to move.

I really have never worked on a plotter except to use so I am only guessing. I assume that the slider switch is a real switch and is changing the amount of current that is applied. Does the switch have multiple steps like 5 or 6 or does it smoothly slide to increase force? Are you sure that it is not mechanical that changes the force limits but electronic control such as described above?

I still would guess that the servo motor or whatever is not getting enough current to force the head down as required.

Let me know what you find out.

Joe
joelaw
 
Posts: 99
Joined: Wed Apr 21, 2010 8:46 pm
Location: Upper Marlboro, MD
CNC Machine: BlackToe v4 2x4

Re: Vinyl Cutter Z axis Broke!!

Postby Rob366 » Wed Aug 27, 2014 7:28 pm

Joe,
Of course you are right, its a "solenoid"! Another senior moment, getting more than my fair share lately.
My son did check the solenoid with a multimeter and, from memory, he recalls it was drawing less than 1 volt.
He was able to check the solenoid on a similar machine, though not the same model, belonging to a friend.
Though he can't remember the exact number it was considerably more than 1 volt.He checked the function
of the solenoid with an external power source and it worked fine.

The slider, to alter the down force, is a variable resistor type.

My son also changed a couple of electrolytic capacitors that had been leaking, and checked the surrounding area for damage
and found none.He's wondering, because of the way the fault developed,if the problem could be a capacitor?

As an aside. I've been looking on the forum and I have to say, I'm amazed at some of the machines that have been constructed.
I think it must be fantastic to be able to build such a machine.

I've built a few machines myself over the years, but nothing in this league.

Looking forward to hearing from you.

Rob.
Rob366
 
Posts: 12
Joined: Mon Aug 25, 2014 4:33 pm
Location: Durham, Englang, Great Britain.
CNC Machine: Other

Re: Vinyl Cutter Z axis Broke!!

Postby joelaw » Thu Aug 28, 2014 3:14 am

Rob,

My best guess for now is that they are using a 5 volt or 12 volt power input and a regulated (variable) current to adjust the pressure on solonoid when it is activated. It probably has a signal to turn it on and off and the force depends on how much current is available to activate the solonoid.

Try to figure out where the signal goes into the current regulator and if it just goes high and low (on, off). If so, you have control and only need to fix the current power supply. It depends on the power supply voltage and the solonoid resistance to figure out how much current is needed. We can make a new current regulator from a LM 317 IC and make it work.

Of course I am making an educated guess on all this. :-). It is hard when you cannot get your hands on something like this to solve problems.

I know all about senior moments, I am in the 70's now and trying to keep my brain working for a while longer.

Let me know.

Joe
joelaw
 
Posts: 99
Joined: Wed Apr 21, 2010 8:46 pm
Location: Upper Marlboro, MD
CNC Machine: BlackToe v4 2x4

Re: Vinyl Cutter Z axis Broke!!

Postby kevinl » Thu Aug 28, 2014 6:43 pm

Rob,

a couple of pictures might help in understanding the wiring around the solenoid and slider.. it also might cuause a request for more pictures..
kevinl
 
Posts: 886
Joined: Tue Feb 02, 2010 3:47 pm
Location: Birmingham, AL, USA
CNC Machine: Custom

Re: Vinyl Cutter Z axis Broke!!

Postby Rob366 » Thu Aug 28, 2014 8:42 pm

Joe,
I spoke to my son on the phone today, and explained what you said in your post.
He seems to understand what you mean. He's going to try and get over at the weekend
and he will look at the machine then. Thanks again, I really appreciate your help.

Rob
Rob366
 
Posts: 12
Joined: Mon Aug 25, 2014 4:33 pm
Location: Durham, Englang, Great Britain.
CNC Machine: Other

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