Agiecut 250 SF HFSS problems

Hi all

I am quite new to wire EDM, I got an Agiecut 250 FS HSS. I am currently working on some tall parts (160mm high and the cut I need to make is only 0.3mm wide). I am working on this since a couple days, so far it worked well, but today I got some issues and I wonder what could be the reason for that.

First of all, I have problems that my wire is often ripped off in the centre of the cut. I believe this is because the cut is so narrow and my part is so tall, that the flushing is not very good. How can I improve the reliability?

Second, and more specific to this machine, I have following two problems: sometimes, when the wire breaks and needs to be threaded after it has been ripped, the water jet is a bit too weak and has bubbles in it. Then the wire isn't properly guided and the automatic threading fails. This is especially annoying when I let the machine run over night. However I replaced the water filters, and I do have enough water in the tank. Is this a common problem with this machine, does anyone know whethere there are any "notorious" parts causing that? would it be a smart idea to change all the installed hoses?
Further, since this morning, I have a new problem: the wire gets properly threaded and everything works nicely, but after a couple seconds, I get the error message that the wire is ripped off or not properly threaded. According to the manual, I found out that this problem could be due to the "wire detector". So I pulled that out according to the manual, and cleaned it (was not really dirty, but anyway) and reinstalled it. Still no success. The manual says that the wire detector shall have a distance of 2.6mm to the wire; how critical is that? any experience with those detectors? the manual also says that if the error persists, the wire detector is faulty and needs to be replaced. However, the wire detector has only one single electrical wire attached to it, so I wonder how it works and how it can get damaged. And of course, as an electronics engineer, I wonder whether it is possible to fix that problem. Any experience with that? However I am not really sure whether the wire detector is the actual problem; I noticed that the little green wheel on the head does not rotate smoothly but sometimes runs a bit jerking, so perhaps the problem is more likely with the wire or the transport belts? I already did the demagnetizing procedure of this little wheel (also according to the manual), but it didn't help.
Unfortunately, I have never looked at this wheel so intensively, so I cannot tell whether it ran smoothly before or whether it was always a bit jerky.

Yesterday I had to replace the wire spool, and I did that step by step according to the manual, and afterwards the machine worked very well until this morning. So I wonder whether I possibly did something wrong when inserting the new wire into all those wheels and stuff. Is there any pitfalls or problematic things one should know about this and which are probably not mentioned in the manual?

I got the machine from a friend who used it in his own workshop, it seems like the machine worked reliably since 1996. The only reason why he gave it to me was that he needed a larger one, so I assume the machine itself should be actually OK but I guess the origin of most problems is the operator ;-) my friend gave me a short introductory course, but is in holidays now so I cannot ask.

i am going to assume you mean a 420 message. the following info is if that is the situation. Most likely the wire is slipping. thread the wire AND with the handbox ON run the belts. grab the black wheel on the upper head if you hold it tight enough to stop movement the wire should break. if it does not then it is slipping. Determine if it is slipping in the belts or around the brake ring.
1. check the condition of the wire transport belts (move to a new spot)
2. check the condition of the brake rings. (to clean bead blast or scotch brite then wipe with Acetone.
3. check the condition of all the rollers in the belt transports system. ( the closer to the work zone the more important a smooth turning roller is.)
4. make sure o-ring in pivot head that drives the encoder is clean and free of any oil.

Hey agieman,
thank you very much for your reply. Indeed, I do have a 420 message! I recently saw also 423, but the belts are new (and original +GF+ spare parts) so I guess that one must have been a false positive.
Just to make sure I understood you correctly: you mean the little black wheel with the green insulator plastic inside? the one with the four screws:

https://www.practicalmachinist.com/...-agie-hss-150-wire-sensor-problem-tension.jpg

is it allowed to block this wheel or can I damage something? I read in the manual that it is forbidden to turn it clockwise, so I assume there must be an incredibly delicate assembly behind it. However I guess I will disassemble the housing and see whether there is dirt or stuff inside.

When I dismounted the wire sensor to clean it, is it possible to reinstall it wrong? I saw in the manual that the distance between the sensor and the wheel should be 2.6mm. I cannot measure this distance properly, but if it is 2.5mm or 2mm or 3mm - will it still work?

anyways, thank you very much for your hints! I really appreciate it. I'll let you know if I was successful.

the screw head being pointed to in the pic sets the tension for the "pizza cutter" at the end of the green arm. (250grams). The black wheel that the "pizza cutter" is resting on with green hub and 4 screws is the brake wheel. you are correct do not turn clockwise. it will turn CCW with wire running. hold onto it while it is turning. the wire should break before you can stop it. if you can stop it the wire is slipping. the sensor you are referring to is the one at 9:00 with respect to the shaft of the brake wheel. that is there to sense if something is blocking the path of the wire as it is threading. the wire will bow out away from the wheel and contact the sensor stopping the process. yes it will still work even if sensor is missing in normal operation the wire should NOT contact it at all.To access the back remove the 4 screws in the black metal cover and slowly slide away do not pull off because there is a ciruit board in there and you dont want to disconnect it while its powered up. there you will find the brake, threading motor, encoder and clutch. the threading motor has a toothed drive belt to drive brake wheel when threading. the encoder has an o-ring to turn it when the brake wheel is turning.

Hey agieman,
MANY thanks for your help! I did exactly as you mentioned, and indeed, the wire slipped a bit inside these brake rings because there was a bit of dirt. I cleaned them with scotch brite and some isopropanol, and that did the trick!
the machine is currently running and making some parts for me. If all goes well, it should be finished by tomorrow morning (the cut speed is only 0.5mm/min because the parts are quite tall and the flushing thus does not work so well).

So that is fixed for now!

Another small thing:
one time this evening, the wire broke (as I said I am currently making some tall parts, and the cut even has a 90° corner where I put a small radius, and the wire often breaks there). The machine tries to thread, and most of the time this works really reliably, but sometimes the water jet coming out from the upper head is a bit too weak and it looks as if there are some air bubbles coming out. So I wonder: is this a symptom you also know, and should I replace the water hoses or something else? I have already exchanged the filters for the dielectric and my water is very clean and nice.

Where are you in Switzerland? I think you need a service call I can be on the next plane lol
This can be a few things. do you get air bubbles during erosion?

Hi agieman
no, no bubbles during erosion. But the problem is solved as I had perhaps a bit too low water in the tank.
However I got a new problem now :-( I let the machine run today, and while I was away it stopped. I expected my parts to be finished this evening, but no - the wire transport belts are not moving anymore. Got error 420 again, which is obvious since the belts are stopped. This morning the belts were okay.
I opened the various covers and checked whether there is some loose wire or so, but no. Belts are stopped and error 420 persists. I checked the schematics - actually I am an electronics engineer and very familiar with this :-) but didn't find the problem.
I opened the electronics cabinets and checked fuses and stuff, looks good. Do you have a hint? I am pretty sure the previous owner did skip some service intervals, as soon as he knew he was going to buy a new (larger) machine.